Bug 471356 : Added example of connecting to and using ParaViewWeb service.

Created by: scottwittenburg

Bug 471356

Signed-off-by: Scott Wittenburg scott.wittenburg@kitware.com

src/org.eclipse.ice.viz.service/src/org/eclipse/ice/viz/service/HttpParaViewWebClient.java

+/*******************************************************************************
+ * Copyright (c) 2014, 2015 Kitware Inc. and UT-Battelle, LLC.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Sebastien Jourdain (Kitware Inc.) - initial API and implementation and/or 
+ *      initial documentation
+ *    Jordan Deyton (UT-Battelle, LLC.) - implemented disconnect()
+ *    Jordan Deyton (UT-Battelle, LLC.) - updated to use GSON
+ *    Jordan Deyton (UT-Battelle, LLC.) - removed temporary print statements; 
+ *      rearranged return value in connect()
+ *******************************************************************************/
+package org.eclipse.ice.viz.service.paraview.web;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.google.gson.JsonPrimitive;
+import com.google.gson.JsonSyntaxException;
+
+/**
+ * TODO Documentation
+ * 
+ * @author Sebastien Jourdain
+ *
+ */
+public class HttpParaViewWebClient implements IParaViewWebClient {
+
+	/**
+	 * 
+	 */
+	private String baseEndPointURL;
+
+	/**
+	 * 
+	 */
+	private final ExecutorService requestExecutor;
+
+	/**
+	 * The default constructor.
+	 */
+	public HttpParaViewWebClient() {
+		requestExecutor = Executors.newSingleThreadExecutor();
+	}
+
+	/*
+	 * Implements a method from ParaViewWebClient.
+	 */
+	private JsonObject makeRequest(String method, JsonObject content) {
+
+		JsonObject retVal = null;
+
+		URL url;
+		HttpURLConnection connection = null;
+		try {
+			// Create connection
+			String fullUrl = baseEndPointURL + method;
+			url = new URL(fullUrl);
+			connection = (HttpURLConnection) url.openConnection();
+			connection.setRequestMethod("POST");
+			connection.setRequestProperty("Content-Type",
+					"application/octetstream");
+			connection.setRequestProperty("Content-Length",
+					Integer.toString(content.entrySet().size()));
+			connection.setRequestProperty("Content-Language", "en-US");
+
+			connection.setUseCaches(false);
+			connection.setDoInput(true);
+			connection.setDoOutput(true);
+
+			// Send request
+			connection.getOutputStream().write(content.toString().getBytes());
+			connection.getOutputStream().flush();
+			connection.getOutputStream().close();
+
+			// Get Response
+			InputStream is = connection.getInputStream();
+			BufferedReader rd = new BufferedReader(new InputStreamReader(is));
+			String line;
+			StringBuffer response = new StringBuffer();
+			while ((line = rd.readLine()) != null) {
+				response.append(line);
+				response.append('\n');
+			}
+			rd.close();
+
+			// Parse the response into a JsonObject if possible.
+			try {
+				JsonParser parser = new JsonParser();
+				JsonElement element = parser.parse(response.toString());
+				if (element.isJsonObject()) {
+					retVal = element.getAsJsonObject();
+				}
+			} catch (JsonSyntaxException e) {
+				// Do nothing if the response is not a parseable JsonObject.
+			}
+			// If a response could not be processed, create an empty one.
+			if (retVal == null) {
+				retVal = new JsonObject();
+			}
+		} catch (Exception e) {
+			e.printStackTrace();
+			// If there was an error connecting, try to disconnect.
+			if (connection != null) {
+				connection.disconnect();
+			}
+		}
+
+		return retVal;
+	}
+
+	/*
+	 * Implements a method from ParaViewWebClient.
+	 */
+	@Override
+	public Future<Boolean> connect(String url) {
+		this.baseEndPointURL = url;
+
+		return requestExecutor.submit(new Callable<Boolean>() {
+			@Override
+			public Boolean call() throws Exception {
+
+				boolean connected = false;
+
+				// ---- Send a HEAD request. ---- //
+				URL url = new URL(baseEndPointURL);
+				HttpURLConnection connection = (HttpURLConnection) url
+						.openConnection();
+				connection.setRequestMethod("HEAD");
+				connection.setDoInput(true);
+				connection.setDoOutput(true);
+				// ------------------------------ //
+
+				// ---- Get the response. ---- //
+				// Note: We let the ExecutorService handle the timeout.
+
+				// Determine the connection code from the request.
+				int code = -1;
+				try {
+					code = connection.getResponseCode();
+					if (code == HttpURLConnection.HTTP_OK) {
+						connected = true;
+					}
+				} catch (IOException e) {
+					// There was an error. The connection failed.
+				}
+				// --------------------------- //
+
+				return connected;
+			}
+		});
+	}
+
+	/*
+	 * Implements a method from ParaViewWebClient.
+	 */
+	@Override
+	public Future<Boolean> disconnect() {
+		return requestExecutor.submit(new Callable<Boolean>() {
+			@Override
+			public Boolean call() throws Exception {
+				return true;
+			}
+		});
+	}
+
+	/*
+	 * Implements a method from ParaViewWebClient.
+	 */
+	@Override
+	public Future<JsonObject> render(int viewId, int quality, int width,
+			int height) {
+
+		// Set up the size array (with x height).
+		JsonArray size = new JsonArray();
+		size.add(new JsonPrimitive(width));
+		size.add(new JsonPrimitive(height));
+
+		// Set up the content of the request.
+		JsonObject reqObj = new JsonObject();
+		reqObj.add("size", size);
+		reqObj.addProperty("view", viewId);
+		reqObj.addProperty("quality", quality);
+		reqObj.addProperty("localtime", System.currentTimeMillis());
+
+		// Set up the main request object. Note that it *must* provide an "args"
+		// property set to a JSON array.
+		JsonArray args = new JsonArray();
+		args.add(reqObj);
+		final JsonObject mainObj = new JsonObject();
+		mainObj.add("args", args);
+
+		Callable<JsonObject> request = new Callable<JsonObject>() {
+			public JsonObject call() throws Exception {
+				return makeRequest("viewport.image.render", mainObj);
+			}
+		};
+		return requestExecutor.submit(request);
+	}
+
+	/*
+	 * Implements a method from ParaViewWebClient.
+	 */
+	@Override
+	public Future<JsonObject> event(int viewId, double x, double y,
+			String action, boolean[] mouseState) {
+
+		// Set up the content of the request.
+		JsonObject reqObj = new JsonObject();
+		reqObj.addProperty("view", viewId);
+		reqObj.addProperty("x", x);
+		reqObj.addProperty("y", y);
+		reqObj.addProperty("buttonLeft", mouseState[0] ? 1 : 0);
+		reqObj.addProperty("buttonMiddle", mouseState[1] ? 1 : 0);
+		reqObj.addProperty("buttonRight", mouseState[2] ? 1 : 0);
+		reqObj.addProperty("shiftKey", mouseState[3] ? 1 : 0);
+		reqObj.addProperty("ctrlKey", mouseState[4] ? 1 : 0);
+		reqObj.addProperty("altKey", mouseState[5] ? 1 : 0);
+		reqObj.addProperty("metaKey", mouseState[6] ? 1 : 0);
+		reqObj.addProperty("action", action);
+
+		// Set up the main request object. Note that it *must* provide an "args"
+		// property set to a JSON array.
+		JsonArray args = new JsonArray();
+		args.add(reqObj);
+		final JsonObject mainObj = new JsonObject();
+		mainObj.add("args", args);
+
+		Callable<JsonObject> request = new Callable<JsonObject>() {
+			public JsonObject call() throws Exception {
+				return makeRequest("viewport.mouse.interaction", mainObj);
+			}
+		};
+		return requestExecutor.submit(request);
+	}
+
+	/*
+	 * Implements a method from ParaViewWebClient.
+	 */
+	@Override
+	public Future<JsonObject> call(String method, JsonArray args) {
+
+		final String methodRef = method;
+		final JsonObject reqObj = new JsonObject();
+
+		reqObj.add("args", args);
+		Callable<JsonObject> request = new Callable<JsonObject>() {
+			public JsonObject call() throws Exception {
+				return makeRequest(methodRef, reqObj);
+			}
+		};
+		return requestExecutor.submit(request);
+	}
+}