Extend the example to include a construct and unit test

examples/cdk-examples-java/README.md

@@ -0,0 +1,51 @@
+# CDK Java Example
+
+This an example of a CDK program written in Java.
+
+> NOTE: Since this example currently resides inside the CDK repository, it takes
+  a dependency on the CDK for Java maven package that's built under
+  `packages/aws-cdk-java`. To enable this, we generate the `pom.xml` file, so we
+  can plug in the locations of the local maven repositories. This is not
+  something you will need to do if you are simply using the published CDK maven
+  package.
+
+## Building
+
+To build this app, run `npm run prepare`. This will:
+
+1. Generate `project/pom.xml` with correct references to jsii and CDK
+   dependencies.
+2. Run `mvn package`, which will compile, test and assemble an executable jar.
+
+## IDE
+
+Once the `pom.xml` file is generated, the [`./project`](./project) directory is
+fully functional Maven project, and you should be able to open it from any Java
+IDE which supports Maven.
+
+You can use the IDE to write code and unit tests, but you will need to use the
+CDK toolkit if you wish to synthesize/deploy stacks.
+
+## CDK Toolkit
+
+The [`cdk.json`](./cdk.json) file in the root of this repository includes
+instructions for the CDK toolkit on how to execute this program. Specifically,
+it will use `java -jar <executale-jar> app` for the `--app` switch. This means,
+you should be able to use the toolkit normally:
+
+```
+$ cdk ls
+<list all stacks in this program>
+
+$ cdk synth
+<cloudformation template>
+
+$ cdk deploy
+<deploy stack to your account>
+
+$ cdk diff
+<diff against deployed stack>
+```
+
+If you make modifications, make sure to rebuild the app, either by callign `mvn
+package` from `./project` or `npm run prepare` from the root.

examples/cdk-examples-java/cdk.json

@@ -1,3 +1,3 @@
 {
-  "app": "/bin/bash run-program.sh"
-}
+  "app": "java -jar project/target/cdk-examples-java-0.7.2-beta-jar-with-dependencies.jar app"
+}

examples/cdk-examples-java/package.json

@@ -12,6 +12,7 @@
   },
   "scripts": {
     "prepare": "/bin/bash generate.sh && cd project && mvn package",
+    "cdk": "cdk",
     "test": "echo ok"
   },
   "author": {
@@ -23,6 +24,7 @@
     "aws-cdk-java": "^0.7.2-beta"
   },
   "devDependencies": {
+    "aws-cdk": "^0.7.2-beta",
     "pkgtools": "^0.7.2-beta"
   }
 }

examples/cdk-examples-java/pom.xml.t.js

@@ -11,12 +11,9 @@ const jsii = mavenFromNpm('jsii-java-runtime');
 
 process.stdout.write(`
 <?xml version="1.0" encoding="UTF-8"?>
-<project
-        xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
-        xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
-
-    <!-- Generated by ${__filename} at ${new Date().toISOString()} -->
 
+<!-- Generated by ${__filename} at ${new Date().toISOString()} -->
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
     <modelVersion>4.0.0</modelVersion>
 
     <repositories>
@@ -43,22 +40,46 @@ process.stdout.write(`
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.6.1</version>
+                <version>3.7.0</version>
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>
+                    <annotationProcessorPaths>
+                        <path>
+                            <groupId>org.projectlombok</groupId>
+                            <artifactId>lombok</artifactId>
+                            <version>1.18.0</version>
+                        </path>
+                    </annotationProcessorPaths>
                 </configuration>
             </plugin>
 
             <plugin>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>exec-maven-plugin</artifactId>
-                <version>1.6.0</version>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <version>3.1.0</version>
+                <configuration>
+                    <descriptorRefs>
+                        <descriptorRef>jar-with-dependencies</descriptorRef>
+                    </descriptorRefs>
+                    <archive>
+                        <manifest>
+                            <mainClass>com.amazonaws.cdk.examples.HelloJavaApp</mainClass>
+                        </manifest>
+                    </archive>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>make-assembly</id> <!-- this is used for inheritance merges -->
+                        <phase>package</phase> <!-- bind to the packaging phase -->
+                            <goals>
+                            <goal>single</goal>
+                        </goals>
+                    </execution>
+              </executions>
             </plugin>
-            
-        </plugins>
-
 
+        </plugins>
     </build>
 
     <dependencies>
@@ -88,6 +109,22 @@ process.stdout.write(`
             <version>2.9.5</version>
         </dependency>
 
+        <!-- https://mvnrepository.com/artifact/junit/junit -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.0</version>
+            <scope>provided</scope>
+        </dependency>
+
     </dependencies>
 
 

examples/cdk-examples-java/project/.gitignore

@@ -3,4 +3,7 @@ target
 # generated by pom.xml.t.js
 pom.xml
 
-.idea
+.idea
+.classpath
+.project
+.settings

examples/cdk-examples-java/project/src/main/java/com/amazonaws/cdk/examples/SinkQueue.java

@@ -0,0 +1,64 @@
+package com.amazonaws.cdk.examples;
+
+import com.amazonaws.cdk.Construct;
+import com.amazonaws.cdk.sns.Topic;
+import com.amazonaws.cdk.sqs.Queue;
+import com.amazonaws.cdk.sqs.QueueProps;
+
+/**
+ * A sink queue is a queue aggregates messages published to any number of SNS topics.
+ */
+public class SinkQueue extends Construct {
+    private final Queue queue;
+    private int numberOfTopics = 0;
+    private final int maxTopics;
+
+    /**
+     * Defines a SinkQueue.
+     *
+     * @param parent Parent construct
+     * @param name   Logical name
+     * @param props  Props
+     */
+    public SinkQueue(final Construct parent, final String name, SinkQueueProps props) {
+        super(parent, name);
+
+        // ensure props is non-null
+        props = props != null ? props : SinkQueueProps.builder().build();
+
+        // defaults
+        QueueProps queueProps = props.getQueueProps();
+        this.maxTopics = props.getMaxTopics() != null ? props.getMaxTopics().intValue() : 10;
+
+        // WORKAROUND: https://github.com/awslabs/aws-cdk/issues/157
+        if (queueProps == null) {
+            queueProps = QueueProps.builder().build();
+        }
+
+        this.queue = new Queue(this, "Resource", queueProps);
+    }
+
+    /**
+     * Defines a SinkQueue with default props.
+     * @param parent Parent construct
+     * @param name   Logical name
+     */
+    public SinkQueue(final Construct parent, final String name) {
+        this(parent, name, null);
+    }
+
+    /**
+     * Subscribes this queue to receive messages published to the specified topics.
+     *
+     * @param topics The topics to subscribe to
+     */
+    public void subscribe(final Topic... topics) {
+        for (Topic topic: topics) {
+            if (numberOfTopics == maxTopics) {
+                throw new RuntimeException("Cannot add more topics to the sink. Maximum topics is configured to " + this.maxTopics);
+            }
+            topic.subscribeQueue(this.queue);
+            numberOfTopics++;
+        }
+    }
+}

examples/cdk-examples-java/project/src/main/java/com/amazonaws/cdk/examples/SinkQueueProps.java

@@ -0,0 +1,25 @@
+package com.amazonaws.cdk.examples;
+
+import com.amazonaws.cdk.sqs.QueueProps;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+/**
+ * Props for {@link SinkQueue}
+ */
+@Data @Builder @NoArgsConstructor @AllArgsConstructor
+public class SinkQueueProps {
+    /**
+     * Props for the queue itself
+     * @default See {@link com.amazonaws.cdk.sqs.Queue} defaults
+     */
+    private QueueProps queueProps;
+
+    /**
+     * The maximum number of topics allowed to subscribe to this queue.
+     * @default 10
+     */
+    private Number maxTopics;
+}

examples/cdk-examples-java/project/src/test/java/com/amazonaws/cdk/examples/SinkQueueTest.java

@@ -0,0 +1,100 @@
+package com.amazonaws.cdk.examples;
+
+import com.amazonaws.cdk.Stack;
+import com.amazonaws.cdk.sns.Topic;
+import com.amazonaws.cdk.sqs.QueueProps;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.URL;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class SinkQueueTest {
+
+    private static ObjectMapper JSON = new ObjectMapper();
+
+    /** Defines a queue sink with default props */
+    @Test public void testDefaults() throws IOException {
+        Stack stack = new Stack();
+        new SinkQueue(stack, "MySinkQueue");
+        assertTemplate(stack, "{\"Resources\":{\"MySinkQueueEFCD79C2\":{\"Type\":\"AWS::SQS::Queue\"}}}");
+    }
+
+    /** Defines a sink with custom queue props */
+    @Test public void testQueueProps() throws IOException {
+        Stack stack = new Stack();
+        new SinkQueue(stack, "MySinkQueue", SinkQueueProps.builder()
+                .queueProps(QueueProps.builder()
+                        .withVisibilityTimeoutSec(500)
+                        .build())
+                .build());
+        assertTemplate(stack, "{\n" +
+                "  \"Resources\" : {\n" +
+                "    \"MySinkQueueEFCD79C2\" : {\n" +
+                "      \"Type\" : \"AWS::SQS::Queue\",\n" +
+                "      \"Properties\" : {\n" +
+                "        \"VisibilityTimeout\" : 500\n" +
+                "      }\n" +
+                "    }\n" +
+                "  }\n" +
+                "}");
+    }
+
+    /** Calls "subscribe" to add topics to the sink */
+    @Test public void testSubscribeTopics() throws IOException {
+        Stack stack = new Stack();
+
+        SinkQueue sink = new SinkQueue(stack, "MySinkQueue");
+
+        // add three topics in two calls to "subscribe"
+        sink.subscribe(new Topic(stack, "Topic1"), new Topic(stack, "Topic2"));
+        sink.subscribe(new Topic(stack, "Topic3"));
+
+        assertTemplate(stack, getClass().getResource("testSubscribeTopics.expected.json"));
+    }
+
+    /** Verifies that if we exceed the number of allows topics, an exception is thrown */
+    @Test public void failsIfExceedMaxTopic() throws IOException {
+        Stack stack = new Stack();
+
+        SinkQueue sink = new SinkQueue(stack, "MySinkQueue", SinkQueueProps.builder()
+                .maxTopics(3)
+                .build());
+
+        sink.subscribe(new Topic(stack, "Topic1"));
+        sink.subscribe(new Topic(stack, "Topic2"));
+        sink.subscribe(new Topic(stack, "Topic3"));
+
+        boolean thrown = false;
+        try {
+            sink.subscribe(new Topic(stack, "Topic4"));
+        } catch (RuntimeException e) {
+            thrown = true;
+        }
+        assertTrue(thrown);
+    }
+
+    private static void assertTemplate(final Stack stack, final URL expectedResource) throws IOException {
+        assertTemplate(stack, JSON.readTree(expectedResource));
+    }
+
+    private static void assertTemplate(final Stack stack, final String expectedTemplate) throws IOException {
+        assertTemplate(stack, JSON.readTree(expectedTemplate));
+    }
+
+    private static void assertTemplate(final Stack stack, final JsonNode expected) throws IOException {
+        JsonNode actual = JSON.valueToTree(stack.toCloudFormation());
+
+        // print to stderr if non-equal, so it will be easy to grab
+        if (expected == null || !expected.equals(actual)) {
+            String prettyActual = JSON.writerWithDefaultPrettyPrinter().writeValueAsString(actual);
+            System.err.println(prettyActual);
+        }
+
+        assertEquals(expected, actual);
+    }
+}