Chapter 42. Facebook

Available as of Camel 2.12

The Facebook component provides access to all of the Facebook APIs accessible using Facebook4J. It allows producing messages to retrieve, add, and delete posts, likes, comments, photos, albums, videos, photos, checkins, locations, links, etc. It also supports APIs that allow polling for posts, users, checkins, groups, locations, etc.

Facebook requires the use of OAuth for all client application authentication. In order to use camel-facebook with your account, you'll need to create a new application within Facebook at https://developers.facebook.com/apps and grant the application access to your account. The Facebook application's id and secret will allow access to Facebook APIs which do not require a current user. A user access token is required for APIs that require a logged in user. More information on obtaining a user access token can be found at https://developers.facebook.com/docs/facebook-login/access-tokens/.

Maven users will need to add the following dependency to their pom.xml for this component:

	<dependency>
    	<groupId>org.apache.camel</groupId>
    	<artifactId>camel-facebook</artifactId>
    	<version>${camel-version}</version>
	</dependency>

facebook://[endpoint]?[options]

The facebook component can be configured with the Facebook account settings below, which are mandatory. The values can be provided to the component using the bean property configuration of type org.apache.camel.component.facebook.config.FacebookConfiguration. The oAuthAccessToken option may be ommited but that will only allow access to application APIs.

You can also configure these options directly in an endpoint URI.

In addition to the above settings, non-mandatory options below can be used to configure the underlying Facebook4J runtime through either the component's configuration property or in an endpoint URI.

Producer endpoints can use endpoint names and options from the table below. Endpoints can also use the short name without the get or search prefix, except checkin due to ambiguity between getCheckin and searchCheckin. Endpoint options that are not mandatory are denoted by [].

Producer endpoints can also use a special option *inBody* that in turn should contain the name of the endpoint option whose value will be contained in the Camel Exchange In message. For example, the facebook endpoint in the following route retrieves activities for the user id value in the incoming message body.

from("direct:test").to("facebook://activities?inBody=userId")...

Any of the endpoint options can be provided in either the endpoint URI, or dynamically in a message header. The message header name must be of the format CamelFacebook.option. For example, the userId option value in the previous route could alternately be provided in the message header CamelFacebook.userId. Note that the inBody option overrides message header, e.g. the endpoint option inBody=user would override a CamelFacebook.userId header.

Endpoints that return a String return an Id for the created or modified entity, e.g. addAlbumPhoto returns the new album Id. Endpoints that return a boolean, return true for success and false otherwise. In case of Facebook API errors the endpoint will throw a RuntimeCamelException with a facebook4j.FacebookException cause.

Any of the producer endpoints that take a reading#reading parameter can be used as a consumer endpoint. The polling consumer uses the since and until fields to get responses within the polling interval. In addition to other reading fields, an initial since value can be provided in the endpoint for the first poll.

Rather than the endpoints returning a List (or facebook4j.ResponseList) through a single route exchange, camel-facebook creates one route exchange per returned object. As an example, if "facebook://home" results in five posts, the route will be executed five times (once for each Post).

The reading option of type facebook4j.Reading adds support for reading parameters, which allow selecting specific fields, limits the number of results, etc. For more information see Graph API at Facebook Developers.

It is also used by consumer endpoints to poll Facebook data to avoid sending duplicate messages across polls.

The reading option can be a reference or value of type facebook4j.Reading, or can be specified using the following reading options in either the endpoint URI or exchange header with CamelFacebook. prefix.

Any of the URI options can be provided in a message header for producer endpoints with CamelFacebook. prefix.

All result message bodies utilize objects provided by the Facebook4J API. Producer endpoints can specify the option name for incoming message body in the inBody endpoint parameter.

For endpoints that return an array, or facebook4j.ResponseList, or java.util.List, a consumer endpoint will map every elements in the list to distinct messages.

To create a post within your Facebook profile, send this producer a facebook4j.PostUpdate body.

	from("direct:foo")
		.to("facebook://postFeed/inBody=postUpdate);

To poll all statuses on your home feed every 5 seconds:

	from("facebook://home?consumer.delay=5000")
		.to("bean:blah");

Searching using a producer with dynamic options from header.

In the bar header we have the Facebook search string we want to execute in public posts, so we need to assign this value to the CamelFacebook.query header.

	from("direct:foo")
		.setHeader("CamelFacebook.query", header("bar"))
		.to("facebook://posts");