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h1. Feature

The REST component is a Binding Component (BC) which enables to interact with external RESTful Web Services and to expose JBI services as RESTful Web Services.

In provider role, when a JBI MessageExchange is sent to a ServiceEndpoint (mapped to a Web Service), it is transformed into a REST message and sent to the linked external Web Service. In consumer role, when a REST message is received on an exposed Web Service, it is transformed into a JBI MessageExchange and sent to the corresponding JBI ServiceEndpoint.

The REST component is based on Restlet, Jersey, Resteasy, CXF or Axis2 (TBD). It provides the following features:
* Expose Restful Web Services as JBI Services
* Expose Restful Web Services as JBI Services using a WADL
* Expose Restful Web Services as JBI Services using a WSDL 2.0
* Expose JBI Services as Restful Web Services


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REST is a style of software architecture not a standard. If you want more details about REST, you can consult the Wikipedia page: [http://en.wikipedia.org/wiki/Representational_State_Transfer]
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h1. Exposing an external Restful Web Service as a JBI service endpoint

In provide mode, the component exposes an external Web Service in the JBI environment to send REST requests to the external Web Service.


h2. Usage

The petals-bc-rest component can expose an external Web Service as a JBI service endpoint by deploying a Service Unit on it:

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*Provides an external Web Service as a JBI service*
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When a message is received on a REST linked endpoint from the JBI environment, it is transformed into a REST message and sent to the Web Service. The address of the Web Service to send the REST message to is defined in the address extension of the deployed Service Unit.

The REST request is created according the HTTP method to used:
* GET:
** The REST URI is created from the address extension, JBI operation and JBI payload (only the children of the XML root of the JBI payload are used, the local name is the URI parameter name and the content of the tag is the URI parameter value).
** There is no HTTP body
* POST:
** The REST URI is created from the address extension and the JBI operation.
** The HTTP body is created from the JBI payload (The value of the XML root of the JBI payload is used)
* PUT:
** The REST URI is created from the address extension and the JBI operation.
** The HTTP body is created from an attachment (the first attachment found in the JBI message is used if there is one)
* DELETE:

The external Web Service is called and the REST response is processed and returned to the JBI environment.

The REST response is transformed into a JBI message like this:
* In case of error (HTTP status different from 200) a JBI fault is created.
* The HTTP body if it is present is used to create a JBI attachment (the HTTP body is not a XML in all the cases).
* The JBI payload is empty.
* The HTTP headers are added to the protocol header JBI message property

In all the cases, the MEP used to call the RESTful services is defined by the petalsCDK:mep extension.

h3. With no description of the RESTful Web Service

The HTTP method is defined in the http-method SU extension.

h3. With a WADL

The REST operation corresponding to the JBI operation is found in the WADL.
The HTTP method is defined in the WADL for the operation.

h3. With a WSDL 2.0

The REST operation corresponding to the JBI operation is found in the WSDL 2.0.
The HTTP method is defined in the WSDL 2.0 for the operation.

h2. Configuration

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{center}{*}Service Unit attributes to provide services{*}{center}
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| http-method | HTTP method to use. \\
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Possible values are: GET for the HTTP method GET, POST for the HTTP method POST, PUT for the HTTP method PUT and DELETE for the HTTP method DELETE. \\ | | {center}Yes\*{center} |
| wadl | WADL which defines the partner service | | {center}Yes\*{center} |
| wsdl2 | WSDL2 which defines the partner service | | {center}Yes\*{center} |
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\*Only one of these extensions must be used and is required in a specific SU.

h3. Service Unit descriptor

The service unit is configurable via its extensions in the jbi.xml file:
{code:lang=xml}
{code}

h3. Service Unit content

The Service Unit has to contain the following elements, packaged in an archive:
* The META-INF/jbi.xml descriptor file as described above,
* An optional imported WADL/WSDL 2.0 file describing the partner service


h1. Exposing an internal JBI service endpoint as a RESTful Web Service

In consumer mode, the component exposes an internal JBI service outside the bus to transfer incoming REST requests to the internal service.

h2. Usage

The petals-bc-rest component can listen incoming REST messages and send messages to a JBI service endpoint by deploying a Service Unit on it. The component consumes the JBI service:


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*Consumes a JBI service on a REST message*
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The service-name Service Unit extension value will be used as service name.

When a REST message is handled by the component, it is transformed into a JBI Message and sent to the JBI service endpoint configured in the Service Unit. The JBI message is created like this:
* The JBI operation is created from the SOAP action.
* Copy the SOAP body into the JBI one.
* Put the SOAP attachments into JBI ones.
* Put the SOAP headers into the protocol header JBI message property.


h2. Configuration

{include:0 CDK SU Consume Configuration}
\\
{center}{*}Service Unit attributes to consume services{*}{center}
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h3. Service Unit descriptor

The service unit is configurable via its extensions in the jbi.xml file:
{code:lang=xml}
{code}

h3. Service Unit content

The Service Unit has to contain the following elements, packaged in an archive:
* The META-INF/jbi.xml descriptor file as described above
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