RestFB Messenger is a Java library for implementing chatbots on the Facebook Messenger Platform.
It utilizes the RestFB client for the low level communication with the Facebook Graph API. It also uses the RestFB Java types for input arguments and return types.
The RestFB Messenger library does basically all the low level plumbing and provides the user a high level API to implement the chatbot.
The user has to implement the com.github.marsbits.restfbmessenger.webhook.CallbackHandler
interface or extending the convenient com.github.marsbits.restfbmessenger.webhook.AbstractCallbackHandler
like below:
public class MyCallbackHandler extends AbstractCallbackHandler {
@Override
public void onMessage(Messenger messenger, MessagingItem messaging) {
String senderId = messaging.getSender().getId();
IdMessageRecipient recipient = new IdMessageRecipient(senderId);
MessageItem message = messaging.getMessage();
messenger.send().markSeen(recipient);
messenger.send().typingOn(recipient);
messenger.send().textMessage(recipient,
format("Hi human, I received your message: %s", message.getText()));
messenger.send().typingOff(recipient);
}
@Override
public void onPostback(Messenger messenger, MessagingItem messaging) {
// TODO implement..
}
// TODO override other methods the chatbot need to respond to..
}Add the restfbmessenger-core dependency to your project:
Maven:
<dependency>
<groupId>com.github.marsbits.restfbmessenger</groupId>
<artifactId>restfbmessenger-core</artifactId>
<version>2.2.1</version>
</dependency>Gradle:
dependencies {
compile "com.github.marsbits.restfbmessenger:restfbmessenger-core:2.2.1"
}If you want to use RestFB Messenger in a Spring Boot application see the Spring Boot configuration instead.
In a standard webapp the WebhookServlet can be configured in the web.xml like:
<servlet>
<servlet-name>webhook</servlet-name>
<servlet-class>com.github.marsbits.restfbmessenger.webhook.WebhookServlet</servlet-class>
<init-param>
<param-name>messengerProviderClass</param-name>
<param-value>[fully-qualified class name of the MessengerProvider]</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>webhook</servlet-name>
<url-pattern>/webhook</url-pattern>
</servlet-mapping>The messengerProviderClass init param must point to a custom
class implementing the com.github.marsbits.restfbmessenger.MessengerProvider
to provide the Messenger instance to the WebhookServlet.
See the RestFB Messenger Echo App Engine sample for a full sample
using the web.xml configuration.
In a Servlet 3 environment the WebhookServlet can also be configured
programmatically like:
@WebListener
public class EchoInitializer implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent event) {
Messenger messenger = new EchoMessengerProvider().getMessenger();
WebhookServlet webhookServlet = new WebhookServlet(messenger);
ServletRegistration.Dynamic webhook =
event.getServletContext().addServlet("WebhookServlet", webhookServlet);
webhook.setLoadOnStartup(1);
webhook.addMapping("/webhook");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
}
}Another option is to extend the com.github.marsbits.restfbmessenger.webhook.WebhookServlet
and annotate it with the @WebServlet annotation.
See the RestFB Messenger Echo Servlet 3 sample for a full sample
using a @WebListener to do the configuration programmatically.
When using Spring one option is to simply configure the WebhookServlet
like the previous examples.
In a Spring environment the Messenger bean will typically be created
manually in the Spring application context and use other injected beans
as well.
In that case the MessengerProvider implementation must find a way to
retrieve the Messenger instance from the Spring application context.
Another option is to create a custom controller and use that instead of
the WebhookServlet. This custom controller should then listen to Facebook
callbacks and act on them appropriately.
This could look like:
@Controller
@RequestMapping("/webhook")
public class EchoWebhookController {
private static final Logger logger = Logger.getLogger(EchoWebhookController.class.getName());
@Autowired
private Messenger messenger;
@RequestMapping(method = RequestMethod.GET)
public ResponseEntity<String> get(
@RequestParam(HUB_MODE_PARAM_NAME) String mode,
@RequestParam(HUB_VERIFY_TOKEN_PARAM_NAME) String verifyToken,
@RequestParam(HUB_CHALLENGE_PARAM_NAME) String challenge) {
logger.info("Validating webhook...");
if (HUB_MODE_SUBSCRIBE_VALUE.equals(mode) && messenger.verifyToken(verifyToken)) {
logger.info("Validating webhook succeeded");
return new ResponseEntity<>(challenge, HttpStatus.OK);
} else {
logger.warning("Validating webhook failed");
return new ResponseEntity<>("Failed validation. Make sure the validation tokens match.",
HttpStatus.FORBIDDEN);
}
}
@RequestMapping(method = RequestMethod.POST)
public void post(
@RequestHeader(HUB_SIGNATURE_HEADER_NAME) String signature,
@RequestBody String payload) {
logger.info("Webhook received");
try {
messenger.handleCallback(payload, signature);
} catch (Exception e) {
logger.severe(format("Exception handling webhook: %s", e.getMessage()));
throw e;
}
}
}See the RestFB Messenger Echo Spring sample for a full sample using a custom Spring controller.
Add the restfbmessenger-spring-boot-starter dependency to your project:
Maven:
<dependency>
<groupId>com.github.marsbits.restfbmessenger</groupId>
<artifactId>restfbmessenger-spring-boot-starter</artifactId>
<version>2.2.1</version>
</dependency>Gradle:
dependencies {
compile "com.github.marsbits.restfbmessenger:restfbmessenger-spring-boot-starter:2.2.1"
}The restfbmessenger-spring-boot-starter will automatically add the
restfbmessenger-core dependency and trigger the auto configuration to
create the com.github.marsbits.restfbmessenger.Messenger instance and
register the com.github.marsbits.restfbmessenger.webhook.WebhookServlet
servlet.
Only a class implementing the CallbackHandler need to be added to the
Spring context like:
@Component
public class MyCallbackHandler extends AbstractCallbackHandler {
@Override
public void onMessage(Messenger messenger, MessagingItem messaging) {
// TODO implement..
}The auto configuration will automatically hook the CallbackHandler in
the Messenger instance.
The following properties can be specified inside your
application.properties/application.yml file:
restfbmessenger:
enabled: true # Enable RestFB Messenger
verify-token: # The Facebook verify token (required the verify the webhook)
access-token: # The Facebook access token (required to send messages)
app-secret: # The Facebook app secret (if not provided the payload signature will not be validated; useful in e.g. dev environment)
api-version: v2.8 # The Facebook api version
webhook:
enabled: true # Enable the webhook servlet
path: /webhook # The path of the webhook servletSee the RestFB Messenger Echo Spring Boot sample for a full sample using the RestFB Messenger Spring Boot Starter.
The RestFB Messenger library is released under version 2.0 of the Apache License.