REST client support

Plugin page: http://artifacts.griffon-framework.org/plugin/rest

The Rest plugin enables the usage of groovy-rest on a Griffon application.

Usage

The plugin will inject the following dynamic methods:

• <R> R withRest(Map<String, Object> params, Closure<R> stmts) - executes stmts using a RESTClient
• <R> R withHttp(Map<String, Object> params, Closure<R> stmts) - executes stmts using an HTTPBuilder
• <R> R withAsyncHttp(Map<String, Object> params, Closure<R> stmts) - executes stmts using a AsyncHTTPBuilder
• <R> R withRest(Map<String, Object> params, CallableWithArgs<R> stmts) - executes stmts using a RESTClient
• <R> R withHttp(Map<String, Object> params, CallableWithArgs<R> stmts) - executes stmts using an HTTPBuilder
• <R> R withAsyncHttp(Map<String, Object> params, CallableWithArgs<R> stmts) - executes stmts using a AsyncHTTPBuilder

Where params may contain

Property	Type	Required
uri	String	yes
contentType	String
id	String

All dynamic methods will create a new client when invoked unless you define an id: attribute. When this attribute is supplied the client will be stored in a cache managed by the RestProvider that handled the call. You may specify parameters for configuring an HTTP proxy, for example

Property	Type	Required	Default
scheme	String		http
port	int		80
host	String	yes
username	String
password	String

Configuring a proxy host for http://acme.com:81 can be done in this way

withRest(uri: 'http://foo.com/', proxy: [host: 'acme.com', port: 81]) {
    ...
}

The method withAsyncHttp accepts the following additional properties

Property	Type
threadPool	ExecutorService
poolSize	int
timeout	int

These methods are also accessible to any component through the singleton griffon.plugins.rest.RestEnhancer. You can inject these methods to non-artifacts via metaclasses. Simply grab hold of a particular metaclass and call RestEnhancer.enhance(metaClassInstance).

Configuration

RestAware AST Transformation

The preferred way to mark a class for method injection is by annotating it with @griffon.plugins.rest.RestAware. This transformation injects the griffon.plugins.rest.RestContributionHandler interface and default behavior that fulfills the contract.

Dynamic Method Injection

Dynamic methods will be added to controllers by default. You can change this setting by adding a configuration flag in griffon-app/conf/Config.groovy

griffon.rest.injectInto = ['controller', 'service']

Dynamic method injection will be skipped for classes implementing griffon.plugins.rest.RestContributionHandler.

Example

This example relies on Grails as the service provider. Follow these steps to configure the service on the Grails side:

1. Download a copy of Grails and install it.

2. Create a new Grails application. We'll pick 'exporter' as the application name.

    grails create-app exporter
   

3. Create a controller named Calculator

    grails create-controller calculator
   

4. Paste the following code in grails-app/controllers/exporter/CalculatorController.groovy

    package exporter
    import grails.converters.JSON
    class CalculatorController {
        def add() {
            double a = params.a.toDouble()
            double b = params.b.toDouble()
            render([result: (a + b)] as JSON)
        }
    }
   

5. Run the application

    grails run-app
   

Now we're ready to build the Griffon application

1. Create a new Griffon application. We'll pick calculator as the application name

    griffon create-app calculator
   

2. Install the rest plugin

    griffon install-plugin rest
   

3. Fix the view script to look like this

    package calculator
    application(title: 'Rest Plugin Example',
      pack: true,
      locationByPlatform: true,
      iconImage: imageIcon('/griffon-icon-48x48.png').image,
      iconImages: [imageIcon('/griffon-icon-48x48.png').image,
                   imageIcon('/griffon-icon-32x32.png').image,
                   imageIcon('/griffon-icon-16x16.png').image]) {
        gridLayout(cols: 2, rows: 4)
        label('Num1:')
        textField(columns: 20, text: bind(target: model, targetProperty: 'num1'))
        label('Num2:')
        textField(columns: 20, text: bind(target: model, targetProperty: 'num2'))
        label('Result:')
        label(text: bind{model.result})
        button(calculateAction, enabled: bind{model.enabled})
    }
   

4. Let's add required properties to the model

    package calculator
    @Bindable
    class CalculatorModel {
        String num1
        String num2
        String result
        boolean enabled = true
    }
   

5. Now for the controller code. Notice that there is minimal error handling in place. If the user types something that is not a number the client will surely break, but the code is sufficient for now.

    package calculator
    import rest.rest.ContentType
    @griffon.plugins.rest.RestAware
    class CalculatorController {
        def model
   
        def calculate = { evt = null ->
            String a = model.num1
            String b = model.num2
            execInsideUIAsync { model.enabled = false }
            try {
                def result = withRest(url: 'http://localhost:8080/exporter/calculator/', id: 'client') {
                    def response = get(path: 'add', query: [a: a, b: b], accept: ContentType.JSON)
                    response.json.result
                }
                execInsideUIAsync { model.result = result }
            } finally {
                execInsideUIAsync { model.enabled = true }
            }
        }
    }
   

6. Run the application

    griffon run-app
   

The plugin exposes a Java friendly API to make the exact same calls from Java, or any other JVM language for that matter. Here's for example the previous code rewritten in Java. Note the usage of @RestWare on a Java class

package calculator;
import static griffon.util.CollectionUtils.newMap;
import griffon.util.CallableWithArgs;
import griffon.util.CollectionUtils;
import groovyx.net.http.HttpResponseDecorator;
import groovyx.net.http.RESTClient;
import java.awt.event.ActionEvent;
import java.util.Map;
import net.sf.json.JSONObject;
import org.codehaus.griffon.runtime.core.AbstractGriffonController;
@griffon.plugins.rest.RestAware
public class CalculatorController extends AbstractGriffonController {
    private CalculatorModel model;

    public void setModel(CalculatorModel model) {
        this.model = model;
    }

    public void calculate(ActionEvent event) {
        final String a = model.getNum1();
        final String b = model.getNum2();
        enableModel(false);
        try {
            Map<String, Object> params = CollectionUtils.<String, Object> map()
                    .e("uri", "http://localhost:8080/exporter/calculator/")
                    .e("id", "client");
            final String result = withRest(params,
                    new CallableWithArgs<String>() {
                        public String call(Object[] args) {
                            RESTClient client = (RESTClient) args[0];
                            try {
                                HttpResponseDecorator response = (HttpResponseDecorator) client.get(
                                    newMap(
                                        "path", "add",  
                                        "query", newMap("a", a, "b", b)));
                                JSONObject json = (JSONObject) response.getData();
                                return json.getString("result");
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                            return "";
                        }
                    });
            execInsideUIAsync(new Runnable() {
                public void run() {
                    model.setResult(result);
                }
            });
        } finally {
            enableModel(true);
        }
    }

    private void enableModel(final boolean enabled) {
        execInsideUIAsync(new Runnable() {
            public void run() {
                model.setEnabled(enabled);
            }
        });
    }
}

Testing

Dynamic methods will not be automatically injected during unit testing, because addons are simply not initialized for this kind of tests. However you can use RestEnhancer.enhance(metaClassInstance, restProviderInstance) where restProviderInstance is of type griffon.plugins.rest.RestProvider. The contract for this interface looks like this

public interface RestProvider {
    <R> R withAsyncHttp(Map<String, Object> params, Closure<R> closure);
    <R> R withHttp(Map<String, Object> params, Closure<R> closure);
    <R> R withRest(Map<String, Object> params, Closure<R> closure);
    <R> R withAsyncHttp(Map<String, Object> params, CallableWithArgs<R> callable);
    <R> R withHttp(Map<String, Object> params, CallableWithArgs<R> callable);
    <R> R withRest(Map<String, Object> params, CallableWithArgs<R> callable);
}

It's up to you define how these methods need to be implemented for your tests. For example, here's an implementation that never fails regardless of the arguments it receives

class MyRestProvider implements RestProvider {
    public <R> R withAsyncHttp(Map<String, Object> params, Closure<R> closure) { null }
    public <R> R withHttp(Map<String, Object> params, Closure<R> closure) { null }
    public <R> R withRest(Map<String, Object> params, Closure<R> closure) { null }
    public <R> R withAsyncHttp(Map<String, Object> params, CallableWithArgs<R> callable) { null }
    public <R> R withHttp(Map<String, Object> params, CallableWithArgs<R> callable) { null }
    public <R> R withRest(Map<String, Object> params, CallableWithArgs<R> callable) { null }
}

This implementation may be used in the following way

class MyServiceTests extends GriffonUnitTestCase {
    void testSmokeAndMirrors() {
        MyService service = new MyService()
        RestEnhancer.enhance(service.metaClass, new MyRestProvider())
        // exercise service methods
    }
}

On the other hand, if the service is annotated with @RestAware then usage of RestEnhancer should be avoided at all costs. Simply set restProviderInstance on the service instance directly, like so, first the service definition

@griffon.plugins.rest.RestAware
class MyService {
    def serviceMethod() { ... }
}

Next is the test

class MyServiceTests extends GriffonUnitTestCase {
    void testSmokeAndMirrors() {
        MyService service = new MyService()
        service.restProvider = new MyRestProvider()
        // exercise service methods
    }
}

Tool Support

DSL Descriptors

This plugin provides DSL descriptors for Intellij IDEA and Eclipse (provided you have the Groovy Eclipse plugin installed). These descriptors are found inside the griffon-rest-compile-x.y.z.jar, with locations

• dsdl/rest.dsld
• gdsl/rest.gdsl

Lombok Support

Rewriting Java AST in a similar fashion to Groovy AST transformations is possible thanks to the lombok plugin.

JavaC

Support for this compiler is provided out-of-the-box by the command line tools. There's no additional configuration required.

Eclipse

Follow the steps found in the Lombok plugin for setting up Eclipse up to number 5.

6. Go to the path where the lombok.jar was copied. This path is either found inside the Eclipse installation directory or in your local settings. Copy the following file from the project's working directory

    $ cp $USER_HOME/.griffon/<version>/projects/<project>/plugins/rest-<version>/dist/griffon-rest-compile-<version>.jar .
   

7. Edit the launch script for Eclipse and tweak the boothclasspath entry so that includes the file you just copied

   -Xbootclasspath/a:lombok.jar:lombok-pg-<version>.jar:        griffon-lombok-compile-<version>.jar:griffon-rest-compile-<version>.jar
   

8. Launch Eclipse once more. Eclipse should be able to provide content assist for Java classes annotated with @RestAware.

NetBeans

Follow the instructions found in Annotation Processors Support in the NetBeans IDE, Part I: Using Project Lombok. You may need to specify lombok.core.AnnotationProcessor in the list of Annotation Processors.

NetBeans should be able to provide code suggestions on Java classes annotated with @RestAware.

Intellij IDEA

Follow the steps found in the Lombok plugin for setting up Intellij IDEA up to number 5.

6. Copy griffon-rest-compile-<version>.jar to the lib directory

    $ pwd
      $USER_HOME/Library/Application Support/IntelliJIdea11/lombok-plugin
    $ cp $USER_HOME/.griffon/<version>/projects/<project>/plugins/rest-<version>/dist/griffon-rest-compile-<version>.jar lib
   

7. Launch IntelliJ IDEA once more. Code completion should work now for Java classes annotated with @RestAware.

Building

This project requires all of its dependencies be available from maven compatible repositories. Some of these dependencies have not been pushed to the Maven Central Repository, however you can obtain them from lombok-dev-deps.

Follow the instructions found there to install the required dependencies into your local Maven repository before attempting to build this plugin.