I'm using Intellij IDE and I want to implement websocket in a javascript that's evaluated by Nashorn Java8. I have the following line at the top of my javascript file:
var socket = new WebSocket("http://localhost:12345/echo");
Yet it is giving me this error:
Caused by: javax.script.ScriptException: ReferenceError: "WebSocket" is not defined in src/sample/hello.js at line number 8
at jdk.nashorn.api.scripting.NashornScriptEngine.throwAsScriptException(NashornScriptEngine.java:564)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:548)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:528)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:524)
at jdk.nashorn.api.scripting.NashornScriptEngine.eval(NashornScriptEngine.java:194)
at javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:264)
at sample.Main.start(Main.java:28)
at com.sun.javafx.application.LauncherImpl$8.run(LauncherImpl.java:837)
at com.sun.javafx.application.PlatformImpl$7.run(PlatformImpl.java:335)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:301)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:298)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl$6.run(PlatformImpl.java:298)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$300(WinApplication.java:39)
at com.sun.glass.ui.win.WinApplication$4$1.run(WinApplication.java:112)
... 1 more
Caused by: src/sample/hello.js:8 ReferenceError: "WebSocket" is not defined
at jdk.nashorn.internal.runtime.ECMAErrors.error(ECMAErrors.java:56)
at jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:318)
at jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:290)
at jdk.nashorn.api.scripting.NashornScriptEngine.__noSuchProperty__(NashornScriptEngine.java:274)
at jdk.nashorn.internal.scripts.Script$engine._L35(nashorn:engine/resources/engine.js:37)
at jdk.nashorn.internal.scripts.Script$hello.runScript(src/sample/hello.js:8)
at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:498)
at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:206)
at jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:378)
at jdk.nashorn.internal.runtime.Context.evaluateSource(Context.java:885)
at jdk.nashorn.internal.runtime.Context.load(Context.java:563)
at jdk.nashorn.internal.objects.Global.load(Global.java:857)
at jdk.nashorn.internal.scripts.Script$\^eval\_.runScript(<eval>:1)
at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:498)
at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:206)
at jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:378)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:546)
... 16 more
WebSocket is defined in the HTML5 plugin, so I am not really sure why Nashorn can't find the websocket in the library.
Nashorn is a ECMAScript5 compatible JavaScript engine. WebSocket API is not a part of ECMAScript 5 but browser API. You can implement WebSocket API using any available Java WebSocket client libraries.
For example, http://jfarcand.wordpress.com/2011/12/21/writing-websocket-clients-using-asynchttpclient/ or https://tyrus.java.net/documentation/1.7/user-guide.html#websocket-client-endpoint
In case of vertx framework, it has API to connect to WebSocket endpoint https://github.com/vert-x/vertx-examples/blob/master/src/raw/javascript/websockets/ws_client.js