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An initial commit for Firebase Event Proxy (#236)
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* initial commit of Firebase Event Proxy

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@misterwilliam @lesv
misterwilliam authored and lesv committed May 12, 2016
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49 changes: 49 additions & 0 deletions appengine/firebase-event-proxy/README.md
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# App Engine Firebase Event Proxy

An example app that illustrates how to create a Java App Engine Standard Environment
app that proxies Firebase events to another App Engine app.

# Java Firebase Event Proxy
Illustrates how to authenticate and subscribe to Firebase from Java App Engine.

# Python App Engine Listener
Illustrates how to authenticate messages received from the proxy app.

## Setup

### Java Firebase Event Proxy
Firebase Secret
Put your Firebase secret in the file:
gae-firebase-event-proxy/src/main/webapp/firebase-secret.properties
```
firebaseSecret=<Your Firebase secret>
```

* Billing must be enabled from Cloud console.
* Manual scaling should turned on and configured to 1 instance in appengine-web.xml

## Running locally
### Java Firebase Event Proxy
```
cd gae-firebase-event-proxy
mvn appengine:devserver
```

### Python App Engine Listener
```
cd gae-firebase-listener-python
dev_appserver .
```

## Deploying

### Java Firebase Event Proxy
```
cd gae-firebase-event-proxy
mvn appengine:upload
```

### Python App Engine Listener
```
appcfg.py -A <your app id> -V v1 update gae-firebase-listener-python
```
156 changes: 156 additions & 0 deletions appengine/firebase-event-proxy/gae-firebase-event-proxy/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.
-->
<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">

<modelVersion>4.0.0</modelVersion>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>

<groupId>com.example.GaeFirebaseEventProxy</groupId>
<artifactId>GaeFirebaseEventProxy</artifactId>

<properties>
<app.id>gae-firebase-event-proxy</app.id>
<app.version>1</app.version>
<appengine.version>1.9.36</appengine.version>
<gcloud.plugin.version>2.0.9.74.v20150814</gcloud.plugin.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.showDeprecation>true</maven.compiler.showDeprecation>
</properties>

<prerequisites>
<maven>3.1.0</maven>
</prerequisites>

<dependencies>
<!-- Compile/runtime dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-1.0-sdk</artifactId>
<version>${appengine.version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>com.firebase</groupId>
<artifactId>firebase-client-jvm</artifactId>
<version>[1.0.8,)</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.7.3</version>
</dependency>
<dependency>
<groupId>com.firebase</groupId>
<artifactId>firebase-token-generator</artifactId>
<version>2.0.0</version>
</dependency>

<!-- Test Dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-testing</artifactId>
<version>${appengine.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-stubs</artifactId>
<version>${appengine.version}</version>
<scope>test</scope>
</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.codehaus.mojo</groupId>
<artifactId>versions-maven-plugin</artifactId>
<version>2.1</version>
<executions>
<execution>
<phase>compile</phase>
<goals>
<goal>display-dependency-updates</goal>
<goal>display-plugin-updates</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<version>3.1</version>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.4</version>
<configuration>
<archiveClasses>true</archiveClasses>
<webResources>
<!-- in order to interpolate version from pom into appengine-web.xml -->
<resource>
<directory>${basedir}/src/main/webapp/WEB-INF</directory>
<filtering>true</filtering>
<targetPath>WEB-INF</targetPath>
</resource>
</webResources>
</configuration>
</plugin>

<plugin>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>${appengine.version}</version>
<configuration>
<enableJarClasses>false</enableJarClasses>
<version>${app.version}</version>
<!-- Comment in the below snippet to bind to all IPs instead of just localhost -->
<!-- address>0.0.0.0</address>
<port>8080</port -->
<!-- Comment in the below snippet to enable local debugging with a remote debugger
like those included with Eclipse or IntelliJ -->
<!-- jvmFlags>
<jvmFlag>-agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n</jvmFlag>
</jvmFlags -->
</configuration>
</plugin>
<plugin>
<groupId>com.google.appengine</groupId>
<artifactId>gcloud-maven-plugin</artifactId>
<version>${gcloud.plugin.version}</version>
<configuration>
<set_default>true</set_default>
</configuration>
</plugin>
</plugins>
</build>
</project>
144 changes: 144 additions & 0 deletions ...ebase-event-proxy/src/main/java/com/example/GaeFirebaseEventProxy/FirebaseEventProxy.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.GaeFirebaseEventProxy;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.logging.Logger;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.firebase.client.AuthData;
import com.firebase.client.DataSnapshot;
import com.firebase.client.Firebase;
import com.firebase.client.FirebaseError;
import com.firebase.client.ValueEventListener;
import com.firebase.security.token.TokenGenerator;
import com.google.appengine.api.utils.SystemProperty;

public class FirebaseEventProxy {

private static final Logger log = Logger.getLogger(FirebaseEventProxy.class.getName());

private String firebaseAuthToken;

public FirebaseEventProxy() {
// Store Firebase authentication token as an instance variable.
this.firebaseAuthToken = this.getFirebaseAuthToken(this.getFirebaseSecret());
}

public void start() {
String FIREBASE_LOCATION = "https://gae-fb-proxy.firebaseio.com/";
Firebase firebase = new Firebase(FIREBASE_LOCATION);

// Authenticate with Firebase
firebase.authWithCustomToken(this.firebaseAuthToken, new Firebase.AuthResultHandler() {
@Override
public void onAuthenticationError(FirebaseError error) {
log.severe("Firebase login error: " + error.getMessage());
}

@Override
public void onAuthenticated(AuthData auth) {
log.info("Firebase login successful");
}
});

// Subscribe to value events. Depending on use case, you may want to subscribe to child events
// through childEventListener.
firebase.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
if (snapshot.exists()) {
try {
// Convert value to JSON using Jackson
String json = new ObjectMapper().writeValueAsString(snapshot.getValue());

// Replace the URL with the url of your own listener app.
URL dest = new URL("http://gae-firebase-listener-python.appspot.com/log");
HttpURLConnection connection = (HttpURLConnection) dest.openConnection();
connection.setRequestMethod("POST");
connection.setDoOutput(true);

// Rely on X-Appengine-Inbound-Appid to authenticate. Turning off redirects is
// required to enable.
connection.setInstanceFollowRedirects(false);

// Fill out header if in dev environment
if (SystemProperty.environment.value() != SystemProperty.Environment.Value.Production) {
connection.setRequestProperty("X-Appengine-Inbound-Appid", "dev-instance");
}

// Put Firebase data into http request
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.append("&fbSnapshot=");
stringBuilder.append(URLEncoder.encode(json, "UTF-8"));
connection.getOutputStream().write(stringBuilder.toString().getBytes());
if (connection.getResponseCode() != 200) {
log.severe("Forwarding failed");
} else {
log.info("Sent: " + json);
}
} catch (JsonProcessingException e) {
log.severe("Unable to convert Firebase response to JSON: " + e.getMessage());
} catch (IOException e) {
log.severe("Error in connecting to app engine: " + e.getMessage());
}
}
}

@Override
public void onCancelled(FirebaseError error) {
log.severe("Firebase connection cancelled: " + error.getMessage());
}
});
}

private String getFirebaseSecret() {
Properties props = new Properties();
try {
// Read from src/main/webapp/firebase-secrets.properties
InputStream inputStream = new FileInputStream("firebase-secret.properties");
props.load(inputStream);
return props.getProperty("firebaseSecret");
} catch (java.net.MalformedURLException e) {
throw new RuntimeException(
"Error reading firebase secrets from file: src/main/webapp/firebase-sercrets.properties: "
+ e.getMessage());
} catch (IOException e) {
throw new RuntimeException(
"Error reading firebase secrets from file: src/main/webapp/firebase-sercrets.properties: "
+ e.getMessage());
}
}

private String getFirebaseAuthToken(String firebaseSecret) {
Map<String, Object> authPayload = new HashMap<String, Object>();
// uid and provider will have to match what you have in your firebase security rules
authPayload.put("uid", "gae-firebase-event-proxy");
authPayload.put("provider", "com.example");
TokenGenerator tokenGenerator = new TokenGenerator(firebaseSecret);
return tokenGenerator.createToken(authPayload);
}
}
40 changes: 40 additions & 0 deletions ...ent-proxy/src/main/java/com/example/GaeFirebaseEventProxy/ServletContextListenerImpl.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.GaeFirebaseEventProxy;

import java.util.logging.Logger;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

// ServletContextListener that is called whenever your App Engine app starts up.
public class ServletContextListenerImpl implements ServletContextListener {

private static final Logger log = Logger.getLogger(ServletContextListener.class.getName());

@Override
public void contextInitialized(ServletContextEvent event) {
log.info("Starting ....");
FirebaseEventProxy proxy = new FirebaseEventProxy();
proxy.start();
}

@Override
public void contextDestroyed(ServletContextEvent event) {
// App Engine does not currently invoke this method.
}
}
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