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const {Fragment: _Fragment, jsx: _jsx, jsxs: _jsxs} = arguments[0];
function _createMdxContent(props) {
  const _components = Object.assign({
    p: "p",
    h2: "h2",
    a: "a",
    code: "code",
    pre: "pre",
    span: "span",
    h3: "h3",
    ul: "ul",
    li: "li"
  }, props.components), {Gist, Alert} = _components;
  if (!Alert) _missingMdxReference("Alert", true);
  if (!Gist) _missingMdxReference("Gist", true);
  return _jsxs(_Fragment, {
    children: [_jsx(_components.p, {
      children: "As part of my hobby project to con­trol Rasp­ber­ryPi using Google Home Mini and/or Alexa, I wanted to write a very sim­ple TCP client that keeps a con­nec­tion open to one of my cus­tom writ­ten server in cloud (I will write an­other blog post to cover the server side on a later date). The re­quire­ment of the client is to send a shared se­cret upon con­nect­ing and then keep wait­ing for mes­sage from server. Vert.x, Kotlin and Gra­dle allow rapid de­vel­op­ment of such project. The gen­er­ated jar can be ex­e­cuted on Rasp­berry Pi. These steps out­line the project setup and re­lated source code to show­case a Vert.x and Kotlin project with Gra­dle."
    }), "\n", _jsxs(_components.h2, {
      id: "project-directory-structure",
      children: [_jsx(_components.a, {
        "aria-hidden": true,
        tabIndex: "-1",
        className: "heading-anchor",
        href: "#project-directory-structure"
      }), "Project Directory Structure"]
    }), "\n", _jsxs(_components.p, {
      children: ["From com­mand line (or via Win­dows Ex­plorer, what­ever you pre­fer to use) cre­ate a di­rec­tory for project,for in­stance ", _jsx(_components.code, {
        children: "vertx-net-client"
      }), ". Since we are using Kotlin, we will place all Kotlin files in ", _jsx(_components.code, {
        children: "src/main/kotlin"
      }), " folder. The ", _jsx(_components.code, {
        children: "src/main/resources"
      }), " folder will con­tain our log­ging con­fig­u­ra­tion re­lated files."]
    }), "\n", _jsx(_components.pre, {
      children: _jsxs(_components.code, {
        className: "hljs language-css",
        children: ["cd vertx-net-client\nmkdir -", _jsx(_components.span, {
          className: "hljs-selector-tag",
          children: "p"
        }), " ", _jsx(_components.span, {
          className: "hljs-attribute",
          children: "src"
        }), "/", _jsx(_components.span, {
          className: "hljs-selector-tag",
          children: "main"
        }), "/kotlin\nmkdir -", _jsx(_components.span, {
          className: "hljs-selector-tag",
          children: "p"
        }), " ", _jsx(_components.span, {
          className: "hljs-attribute",
          children: "src"
        }), "/", _jsx(_components.span, {
          className: "hljs-selector-tag",
          children: "main"
        }), "/resources\n"]
      })
    }), "\n", _jsxs(_components.h3, {
      id: "project-files",
      children: [_jsx(_components.a, {
        "aria-hidden": true,
        tabIndex: "-1",
        className: "heading-anchor",
        href: "#project-files"
      }), "Project Files"]
    }), "\n", _jsx(_components.p, {
      children: "We need to add fol­low­ing files in the project"
    }), "\n", _jsxs(_components.ul, {
      children: ["\n", _jsxs(_components.li, {
        children: [_jsx(_components.code, {
          children: ".gitignore"
        }), "\nIf you want to check your project into git, you may con­sider adding fol­low­ing ", _jsx(_components.code, {
          children: ".gitignore"
        }), " file at root of your project"]
      }), "\n"]
    }), "\n", _jsx(Gist, {
      url: "https://gist.github.com/usmansaleem/b5838484a20cb8b08f236f2265ad7a8e"
    }), "\n", _jsxs(_components.ul, {
      children: ["\n", _jsxs(_components.li, {
        children: [_jsx(_components.code, {
          children: "logback.xml"
        }), "\nThis ex­am­ple is using slf4j and log­back for log­ging. If you de­cide to use it in your project, you may also add fol­low­ing log­back.xml file in ", _jsx(_components.code, {
          children: "src/main/resources"
        }), ". Mod­ify it as per your re­quire­ments. This ex­am­ple will\nlog on con­sole."]
      }), "\n"]
    }), "\n", _jsx(Gist, {
      url: "https://gist.github.com/usmansaleem/750c6d1cad0721b52be2ff00f758fb9f"
    }), "\n", _jsxs(_components.h2, {
      id: "gradle-setup",
      children: [_jsx(_components.a, {
        "aria-hidden": true,
        tabIndex: "-1",
        className: "heading-anchor",
        href: "#gradle-setup"
      }), "Gradle Setup"]
    }), "\n", _jsxs(_components.p, {
      children: ["We will use Gra­dle build sys­tem for this project. If you don’t al­ready have Gra­dle avail­able on your sys­tem, down­load and unzip gra­dle in a di­rec­tory of your choice (", _jsx(_components.code, {
        children: "$GRADLE_HOME"
      }), " is used here to rep­re­sent this di­rec­tory). This gra­dle dis­tri­b­u­tion will be used as a start­ing point to cre­ate Gra­dle wrap­per scripts for our project. These scripts will allow our project to down­load and use cor­rect ver­sion of gra­dle dis­tri­b­u­tion au­to­mat­i­cally with­out mess­ing up sys­tem. Re­ally use­ful when build­ing your project on CI tool or on any other de­vel­oper’s ma­chine."]
    }), "\n", _jsx(_components.p, {
      children: "Run fol­low­ing com­mand in project’s di­rec­tory"
    }), "\n", _jsx(_components.pre, {
      children: _jsxs(_components.code, {
        className: "hljs language-bash",
        children: [_jsx(_components.span, {
          className: "hljs-variable",
          children: "$GRADLE_HOME"
        }), "/bin/gradle wrapper\n"]
      })
    }), "\n", _jsx(_components.p, {
      children: "The above com­mands will gen­er­ate fol­low­ing files and di­rec­to­ries."
    }), "\n", _jsx(_components.pre, {
      children: _jsx(_components.code, {
        className: "hljs language-bash",
        children: "gradle/  gradlew  gradlew.bat\n"
      })
    }), "\n", _jsxs(_components.h3, {
      id: "gradle-build-file-buildgradle",
      children: [_jsx(_components.a, {
        "aria-hidden": true,
        tabIndex: "-1",
        className: "heading-anchor",
        href: "#gradle-build-file-buildgradle"
      }), "Gradle build file ", _jsx(_components.code, {
        children: "build.gradle"
      })]
    }), "\n", _jsxs(_components.p, {
      children: ["Cre­ate (and/or copy and mod­ify) fol­low­ing ", _jsx(_components.code, {
        children: "build.gradle"
      }), " in your project’s root di­rec­tory. Our ex­am­ple gra­dle build file is using ", _jsx(_components.a, {
        href: "https://github.com/jponge/vertx-gradle-plugin/",
        children: "vertx-​gradle-plugin"
      }), "."]
    }), "\n", _jsx(Gist, {
      url: "https://gist.github.com/usmansaleem/e723f25b827e0a925eaef2957a80132d"
    }), "\n", _jsx(_components.p, {
      children: "In the project di­rec­tory, run fol­low­ing com­mand to down­load local gra­dle dis­tri­b­u­tion:"
    }), "\n", _jsx(_components.pre, {
      children: _jsx(_components.code, {
        className: "hljs language-bash",
        children: "./gradlew\n"
      })
    }), "\n", _jsxs(_components.p, {
      children: ["(or ", _jsx(_components.code, {
        children: ".\\gradlew.bat"
      }), " if in Win­dows)"]
    }), "\n", _jsx(_components.p, {
      children: "At this stage we should have fol­low­ing file struc­ture. This is also a good time to com­mit changes if you are work­ing with git."
    }), "\n", _jsxs(_components.ul, {
      children: ["\n", _jsx(_components.li, {
        children: _jsx(_components.code, {
          children: ".gitignore"
        })
      }), "\n", _jsx(_components.li, {
        children: _jsx(_components.code, {
          children: "build.gradle"
        })
      }), "\n", _jsx(_components.li, {
        children: _jsx(_components.code, {
          children: "gradle/wrapper/gradle-wrapper.jar"
        })
      }), "\n", _jsx(_components.li, {
        children: _jsx(_components.code, {
          children: "gradle/wrapper/gradle-wrapper.properties"
        })
      }), "\n", _jsx(_components.li, {
        children: _jsx(_components.code, {
          children: "gradlew"
        })
      }), "\n", _jsx(_components.li, {
        children: _jsx(_components.code, {
          children: "gradlew.bat"
        })
      }), "\n", _jsx(_components.li, {
        children: _jsx(_components.code, {
          children: "src/main/resources/logback.xml"
        })
      }), "\n"]
    }), "\n", _jsx(_components.p, {
      children: "Now that our project struc­ture is ready, time to add the meat of the project. You may use any IDE of your choice. My pref­er­ence is In­tel­liJ IDEA."
    }), "\n", _jsxs(_components.p, {
      children: ["Cre­ate a new pack­age under ", _jsx(_components.code, {
        children: "src/main/kotlin"
      }), ". The pack­age name should be adapted from the fol­low­ing sec­tion of ", _jsx(_components.code, {
        children: "build.gradle"
      })]
    }), "\n", _jsx(_components.pre, {
      children: _jsxs(_components.code, {
        className: "hljs language-ini",
        children: ["vertx {\n    ", _jsx(_components.span, {
          className: "hljs-attr",
          children: "mainVerticle"
        }), " = ", _jsx(_components.span, {
          className: "hljs-string",
          children: "\"info.usmans.blog.vertx.NetClientVerticle\""
        }), "\n}\n"]
      })
    }), "\n", _jsxs(_components.p, {
      children: ["From the above ex­am­ple, the pack­age name is ", _jsx(_components.code, {
        children: "info.usmans.blog.vertx"
      })]
    }), "\n", _jsxs(_components.p, {
      children: ["Add a new Kotlin Class/file in ", _jsx(_components.code, {
        children: "src/main/kotlin/info/usmans/blog/vertx"
      }), " as ", _jsx(_components.code, {
        children: "NetClientVerticle.kt"
      })]
    }), "\n", _jsx(_components.p, {
      children: "The con­tents of this class is as fol­lows"
    }), "\n", _jsx(Gist, {
      url: "https://gist.github.com/usmansaleem/2a176a7b752fcb72f7f31964809696fe"
    }), "\n", _jsxs(_components.h2, {
      id: "explaining-the-code",
      children: [_jsx(_components.a, {
        "aria-hidden": true,
        tabIndex: "-1",
        className: "heading-anchor",
        href: "#explaining-the-code"
      }), "Explaining the Code"]
    }), "\n", _jsxs(_components.p, {
      children: ["The ", _jsx(_components.code, {
        children: "fun main(args: Array<String>)"
      }), " is not strictly re­quired, it quickly al­lows run­ning the Vert.x ver­ti­cle from within IDE. You will also no­tice a small hack in the method for set­ting sys­tem prop­erty ", _jsx(_components.code, {
        children: "vertx.disableDnsResolver"
      }), " which is to avoid a Netty bug that I ob­served when run­ning on Win­dows ma­chine and re­mote server is down. Of course, since we are using vertx-​gradle-plugin, we can also use ", _jsx(_components.code, {
        children: "gradle vertxRun"
      }), " to run our ver­ti­cle. In this case the ", _jsx(_components.code, {
        children: "main"
      }), " method will not get called."]
    }), "\n", _jsxs(_components.p, {
      children: ["The ", _jsx(_components.code, {
        children: "override fun start()"
      }), " method calls ", _jsx(_components.code, {
        children: "fireReconnectTimer"
      }), " which in turn calls ", _jsx(_components.code, {
        children: "reconnect"
      }), " method. ", _jsx(_components.code, {
        children: "reconnect"
      }), " method con­tains the con­nec­tion logic to server as well as it calls ", _jsx(_components.code, {
        children: "fireReconnectTimer"
      }), " if it is un­able to con­nect to server or dis­con­nects from server. In ", _jsx(_components.code, {
        children: "reconnect"
      }), " method the ", _jsx(_components.code, {
        children: "socket.handler"
      }), " gets called when server send mes­sage to client."]
    }), "\n", _jsx(_components.pre, {
      children: _jsxs(_components.code, {
        className: "hljs language-kotlin",
        children: ["socket.handler({ ", _jsx(_components.span, {
          className: "hljs-keyword",
          children: "data"
        }), " ->\n                        logger.info(", _jsxs(_components.span, {
          className: "hljs-string",
          children: ["\"Data received: ", _jsx(_components.span, {
            className: "hljs-subst",
            children: "${data}"
          }), "\""]
        }), ")\n                        ", _jsxs(_components.span, {
          className: "hljs-comment",
          children: ["//", _jsx(_components.span, {
            className: "hljs-doctag",
            children: "TODO:"
          }), " Do the work here ..."]
        }), "\n               })\n"]
      })
    }), "\n", _jsxs(_components.h2, {
      id: "distributing-the-project",
      children: [_jsx(_components.a, {
        "aria-hidden": true,
        tabIndex: "-1",
        className: "heading-anchor",
        href: "#distributing-the-project"
      }), "Distributing the project"]
    }), "\n", _jsxs(_components.p, {
      children: ["To cre­ate re­dis­trib­utable jar, use ", _jsx(_components.code, {
        children: "./gradlew shadowJar"
      }), " com­mand. Or if using In­tel­liJ: from Gra­dle projects, Tasks, shadow, shad­ow­Jar (right click run). This com­mand will gen­er­ate ", _jsx(_components.code, {
        children: "./build/libs/vertx-net-client-fat.jar"
      }), "."]
    }), "\n", _jsxs(_components.h3, {
      id: "executing-the-client",
      children: [_jsx(_components.a, {
        "aria-hidden": true,
        tabIndex: "-1",
        className: "heading-anchor",
        href: "#executing-the-client"
      }), "Executing the client"]
    }), "\n", _jsx(_components.p, {
      children: "The client jar can be ex­e­cuted using fol­low­ing com­mand:"
    }), "\n", _jsx(_components.pre, {
      children: _jsxs(_components.code, {
        className: "hljs language-bash",
        children: [" java -DserverHost=127.0.0.1 -DserverPort=8888 -DconnectMessage=", _jsx(_components.span, {
          className: "hljs-string",
          children: "\"hello\""
        }), " -jar vertx-net-client-full.jar\n"]
      })
    }), "\n", _jsxs(_components.p, {
      children: ["If you wish to use SLF4J for Vert.x in­ter­nal log­ging, you need to pass sys­tem prop­erty ", _jsx(_components.code, {
        children: "vertx.logger-delegate-factory-class-name"
      }), " with value of ", _jsx(_components.code, {
        children: "io.vertx.core.logging.SLF4JLogDelegateFactory"
      }), ". The final com­mand would look like:"]
    }), "\n", _jsx(_components.pre, {
      children: _jsxs(_components.code, {
        className: "hljs language-bash",
        children: ["java -DserverHost=127.0.0.1 -DserverPort=8888 -DconnectMessage=", _jsx(_components.span, {
          className: "hljs-string",
          children: "\"hello\""
        }), " -Dvertx.logger-delegate-factory-class-name=", _jsx(_components.span, {
          className: "hljs-string",
          children: "\"io.vertx.core.logging.SLF4JLogDelegateFactory\""
        }), " -jar vertx-net-client-full.jar\n"]
      })
    }), "\n", _jsx(_components.p, {
      children: "You can con­fig­ure Vert.x log­ging lev­els in log­back.xml file if re­quired."
    }), "\n", _jsxs(_components.h2, {
      id: "conclusion",
      children: [_jsx(_components.a, {
        "aria-hidden": true,
        tabIndex: "-1",
        className: "heading-anchor",
        href: "#conclusion"
      }), "Conclusion"]
    }), "\n", _jsx(_components.p, {
      children: "This post de­scribes how easy it is to cre­ate a sim­ple TCP client using Vert.x, Kotlin and Gra­dle build sys­tem. Hope­fully the tech­niques shown here will serve as a start­ing point for your next DIY project."
    }), "\n", _jsx(Alert, {
      info: true,
      children: _jsxs(_components.p, {
        children: ["This post is adapted and re­pro­duced from ", _jsx(_components.a, {
          href: "https://usmans.info/view/blog/tcp_client_using_vertx_kotlin_gradle",
          children: "au­thor’s blog post"
        })]
      })
    })]
  });
}
function MDXContent(props = {}) {
  const {wrapper: MDXLayout} = props.components || ({});
  return MDXLayout ? _jsx(MDXLayout, Object.assign({}, props, {
    children: _jsx(_createMdxContent, props)
  })) : _createMdxContent(props);
}
return {
  default: MDXContent
};
function _missingMdxReference(id, component) {
  throw new Error("Expected " + (component ? "component" : "object") + " `" + id + "` to be defined: you likely forgot to import, pass, or provide it.");
}


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TCP Client using Eclipse Vert.x, Kotlin and Gradle build

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TCP Client using Eclipse Vert.x, Kotlin and Gradle build

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