Final additions in private beta (IoT) (#861)

* Final additions in private beta

iot/api-client/http_example/README.md

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+# Cloud IoT Core Java HTTP example
+
+This sample app publishes data to Cloud Pub/Sub using the HTTP bridge provided
+as part of Google Cloud IoT Core.
+
+Note that before you can run the sample, you must configure a Google Cloud
+PubSub topic for Cloud IoT Core and register a device as described in the
+[parent README](../README.md).
+
+## Setup
+
+Run the following command to install the dependencies using Maven:
+
+    mvn clean compile
+
+## Running the sample
+
+The following command summarizes the sample usage:
+
+```
+    mvn exec:java \
+        -Dexec.mainClass="com.google.cloud.iot.examples.HttpExample" \
+        -Dexec.args="-project_id=my-iot-project \
+                     -registry_id=my-registry \
+                     -device_id=my-device \
+                     -private_key_file=rsa_private_pkcs8 \
+                     -algorithm=RS256"
+```
+
+For example, if your project ID is `blue-jet-123`, your service account
+credentials are stored in your home folder in creds.json and you have generated
+your credentials using the [`generate_keys.sh`](../generate_keys.sh) script
+provided in the parent folder, you can run the sample as:
+
+```
+    mvn exec:java \
+        -Dexec.mainClass="com.google.cloud.iot.examples.HttpExample" \
+        -Dexec.args="-project_id=blue-jet-123 \
+                     -registry_id=my-registry \
+                     -device_id=my-java-device \
+                     -private_key_file=../rsa_private_pkcs8 \
+                     -algorithm=RS256"
+```
+
+## Reading the messages written by the sample client
+
+1. Create a subscription to your topic.
+
+```
+    gcloud beta pubsub subscriptions create \
+        projects/your-project-id/subscriptions/my-subscription \
+        --topic device-events
+```
+
+2. Read messages published to the topic
+
+```
+    gcloud beta pubsub subscriptions pull --auto-ack \
+        projects/my-iot-project/subscriptions/my-subscription
+```

iot/api-client/http_example/pom.xml

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+<!--
+  Copyright 2017 Google Inc.
+
+  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 xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.google.cloud.iot.examples</groupId>
+  <artifactId>cloudiot-http-example</artifactId>
+  <packaging>jar</packaging>
+  <version>1.0</version>
+  <name>cloudiot-http-example</name>
+  <url>http://maven.apache.org</url>
+
+  <properties>
+    <maven.compiler.source>1.7</maven.compiler.source>
+    <maven.compiler.target>1.7</maven.compiler.target>
+  </properties>
+
+  <!-- Parent defines config for testing & linting. -->
+  <parent>
+    <artifactId>doc-samples</artifactId>
+    <groupId>com.google.cloud</groupId>
+    <version>1.0.0</version>
+    <relativePath>../../../</relativePath>
+  </parent>
+
+  <dependencies>
+    <dependency>
+      <groupId>io.jsonwebtoken</groupId>
+      <artifactId>jjwt</artifactId>
+      <version>0.7.0</version>
+    </dependency>
+    <dependency>
+      <groupId>joda-time</groupId>
+      <artifactId>joda-time</artifactId>
+      <version>2.1</version>
+    </dependency>
+    <dependency>
+      <groupId>commons-cli</groupId>
+      <artifactId>commons-cli</artifactId>
+      <version>1.3</version>
+    </dependency>
+    <dependency>
+      <groupId>org.json</groupId>
+      <artifactId>json</artifactId>
+      <version>20090211</version>
+    </dependency>
+  </dependencies>
+
+</project>

iot/api-client/http_example/src/main/java/com/google/cloud/iot/examples/HttpExample.java

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+/**
+ * Copyright 2017, Google, Inc.
+ *
+ * <p>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
+ *
+ * <p>http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * <p>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.google.cloud.iot.examples;
+
+import io.jsonwebtoken.JwtBuilder;
+import io.jsonwebtoken.Jwts;
+import io.jsonwebtoken.SignatureAlgorithm;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.security.KeyFactory;
+import java.security.spec.PKCS8EncodedKeySpec;
+import java.util.Base64;
+import org.joda.time.DateTime;
+import org.json.JSONObject;
+
+/**
+ * Java sample of connecting to Google Cloud IoT Core vice via HTTP, using JWT.
+ *
+ * <p>This example connects to Google Cloud IoT Core via HTTP Bridge, using a JWT for device
+ * authentication. After connecting, by default the device publishes 100 messages at a rate of one
+ * per second, and then exits. You can change The behavior to set state instead of events by using
+ * flag -message_type to 'state'.
+ *
+ * <p>To run this example, follow the instructions in the README located in the sample's parent
+ * folder.
+ */
+public class HttpExample {
+  /** Create a Cloud IoT Core JWT for the given project id, signed with the given private key. */
+  private static String createJwtRsa(String projectId, String privateKeyFile) throws Exception {
+    DateTime now = new DateTime();
+    // Create a JWT to authenticate this device. The device will be disconnected after the token
+    // expires, and will have to reconnect with a new token. The audience field should always be set
+    // to the GCP project id.
+    JwtBuilder jwtBuilder =
+        Jwts.builder()
+            .setIssuedAt(now.toDate())
+            .setExpiration(now.plusMinutes(20).toDate())
+            .setAudience(projectId);
+
+    byte[] keyBytes = Files.readAllBytes(Paths.get(privateKeyFile));
+    PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
+    KeyFactory kf = KeyFactory.getInstance("RSA");
+
+    return jwtBuilder.signWith(SignatureAlgorithm.RS256, kf.generatePrivate(spec)).compact();
+  }
+
+  private static String createJwtEs(String projectId, String privateKeyFile) throws Exception {
+    DateTime now = new DateTime();
+    // Create a JWT to authenticate this device. The device will be disconnected after the token
+    // expires, and will have to reconnect with a new token. The audience field should always be set
+    // to the GCP project id.
+    JwtBuilder jwtBuilder =
+        Jwts.builder()
+            .setIssuedAt(now.toDate())
+            .setExpiration(now.plusMinutes(20).toDate())
+            .setAudience(projectId);
+
+    byte[] keyBytes = Files.readAllBytes(Paths.get(privateKeyFile));
+    PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
+    KeyFactory kf = KeyFactory.getInstance("ES256");
+
+    return jwtBuilder.signWith(SignatureAlgorithm.ES256, kf.generatePrivate(spec)).compact();
+  }
+
+  public static void main(String[] args) throws Exception {
+    HttpExampleOptions options = HttpExampleOptions.fromFlags(args);
+    if (options == null) {
+      // Could not parse the flags.
+      System.exit(1);
+    }
+
+    // Build the resource path of the device that is going to be authenticated.
+    String devicePath =
+        String.format(
+            "projects/%s/locations/%s/registries/%s/devices/%s",
+            options.projectId, options.cloudRegion, options.registryId, options.deviceId);
+
+    // This describes the operation that is going to be perform with the device.
+    String urlSuffix = options.messageType.equals("event") ? "publishEvent" : "setState";
+
+    String urlPath =
+        String.format(
+            "%s/%s/%s:%s", options.httpBridgeAddress, options.apiVersion, devicePath, urlSuffix);
+    URL url = new URL(urlPath);
+    System.out.format("Using URL: '%s'\n", urlPath);
+
+    // Create the corresponding JWT depending on the selected algorithm.
+    String token;
+    if (options.algorithm.equals("RS256")) {
+      token = createJwtRsa(options.projectId, options.privateKeyFile);
+    } else if (options.algorithm.equals("ES256")) {
+      token = createJwtEs(options.projectId, options.privateKeyFile);
+    } else {
+      throw new IllegalArgumentException(
+          "Invalid algorithm " + options.algorithm + ". Should be one of 'RS256' or 'ES256'.");
+    }
+
+    // Data sent through the wire has to be base64 encoded.
+    Base64.Encoder encoder = Base64.getEncoder();
+
+    // Publish numMessages messages to the HTTP bridge.
+    for (int i = 1; i <= options.numMessages; ++i) {
+      String payload = String.format("%s/%s-payload-%d", options.registryId, options.deviceId, i);
+      System.out.format(
+          "Publishing %s message %d/%d: '%s'\n",
+          options.messageType, i, options.numMessages, payload);
+      String encPayload = encoder.encodeToString(payload.getBytes("UTF-8"));
+
+      HttpURLConnection httpCon = (HttpURLConnection) url.openConnection();
+      httpCon.setDoOutput(true);
+      httpCon.setRequestMethod("POST");
+
+      // Adding headers.
+      httpCon.setRequestProperty("Authorization", String.format("Bearer %s", token));
+      httpCon.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
+
+      // Adding the post data. The structure of the data send depends on whether it is event or a
+      // state message.
+      JSONObject data = new JSONObject();
+      if (options.messageType.equals("event")) {
+        data.put("binary_data", encPayload);
+      } else {
+        JSONObject state = new JSONObject();
+        state.put("binary_data", encPayload);
+        data.put("state", state);
+      }
+      httpCon.getOutputStream().write(data.toString().getBytes("UTF-8"));
+      httpCon.getOutputStream().close();
+
+      // This will perform the connection as well.
+      System.out.println(httpCon.getResponseCode());
+      System.out.println(httpCon.getResponseMessage());
+
+      if (options.messageType.equals("event")) {
+        // Frequently send event payloads (every second)
+        Thread.sleep(1000);
+      } else {
+        // Update state with low frequency (once every 5 seconds)
+        Thread.sleep(5000);
+      }
+    }
+    System.out.println("Finished loop successfully. Goodbye!");
+  }
+}