We previously discussed how a verticle is the unit of deployment in vert.x. Let's look in more detail about how to write a verticle.
As an example we'll write a simple TCP echo server. The server just accepts connections and any data received by it is echoed back on the connection.
Copy the following into a text editor and save it as server.js
load('vertx.js')
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
new vertx.Pump(sock, sock).start();
}).listen(1234, 'localhost');
function vertxStop() {
server.close();
}
Now, go to the directory where you saved the file and type
vertx run server.js
The server will now be running. Connect to it using telnet:
telnet localhost 1234
And notice how data you send (and hit enter) is echoed back to you.
Congratulations! You've written your first verticle.
To load other scripts from within your verticle you use the load function. The argument to load is the name of the script you want to load. You can use load to load any other scripts in your verticle, or to load system scripts such as vertx.js which are always available to verticles.
If you want to access the vert.x core API from within your verticle (which you almost certainly want to do), you need to call load('vertx.js') at the top of your script. Normally this will be the first thing at the top of your verticle main. vert.js is just the name of the script that contains the core API.
Servers, clients and event bus handlers will be automatically closed when the verticles is stopped, however if you need to provide any custom clean-up code when the verticle is stopped you can provide a vertxStop top-level function. Vert.x will then call this when the verticle is stopped.
If JSON configuration has been passed when deploying a verticle from either the command line using vertx run or vertx deploy and specifying a configuration file, or when deploying programmatically, that configuration is available to the verticle in the vertx.config variable. For example:
var config = vertx.config;
stdout.println("Config is " + JSON.stringify(config));
The config returned is a JSON object. You can use this object to configure the verticle. Allowing verticles to be configured in a consistent way like this allows configuration to be easily passed to them irrespective of the language.
Each verticle is given its own logger. :
var logger = vertx.logger;
logger.info("I am logging something");
The logger has the functions:
Which have the normal meanings you would expect.
The log files by default go in a file called vertx.log in the system temp directory. On my Linux box this is \tmp.
For more information on configuring logging, please see the main manual.
You can access environment variables from a Verticle with the variable vertx.env.
The variables stdout and stderr are injected into all verticles. Unsurprisingly, you use these to print to stdout and stderr.
stdout.println("Hello from the verticle");
You can deploy and undeploy verticles programmatically from inside another verticle. Any verticles deployed programmatically inherit the path of the parent verticle.
To deploy a verticle programmatically call the function vertx.deployVerticle. The return value of vertx.deployVerticle is the unique id of the deployment, which can be used later to undeploy the verticle.
To deploy a single instance of a verticle :
vertx.deployVerticle('my_verticle.js');
You should use deployModule to deploy a module, for example:
container.deployModule("vertx.mailer-v1.0", config);
Would deploy an instance of the vertx.mailer module with the specified configuration. Please see the modules manual
for more information about modules.
JSON configuration can be passed to a verticle that is deployed programmatically. Inside the deployed verticle the configuration is accessed with the vertx.getConfig function. For example:
var config = { name: 'foo', age: 234 };
vertx.deployVerticle('my_verticle.js', config);
Then, in my_verticle.js you can access the config via vertx.getConfig as previously explained.
If you have an application that is composed of multiple verticles that all need to be started at application start-up, then you can use another verticle that maintains the application configuration and starts all the other verticles. You can think of this as your application starter verticle.
For example, you could create a verticle app.js as follows:
// Application config
var appConfig = {
verticle1Config: {
// Config for verticle1
},
verticle2Config: {
// Config for verticle2
},
verticle3Config: {
// Config for verticle3
},
verticle4Config: {
// Config for verticle4
},
verticle5Config: {
// Config for verticle5
}
}
// Start the verticles that make up the app
vertx.deployVerticle("verticle1.js", appConfig.verticle1Config);
vertx.deployVerticle("verticle2.js", appConfig.verticle2Config, 5);
vertx.deployVerticle("verticle3.js", appConfig.verticle3Config);
vertx.deployWorkerVerticle("verticle4.js", appConfig.verticle4Config);
vertx.deployWorkerVerticle("verticle5.js", appConfig.verticle5Config, 10);
Then you can start your entire application by simply running:
vertx run app.js
or
vertx deploy app.js
By default, when you deploy a verticle only one instance of the verticle is deployed. If you want more than one instance to be deployed, e.g. so you can scale over your cores better, you can specify the number of instances as follows:
vertx.deployVerticle('my_verticle.js', null, 10);
The above example would deploy 10 instances.
The actual verticle deployment is asynchronous and might not complete until some time after the call to deployVerticle has returned. If you want to be notified when the verticle has completed being deployed, you can pass a handler as the final argument to deployVerticle:
vertx.deployVerticle('my_verticle.js', null, 10, function() {
log.info("It's been deployed!");
});
The vertx.deployVerticle method deploys standard (non worker) verticles. If you want to deploy worker verticles use the vertx.deployWorkerVerticle function. This function takes the same parameters as vertx.deployVerticle with the same meanings.
Any verticles that you deploy programmatically from within a verticle, and all of their children are automatically undeployed when the parent verticle is undeployed, so in most cases you will not need to undeploy a verticle manually, however if you do want to do this, it can be done by calling the function vertx.undeployVerticle passing in the deployment id that was returned from the call to vertx.deployVerticle
var deploymentID = vertx.deployVerticle('my_verticle.js');
vertx.undeployVerticle(deploymentID);
The event bus is the nervous system of vert.x.
It allows verticles to communicate with each other irrespective of what language they are written in, and whether they're in the same vert.x instance, or in a different vert.x instance. It even allows client side JavaScript running in a browser to communicate on the same event bus. (More on that later).
It creates a distributed polyglot overlay network spanning multiple server nodes and multiple browsers.
The event bus API is incredibly simple. It basically involves registering handlers, unregistering handlers and sending messages.
First some theory:
Messages are sent on the event bus to an address.
Vert.x doesn't bother with any fancy addressing schemes. In vert.x an address is simply a string, any string is valid. However it is wise to use some kind of scheme, e.g. using periods to demarcate a namespace.
Some examples of valid addresses are europe.news.feed1, acme.games.pacman, sausages, and X.
A handler is a thing that receives messages from the bus. You register a handler at an address.
Many different handlers from the same or different verticles can be registered at the same address. A single handler can be registered by the verticle at many different addresses.
The event bus supports publishing messages. Messages are published to an address. Publishing means delivering the message to all handlers that are registered at that address. This is the familiar publish/subscribe messaging pattern.
The event bus supports point to point messaging. Messages are sent to an address. This means a message is delivered to at most one of the handlers registered at that address. If there is more than one handler regsitered at the address, one will be chosen using a non-strict round-robin algorithm.
With point to point messaging, an optional reply handler can be specified when sending the message. When a message is received by a recipient, and has been processed, the recipient can optionally decide to reply to the message. If they do so that reply handler will be called.
When the reply is received back at the sender, it too can be replied to. This can be repeated ad-infinitum, and allows a dialog to be set-up between two different verticles. This is a common messaging pattern called the Request-Response pattern.
All messages in the event bus are transient, and in case of failure of all or parts of the event bus, there is a possibility messages will be lost. If your application cares about lost messages, you should code your handlers to be idempotent, and your senders to retry after recovery.
If you want to persist your messages you can use a persistent work queue module for that.
Messages that you send on the event bus can be as simple as a string, a number or a boolean. You can also send vert.x buffers or JSON messages.
It's highly recommended you use JSON messages to communicate between verticles. JSON is easy to create and parse in all the languages that vert.x supports.
Let's jump into the API
The eventbus is accessible as the eventBus property on the vertx instance.
To set a message handler on the address test.address, you do the following:
var eb = vertx.eventBus;
var myHandler = function(message)) {
log.info('I received a message ' + message);
}
eb.registerHandler('test.address', myHandler);
It's as simple as that. The handler will then receive any messages sent to that address.
When you register a handler on an address and you're in a cluster it can take some time for the knowledge of that new handler to be propagated across the entire cluster. If you want to be notified when that has completed you can optionally specify another function to the registerHandler function as the third argument. This function will then be called once the information has reached all nodes of the cluster. E.g. :
eb.registerHandler('test.address', myHandler, function() {
log.info('Yippee! The handler info has been propagated across the cluster');
});
To unregister a handler it's just as straightforward. You simply call unregisterHandler passing in the address and the handler:
eb.unregisterHandler('test.address', myHandler);
A single handler can be registered multiple times on the same, or different, addresses so in order to identify it uniquely you have to specify both the address and the handler.
As with registering, when you unregister a handler and you're in a cluster it can also take some time for the knowledge of that unregistration to be propagated across the entire to cluster. If you want to be notified when that has completed you can optionally specify another function to the registerHandler as the third argument. E.g. :
eb.unregisterHandler('test.address', myHandler, function() {
log.info('Yippee! The handler unregister has been propagated across the cluster');
});
If you want your handler to live for the full lifetime of your verticle there is no need to unregister it explicitly - vert.x will automatically unregister any handlers when the verticle is stopped.
Publishing a message is also trivially easy. Just publish it specifying the address, for example:
eb.publish('test.address', 'hello world');
That message will then be delivered to any handlers registered against the address "test.address".
Sending a message will result in at most one handler registered at the address receiving the message. This is the point to point messaging pattern.
eb.send('test.address", 'hello world');
Sometimes after you send a message you want to receive a reply from the recipient. This is known as the request-response pattern.
To do this you send a message, and specify a reply handler as the third argument. When the receiver receives the message they are passed a replier function as the second parameter to the handler. When this function is invoked it causes a reply to be sent back to the sender where the reply handler is invoked. An example will make this clear:
The receiver:
var myHandler = function(message, replier) {
log.info('I received a message ' + message);
// Do some stuff
// Now reply to it
replier('This is a reply');
}
eb.registerHandler('test.address', myHandler);
The sender:
eb.send('test.address', 'This is a message', function(reply) {
log.info('I received a reply ' + reply);
});
It is legal also to send an empty reply or null reply.
The replies themselves can also be replied to so you can create a dialog between two different verticles consisting of multiple rounds.
The message you send can be any of the following types:
Vert.x buffers and JSON objects are copied before delivery if they are delivered in the same JVM, so different verticles can't access the exact same object instance.
Here are some more examples:
Send some numbers:
eb.send('test.address', 1234);
eb.send('test.address', 3.14159);
Send a boolean:
eb.send('test.address', true);
Send a JSON object:
var myObj = {
name: 'Tim',
address: 'The Moon',
age: 457
}
eb.send('test.address', myObj);
Null messages can also be sent:
eb.send('test.address', null);
It's a good convention to have your verticles communicating using JSON.
To make each vert.x instance on your network participate on the same event bus, start each vert.x instance with the -cluster command line switch.
See the chapter in the main manual on running vert.x for more information on this.
Once you've done that, any vert.x instances started in cluster mode will merge to form a distributed event bus.
Sometimes it makes sense to allow different verticles instances to share data in a safe way. Vert.x allows simple Map and Set data structures to be shared between verticles.
There is a caveat: To prevent issues due to mutable data, vert.x only allows simple immutable types such as number, boolean and string or Buffer to be used in shared data. With a Buffer, it is automatically copied when retrieved from the shared data, so different verticle instances never see the same object instance.
Currently data can only be shared between verticles in the same vert.x instance. In later versions of vert.x we aim to extend this to allow data to be shared by all vert.x instances in the cluster.
To use a shared map to share data between verticles first we get a reference to the map, and then we just use standard put and get to put and get data from the map:
var map = vertx.getMap('demo.mymap');
map.put('some-key', 'some-value');
And then, in a different verticle:
var map = vertx.getMap('demo.mymap');
log.info('value of some-key is ' + map.get('some-key');
TODO More on map API
To use a shared set to share data between verticles first we get a reference to the set.
var set = vertx.getSet('demo.myset');
set.add('some-value');
And then, in a different verticle:
var set = vertx.getSet('demo.myset');
// Do something with the set
TODO - More on set API
API - atomic updates etc
Most data in vert.x is shuffled around using buffers.
A Buffer represents a sequence of zero or more bytes that can be written to or read from, and which expands automatically as necessary to accomodate any bytes written to it. You can perhaps think of a buffer as smart byte array.
Create a buffer from a String. The String will be encoded in the buffer using UTF-8.
var buff = new vertx.Buffer('some-string');
Create a buffer from a String: The String will be encoded using the specified encoding, e.g:
var buff = new vertx.Buffer('some-string', 'UTF-16');
Create a buffer with an initial size hint. If you know your buffer will have a certain amount of data written to it you can create the buffer and specify this size. This makes the buffer initially allocate that much memory and is more efficient than the buffer automatically resizing multiple times as data is written to it.
Note that buffers created this way are empty. It does not create a buffer filled with zeros up to the specified size.
var buff = new vertx.Buffer(100000);
There are two ways to write to a buffer: appending, and random access. In either case buffers will always expand automatically to encompass the bytes. It's not possible to write outside the bounds of the buffer.
To append to a buffer, you use the appendXXX methods. Append methods exist for appending other buffers, strings and numbers.
The return value of the appendXXX methods is the buffer itself, so these can be chained:
var buff = new vertx.Buffer();
buff.appendInt(123).appendString("hello").appendChar('\n');
socket.writeBuffer(buff);
If you want to append a number as an integer to a buffer you must specify how you want to encode it in the buffer
buff.appendByte(number); // To append the number as 8 bits (signed) buff.appendShort(number); // To append the number as 16 bits (signed) buff.appendInt(number); // To append the number as 32 bits (signed) buff.appendLong(number); // To append the number as 64 bits (signed)
With floats, you have to specify whether you want to write the number as a 32 bit or 64 bit double precision float
buff.appendFloat(number); // To append the number as a 32-bit IEEE 754 floating point number buff.appendDouble(number); // To append the number as a 64-bit IEEE 754 double precision floating point number
With strings you can specify the encoding, or it will default to UTF-8:
buff.appendString("hello"); // Write string as UTF-8
buff.appendString("hello", "UTF-16"); // Write string in specified encoding
Use appendBuffer to append another buffer
buff.appendBuffer(anotherBuffer);
You can also write into the buffer at a specific index, by using the setXXX methods. Set methods exist for other buffers, string and numbers. All the set methods take an index as the first argument - this represents the position in the buffer where to start writing the data.
The buffer will always expand as necessary to accomodate the data.
var buff = new vertx.Buffer(); buff.setInt(1000, 123); buff.setBytes(0, "hello");
Similarly to the appendXXX methods, when you set a number as an integer you must specify how you want to encode it in the buffer
buff.setByte(pos, number); // To set the number as 8 bits (signed) buff.setShort(pos, number); // To set the number as 16 bits (signed) buff.setInt(pos, number); // To set the number as 32 bits (signed) buff.setLong(pos, number); // To set the number as 64 bits (signed)
Also with floats, you have to specify whether you want to set the number as a 32 bit or 64 bit double precision float
buff.setFloat(pos, number); // To set the number as a 32-bit IEEE 754 floating point number buff.setDouble(pos, number); // To set the number as a 64-bit IEEE 754 double precision floating point number
To set strings use the setString methods:
buff.setString(pos, "hello"); // Write string in default UTF-8 encoding buff.setString(pos, "hello", "UTF-16"); // Write the string in the specified encoding
Use setBuffer to set another buffer:
buff.setBuffer(pos, anotherBuffer);
Data is read from a buffer using the getXXX methods. Get methods exist for strings and numbers. The first argument to these methods is an index in the buffer from where to get the data.
var buff = ...;
for (var i = 0; i < buff.length(); i += 4) {
console.log("int value at " + i + " is " + buff.getInt(i));
}
To read data as integers, you must specify how many bits you want to read:
var num = buff.getByte(pos); // Read signed 8 bits var num = buff.getShort(pos); // Read signed 16 bits var num = buff.getInt(pos); // Read signed 32 bits var num = buff.getLong(pos); // Read signed 64 bits
And with floats, you must specify if you want to read the number as a 32 bit or 64 bit floating point number:
var num = buff.getFloat(pos); // Read a 32-bit IEEE 754 floating point number var num = buff.getDouble(pos); // Read as a 64-bit IEEE 754 double precision floating point number
You can read data as strings
var str = buff.getString(pos, end); // Read from pos to end interpreted as a string in UTF-8 encoding. var str = buff.getString(pos, end, 'UTF-16'); // Read from pos to end interpreted as a string in the specified encoding.
Or as buffers
var subBuffer = buff.getBuffer(pos, end); // Read from pos to end into another buffer
length(). To obtain the length of the buffer. The length of a buffer is the index of the byte in the buffer with the largest index + 1.copy(). Copy the entire bufferSee the JavaDoc for more detailed method level documentation.
It's very common in vert.x to want to perform an action after a delay, or periodically.
In standard verticles you can't just make the thread sleep to introduce a delay, as that will block the event loop thread.
Instead you use vert.x timers. Timers can be one-shot or periodic. We'll discuss both
A one shot timer calls an event handler after a certain delay, expressed in milliseconds.
To set a timer to fire once you use the vertx.setTimer function passing in the delay and the handler
vertx.setTimer(1000, function() {
log.info('And one second later this is printed');
});
log.info('First this is printed');
You can also set a timer to fire periodically by using the setPeriodic function. There will be an initial delay equal to the period. The return value of setPeriodic is a unique timer id (number). This can be later used if the timer needs to be cancelled. The argument passed into the timer event handler is also the unique timer id:
var id = vertx.setPeriodic(1000, function(id) {
log.info('And every second this is printed');
});
log.info('First this is printed');
To cancel a periodic timer, call the cancelTimer function specifying the timer id. For example:
var id = vertx.setPeriodic(1000, function(id) {
log.info('This is not gonna be printed');
});
// And immediately cancel it
vertx.cancelTimer(id);
Or you can cancel it from inside the event handler. The following example cancels the timer after it has fired 10 times.
var count = 0;
vertx.setPeriodic(1000, function(id) {
log.info('In event handler ' + count);
count++;
if (count === 10) {
vertx.cancelTimer(id);
}
});
Creating TCP servers and clients is incredibly easy with vert.x.
To create a TCP server you invoke the createNetServer function on the vertx instance
var server = vertx.createNetServer();
To tell that server to listen for connections we do:
var server = vertx.createNetServer(); server.listen(1234, 'myhost');
The first parameter to listen is the port. The second parameter is the hostname or ip address. If it is omitted it will default to 0.0.0.0 which means it will listen at all available interfaces.
Just having a TCP server listening creates a working server that you can connect to (try it with telnet!), however it's not very useful since it doesn't do anything with the connections.
To be notified when a connection occurs we need to call the connectHandler function of the server, passing in a handler. The handler will be called when a connection is made:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
log.info('A client has connected!');
})
server.listen(1234, 'localhost');
That's a bit more interesting. Now it displays 'A client has connected!' every time a client connects.
The return value of the connectHandler method is the server itself, so multiple invocations can be chained together. That means we can rewrite the above as:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
log.info('A client has connected!');
}).listen(1234, 'localhost');
or
vertx.createNetServer().connectHandler(function(sock) {
log.info('A client has connected!');
}).listen(1234, 'localhost');
This is a common pattern throughout the vert.x API.
To close a net server just call the close function.
server.close();
The close is actually asynchronous and might not complete until some time after the close function has returned. If you want to be notified when the actual close has completed then you can pass in a handler to the close function.
This handler will then be called when the close has fully completed.
server.close(function() {
log.info('The server is now fully closed.');
});
If you want your net server to last the entire lifetime of your verticle, you don't need to call close explicitly, the Vert.x container will automatically close any servers that you created when the verticle is stopped.
NetServer has a set of properties you can set which affect its behaviour. Firstly there are bunch of properties used to tweak the TCP parameters, in most cases you won't need to set these:
setTCPNoDelay(tcpNoDelay) If tcpNoDelay is true then Nagle's Algorithm is disabled. If false then it is enabled.
setSendBufferSize(size) Sets the TCP send buffer size in bytes.
setReceiveBufferSize(size) Sets the TCP receive buffer size in bytes.
setTCPKeepAlive(keepAlive) if keepAlive is true then TCP keep alive is enabled, if false it is disabled.
setReuseAddress(reuse) if reuse is true then addresses in TIME_WAIT state can be reused after they have been closed.
setSoLinger(linger)
setTrafficClass(trafficClass)
NetServer has a further set of properties which are used to configure SSL. We'll discuss those later on.
So far we have seen how to create a NetServer, and accept incoming connections, but not how to do anything interesting with the connections. Let's remedy that now.
When a connection is made, the connect handler is called passing in an instance of NetSocket. This is a socket-like interface to the actual connection, and allows you to read and write data as well as do various other things like close the socket.
To read data from the socket you need to set the dataHandler on the socket. This handler will be called with a Buffer every time data is received on the socket. You could try the following code and telnet to it to send some data:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
sock.dataHandler(function(buffer) {
log.info('I received ' + buffer.length() + ' bytes of data');
});
}).listen(1234, 'localhost');
To write data to a socket, you invoke the write function. This function can be invoked in a few ways:
With a single buffer:
var myBuffer = new vertx.Buffer(...); sock.write(myBuffer);
A string. In this case the string will encoded using UTF-8 and the result written to the wire.
sock.write('hello');
A string and an encoding. In this case the string will encoded using the specified encoding and the result written to the wire.
sock.write('hello', 'UTF-16');
The write function is asynchronous and always returns immediately after the write has been queued.
The actual write might occur some time later. If you want to be informed when the actual write has happened you can pass in a function as a final argument.
This function will then be invoked when the write has completed:
sock.write('hello', function() {
log.info('It has actually been written');
});
Let's put it all together.
Here's an example of a simple TCP echo server which simply writes back (echoes) everything that it receives on the socket:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
sock.dataHandler(function(buffer) {
sock.write(buffer);
});
}).listen(1234, 'localhost');
You can close a socket by invoking the close method. This will close the underlying TCP connection.
If you want to be notified when a socket is closed, you can set the `closedHandler':
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
sock.closedHandler(function() {
log.info('The socket is now closed');
});
});
The closed handler will be called irrespective of whether the close was initiated by the client or server.
You can set an exception handler on the socket that will be called if an exception occurs:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
sock.exceptionHandler(function() {
log.error('Oops. Something went wrong');
});
});
NetSocket also can at as a ReadStream and a WriteStream. This allows flow control to occur on the connection and the connection data to be pumped to and from other object such as HTTP requests and responses, WebSockets and asynchronous files.
This will be discussed in depth in the chapter on streams and pumps.
A verticle instance is strictly single threaded.
If you create a simple TCP server and deploy a single instance of it then all the handlers for that server are always executed on the same event loop (thread).
This means that if you are running on a server with a lot of cores, and you only have this one instance deployed then you will have at most one core utilised on your server! That's not very good, right?
To remedy this you can simply deploy more instances of the verticle in the server, e.g.
vertx run echo_server.js -instances 20
The above would run 20 instances of echo_server.js to a locally running vert.x instance.
Once you do this you will find the echo server works functionally identically to before, but, as if by magic, all your cores on your server can be utilised and more work can be handled.
At this point you might be asking yourself 'Hold on, how can you have more than one server listening on the same host and port? Surely you will get port conflicts as soon as you try and deploy more than one instance?'
Vert.x does a little magic here.
When you deploy another server on the same host and port as an existing server it doesn't actually try and create a new server listening on the same host/port.
Instead it internally maintains just a single server, and, as incoming connections arrive it distributes them in a round-robin fashion to any of the connect handlers set by the verticles.
Consequently vert.x TCP servers can scale over available cores while each vert.x verticle instance remains strictly single threaded, and you don't have to do any special tricks like writing load-balancers in order to scale your server on your multi-core machine.
A NetClient is used to make TCP connections to servers.
To create a TCP client you invoke the createNetClient function on the vertx instance.
var client = vertx.createNetClient();
To actually connect to a server you invoke the connect method:
var client = vertx.createNetClient();
client.connect(1234, 'localhost', function(sock) {
log.info('We have connected');
});
The connect method takes the port number as the first parameter, followed by the hostname or ip address of the server. The third parameter is a connect handler. This handler will be called when the connection actually occurs.
The argument passed into the connect handler is an instance of NetSocket, exactly the same as what is passed into the server side connect handler. Once given the NetSocket you can read and write data from the socket in exactly the same way as you do on the server side.
You can also close it, set the closed handler, set the exception handler and use it as a ReadStream or WriteStream exactly the same as the server side NetSocket.
You can set an exception handler on the NetClient. This will catch any exceptions that occur during connection.
var client = vertx.createNetClient();
client.exceptionHandler(function(ex) {
log.info('Cannot connect since the host does not exist!');
});
client.connect(4242, 'host-that-doesnt-exist', function(sock) {
log.info('this won't get called');
});
A NetClient can be configured to automatically retry connecting or reconnecting to the server in the event that it cannot connect or has lost its connection. This is done by invoking the functions setReconnectAttempts and setReconnectInterval:
var client = vertx.createNetClient(); client.setReconnectAttempts(1000); client.setReconnectInterval(500);
ReconnectAttempts determines how many times the client will try to connect to the server before giving up. A value of -1 represents an infinite number of times. The default value is 0. I.e. no reconnection is attempted.
ReconnectInterval detemines how long, in milliseconds, the client will wait between reconnect attempts. The default value is 1000.
If an exception handler is set on the client, and reconnect attempts is not equal to 0. Then the exception handler will not be called until the client gives up reconnecting.
Just like NetServer, NetClient also has a set of TCP properties you can set which affect its behaviour. They have the same meaning as those on NetServer.
NetClient also has a further set of properties which are used to configure SSL. We'll discuss those later on.
Net servers can also be configured to work with Transport Layer Security (previously known as SSL).
When a NetServer is working as an SSL Server the API of the NetServer and NetSocket is identical compared to when it working with standard sockets. Getting the server to use SSL is just a matter of configuring the NetServer before listen is called.
To enabled SSL the function setSSL(true) must be called on the Net Server.
The server must also be configured with a key store and an optional trust store.
These are both Java keystores which can be managed using the keytool utility which ships with the JDK.
The keytool command allows you to create keystores, and import and export certificates from them.
The key store should contain the server certificate. This is mandatory - the client will not be able to connect to the server over SSL if the server does not have a certificate.
The key store is configured on the server using the setKeyStorePath and setKeyStorePassword functions.
The trust store is optional and contains the certificates of any clients it should trust. This is only used if client authentication is required.
To configure a server to use server certificates only:
var server = vertx.createNetServer().
.setSSL(true)
.setKeyStorePath('/path/to/your/keystore/server-keystore.jks')
.setKeyStorePassword('password');
Making sure that server-keystore.jks contains the server certificate.
To configure a server to also require client certificates:
var server = vertx.createNetServer()
.setSSL(true)
.setKeyStorePath('/path/to/your/keystore/server-keystore.jks')
.setKeyStorePassword('password')
.setTrustStorePath('/path/to/your/truststore/server-truststore.jks')
.setTrustStorePassword('password')
.setClientAuthRequired(true);
Making sure that server-truststore.jks contains the certificates of any clients who the server trusts.
If clientAuthRequired is set to true and the client cannot provide a certificate, or it provides a certificate that the server does not trust then the connection attempt will not succeed.
Net Clients can also be easily configured to use SSL. They have the exact same API when using SSL as when using standard sockets.
To enable SSL on a NetClient the function setSSL(true) is called.
If the setTrustAll(true) is invoked on the client, then the client will trust all server certificates. The connection will still be encrypted but this mode is vulnerable to 'man in the middle' attacks. I.e. you can't be sure who you are connecting to. Use this with caution. Default value is false.
If setTrustAll(true) has not been invoked then a client trust store must be configured and should contain the certificates of the servers that the client trusts.
The client trust store is just a standard Java key store, the same as the key stores on the server side. The client trust store location is set by using the function setTrustStorePath on the NetClient. If a server presents a certificate during connection which is not in the client trust store, the connection attempt will not succeed.
If the server requires client authentication then the client must present its own certificate to the server when connecting. This certificate should reside in the client key store. Again it#s just a regular Java key store. The client keystore location is set by using the function setKeyStorePath on the NetClient.
To configure a client to trust all server certificates (dangerous):
var client = vertx.createNetClient()
.setSSL(true)
.setTrustAll(true);
To configure a client to only trust those certificates it has in its trust store:
var client = vertx.createNetClient()
.setSSL(true)
.setTrustStorePath('/path/to/your/client/truststore/client-truststore.jks')
.setTrustStorePassword('password');
To configure a client to only trust those certificates it has in its trust store, and also to supply a client certificate:
var client = vertx.createNetClient()
.setSSL(true)
.setTrustStorePath('/path/to/your/client/truststore/client-truststore.jks')
.setTrustStorePassword('password')
.setClientAuthRequired(true)
.setKeyStorePath('/path/to/keystore/holding/client/cert/client-keystore.jks')
.setKeyStorePassword('password');
There are several objects in vert.x that allow data to be read from and written to in the form of Buffers.
All operations in the vert.x API are non blocking; calls to write data return immediately and writes are internally queued.
It's not hard to see that if you write to an object faster than it can actually write the data to its underlying resource then the write queue could grow without bound - eventually resulting in exhausting available memory.
To solve this problem a simple flow control capability is provided by some objects in the vert.x API.
Any flow control aware object that can be written to is said to implement ReadStream, and any flow control object that can be read from is said to implement WriteStream.
Let's take an example where we want to read from a ReadStream and write the data to a WriteStream.
A very simple example would be reading from a NetSocket on a server and writing back to the same NetSocket - since NetSocket implements both ReadStream and WriteStream, but you can do this between any ReadStream and any WriteStream, including HTTP requests and response, async files, WebSockets, etc.
A naive way to do this would be to directly take the data that's been read and immediately write it to the NetSocket, for example:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
sock.dataHandler(function(buffer) {
// Write data straight back on the socket
sock.write(buffer);
});
}).listen(1234, 'localhost');
There's a problem with the above example: If data is read from the socket faster than it can be written back to the socket, it will build up in the write queue of the AsyncFile, eventually running out of RAM. This might happen, for example if the client at the other end of the socket wasn't reading very fast, effectively putting back-pressure on the connection.
Since NetSocket implements WriteStream, we can check if the WriteStream is full before writing to it:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
sock.dataHandler(function(buffer) {
if (!sock.writeQueueFull()) {
sock.write(buffer);
}
});
}).listen(1234, 'localhost');
This example won't run out of RAM but we'll end up losing data if the write queue gets full. What we really want to do is pause the NetSocket when the write queue is full. Let's do that:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
sock.dataHandler(function(buffer) {
if (!sock.writeQueueFull()) {
sock.write(buffer);
} else {
sock.pause();
}
});
}).listen(1234, 'localhost');
We're almost there, but not quite. The NetSocket now gets paused when the file is full, but we also need to unpause it when the write queue has processed its backlog:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
sock.dataHandler(function(buffer) {
if (!sock.writeQueueFull()) {
sock.write(buffer);
} else {
sock.pause();
sock.drainHandler(function() {
sock.resume();
});
}
});
}).listen(1234, 'localhost');
And there we have it. The drainHandler event handler will get called when the write queue is ready to accept more data, this resumes the NetSocket which allows it to read more data.
It's very common to want to do this when writing vert.x applications, so we provide a helper class called Pump which does all this hard work for you. You just feed it the ReadStream and the WriteStream and it tell it to start:
var server = vertx.createNetServer();
server.connectHandler(function(sock) {
var pump = new vertx.Pump(sock, sock);
pump.start();
}).listen(1234, 'localhost');
Which does exactly the same thing as the more verbose example.
Let's look at the methods on ReadStream and WriteStream in more detail:
ReadStream is implemented by AsyncFile, HttpClientResponse, HttpServerRequest, WebSocket, NetSocket and SockJSSocket.
Functions:
dataHandler(handler): set a handler which will receive data from the ReadStream. As data arrives the handler will be passed a Buffer.pause(): pause the handler. When paused no data will be received in the dataHandler.resume(): resume the handler. The handler will be called if any data arrives.exceptionHandler(handler): Will be called if an exception occurs on the ReadStream.endHandler(handler): Will be called when end of stream is reached. This might be when EOF is reached if the ReadStream represents a file, or when end of request is reached if it's an HTTP request, or when the connection is closed if it's a TCP socket.WriteStream is implemented by AsyncFile, HttpClientRequest, HttpServerResponse, WebSocket, NetSocket and SockJSSocket
Functions:
writeBuffer(buffer): write a Buffer to the WriteStream. This method will never block. Writes are queued internally and asynchronously written to the underlying resource.setWriteQueueMaxSize(size): set the number of bytes at which the write queue is considered full, and the function writeQueueFull() returns true. Note that, even if the write queue is considered full, if writeBuffer is called the data will still be accepted and queued.writeQueueFull(): returns true if the write queue is considered full.exceptionHandler(handler): Will be called if an exception occurs on the WriteStream.drainHandler(handler): The handler will be called if the WriteStream is considered no longer full.Instances of Pump have the following methods:
start(): Start the pump.stop(): Stops the pump. When the pump starts it is in stopped mode.setWriteQueueMaxSize(): This has the same meaning as setWriteQueueMaxSize on the WriteStream.getBytesPumped(): Returns total number of bytes pumped.A pump can be started and stopped multiple times.
Vert.x allows you to easily write full featured, highly performant and scalable HTTP servers.
To create an HTTP server you invoke the createHttpServer function on the vertx instance.
var server = vertx.createHttpServer();
To tell that server to listen for incoming requests you use the listen method:
var server = vertx.createHttpServer(); server.listen(8080, 'myhost');
The first parameter to listen is the port. The second parameter is the hostname or ip address. If the hostname is omitted it will default to 0.0.0.0 which means it will listen at all available interfaces.
To be notified when a request arrives you need to set a request handler. This is done by calling the requestHandler function of the server, passing in the handler:
var server = vertx.createHttpServer();
server.requestHandler(function(request) {
log.info('An HTTP request has been received');
})
server.listen(8080, 'localhost');
This displays 'An HTTP request has been received!' every time an HTTP request arrives on the server. You can try it by running the verticle and pointing your browser at http://localhost:8080.
Similarly to NetServer, the return value of the requestHandler method is the server itself, so multiple invocations can be chained together. That means we can rewrite the above with:
var server = vertx.createHttpServer();
server.requestHandler(function(request) {
log.info('An HTTP request has been received');
}).listen(8080, 'localhost');
Or:
vertx.createHttpServer().requestHandler(function(request) {
log.info('An HTTP request has been received');
}).listen(8080, 'localhost');
So far we have seen how to create an 'HttpServer' and be notified of requests. Lets take a look at how to handle the requests and do something useful with them.
When a request arrives, the request handler is called passing in an instance of HttpServerRequest. This object represents the server side HTTP request.
The handler is called when the headers of the request have been fully read. If the request contains a body, that body may arrive at the server some time after the request handler has been called.
It contains functions to get the URI, path, request headers and request parameters. It also contains a response property which is a reference to an object that represents the server side HTTP response for the object.
The request object has a property method which is a string representing what HTTP method was requested. Possible values for method are: GET, PUT, POST, DELETE, HEAD, OPTIONS, CONNECT, TRACE, PATCH.
The request object has a property uri which contains the full URI (Uniform Resource Locator) of the request. For example, if the request URI was:
/a/b/c/page.html?param1=abc¶m2=xyz
Then request.uri would contain the string /a/b/c/page.html?param1=abc¶m2=xyz.
Request URIs can be relative or absolute (with a domain) depending on what the client sent. In many cases they will be relative.
The request uri contains the value as defined in Section 5.1.2 of the HTTP specification - Request-URI
The request object has a property path which contains the path of the request. For example, if the request URI was:
/a/b/c/page.html?param1=abc¶m2=xyz
Then request.path would contain the string /a/b/c/page.html
The request object has a property query which contains the query of the request. For example, if the request URI was:
/a/b/c/page.html?param1=abc¶m2=xyz
Then request.query would contain the string param1=abc¶m2=xyz
The request headers are available as the headers() function of the request object. The return value is just a JavaScript object (associative array).
Note that the header keys are always lower-cased before being they are returned to you.
Here's an example that echoes the headers to the output of the response. Run it and point your browser at http://localhost:8080 to see the headers.
var server = vertx.createHttpServer();
server.requestHandler(function(request) {
var str = '';
for (var k in request.headers()) {
str = str.concat(k, ': ', headers[k], '\n');
}
request.response.end(str);
}).listen(8080, 'localhost');
Similarly to the headers, the request parameters are available as the params() function on the request object. Again, this is just a JavaScript object (associative array).
Request parameters are sent on the request URI, after the path. For example if the URI was:
/page.html?param1=abc¶m2=xyz
Then the params hash would be the following JS object:
{ param1: 'abc', param2: 'xyz' }
Sometimes an HTTP request contains a request body that we want to read. As previously mentioned the request handler is called when only the headers of the request have arrived so the HttpServerRequest object does not contain the body. This is because the body may be very large and we don't want to create problems with exceeding available memory.
To receive the body, you set the dataHandler on the request object. This will then get called every time a chunk of the request body arrives. Here's an example:
var server = vertx.createHttpServer();
server.requestHandler(function(request) {
request.dataHandler(function(buffer) {
log.info('I received ' + buffer.length() + ' bytes');
});
}).listen(8080, 'localhost');
The dataHandler may be called more than once depending on the size of the body.
You'll notice this is very similar to how data from NetSocket is read.
The request object implements the ReadStream interface so you can pump the request body to a WriteStream. See the chapter on streams and pumps for a detailed explanation.
In many cases, you know the body is not large and you just want to receive it in one go. To do this you could do something like the following:
var server = vertx.createHttpServer();
server.requestHandler(function(request) {
// Create a buffer to hold the body
var body = new vertx.Buffer();
request.dataHandler(function(buffer) {
// Append the chunk to the buffer
body.appendBuffer(buffer);
});
request.endHandler(function() {
// The entire body has now been received
log.info('The total body received was ' + body.length() + ' bytes');
});
}).listen(8080, 'localhost');
Like any ReadStream the end handler is invoked when the end of stream is reached - in this case at the end of the request.
If the HTTP request is using HTTP chunking, then each HTTP chunk of the request body will correspond to a single call of the data handler.
It's a very common use case to want to read the entire body before processing it, so vert.x allows a bodyHandler to be set on the request object.
The body handler is called only once when the entire request body has been read.
Beware of doing this with very large requests since the entire request body will be stored in memory.
Here's an example using bodyHandler:
var server = vertx.createHttpServer();
server.requestHandler(function(request) {
request.bodyHandler(function(body) {
log.info('The total body received was ' + body.length() + ' bytes');
});
}).listen(8080, 'localhost');
Simples, innit?
As previously mentioned, the HTTP request object contains a property response. This is the HTTP response for the request. You use it to write the response back to the client.
To set the HTTP status code for the response use the statusCode property, e.g.
var server = vertx.createHttpServer();
server.requestHandler(function(request) {
request.response.statusCode = 404;
request.response.end();
}).listen(8080, 'localhost');
You can also use the statusMessage property to set the status message. If you do not set the status message a default message will be used.
The default value for statusCode is 200.
To write data to an HTTP response, you invoke the write function. This function can be invoked multiple times before the response is ended. It can be invoked in a few ways:
With a single buffer:
var myBuffer = ... request.response.write(myBuffer);
A string. In this case the string will encoded using UTF-8 and the result written to the wire.
request.response.write('hello');
A string and an encoding. In this case the string will encoded using the specified encoding and the result written to the wire.
request.response.write('hello', 'UTF-16');
The write function is asynchronous and always returns immediately after the write has been queued.
The actual write might complete some time later. If you want to be informed when the actual write has completed you can pass in a function as a final argument. This function will then be invoked when the write has completed:
request.response.write('hello', function() {
log.info('It has actually been written');
});
If you are just writing a single string or Buffer to the HTTP response you can write it and end the response in a single call to the end function.
The first call to write results in the response header being being written to the response.
Consequently, if you are not using HTTP chunking then you must set the Content-Length header before writing to the response, since it will be too late otherwise. If you are using HTTP chunking you do not have to worry.
Once you have finished with the HTTP response you must call the end() function on it.
This function can be invoked in several ways:
With no arguments, the response is simply ended.
request.response.end();
The function can also be called with a string or Buffer in the same way write is called. In this case it's just the same as calling write with a string or Buffer followed by calling end with no arguments. For example:
request.response.end("That's all folks");
You can close the underlying TCP connection of the request by calling the close function.
request.response.close();
You can write headers to the response by simply adding them to the headers hash on the response object:
request.response.headers()['Some-Header'] = 'foo';
Individual HTTP response headers can also be written using the putHeader function. This allows a more fluent API since they can be chained. For example:
request.response.putHeader('Some-Header', 'foo').putHeader('Other-Header', 'bar');
You can also put multiple headers in one go:
request.response.putAllHeaders({'Some-Header': 'foo', 'Other-Header': 'bar'});
Response headers must all be added before any parts of the response body are written.
Vert.x supports HTTP Chunked Transfer Encoding. This allows the HTTP response body to be written in chunks, and is normally used when a large response body is being streamed to a client, whose size is not known in advance.
You put the HTTP response into chunked mode as follows:
req.response.setChunked(true);
Default is non-chunked. When in chunked mode, each call to response.write(...) will result in a new HTTP chunk being written out.
When in chunked mode you can also write HTTP response trailers to the response. These are actually written in the final chunk of the response.
As with headers, you can write trailers to the response by simply adding them to the trailers hash on the response object:
request.response.trailers()['Some-Trailer'] = 'quux';
Individual HTTP response headers can also be written using the putTrailer function. This allows a more fluent API since they can be chained. For example:
request.response.putTrailer('Some-Trailer', 'foo').putTrailer('Other-Trailer', 'bar');
You can also put multiple trailers in one go:
request.response.putAllTrailers({'Some-Trailer': 'foo', 'Other-Trailer': 'bar'});
If you were writing a web server, one way to serve a file from disk would be to open it as an AsyncFile and pump it to the HTTP response. Or you could load it it one go using the file system API and write that to the HTTP response.
Alternatively, vert.x provides a method which allows you to send serve a file from disk to HTTP response in one operation. Where supported by the underlying operating system this may result in the OS directly transferring bytes from the file to the socket without being copied through userspace at all.
Using sendFile is usually more efficient for large files, but may be slower than using readFile to manually read the file as a buffer and write it directly to the response.
To do this use the sendFile function on the HTTP response. Here's a simple HTTP web server that serves static files from the local web directory:
var server = vertx.createHttpServer();
server.requestHandler(function(req) {
var file = '';
if (req.path == '/') {
file = 'index.html';
} else if (req.path.indexOf('..') == -1) {
file = req.path;
}
req.response.sendFile('web/' + file);
}).listen(8080, 'localhost');
Note: If you use sendFile while using HTTPS it will copy through userspace, since if the kernel is copying data directly from disk to socket it doesn't give us an opportunity to apply any encryption.
If you're going to write web servers using vert.x be careful that users cannot exploit the path to access files outside the directory from which you want to serve them.
Since the HTTP Response implements WriteStream you can pump to it from any ReadStream, e.g. an AsyncFile, NetSocket or HttpServerRequest.
Here's an example which echoes HttpRequest headers and body back in the HttpResponse. It uses a pump for the body, so it will work even if the HTTP request body is much larger than can fit in memory at any one time:
var server = vertx.createHttpServer();
server.requestHandler(function(req) {
req.response.putAllHeaders(req.headers());
var p = new Pump(req, req.response);
p.start();
req.endHandler(function() { req.response.end(); });
}).listen(8080, 'localhost');
To create an HTTP client you invoke the createHttpClient function on the vertx instance.
var client = vertx.createHttpClient();
You set the port and hostname (or ip address) that the client will connect to using the setHost and setPort functions:
var client = vertx.createHttpClient();
client.setPort(8181)
client.setHost('foo.com');
This, of course, can be chained:
var client = vertx.createHttpClient()
.setPort(8181)
.setHost('foo.com');
A single HTTPClient always connects to the same host and port. If you want to connect to different servers, create more instances.
The default port is 80 and the default host is localhost. So if you don't explicitly set these values that's what the client will attempt to connect to.
By default the HTTPClient pools HTTP connections. As you make requests a connection is borrowed from the pool and returned when the HTTP response has ended.
If you do not want connections to be pooled you can call setKeepAlive with false:
var client = vertx.createHttpClient()
.setPort(8181)
.setHost('foo.com').
.setKeepAlive(false);
In this case a new connection will be created for each HTTP request and closed once the response has ended.
You can set the maximum number of connections that the client will pool as follows:
var client = vertx.createHttpClient()
.setPort(8181)
.setHost('foo.com').
.setMaxPoolSize(10);
The default value is 1.
Vert.x will automatically close any clients when the verticle is stopped, but if you want to close it explicitly you can:
client.close
To make a request using the client you invoke one the methods named after the HTTP method that you want to invoke.
For example, to make a POST request:
var client = vertx.createHttpClient();
var request = client.post('http://localhost:8080/some-path/', function(resp) {
log.info('Got a response, status code: ' + resp.statusCode);
});
request.end();
To make a PUT request use the put method, to make a GET request use the get method, etc.
Legal request methods are: get, put, post, delete, head, options, connect, trace and patch.
The general modus operandi is you invoke the appropriate method passing in the request URI as the first parameter, the second parameter is an event handler which will get called when the corresponding response arrives. The response handler is passed the client response object as an argument.
The value specified in the request URI corresponds to the Request-URI as specified in Section 5.1.2 of the HTTP specification. In most cases it will be a relative URI.
Please note that the domain/port that the client connects to is determined by setPort and setHost, and is not parsed from the uri.
The return value from the appropriate request method is an HTTPClientRequest object. You can use this to add headers to the request, and to write to the request body. The request object implements WriteStream.
Once you have finished with the request you must call the end function.
If you don't know the name of the request method in advance there is a general request method which takes the HTTP method as a parameter:
var client = vertx.createHttpClient().setHost('foo.com');
var request = client.request('POST', '/some-path', function(resp) {
log.info('Got a response, status code: ' + resp.statusCode);
});
request.end();
There is also a method called getNow which does the same as get, but automatically ends the request. This is useful for simple GETs which don't have a request body:
var client = vertx.createHttpClient().setHost('foo.com');
client.getNow('/some-path', function(resp) {
log.info('Got a response, status code: ' + resp.statusCode);
});
With getNow there is no return value.
Writing to the client request body has a very similar API to writing to the server response body.
To write data to an HttpClientRequest object, you invoke the write function. This function can be called multiple times before the request has ended. It can be invoked in a few ways:
With a single buffer:
var myBuffer = ... request.write(myBuffer);
A string. In this case the string will encoded using UTF-8 and the result written to the wire.
request.write('hello');
A string and an encoding. In this case the string will encoded using the specified encoding and the result written to the wire.
request.write('hello', 'UTF-16');
The write function is asynchronous and always returns immediately after the write has been queued. The actual write might complete some time later.
If you want to be informed when the actual write has completed you can pass in a function as a final argument. This function will be invoked when the write has completed:
request.response.write('hello', function() {
log.info('It has actually been written');
});
If you are just writing a single string or Buffer to the HTTP request you can write it and end the request in a single call to the end function.
The first call to write results in the request header being being written to the request.
Consequently, if you are not using HTTP chunking then you must set the Content-Length header before writing to the request, since it will be too late otherwise. If you are using HTTP chunking you do not have to worry.
Once you have finished with the HTTP request you must call the end function on it.
This function can be invoked in several ways:
With no arguments, the request is simply ended.
request.end();
The function can also be called with a string or Buffer in the same way write is called. In this case it's just the same as calling write with a string or Buffer followed by calling end with no arguments.
To write headers to the request you can just add them to the headers hash:
var client = vertx.createHttpClient().setHost('foo.com');
var request = client.post('/some-path', function(resp) {
log.info('Got a response, status code: ' + resp.statusCode);
});
request.headers()['Some-Header'] = 'Some-Value';
request.end();
Or you can use the putHeader method if you prefer a more fluent API:
client.post('/some-uri', function(resp) {
log.info('Got a response, status code: ' + resp.statusCode);
}).putHeader('Some-Header', 'Some-Value')
.putHeader('Some-Other-Header', 'Some-Other-Value')
.end();
If you want to put more than one header at the same time, you can instead use the putAllHeaders function.
client.post('/some-uri', function(resp) {
log.info('Got a response, status code: ' + resp.statusCode);
}).putAllHeaders({'Some-Header': 'Some-Value',
'Some-Other-Header': 'Some-Other-Value',
'Yet-Another-Header': 'Yet-Another-Value'})
.end();
Vert.x supports HTTP Chunked Transfer Encoding for requests. This allows the HTTP request body to be written in chunks, and is normally used when a large request body is being streamed to the server, whose size is not known in advance.
You put the HTTP request into chunked mode as follows:
request.setChunked(true);
Default is non-chunked. When in chunked mode, each call to request.write(...) will result in a new HTTP chunk being written out.
Client responses are received as an argument to the response handler that is passed into one of the request methods on the HTTP client.
The response object implements ReadStream, so it can be pumped to a WriteStream like any other ReadStream.
To query the status code of the response use the statusCode property. The statusMessage property contains the status message. For example:
var client = vertx.createHttpClient().setHost('foo.com');
client.getNow('/some-path', function(resp) {
log.info('server returned status code: ' + resp.statusCode);
log.info('server returned status message: ' + resp.statusMessage);
});
The API for reading a http client response body is very similar to the API for reading a http server request body.
Sometimes an HTTP response contains a request body that we want to read. Like an HTTP request, the client response handler is called when all the response headers have arrived, not when the entire response body has arrived.
To receive the response body, you set a dataHandler on the response object which gets called as parts of the HTTP response arrive. Here's an example:
var client = vertx.createHttpClient().setHost('foo.com');
client.getNow('/some-path', function(resp) {
resp.dataHandler(function(buffer) {
log.info('I received ' + buffer.length() + ' bytes');
});
});
The response object implements the ReadStream interface so you can pump the response body to a WriteStream. See the chapter on streams and pump for a detailed explanation.
The dataHandler can be called multiple times for a single HTTP response.
As with a server request, if you wanted to read the entire response body before doing something with it you could do something like the following:
var client = vertx.createHttpClient().setHost('foo.com');
client.getNow('/some-path', function(resp) {
// Create a buffer to hold the entire response body
var body = new vertx.Buffer();
resp.dataHandler(function(buffer) {
// Add chunk to the buffer
body.appendBuffer(buffer);
});
resp.endHandler(function() {
// The entire response body has been received
log.info('The total body received was ' + body.length() + ' bytes');
});
});
Like any ReadStream the end handler is invoked when the end of stream is reached - in this case at the end of the response.
If the HTTP response is using HTTP chunking, then each chunk of the response body will correspond to a single call to the dataHandler.
It's a very common use case to want to read the entire body in one go, so vert.x allows a bodyHandler to be set on the response object.
The body handler is called only once when the entire response body has been read.
Beware of doing this with very large responses since the entire response body will be stored in memory.
Here's an example using bodyHandler:
var client = vertx.createHttpClient().setHost('foo.com');
client.getNow('/some-uri', function(resp) {
resp.bodyHandler(function(body) {
log.info('The total body received was ' + body.length() + ' bytes');
});
});
The HTTP client and server requests and responses all implement either ReadStream or WriteStream. This means you can pump between them and any other read and write streams.
According to the HTTP 1.1 specification a client can set a header Expect: 100-Continue and send the request header before sending the rest of the request body.
The server can then respond with an interim response status Status: 100 (Continue) to signify the client is ok to send the rest of the body.
The idea here is it allows the server to authorise and accept/reject the request before large amounts of data is sent. Sending large amounts of data if the request might not be accepted is a waste of bandwidth and ties up the server in reading data that it will just discard.
Vert.x allows you to set a continueHandler on the client request object. This will be called if the server sends back a Status: 100 (Continue) response to signify it is ok to send the rest of the request.
This is used in conjunction with the sendHead function to send the head of the request.
An example will illustrate this:
var client = vertx.createHttpClient().setHost('foo.com');
var request = client.put('/some-path', function(resp) {
log.info('Got a response ' + resp.statusCode);
});
request.putHeader('Expect', '100-Continue');
request.continueHandler(function() {
// OK to send rest of body
request.write('Some data').end();
});
request.sendHead();
HTTPS servers are very easy to write using vert.x.
An HTTPS server has an identical API to a standard HTTP server. Getting the server to use HTTPS is just a matter of configuring the HTTP Server before listen is called.
Configuration of an HTTPS server is done in exactly the same way as configuring a NetServer for SSL. Please see SSL server chapter for detailed instructions.
HTTPS clients can also be very easily written with vert.x
Configuring an HTTP client for HTTPS is done in exactly the same way as configuring a NetClient for SSL. Please see SSL client chapter for detailed instructions.
Scaling an HTTP or HTTPS server over multiple cores is as simple as deploying more instances of the verticle. For example:
vertx deploy http_server.js -instances 20
The scaling works in the same way as scaling a NetServer. Please see the chapter on scaling Net Servers for a detailed explanation of how this works.
Vert.x lets you route HTTP requests to different handlers based on pattern matching on the request path. It also enables you to extract values from the path and use them as parameters in the request.
This is particularly useful when developing REST-style web applications.
To do this you simply create an instance of vertx.RouteMatcher and use it as handler in an HTTP server. See the chapter on HTTP servers for more information on setting HTTP handlers. Here's an example:
var server = vertx.createHttpServer(); var routeMatcher = new vertx.RouteMatcher(); server.requestHandler(routeMatcher).listen(8080, 'localhost');
You can then add different matches to the route matcher. For example, to send all GET requests with path /animals/dogs to one handler and all GET requests with path /animals/cats to another handler you would do:
var server = vertx.createHttpServer();
var routeMatcher = new vertx.RouteMatcher();
routeMatcher.get('/animals/dogs', function(req) {
req.response.end('You requested dogs');
});
routeMatcher.get('/animals/cats', function(req) {
req.response.end('You requested cats');
});
server.requestHandler(routeMatcher).listen(8080, 'localhost');
Corresponding methods exist for each HTTP method - get, post, put, delete, head, options, trace, connect and patch.
There's also an all method which applies the match to any HTTP request method.
The handler specified to the method is just a normal HTTP server request handler, the same as you would supply to the requestHandler method of the HTTP server.
You can provide as many matches as you like and they are evaluated in the order you added them, the first matching one will receive the request.
A request is sent to at most one handler.
If you want to extract parameters from the path, you can do this too, by using the : (colon) character to denote the name of a parameter. For example:
var server = vertx.createHttpServer();
var routeMatcher = new vertx.RouteMatcher();
routeMatcher.put('/:blogname/:post', function(req) {
var blogName = req.params().blogname;
var post = req.params().post;
req.response.end('blogname is ' + blogName + ', post is ' + post);
});
server.requestHandler(routeMatcher).listen(8080, 'localhost');
Any params extracted by pattern matching are added to the map of request parameters.
In the above example, a PUT request to /myblog/post1 would result in the variable blogName getting the value myblog and the variable post getting the value post1.
Valid parameter names must start with a letter of the alphabet and be followed by any letters of the alphabet or digits.
Regular Expressions can be used to extract more complex matches. In this case capture groups are used to capture any parameters.
Since the capture groups are not named they are added to the request with names param0, param1, param2, etc.
Corresponding methods exist for each HTTP method - getWithRegEx, postWithRegEx, putWithRegEx, deleteWithRegEx, headWithRegEx, optionsWithRegEx, traceWithRegEx, connectWithRegEx and patchWithRegEx.
There's also an allWithRegEx method which applies the match to any HTTP request method.
For example:
var server = vertx.createHttpServer();
var routeMatcher = new vertx.RouteMatcher();
routeMatcher.allWithRegEx('\/([^\/]+)\/([^\/]+)', function(req) {
var first = req.params().param0
var second = req.params().param1;
req.response.end("first is " + first + " and second is " + second);
});
server.requestHandler(routeMatcher).listen(8080, 'localhost');
Run the above and point your browser at http://localhost:8080/animals/cats.
It will display 'first is animals and second is cats'.
You can use the noMatch function to specify a handler that will be called if nothing matches. If you don't specify a no match handler and nothing matches, a 404 will be returned.
routeMatcher.noMatch(function(req) { req.response.end("Nothing matched"); });
WebSockets are a feature of HTML 5 that allows a full duplex socket-like connection between HTTP servers and HTTP clients (typically browsers).
To use WebSockets on the server you create an HTTP server as normal, but instead of setting a requestHandler you set a websocketHandler on the server.
var server = vertx.createHttpServer();
server.websocketHandler(function(websocket) {
// A WebSocket has connected!
}).listen(8080, 'localhost');
The websocket instance passed into the handler implements both ReadStream and WriteStream, so you can read and write data to it in the normal ways. I.e by setting a dataHandler and calling the writeBuffer method.
See the chapter on NetSocket and streams and pumps for more information.
For example, to echo all data received on a WebSocket:
var server = vertx.createHttpServer();
server.websocketHandler(function(websocket) {
var p = new Pump(websocket, websocket);
p.start();
}).listen(8080, 'localhost');
The websocket instance also has method writeBinaryFrame for writing binary data. This has the same effect as calling writeBuffer.
Another method writeTextFrame also exists for writing text data. This is equivalent to calling
websocket.writeBuffer(new vertx.Buffer('some-string'));
Sometimes you may only want to accept WebSockets which connect at a specific path.
To check the path, you can query the path property of the websocket. You can then call the reject function to reject the websocket.
var server = vertx.createHttpServer();
server.websocketHandler(function(websocket) {
if (websocket.path === '/services/echo') {
var p = new vertx.Pump(websocket, websocket);
p.start();
} else {
websocket.reject();
}
}).listen(8080, 'localhost');
To use WebSockets from the HTTP client, you create the HTTP client as normal, then call the connectWebsocket function, passing in the URI that you wish to connect to at the server, and a handler.
The handler will then get called if the WebSocket successfully connects. If the WebSocket does not connect - perhaps the server rejects it, then any exception handler on the HTTP client will be called.
Here's an example of WebSocket connection;
var client = vertx.createHttpClient();
client.connectWebsocket('http://localhost:8080/some-uri', function(websocket) {
// WebSocket has connected!
});
Again, the client side WebSocket implements ReadStream and WriteStream, so you can read and write to it in the same way as any other stream object.
To use WebSockets from a compliant browser, you use the standard WebSocket API. Here's some example client side JavaScript which uses a WebSocket.
<script>
var socket = new WebSocket("ws://localhost:8080/services/echo");
socket.onmessage = function(event) {
alert("Received data from websocket: " + event.data);
}
socket.onopen = function(event) {
alert("Web Socket opened");
socket.send("Hello World");
};
socket.onclose = function(event) {
alert("Web Socket closed");
};
</script>
For more information see the WebSocket API documentation
TODO
WebSockets are a new technology, and many users are still using browsers that do not support them, or which support older, pre-final, versions.
Moreover, WebSockets do not work well with many corporate proxies. This means that's it's not possible to guarantee a WebSocket connection is going to succeed for every user.
Enter SockJS.
SockJS is a client side JavaScript library and protocol which provides a simple WebSocket-like interface to the client side JavaScript developer irrespective of whether the actual browser or network will allow real WebSockets.
It does this by supporting various different transports between browser and server, and choosing one at runtime according to browser and network capabilities. All this is transparent to you - you are simply presented with the WebSocket-like interface which just works.
Please see the SockJS website for more information.
Vert.x provides a complete server side SockJS implementation.
This enables vert.x to be used for modern, so-called real-time (this is the modern meaning of real-time, not to be confused by the more formal pre-existing definitions of soft and hard real-time systems) web applications that push data to and from rich client-side JavaScript applications, without having to worry about the details of the transport.
To create a SockJS server you simply create a HTTP server as normal and then invoke the createSockJSServer function on the vertx instance, specifying the HTTP server:
var httpServer = vertx.createHttpServer(); var sockJSServer = vertx.createSockJSServer(httpServer);
Each SockJS server can host multiple applications.
Each application is defined by some configuration, and provides a handler which gets called when incoming SockJS connections arrive at the server.
For example, to create a SockJS echo application:
var httpServer = vertx.createHttpServer();
var sockJSServer = vertx.createSockJSServer(httpServer);
var config = { prefix: '/echo' };
sockJSServer.installApp(config, function(sock) {
var p = new vertx.Pump(sock, sock);
p.start();
});
httpServer.listen(8080);
The configuration is a JSON object that takes the following fields:
prefix: A url prefix for the application. All http requests whose paths begins with selected prefix will be handled by the application. This property is mandatory.insert_JSESSIONID: Some hosting providers enable sticky sessions only to requests that have JSESSIONID cookie set. This setting controls if the server should set this cookie to a dummy value. By default setting JSESSIONID cookie is enabled. More sophisticated beaviour can be achieved by supplying a function.session_timeout: The server sends a close event when a client receiving connection have not been seen for a while. This delay is configured by this setting. By default the close event will be emitted when a receiving connection wasn't seen for 5 seconds.heartbeat_period: In order to keep proxies and load balancers from closing long running http requests we need to pretend that the connecion is active and send a heartbeat packet once in a while. This setting controlls how often this is done. By default a heartbeat packet is sent every 25 seconds.max_bytes_streaming: Most streaming transports save responses on the client side and don't free memory used by delivered messages. Such transports need to be garbage-collected once in a while. max_bytes_streaming sets a minimum number of bytes that can be send over a single http streaming request before it will be closed. After that client needs to open new request. Setting this value to one effectively disables streaming and will make streaming transports to behave like polling transports. The default value is 128K. library_url: Transports which don't support cross-domain communication natively ('eventsource' to name one) use an iframe trick. A simple page is served from the SockJS server (using its foreign domain) and is placed in an invisible iframe. Code run from this iframe doesn't need to worry about cross-domain issues, as it's being run from domain local to the SockJS server. This iframe also does need to load SockJS javascript client library, and this option lets you specify its url (if you're unsure, point it to the latest minified SockJS client release, this is the default). The default value is http://cdn.sockjs.org/sockjs-0.1.min.jsThe object passed into the SockJS handler implements ReadStream and WriteStream much like NetSocket or WebSocket. You can therefore use the standard API for reading and writing to the SockJS socket or using it in pumps.
See the chapter on Streams and Pumps for more information.
var httpServer = vertx.createHttpServer();
var sockJSServer = vertx.createSockJSServer(httpServer);
var config = { prefix: '/echo' };
sockJSServer.installApp(config, function(sock) {
sock.dataHandler(function(buff) {
sock.writeBuffer(buff);
});
});
httpServer.listen(8080);
For full information on using the SockJS client library please see the SockJS website. A simple example:
<script>
var sock = new SockJS('http://mydomain.com/my_prefix');
sock.onopen = function() {
console.log('open');
};
sock.onmessage = function(e) {
console.log('message', e.data);
};
sock.onclose = function() {
console.log('close');
};
</script>
As you can see the API is very similar to the WebSockets API.
By connecting up SockJS and the vert.x event bus we create a distributed event bus which not only spans multiple vert.x instances on the server side, but can also include client side JavaScript running in browsers.
We can therefore create a huge distributed bus encompassing many browsers and servers. The browsers don't have to be connected to the same server as long as the servers are connected.
On the server side we have already discussed the event bus API.
We also provide a client side JavaScript library called vertxbus.js which provides the same event bus API, but on the client side.
This library internally uses SockJS to send and receive data to a SockJS vert.x server called the SockJS bridge. It's the bridge's responsibility to bridge data between SockJS sockets and the event bus on the server side.
Creating a Sock JS bridge is simple. You just call the bridge function on the SockJS server.
You will also need to secure the bridge (see below).
The following example creates and starts a SockJS bridge which will bridge any events sent to the path eventbus on to the server side event bus.
var httpServer = vertx.createHttpServer();
var sockJSServer = vertx.createSockJSServer(httpServer);
sockJSServer.bridge({prefix : '/eventbus'}, [], [] );
server.listen(8080);
The SockJS bridge currently only works with JSON event bus messages.
Once you've set up a bridge, you can use the event bus from the client side as follows:
In your web page, you need to load the script vertxbus.js, then you can access the vert.x event bus API. Here's a rough idea of how to use it. For a full working examples, please consult the bundled examples.
<script src="http://cdn.sockjs.org/sockjs-0.2.1.min.js"></script>
<script src='vertxbus.js'></script>
<script>
var eb = new vertx.EventBus('http://localhost:8080/eventbus');
eb.onopen = function() {
eb.registerHandler('some-address', function(message) {
console.log('received a message: ' + JSON.stringify(message);
});
eb.send('some-address', {name: 'tim', age: 587});
}
</script>
You can find vertxbus.js in the client directory of the vert.x distribution.
The first thing the example does is to create a instance of the event bus
var eb = new vertx.EventBus('http://localhost:8080/eventbus');
The parameter to the constructor is the URI where to connect to the event bus. Since we create our bridge with the prefix eventbus we will connect there.
You can't actually do anything with the bridge until it is opened. When it is open the onopen handler will be called.
The client side event bus API for registering and unregistering handlers and for sending messages is exactly the same as the server side one. Please consult the chapter on the event bus for full information.
There is one more thing to do before getting this working, please read the following section....
If you started a bridge like in the above example without securing it, and attempted to send messages through it you'd find that the messages mysteriously disappeared. What happened to them?
For most applications you probably don't want client side JavaScript being able to send just any message to any verticle on the server side or to all other browsers.
For example, you may have a persistor verticle on the event bus which allows data to be accessed or deleted. We don't want badly behaved or malicious clients being able to delete all the data in your database! Also, we don't necessarily want any client to be able to listen in on any topic.
To deal with this, a SockJS bridge will, by default refuse to let through any messages. It's up to you to tell the bridge what messages are ok for it to pass through. (There is an exception for reply messages which are always allowed through).
In other words the bridge acts like a kind of firewall which has a default deny-all policy.
Configuring the bridge to tell it what messages it should pass through is easy. You pass in two arrays of JSON objects that represent matches, as the final argument in the call to bridge.
The first array is the inbound list and represents the messages that you want to allow through from the client to the server. The second array is the outbound list and represents the messages that you want to allow through from the server to the client.
Each match can have up to three fields:
address: This represents the exact address the message is being sent to. If you want to filter messages based on an exact address you use this field.address_re: This is a regular expression that will be matched against the address. If you want to filter messages based on a regular expression you use this field. If the address field is specified this field will be ignored.match: This allows you to filter messages based on their structure. Any fields in the match must exist in the message with the same values for them to be passed. This currently only works with JSON messages.When a message arrives at the bridge, it will look through the available permitted entries.
If an address field has been specified then the address must match exactly with the address of the message for it to be considered matched.
If an address field has not been specified and an address_re field has been specified then the regular expression in address_re must match with the address of the message for it to be considered matched.
If a match field has been specified, then also the structure of the message must match.
Here is an example:
var httpServer = vertx.createHttpServer();
var sockJSServer = vertx.createSockJSServer(httpServer);
sockJSServer.bridge({prefix : '/eventbus'},
[
// Let through any messages sent to 'demo.orderMgr'
{
address : 'demo.orderMgr'
},
// Allow calls to the address 'demo.persistor' as long as the messages
// have an action field with value 'find' and a collection field with value
// 'albums'
{
address : 'demo.persistor',
match : {
action : 'find',
collection : 'albums'
}
},
// Allow through any message with a field `wibble` with value `foo`.
{
match : {
wibble: 'foo'
}
}
],
[
// Let through any messages coming from address 'ticker.mystock'
{
address : 'ticker.mystock'
},
// Let through any messages from addresses starting with "news." (e.g. news.europe, news.usa, etc)
{
address_re : 'news\\..+'
}
]
);
server.listen(8080);
To let all messages through you can specify two arrays with a single empty JSON object which will match all messages.
...
sockJSServer.bridge({prefix : '/eventbus'}, [{}], [{}]);
...
Be very careful!
The bridge can also refuse to let certain messages through if the user is not authorised.
To enable this you need to make sure an instance of the vertx.auth-mgr module is available on the event bus. (Please see the modules manual for a full description of modules).
To tell the bridge that certain messages require authorisation before being passed, you add the field requires_auth with the value of true in the match. The default value is false. For example, the following match:
{
address : 'demo.persistor',
match : {
action : 'find',
collection : 'albums'
},
requires_auth: true
}
This tells the bridge that any messages to save orders in the orders collection, will only be passed if the user is successful authenticated (i.e. logged in ok) first.
When a message is sent from the client that requires authorisation, the client must pass a field sessionID with the message that contains the unique session ID that they obtained when they logged in with the auth-mgr.
When the bridge receives such a message, it will send a message to the auth-mgr to see if the session is authorised for that message. If the session is authorised the bridge will cache the authorisation for a certain amount of time (five minutes by default)
Vert.x lets you manipulate files on the file system. File system operations are asynchronous and take a handler function as the last argument. This function will be called when the operation is complete, or an error has occurred.
The first argument passed into the callback is an exception, if an error occurred. This will be null if the operation completed successfully. If the operation returns a result that will be passed in the second argument to the handler.
For convenience, we also provide synchronous forms of most operations. It's highly recommended the asynchronous forms are always used for real applications.
The synchronous form does not take a handler as an argument and returns its results directly. The name of the synchronous function is the same as the name as the asynchronous form with Sync appended.
Copies a file.
This function can be called in two different ways:
copy(source, destination, handler)Non recursive file copy. source is the source file name. destination is the destination file name.
Here's an example:
vertx.fileSystem.copy('foo.dat', 'bar.dat', function(err) {
if (!err) {
log.info('Copy was successful');
}
});
copy(source, destination, recursive, handler)Recursive copy. source is the source file name. destination is the destination file name. recursive is a boolean flag - if true and source is a directory, then a recursive copy of the directory and all its contents will be attempted.
Moves a file.
move(source, destination, handler)
source is the source file name. destination is the destination file name.
Truncates a file.
truncate(file, len, handler)
file is the file name of the file to truncate. len is the length in bytes to truncate it to.
Changes permissions on a file or directory.
This function can be called in two different ways:
chmod(file, perms, handler).Change permissions on a file.
file is the file name. perms is a Unix style permissions string made up of 9 characters. The first three are the owner's permissions. The second three are the group's permissions and the third three are others permissions. In each group of three if the first character is r then it represents a read permission. If the second character is w it represents write permission. If the third character is x it represents execute permission. If the entity does not have the permission the letter is replaced with -. Some examples:
rwxr-xr-x r--r--r--
chmod(file, perms, dirPerms, handler). Recursively change permissions on a directory. file is the directory name. perms is a Unix style permissions to apply recursively to any files in the directory. dirPerms is a Unix style permissions string to apply to the directory and any other child directories recursively.
Retrieve properties of a file.
props(file, handler)
file is the file name. The props are returned in the handler. The results is an object with the following properties:
creationTime. Time of file creation.lastAccessTime. Time of last file access.lastModifiedTime. Time file was last modified.isDirectory. This will have the value true if the file is a directory.isRegularFile. This will have the value true if the file is a regular file (not symlink or directory).isSymbolicLink. This will have the value true if the file is a symbolic link.isOther. This will have the value true if the file is another type.Here's an example:
vertx.fileSystem.props('some-file.txt', function(err, props) {
if (err) {
log.info('Failed to retrieve file props: ' + err);
} else {
log.info('File props are:');
log.info('Last accessed: ' + props.lastAccessTime);
// etc
}
});
Retrieve properties of a link. This is like props but should be used when you want to retrieve properties of a link itself without following it.
It takes the same arguments and provides the same results as props.
Create a hard link.
link(link, existing, handler)
link is the name of the link. existing is the existing file (i.e. where to point the link at).
Create a symbolic link.
symlink(link, existing, handler)
link is the name of the symlink. existing is the existing file (i.e. where to point the symlink at).
Unlink (delete) a link.
unlink(link, handler)
link is the name of the link to unlink.
Reads a symbolic link. I.e returns the path representing the file that the symbolic link specified by link points to.
readSymLink(link, handler)
link is the name of the link to read. An usage example would be:
vertx.fileSystem.readSymLink('somelink', function(err, res) {
if (!err) {
log.info('Link points at ' + res);
}
});
Deletes a file or recursively deletes a directory.
This function can be called in two ways:
delete(file, handler)Deletes a file. file is the file name.
delete(file, recursive, handler)If recursive is true, it deletes a directory with name file, recursively. Otherwise it just deletes a file.
Creates a directory.
This function can be called in three ways:
mkdir(dirname, handler)Makes a new empty directory with name dirname, and default permissions `
mkdir(dirname, createParents, handler)If createParents is true, this creates a new directory and creates any of its parents too. Here's an example
vertx.fileSystem.mkdir('a/b/c', true, function(err, res) {
if (!err) {
log.info('Directory created ok');
}
});
mkdir(dirname, createParents, perms, handler)Like mkdir(dirname, createParents, handler), but also allows permissions for the newly created director(ies) to be specified. perms is a Unix style permissions string as explained earlier.
Reads a directory. I.e. lists the contents of the directory.
This function can be called in two ways:
readDir(dirName)Lists the contents of a directory
readDir(dirName, filter)List only the contents of a directory which match the filter. Here's an example which only lists files with an extension txt in a directory.
vertx.fileSystem.readDir('mydirectory', '.*\.txt', function(err, res) {
if (!err) {
log.info('Directory contains these .txt files');
for (var i = 0; i < res.length; i++) {
log.info(res[i]);
}
}
});
The filter is a regular expression.
Read the entire contents of a file in one go. Be careful if using this with large files since the entire file will be stored in memory at once.
readFile(file). Where file is the file name of the file to read.
The body of the file will be returned as a Buffer in the handler.
Here is an example:
vertx.fileSystem.readFile('myfile.dat', function(err, res) {
if (!err) {
log.info('File contains: ' + res.length() + ' bytes');
}
});
Writes an entire Buffer or a string into a new file on disk.
writeFile(file, data, handler) Where file is the file name. data is a Buffer or string.
Creates a new empty file.
createFile(file, handler). Where file is the file name.
Checks if a file exists.
exists(file, handler). Where file is the file name.
The result is returned in the handler.
vertx.fileSystem.exists('some-file.txt', function(err, res) {
if (!err) {
log.info('File ' + (res ? 'exists' : 'does not exist'));
}
});
Get properties for the file system.
fsProps(file, handler). Where file is any file on the file system.
The result is returned in the handler. The result object has the following fields:
totalSpace. Total space on the file system in bytes.unallocatedSpace. Unallocated space on the file system in bytes.usableSpace. Usable space on the file system in bytes.Here is an example:
vertx.fileSystem.fsProps('mydir', function(err, res) {
if (!err) {
log.info('total space: ' + res.totalSpace);
// etc
}
});
Opens an asynchronous file for reading \ writing.
This function can be called in four different ways:
open(file, handler)Opens a file for reading and writing. file is the file name. It creates it if it does not already exist.
open(file, openFlags, handler)Opens a file using the specified open flags. file is the file name. openFlags is an integer representing whether to open the flag for reading or writing and whether to create it if it doesn't already exist.
openFlags is constructed from a combination of these three constants.
vertx.fileSystem.OPEN_READ = 1 vertx.fileSystem.OPEN_WRITE = 2 vertx.fileSystem.CREATE_NEW = 4
For example:
// Open for reading only var flags = vertx.FileSystem.OPEN_READ; // Open for reading and writing var flags = vertx.FileSystem.OPEN_READ | vertx.FileSystem.OPEN_WRITE;
When the file is opened, an instance of AsyncFile is passed into the result handler:
vertx.fileSystem.open('some-file.dat', vertx.FileSystem.OPEN_READ | vertx.FileSystem.OPEN_WRITE,
function(err, asyncFile) {
if (err) {
log.info('Failed to open file ' + err);
} else {
log.info('File opened ok');
asyncFile.close(); // Close it
}
});
open(file, openFlags, flush, handler)This is the same as open(file, openFlags, handler) but you can also specify whether any file write are flushed immediately to disk (sync'd).
Default is flush = false, so writes are just written into the OS cache.
open(file, openFlags, flush, perms, handler)This is the same as open(file, openFlags, flush, handler) but you can also specify the file permissions to give the file if it is created. Permissions is a Unix-style permissions string as explained earlier in the chapter.
Instances of AsyncFile are returned from calls to open and you use them to read from and write to files asynchronously. They allow asynchronous random file access.
AsyncFile can provide instances of ReadStream and WriteStream via the getReadStream and getWriteStream functions, so you can pump files to and from other stream objects such as net sockets, HTTP requests and responses, and WebSockets.
They also allow you to read and write directly to them.
To use an AsyncFile for random access writing you use the write method.
write(buffer, position, handler).
The parameters to the method are:
buffer: the buffer to write.position: an integer position in the file where to write the buffer. If the position is greater or equal to the size of the file, the file will be enlarged to accomodate the offset.Here is an example of random access writes:
vertx.fileSystem.open('some-file.dat', function(err, asyncFile) {
if (err) {
log.info('Failed to open file ' + err);
} else {
// File open, write a buffer 5 times into a file
var buff = new vertx.Buffer('foo');
for (var i = 0; i < 5; i++) {
asyncFile.write(buff, buff.length() * i, function(err) {
if (err) {
log.info('Failed to write ' + err);
} else {
log.info('Written ok');
}
});
}
}
});
To use an AsyncFile for random access reads you use the read method.
read(buffer, offset, position, length, handler).
The parameters to the method are:
buffer: the buffer into which the data will be read.offset: an integer offset into the buffer where the read data will be placed.position: the position in the file where to read data from.length: the number of bytes of data to readHere's an example of random access reads:
vertx.fileSystem.open('some-file.dat', function(err, asyncFile) {
if (err) {
log.info('Failed to open file ' + err);
} else {
var buff = new vertx.Buffer(1000);
for (var i = 0; i < 10; i++) {
asyncFile.read(buff, i * 100, i * 100, 100, function(err) {
if (err) {
log.info('Failed to read ' + err);
} else {
log.info('Read ok');
}
});
}
}
});
If the AsyncFile was not opened with flush = true, then you can manually flush any writes from the OS cache by calling the flush function.
ReadStream and WriteStreamUse the functions getReadStream and getWriteStream to get read and write streams. You can then use them with a pump to pump data to and from other read and write streams.
Here's an example of pumping data from a file on a client to a HTTP request:
var client = new vertx.HttpClient().setHost('foo.com');
vertx.fileSystem.open('some-file.dat', function(err, asyncFile) {
if (err) {
log.info('Failed to open file ' + err);
} else {
var request = client.put('/uploads', function(resp) {
log.info('resp status code ' + resp.statusCode);
});
var rs = asyncFile.getReadStream();
var pump = new vertx.Pump(rs, request);
pump.start();
rs.endHandler(function() {
// File sent, end HTTP requuest
request.end();
});
}
});
To close an AsyncFile call the close function. Closing is asynchronous and if you want to be notified when the close has been completed you can specify a handler function as an argument to close.