Migrating to Cloud Endpoints Frameworks version 2.0 for App Engine

This page describes migrating an existing Cloud Endpoints version 1.0 application to Endpoints Frameworks for App Engine in Java.

Benefits

The new framework brings a number of benefits, including:

  • Reduced request latency.
  • Better integration with App Engine features, such as custom domains.
  • Official support for Guice configurations.
  • Optionally, new API management features.

Endpoints Frameworks version 2.0 doesn't affect the interfaces to your API. Existing clients continue to work after migration without any client-side code changes.

Currently excluded features and tools

The following features aren't currently available. If you require any of these, please submit a feature request.

  • JSON-RPC protocol, which is required for legacy iOS clients. To create iOS clients for your Endpoints Frameworks version 2.0 API, we recommend that you use Google APIs Objective-C client library for REST APIs.
  • Automatic ETags
  • Automatic kind fields
  • IDE integration
  • fields partial responses
  • Automatic PATCH API method creation

In addition, Android Studio support for Endpoints version 1.0 isn't currently supported for version 2.0.

Migrating to Endpoints Frameworks version 2.0

Endpoints Frameworks version 2.0 has moved to Maven artifacts in group com.google.endpoints. The base required JAR is in the endpoints-framework artifact. If you wish to use Guice configuration, add the endpoints-framework-guice artifact.

The following instructions provide an example of how to migrate from Endpoints Frameworks version 1.0 to Endpoints Frameworks version 2.0 by using a Discovery Document:

  1. Download and initialize the Cloud SDK.
  2. Run the following commands:
    1. Make sure that the Cloud SDK is authorized to access your data and services on Google Cloud:
      gcloud auth login
    2. Use application default credentials:
      gcloud auth application-default login
    3. Install the Cloud SDK app-engine-java component:
      gcloud components install app-engine-java
    4. Update to the latest version of the Cloud SDK and all components:
      gcloud components update

Migrate using Maven or Gradle

Maven

  1. Remove the legacy dependency, which is the appengine-endpoints artifact:
    <dependency>
          <groupId>com.google.appengine</groupId>
          <artifactId>appengine-endpoints</artifactId>
          <version>1.9.53</version>
    </dependency>
  2. Add the new Endpoints Frameworks dependency:
    <dependency>
        <groupId>com.google.endpoints</groupId>
        <artifactId>endpoints-framework</artifactId>
        <version>2.2.1</version>
    </dependency>
  3. Add the new Endpoints Frameworks plugin and define the hostname for a generated discovery document:
    <plugin>
        <groupId>com.google.cloud.tools</groupId>
        <artifactId>endpoints-framework-maven-plugin</artifactId>
        <version>1.0.2</version>
        <configuration>
            <!-- plugin configuration -->
            <hostname>YOUR-PROJECT-ID.appspot.com</hostname>
        </configuration>
    </plugin>
  4. Add the new App Engine Maven plugin:
    <plugin>
        <groupId>com.google.cloud.tools</groupId>
        <artifactId>appengine-maven-plugin</artifactId>
        <version>1.3.2</version>
        <configuration>
            <!-- deploy configuration -->
        </configuration>
    </plugin>
  5. Update the API entry point in your project web.xml file:
    • Rename all occurrences of SystemServiceServlet to EndpointsServlet
    • Replace all occurrences of the path /_ah/spi/ to the new required path /_ah/api/

    The following shows the contents of the web.xml before and after migration:

    Before migration

    Endpoints Frameworks version 1.0 web.xml:
    <servlet>
        <servlet-name>SystemServiceServlet</servlet-name>
        <servlet-class>com.google.api.server.spi.SystemServiceServlet</servlet-class>
        <init-param>
            <param-name>services</param-name>
            <param-value>com.example.helloendpoints.Greetings</param-value>
        </init-param>
        <init-param>
            <param-name>restricted</param-name>
            <param-value>false</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>SystemServiceServlet</servlet-name>
        <url-pattern>/_ah/spi/*</url-pattern>
    </servlet-mapping>

    After migration

    Endpoints Frameworks version 2.0 web.xml:
    <servlet>
        <servlet-name>EndpointsServlet</servlet-name>
        <servlet-class>com.google.api.server.spi.EndpointsServlet</servlet-class>
        <init-param>
            <param-name>services</param-name>
            <param-value>com.example.helloendpoints.Greetings</param-value>
        </init-param>
        <init-param>
            <param-name>restricted</param-name>
            <param-value>false</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>EndpointsServlet</servlet-name>
        <url-pattern>/_ah/api/*</url-pattern>
    </servlet-mapping>

  6. After modifying dependencies clean the projec:
    mvn clean
  7. You can generate a discovery document:
    mvn endpoints-framework:discoveryDocs
    Learn more about the Maven Endpoints Frameworks plugin goals.
  8. You can deploy a project:
    mvn appengine:deploy

    Learn more about the Maven App Engine plugin goals.

Gradle

  1. Remove the legacy dependency, which is the appengine-endpoints artifact:
    compile group: 'com.google.appengine', name: 'appengine-endpoints', version: '+'
  2. Add the new Endpoints Frameworks dependency:
    compile group: 'com.google.endpoints', name: 'endpoints-framework', version: '2.0.8'
  3. Add the new App Engine and Endpoints Frameworks plugins:
    buildscript {    // Configuration for building
      repositories {
        mavenCentral()
        jcenter()    // Bintray's repository - a fast Maven Central mirror & more
      }
      dependencies {
        // App Engine Gradle plugin
        classpath 'com.google.cloud.tools:appengine-gradle-plugin:1.3.3'
    
        // Endpoints Frameworks Gradle plugin
        classpath 'com.google.cloud.tools:endpoints-framework-gradle-plugin:1.0.2'
      }
    }
  4. Apply the new App Engine and Endpoints Frameworks plugins:
    apply plugin: 'com.google.cloud.tools.appengine'
    apply plugin: 'com.google.cloud.tools.endpoints-framework-server'
  5. Define the hostname endpoint for generated discovery documents:
    endpointsServer {
      // Endpoints Framework Plugin server-side configuration
      hostname = "YOUR-PROJECT-ID.appspot.com"
    }
  6. Update the API entry point in your project web.xml file:
    • Rename all occurrences of SystemServiceServlet to EndpointsServlet
    • Replace all occurrences of the path /_ah/spi/ to the new required path /_ah/api/

    The following shows the contents of the web.xml before and after migration:

    Before migration

    Endpoints Frameworks version 1.0 web.xml:
    <servlet>
        <servlet-name>SystemServiceServlet</servlet-name>
        <servlet-class>com.google.api.server.spi.SystemServiceServlet</servlet-class>
        <init-param>
            <param-name>services</param-name>
            <param-value>com.example.helloendpoints.Greetings</param-value>
        </init-param>
        <init-param>
            <param-name>restricted</param-name>
            <param-value>false</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>SystemServiceServlet</servlet-name>
        <url-pattern>/_ah/spi/*</url-pattern>
    </servlet-mapping>

    After migration

    Endpoints Frameworks version 2.0 web.xml:
    <servlet>
        <servlet-name>EndpointsServlet</servlet-name>
        <servlet-class>com.google.api.server.spi.EndpointsServlet</servlet-class>
        <init-param>
            <param-name>services</param-name>
            <param-value>com.example.helloendpoints.Greetings</param-value>
        </init-param>
        <init-param>
            <param-name>restricted</param-name>
            <param-value>false</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>EndpointsServlet</servlet-name>
        <url-pattern>/_ah/api/*</url-pattern>
    </servlet-mapping>

  7. After modifying dependencies clean the project using:
    gradle clean
  8. You can generate a discovery document by using:
    gradle endpointsDiscoveryDocs
    Learn more about the Gradle Endpoints Frameworks plugin tasks
  9. You can deploy a project by using:
    gradle appengineDeploy

    Learn more about the Gradle App Engine plugin tasks.

Using Guice to configure Endpoints Frameworks for Java

If you wish to use Guice:

  1. Add the new Endpoints Frameworks Guice dependency:

    Maven

    <dependency>
        <groupId>com.google.endpoints</groupId>
        <artifactId>endpoints-framework-guice</artifactId>
        <version>2.2.1</version>
    </dependency>

    Gradle

    compile 'com.google.endpoints:endpoints-framework-guice:2.0.9'
  2. Declare a new module that extends EndpointsModule, and configure it, as follows:
    public class EchoEndpointModule extends EndpointsModule {
      @Override
      public void configureServlets() {
        super.configureServlets();
    
        bind(ServiceManagementConfigFilter.class).in(Singleton.class);
        filter("/_ah/api/*").through(ServiceManagementConfigFilter.class);
    
        Map<String, String> apiController = new HashMap<String, String>();
        apiController.put("endpoints.projectId", "YOUR-PROJECT-ID");
        apiController.put("endpoints.serviceName", "YOUR-PROJECT-ID.appspot.com");
    
        bind(GoogleAppEngineControlFilter.class).in(Singleton.class);
        filter("/_ah/api/*").through(GoogleAppEngineControlFilter.class, apiController);
    
        bind(Echo.class).toInstance(new Echo());
        configureEndpoints("/_ah/api/*", ImmutableList.of(Echo.class));
      }
    }

Verifying a new deployment

You can verify that the new framework is serving traffic:

  1. Send some requests to the new deployment.
  2. In the Cloud Console, go to the Stackdriver Logging > Logs (Logs Viewer) page.

    Go to the Logs Viewer page

  3. If requests are shown with paths beginning with /_ah/api, then Endpoints Frameworks version 2.0 is now serving your API. The logs shouldn't show any requests with paths beginning with /_ah/spi. These requests indicate that the Endpoints Frameworks version 1.0 proxy is still serving requests.

Adding Endpoints API management

Endpoints Frameworks version 2.0 also lets you turn on API management features, including:

  • API key management
  • API sharing
  • User authentication
  • API metrics
  • API logs

To get started using these features, see Adding API management.

Troubleshooting

This section describes common erratic behaviors when migrating to Endpoints Frameworks version 2.0 and suggested solutions.

API returns 404 errors, but API Explorer still lists APIs correctly

You are required to remove the old Endpoints Frameworks version 1.0 configuration when migrating to Endpoints Frameworks version 2.0. If the old configuration is still present in the application configuration, the Endpoints service continues to treat the app as a version 1.0 app. You may see requests in your App Engine logs sent to /_ah/spi, which result in HTTP 404 errors sent to the client.

  1. Remove the following lines from your web.xml file, if they are present:

    <servlet>
        <servlet-name>SystemServiceServlet</servlet-name>
        <servlet-class>com.google.api.server.spi.SystemServiceServlet</servlet-class>
        <init-param>
            <param-name>services</param-name>
            <param-value>...</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>SystemServiceServlet</servlet-name>
        <url-pattern>/_ah/spi/*</url-pattern>
    </servlet-mapping>
    
  2. Make sure your web.xml file contains the following:

    <servlet-mapping>
        <servlet-name>EndpointsServlet</servlet-name>
        <url-pattern>/_ah/api/*</url-pattern>
    </servlet-mapping>
    

API is throwing reflection errors

You must package only the endpoints-framework artifact into your application, not the old appengine-endpoints JAR. If you deploy an application with both JARs, you might run into reflection errors or runtime type errors, such as NoClassDefFoundError, NoSuchMethodError, and ClassCastException. Remove the following lines from your build file, if they are present:

Maven

<dependency>
      <groupId>com.google.appengine</groupId>
      <artifactId>appengine-endpoints</artifactId>
      <version>1.9.53</version>
</dependency>

Gradle

compile group: 'com.google.appengine', name: 'appengine-endpoints', version: '+'

In addition, if any of your other dependencies depend on older versions of Guava, this can also manifest as a missing TypeToken method. You must ensure that you use Guava v19 or use the endpoints-framework-all artifact, which shadows dependencies.

Client library sources don't compile

If you see an error such as, method does not override or implement a method from a supertype, or cannot find symbol method setBatchPath(String), then your client application likely depends on an old version of the Google Java client library. You must ensure that your google-api-client artifact is 1.23.0 or higher.

Maven

<dependency>
    <groupId>com.google.api-client</groupId>
    <artifactId>google-api-client</artifactId>
    <version>1.23.0</version>
</dependency>

Gradle

compile group: 'com.google.api-client', name: 'google-api-client', version: '1.23.0'

Issues with JPA/JDO Datanucleus enhancement

Maven

The new Cloud SDK-based App Engine Maven plugin doesn't support Datanucleus enhancement of any type. If your project uses the Datanucleus JDO or JPA enhancement support from the old plugin, you must configure the third-party Datanucleus Maven plugin separately when you migrate. See the following for more information:

Gradle

If your project uses the gradle-appengine-plugin JPA/JDO Datanucleus enhancement, you must manually configure Datanucleus enhancement after switching to the new Cloud SDK-based Gradle plugin. See an example from Stackoverflow.

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