Added samples showcasing XMPP (#182)

* Added samples showcasing XMPP

Added a number of Servlet based examples for XMPP

* Minor fixes to my previous commit

appengine/xmpp/README.md

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+# Google App Engine Standard Environment XMPP Java API Overview
+
+This sample demonstrates how to use XMPP Java API on Google App Engine.
+
+See the [Google App Engine standard environment documentation][ae-docs] for more
+detailed instructions.
+
+[ae-docs]: https://cloud.google.com/appengine/docs/java/
+
+## Setup
+1. Update the `<application>` tag in `src/main/webapp/WEB-INF/appengine-web.xml`
+   with your project name.
+1. Update the `<version>` tag in `src/main/webapp/WEB-INF/appengine-web.xml`
+   with your version name.
+
+## Running locally
+    $ mvn appengine:devserver
+
+## Deploying
+    $ mvn appengine:update

appengine/xmpp/pom.xml

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+<!--
+Copyright 2015 Google Inc. All Rights Reserved.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+<project>
+  <modelVersion>4.0.0</modelVersion>
+  <packaging>war</packaging>
+  <version>1.0-SNAPSHOT</version>
+  <groupId>com.example.appengine</groupId>
+  <artifactId>appengine-xmpp</artifactId>
+  <parent>
+    <groupId>com.google.cloud</groupId>
+    <artifactId>doc-samples</artifactId>
+    <version>1.0.0</version>
+    <relativePath>../..</relativePath>
+  </parent>
+  <dependencies>
+    <dependency>
+      <groupId>javax.servlet</groupId>
+      <artifactId>servlet-api</artifactId>
+      <type>jar</type>
+      <scope>provided</scope>
+    </dependency>
+
+    <!-- [START dependencies] -->
+    <!-- Parent POM defines ${appengine.sdk.version} (updates frequently). -->
+    <dependency>
+      <groupId>com.google.appengine</groupId>
+      <artifactId>appengine-api-1.0-sdk</artifactId>
+    </dependency>
+    <!-- [END dependencies] -->
+
+    <dependency>
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava</artifactId>
+      <version>19.0</version>
+    </dependency>
+
+  </dependencies>
+  <build>
+    <!-- for hot reload of the web application -->
+    <outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <version>3.3</version>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <configuration>
+          <source>1.7</source>
+          <target>1.7</target>
+        </configuration>
+      </plugin>
+      <!-- Parent POM defines ${appengine.sdk.version} (updates frequently). -->
+      <plugin>
+        <groupId>com.google.appengine</groupId>
+        <artifactId>appengine-maven-plugin</artifactId>
+        <version>${appengine.sdk.version}</version>
+      </plugin>
+    </plugins>
+  </build>
+</project>

appengine/xmpp/src/main/java/com/example/appengine/xmpp/ErrorServlet.java

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+/**
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.appengine.xmpp;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.logging.Logger;
+import javax.servlet.ServletInputStream;
+import javax.servlet.http.*;
+import com.google.common.io.ByteStreams;
+
+// [START example]
+@SuppressWarnings("serial")
+public class ErrorServlet extends HttpServlet {
+
+   private static final Logger log = Logger.getLogger(ErrorServlet.class.getName());
+
+    @Override
+    public void doPost(HttpServletRequest req, HttpServletResponse res)
+          throws IOException {
+
+        // Parse the POST data, which is sent as a MIME stream containing the stanza.
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        ServletInputStream inputStream = req.getInputStream();
+        ByteStreams.copy(inputStream, baos);
+
+        // Log the error
+        log.warning("Error stanza received: " + baos.toString());
+    }
+}
+// [END example]

appengine/xmpp/src/main/java/com/example/appengine/xmpp/MessageReceiverServlet.java

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+/**
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.appengine.xmpp;
+
+import java.io.IOException;
+import java.util.logging.Logger;
+import javax.servlet.http.*;
+import com.google.appengine.api.xmpp.JID;
+import com.google.appengine.api.xmpp.Message;
+import com.google.appengine.api.xmpp.XMPPService;
+import com.google.appengine.api.xmpp.XMPPServiceFactory;
+
+// [START example]
+@SuppressWarnings("serial")
+public class MessageReceiverServlet extends HttpServlet {
+
+   private static final Logger log = Logger.getLogger(MessageReceiverServlet.class.getName());
+
+    @Override
+    public void doPost(HttpServletRequest req, HttpServletResponse res)
+          throws IOException {
+
+        XMPPService xmpp = XMPPServiceFactory.getXMPPService();
+        Message message = xmpp.parseMessage(req);
+
+        JID fromJid = message.getFromJid();
+        String body = message.getBody();
+
+        log.info("Received a message with id: " + fromJid + " and body: " + body);
+        // ...
+    }
+}
+// [END example]

appengine/xmpp/src/main/java/com/example/appengine/xmpp/MessageSenderServlet.java

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+/**
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.appengine.xmpp;
+
+import java.io.IOException;
+import java.util.logging.Logger;
+import javax.servlet.http.*;
+import com.google.appengine.api.xmpp.JID;
+import com.google.appengine.api.xmpp.Message;
+import com.google.appengine.api.xmpp.MessageBuilder;
+import com.google.appengine.api.xmpp.SendResponse;
+import com.google.appengine.api.xmpp.XMPPService;
+import com.google.appengine.api.xmpp.XMPPServiceFactory;
+
+// [START example]
+@SuppressWarnings("serial")
+public class MessageSenderServlet extends HttpServlet {
+
+   private static final Logger log = Logger.getLogger(MessageSenderServlet.class.getName());
+
+    @Override
+    public void doGet(HttpServletRequest req, HttpServletResponse res)
+          throws IOException {
+
+        JID jid = new JID("[email protected]");
+        String msgBody = "Someone has sent you a gift on Example.com. To view: http://example.com/gifts/";
+        Message msg = new MessageBuilder()
+            .withRecipientJids(jid)
+            .withBody(msgBody)
+            .build();
+
+        boolean messageSent = false;
+        XMPPService xmpp = XMPPServiceFactory.getXMPPService();
+        SendResponse status = xmpp.sendMessage(msg);
+        messageSent = (status.getStatusMap().get(jid) == SendResponse.Status.SUCCESS);
+
+        log.info("Message sent? " + messageSent);
+
+        if (!messageSent) {
+            // Send an email message instead...
+        }
+    }
+}
+// [END example]

appengine/xmpp/src/main/java/com/example/appengine/xmpp/PresenceServlet.java

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+/**
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.appengine.xmpp;
+
+import java.io.IOException;
+import java.util.logging.Logger;
+import javax.servlet.http.*;
+import com.google.appengine.api.xmpp.Presence;
+import com.google.appengine.api.xmpp.PresenceType;
+import com.google.appengine.api.xmpp.XMPPService;
+import com.google.appengine.api.xmpp.XMPPServiceFactory;
+
+// [START example]
+@SuppressWarnings("serial")
+public class PresenceServlet extends HttpServlet {
+
+   private static final Logger log = Logger.getLogger(PresenceServlet.class.getName());
+
+    @Override
+    public void doPost(HttpServletRequest req, HttpServletResponse res)
+          throws IOException {
+
+        XMPPService xmpp = XMPPServiceFactory.getXMPPService();
+        Presence presence = xmpp.parsePresence(req);
+
+        // Split the XMPP address (e.g., [email protected])
+        // from the resource (e.g., gmail.CD6EBC4A)
+        String from = presence.getFromJid().getId().split("/")[0];
+
+        log.info("Received presence from: " + from);
+
+        // Mirror the contact's presence back to them
+        xmpp.sendPresence(presence.getFromJid(), PresenceType.AVAILABLE, presence.getPresenceShow(), presence.getStatus());
+    }
+}
+// [END example]

appengine/xmpp/src/main/java/com/example/appengine/xmpp/SubscriptionServlet.java

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+/**
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.appengine.xmpp;
+
+import java.io.IOException;
+import java.util.logging.Logger;
+import javax.servlet.http.*;
+import com.google.appengine.api.xmpp.Subscription;
+import com.google.appengine.api.xmpp.XMPPService;
+import com.google.appengine.api.xmpp.XMPPServiceFactory;
+
+// [START example]
+@SuppressWarnings("serial")
+public class SubscriptionServlet extends HttpServlet {
+
+   private static final Logger log = Logger.getLogger(SubscriptionServlet.class.getName());
+
+    @Override
+    public void doPost(HttpServletRequest req, HttpServletResponse res)
+          throws IOException {
+
+        XMPPService xmppService = XMPPServiceFactory.getXMPPService();
+        Subscription sub = xmppService.parseSubscription(req);
+
+        // Split the bare XMPP address (e.g., [email protected])
+        // from the resource (e.g., gmail.CD6EBC4A)
+        String from = sub.getFromJid().getId().split("/")[0];
+
+        log.info("Received subscription event from: " + from);
+    }
+}
+// [END example]

appengine/xmpp/src/main/webapp/WEB-INF/appengine-web.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<!-- [START_EXCLUDE] -->
+<!--
+  Copyright 2016 Google Inc. All Rights Reserved.
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+        http://www.apache.org/licenses/LICENSE-2.0
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+-->
+<!-- [END_EXCLUDE] -->
+<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
+  <application>YOUR-PROJECT-ID</application>
+  <version>YOUR-VERSION-ID</version>
+  <threadsafe>true</threadsafe>
+
+  <inbound-services>
+    <service>xmpp_message</service>
+    <service>xmpp_presence</service>
+    <service>xmpp_subscribe</service>
+    <service>xmpp_error</service>
+  </inbound-services>
+
+</appengine-web-app>