APP-3110 Handlebars template implementation (finos#260)

* APP-3110 Handlebars template engine implementation * APP-3110 doc * APP-3110 Post merge, updated getting-started guide * APP-3110 http and template implementations as runtime dependencies * APP-3110 reverted ./docs/index.md * APP-3110 Updates implementation selection * APP-3110 :symphony-bdk-http-api and :symphony-bdk-template-api as :symphony-bdk-core transitive dependencies
thibauult · Oct 5, 2020 · edb1844 · edb1844
1 parent 0fa637b
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diff --git a/docs/getting-started.md b/docs/getting-started.md
@@ -53,11 +53,13 @@ If you want to use [Maven](https://maven.apache.org/) as build system, you have
         </dependency>
         <dependency>
             <groupId>com.symphony.platformsolutions</groupId>
-            <artifactId>symphony-bdk-core-invoker-jersey2</artifactId>
+            <artifactId>symphony-bdk-http-jersey2</artifactId> <!-- or symphony-bdk-http-webclient -->
+            <scope>runtime</scope>
         </dependency>
         <dependency>
             <groupId>com.symphony.platformsolutions</groupId>
-            <artifactId>symphony-bdk-template-freemarker</artifactId>
+            <artifactId>symphony-bdk-template-freemarker</artifactId>  <!-- or symphony-bdk-http-handlebars -->
+            <scope>runtime</scope>
         </dependency>
         <!-- Logger implementation -->
         <dependency>
@@ -88,8 +90,8 @@ dependencies {
 
     // define dependencies without versions
     implementation 'com.symphony.platformsolutions:symphony-bdk-core'
-    implementation 'com.symphony.platformsolutions:symphony-bdk-core-invoker-jersey2'
-    implementation 'com.symphony.platformsolutions:symphony-bdk-template-freemarker'
+    runtimeOnly 'com.symphony.platformsolutions:symphony-bdk-http-jersey2' //  or symphony-bdk-http-webclient
+    runtimeOnly 'com.symphony.platformsolutions:symphony-bdk-template-freemarker' // or symphony-bdk-http-handlebars
 
     implementation 'ch.qos.logback:logback-classic'
 }

diff --git a/docs/message.md b/docs/message.md
@@ -17,54 +17,103 @@ More precisely:
 
 ## How to use
 The central component for the Message API is the `MessageService`.
-It exposes all the services mentioned above and is accessible from the `SymphonyBdk` object by calling the `messages()` method.
-For instance:
-
+It exposes all the services mentioned above and is accessible from the `SymphonyBdk` object by calling the `messages()` method:
 ```java
-import com.symphony.bdk.core.MessageService;
-
 public class Example {
   public static final String STREAM_ID = "gXFV8vN37dNqjojYS_y2wX___o2KxfmUdA";
 
   public static void main(String[] args) throws Exception {
     // Create BDK entry point
     final SymphonyBdk bdk = new SymphonyBdk(loadFromClasspath("/config.yaml"));
-    // Get the MessageService object
-    final MessageService messageService = bdk.message();
-
-    //send a regular message
-    final V4Message regularMessage = messageService.send(STREAM_ID, "<messageML>Hello, World!</messageML>");
-    System.out.println("Message sent, id: " + regularMessage.getMessageId());
+    // send a regular message
+    final V4Message regularMessage = bdk.message().send(STREAM_ID, "<messageML>Hello, World!</messageML>");
+    log.info("Message sent, id: " + regularMessage.getMessageId());
   }
 }
 ```
 
-A more detailed example with all exposed services can be found [here](../symphony-bdk-examples/bdk-core-examples/src/main/java/com/symphony/bdk/examples/MessageExampleMain.java).
+## Using templates
+The `MessageService` also allows you to send messages using templates. So far, the BDK supports two different template
+engine implementations: 
+- [FreeMarker](https://freemarker.apache.org/) (through dependency `com.symphony.platformsolutions:symphony-bdk-template-freemarker`)
+- [Handlebars](https://github.com/jknack/handlebars.java) (through dependency `com.symphony.platformsolutions:symphony-bdk-template-handlebars`)
+
+### How to send a message from a template
+> In the code examples below, we will assume that FreeMarker as been selected as template engine implementation.
+> See [how to select the template engine implementation](#select-your-template-engine-implementation).
 
-## Send messages with templates
-The Message service also allows you to send messages using templates. So far, we only support [FreeMarker templates](https://freemarker.apache.org/),
-but we may add support for other template engines.
-For instance, if you have the following template file:
+First you need to define your message template file. Here `src/main/resources/templates/simple.ftl`:
 ```
-<messageML>${message}</messageML>
+<messageML>Hello, ${name}!</messageML>
 ```
 you will be able to use it when sending message:
 ```java
-final SymphonyBdk bdk = new SymphonyBdk(loadFromClasspath("/config.yaml"));
-final V4Message regularMessage = bdk().message().send(streamId, "path/to/template.ftl", Collections.singletonMap("message", "Hello!"));
+public class Example {
+  public static final String STREAM_ID = "gXFV8vN37dNqjojYS_y2wX___o2KxfmUdA";
+
+  public static void main(String[] args) {
+    final SymphonyBdk bdk = new SymphonyBdk(loadFromClasspath("/config.yaml"));
+
+    final V4Message regularMessage = bdk.message().send(streamId, "/templates/simple.ftl", Collections.singletonMap("name", "User"));
+  }
+}
+```
+The above will send the message `<messageML>Hello, User!</messageML>` as expected.
+
+> Please note that the `MessageService` will try fetch template from different locations ordered by:
+> 1. classpath
+> 2. file system
+
+It is also possible to get direct access to the `TemplateEngine` through the `MessageService`: 
+```java
+public class Example {
+
+  public static void main(String[] args) {
+    final SymphonyBdk bdk = new SymphonyBdk(loadFromClasspath("/config.yaml"));
+
+    // load template from classpath location
+    final Template template = bdk.messages().templates().newTemplateFromClasspath("/complex-message.ftl");
+
+    // process template with some vars and retrieve content
+    // any POJO can also be processed by the template
+    final String content = template.process(Collections.singletonMap("name", "Freemarker"));
+
+    // display processed template content
+    log.info(content);
+  }
+}
+```
+
+#### Select your template engine implementation
+Developers are free to select the underlying template engine implementation. This can be done importing the right 
+dependency in your classpath. 
+
+With [Maven](./getting-started.md#maven-based-project): 
+```xml
+<dependencies>
+        <dependency>
+            <groupId>com.symphony.platformsolutions</groupId>
+            <artifactId>symphony-bdk-template-freemarker</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <!-- or -->
+        <dependency>
+            <groupId>com.symphony.platformsolutions</groupId>
+            <artifactId>symphony-bdk-template-handlebars</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+</dependencies>
+```
+With [Gradle](./getting-started.md#gradle-based-project): 
+```groovy
+dependencies {
+    runtimeOnly 'com.symphony.platformsolutions:symphony-bdk-template-freemarker'
+    // or
+    runtimeOnly 'com.symphony.platformsolutions:symphony-bdk-template-handlebars'
+}
 ```
-The above will send the message `<messageML>Hello!</messageML>` as expected.
-Please check the [FreeMarker documentation](https://freemarker.apache.org/docs/pgui_quickstart_createdatamodel.html)
-to know more about the data model you can use in templates and about the corresponding object structure you need to pass as parameter.
-
-The template name passed as parameter can be the name of a built-in template
-(only ["simpleMML"](../symphony-bdk-template/symphony-bdk-template-freemarker/src/main/resources/com/symphony/bdk/template/freemarker/simpleMML.ftl)
-available so far), the path to a template file or a URL to a template file.
-The templates will be looked for in this order:
-* in built-in templates
-* in the classpath
-* in the file system
-* lastly as a URL
+> :warning: If multiple implementations found in classpath, an exception is throw in order to help you to define which one
+> your project really needs to use.
 
 ----
 [Home :house:](./index.md)
diff --git a/settings.gradle b/settings.gradle
@@ -9,13 +9,13 @@ include(':symphony-bdk-http:symphony-bdk-http-webclient')
 
 include(':symphony-bdk-template:symphony-bdk-template-api')
 include(':symphony-bdk-template:symphony-bdk-template-freemarker')
+include(':symphony-bdk-template:symphony-bdk-template-handlebars')
 
 include(':symphony-bdk-spring:symphony-bdk-core-spring-boot-starter')
 include(':symphony-bdk-spring:symphony-bdk-app-spring-boot-starter')
 
 include(':symphony-bdk-examples:bdk-core-examples')
 include(':symphony-bdk-examples:bdk-spring-boot-example')
-include(':symphony-bdk-examples:bdk-template-examples')
 
 include(':symphony-bdk-legacy:symphony-bdk-bot-sdk-java')
 include(':symphony-bdk-legacy:symphony-api-client-java')

diff --git a/symphony-bdk-core/build.gradle b/symphony-bdk-core/build.gradle
@@ -29,8 +29,8 @@ jacocoTestCoverageVerification {
 }
 
 dependencies {
-    implementation project(':symphony-bdk-http:symphony-bdk-http-api')
-    implementation project(':symphony-bdk-template:symphony-bdk-template-api')
+    api project(':symphony-bdk-http:symphony-bdk-http-api')
+    api project(':symphony-bdk-template:symphony-bdk-template-api')
 
     compileOnly 'org.projectlombok:lombok'
     annotationProcessor 'org.projectlombok:lombok'

diff --git a/symphony-bdk-core/src/main/java/com/symphony/bdk/core/ServiceFactory.java b/symphony-bdk-core/src/main/java/com/symphony/bdk/core/ServiceFactory.java
@@ -29,6 +29,8 @@
 
 import com.symphony.bdk.http.api.ApiException;
 
+import com.symphony.bdk.template.api.TemplateEngine;
+
 import org.apiguardian.api.API;
 
 /**
@@ -49,13 +51,15 @@ class ServiceFactory {
   private final ApiClient agentClient;
   private final AuthSession authSession;
   private final BdkConfig config;
-  private final RetryWithRecoveryBuilder retryBuilder;
+  private final TemplateEngine templateEngine;
+  private final RetryWithRecoveryBuilder<?> retryBuilder;
 
   public ServiceFactory(ApiClientFactory apiClientFactory, AuthSession authSession, BdkConfig config) {
     this.podClient = apiClientFactory.getPodClient();
     this.agentClient = apiClientFactory.getAgentClient();
     this.authSession = authSession;
     this.config = config;
+    this.templateEngine = TemplateEngine.getDefaultImplementation();
     this.retryBuilder = new RetryWithRecoveryBuilder<>()
         .retryConfig(config.getRetry())
         .recoveryStrategy(ApiException::isUnauthorized, authSession::refresh);
@@ -108,8 +112,17 @@ public DatafeedService getDatafeedService() {
    * @return an new {@link MessageService} instance.
    */
   public MessageService getMessageService() {
-    return new MessageService(new MessagesApi(agentClient), new MessageApi(podClient),
-        new MessageSuppressionApi(podClient), new StreamsApi(podClient), new PodApi(podClient),
-        new AttachmentsApi(agentClient), new DefaultApi(podClient), authSession, retryBuilder);
+    return new MessageService(
+        new MessagesApi(this.agentClient),
+        new MessageApi(this.podClient),
+        new MessageSuppressionApi(this.podClient),
+        new StreamsApi(this.podClient),
+        new PodApi(this.podClient),
+        new AttachmentsApi(this.agentClient),
+        new DefaultApi(this.podClient),
+        this.authSession,
+        this.templateEngine,
+        this.retryBuilder
+    );
   }
 }
diff --git a/symphony-bdk-core/src/main/java/com/symphony/bdk/core/service/MessageService.java b/symphony-bdk-core/src/main/java/com/symphony/bdk/core/service/MessageService.java
@@ -55,38 +55,44 @@ public class MessageService {
   private final AttachmentsApi attachmentsApi;
   private final DefaultApi defaultApi;
   private final AuthSession authSession;
+  private final TemplateEngine templateEngine;
   private final TemplateResolver templateResolver;
-  private final RetryWithRecoveryBuilder retryBuilder;
-
-  public MessageService(MessagesApi messagesApi, MessageApi messageApi, MessageSuppressionApi messageSuppressionApi,
-      StreamsApi streamsApi, PodApi podApi, AttachmentsApi attachmentsApi, DefaultApi defaultApi,
-      AuthSession authSession, RetryWithRecoveryBuilder retryBuilder) {
-    this(messagesApi, messageApi, messageSuppressionApi, streamsApi, podApi, attachmentsApi, defaultApi, authSession,
-        new TemplateResolver(), retryBuilder);
-  }
-
-  public MessageService(MessagesApi messagesApi, MessageApi messageApi, MessageSuppressionApi messageSuppressionApi,
-      StreamsApi streamsApi, PodApi podApi, AttachmentsApi attachmentsApi, DefaultApi defaultApi,
-      AuthSession authSession, TemplateEngine templateEngine, RetryWithRecoveryBuilder retryBuilder) {
-    this(messagesApi, messageApi, messageSuppressionApi, streamsApi, podApi, attachmentsApi, defaultApi, authSession,
-        new TemplateResolver(templateEngine), retryBuilder);
-  }
-
-  private MessageService(MessagesApi messagesApi, MessageApi messageApi, MessageSuppressionApi messageSuppressionApi,
-      StreamsApi streamsApi, PodApi podApi, AttachmentsApi attachmentsApi, DefaultApi defaultApi,
-      AuthSession authSession, TemplateResolver templateResolver, RetryWithRecoveryBuilder retryBuilder) {
+  private final RetryWithRecoveryBuilder<?> retryBuilder;
+
+  public MessageService(
+      final MessagesApi messagesApi,
+      final MessageApi messageApi,
+      final MessageSuppressionApi messageSuppressionApi,
+      final StreamsApi streamsApi,
+      final PodApi podApi,
+      final AttachmentsApi attachmentsApi,
+      final DefaultApi defaultApi,
+      final AuthSession authSession,
+      final TemplateEngine templateEngine,
+      final RetryWithRecoveryBuilder<?> retryBuilder
+  ) {
     this.messagesApi = messagesApi;
     this.messageApi = messageApi;
     this.messageSuppressionApi = messageSuppressionApi;
     this.streamsApi = streamsApi;
     this.podApi = podApi;
     this.attachmentsApi = attachmentsApi;
     this.authSession = authSession;
-    this.templateResolver = templateResolver;
+    this.templateEngine = templateEngine;
+    this.templateResolver = new TemplateResolver(templateEngine);
     this.defaultApi = defaultApi;
     this.retryBuilder = retryBuilder;
   }
 
+  /**
+   * Returns the {@link TemplateEngine} that can be used to load templates from classpath or file system.
+   *
+   * @return the template engine
+   */
+  public TemplateEngine templates() {
+    return templateEngine;
+  }
+
   /**
    * Get messages from an existing stream. Additionally returns any attachments associated with the message.
    *

diff --git a/symphony-bdk-core/src/test/java/com/symphony/bdk/core/service/MessageServiceTest.java b/symphony-bdk-core/src/test/java/com/symphony/bdk/core/service/MessageServiceTest.java
@@ -14,11 +14,7 @@
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
-import com.symphony.bdk.http.api.ApiClient;
-import com.symphony.bdk.http.api.ApiException;
-import com.symphony.bdk.http.api.ApiRuntimeException;
 import com.symphony.bdk.core.auth.AuthSession;
-import com.symphony.bdk.core.config.model.BdkRetryConfig;
 import com.symphony.bdk.core.retry.RetryWithRecoveryBuilder;
 import com.symphony.bdk.core.service.stream.constant.AttachmentSort;
 import com.symphony.bdk.core.test.JsonHelper;
@@ -40,6 +36,9 @@
 import com.symphony.bdk.gen.api.model.V4ImportResponse;
 import com.symphony.bdk.gen.api.model.V4Message;
 import com.symphony.bdk.gen.api.model.V4Stream;
+import com.symphony.bdk.http.api.ApiClient;
+import com.symphony.bdk.http.api.ApiException;
+import com.symphony.bdk.http.api.ApiRuntimeException;
 import com.symphony.bdk.template.api.TemplateEngine;
 import com.symphony.bdk.template.api.TemplateException;
 
@@ -169,8 +168,7 @@ void testSendWithStreamObjectCallsSendWithStreamId() {
 
   @Test
   void testSendWithTemplateAndStreamObjectCallsSendWithCorrectStreamIdAndMessage() throws TemplateException {
-    when(templateEngine.getBuiltInTemplates()).thenReturn(Collections.singleton(TEMPLATE_NAME));
-    when(templateEngine.newBuiltInTemplate(eq(TEMPLATE_NAME))).thenReturn(parameters -> MESSAGE);
+    when(templateEngine.newTemplateFromClasspath(eq(TEMPLATE_NAME))).thenReturn(parameters -> MESSAGE);
 
     MessageService service = spy(messageService);
     doReturn(new V4Message()).when(service).send(anyString(), anyString());
@@ -183,8 +181,7 @@ void testSendWithTemplateAndStreamObjectCallsSendWithCorrectStreamIdAndMessage()
 
   @Test
   void testSendWithTemplateCallsSendWithCorrectMessage() throws TemplateException {
-    when(templateEngine.getBuiltInTemplates()).thenReturn(Collections.singleton(TEMPLATE_NAME));
-    when(templateEngine.newBuiltInTemplate(eq(TEMPLATE_NAME))).thenReturn(parameters -> MESSAGE);
+    when(templateEngine.newTemplateFromClasspath(eq(TEMPLATE_NAME))).thenReturn(parameters -> MESSAGE);
 
     MessageService service = spy(messageService);
     doReturn(new V4Message()).when(service).send(anyString(), anyString());
@@ -195,8 +192,7 @@ void testSendWithTemplateCallsSendWithCorrectMessage() throws TemplateException
 
   @Test
   void testSendWithTemplateThrowingTemplateException() throws TemplateException {
-    when(templateEngine.getBuiltInTemplates()).thenReturn(Collections.singleton(TEMPLATE_NAME));
-    when(templateEngine.newBuiltInTemplate(eq(TEMPLATE_NAME))).thenThrow(new TemplateException("error"));
+    when(templateEngine.newTemplateFromClasspath(eq(TEMPLATE_NAME))).thenThrow(new TemplateException("error"));
 
     assertThrows(TemplateException.class, () -> messageService.send(STREAM_ID, TEMPLATE_NAME, Collections.emptyMap()));
   }

diff --git a/symphony-bdk-examples/bdk-core-examples/build.gradle b/symphony-bdk-examples/bdk-core-examples/build.gradle
@@ -1,22 +1,20 @@
 description = 'Symphony Java BDK Examples - Core'
 
 dependencies {
+
     implementation project(':symphony-bdk-core')
-    implementation project(':symphony-bdk-template:symphony-bdk-template-api')
-    implementation project(':symphony-bdk-http:symphony-bdk-http-api')
-    implementation project(':symphony-bdk-http:symphony-bdk-http-webclient')
-    implementation project(':symphony-bdk-template:symphony-bdk-template-freemarker')
 
-    implementation 'org.slf4j:slf4j-api'
+    runtimeOnly project(':symphony-bdk-http:symphony-bdk-http-webclient')
+    runtimeOnly project(':symphony-bdk-template:symphony-bdk-template-freemarker')
+
     runtimeOnly 'ch.qos.logback:logback-classic'
+
+    implementation 'org.slf4j:slf4j-api'
     implementation 'commons-io:commons-io'
     implementation 'org.apache.commons:commons-lang3'
 
     compileOnly 'org.projectlombok:lombok'
     annotationProcessor 'org.projectlombok:lombok'
-
-    testCompileOnly 'org.projectlombok:lombok'
-    testAnnotationProcessor 'org.projectlombok:lombok'
 }
 
 uploadArchives.enabled = false
diff --git a/...xamples/bdk-core-examples/src/main/java/com/symphony/bdk/examples/MessageExampleMain.java b/...xamples/bdk-core-examples/src/main/java/com/symphony/bdk/examples/MessageExampleMain.java
@@ -38,11 +38,9 @@ public static void main(String[] args) throws Exception {
     final V4Message regularMessage = bdk.messages().send(STREAM_ID, MESSAGE);
 
     //use templates
-    final V4Message sentWithBuiltInTemplate = bdk.messages().send(STREAM_ID, "simpleMML",
-        Collections.singletonMap("message", "Hello from a built-in template!"));
 
     final V4Message sendWithCustomTemplate = bdk.messages()
-        .send(STREAM_ID, "customTemplate.ftl", Collections.emptyMap());
+        .send(STREAM_ID, "/complex-message.ftl", Collections.singletonMap("name", "Freemarker"));
 
     //retrieve the details of existing messages
     final V4Message message = bdk.messages().getMessage(regularMessage.getMessageId());