Exposing Web Services as Callable Objects 

Use

Web services are Web interfaces that are based on open and commonly accepted standards and can be integrated into a company’s business scenarios. Using Web services enables you to combine functions implemented in different software components into a single process.

You can expose any web service as a callable object using Guided Procedures (GP) design time:

·        Local Web services

·        Web services accessed through a logical destination

·        Web services published in a UDDI Services Registry (SR)

The integration into the GP framework is done transparently by the system.

To expose the function module as a callable object, you must use the wizard that GP design time provides.

Currently Web Service callable objects support the following SOAP encoding styles:

§         SOAP Remote Procedure Call Literal encoding (SOAP RPC-literal)

§         SOAP document-style encoding, which is also known as message-style or document-literal encoding

Prerequisites

·        In case you want to access Web services through a logical destination or UDDI SR, you must have created and configured the required destinations in advance.

More information: Configuring Destinations for WS Callable Objects

·        You need to know a precise WSDL URL for internal or external Web services that do not require authentication.

Procedure

       1.      Open the gallery and choose Create Callable Object from the contextual panel.

       2.      Enter the required basic data as follows:

Parameter	Description
Type	Choose Service → Web Service.
Name	Enter a name that is used to distinguish the callable object in the gallery. You are not required to use a unique name for the callable object.
Description	Describe the callable object by entering a brief description of its functions.
Original Language	Select the original language in which the callable object is being created.
Folder	Select the folder where the callable object is stored. You can either use an existing folder, or create a new one.

       3.      To open the Define Object screen, choose Next.

You can choose one of the following options:

Option	Description	Configuration
Case 1: WDSL URL Select
WSDL URL	You use this option when you want to call internal or external web services that do not require authentication. If you are behind a proxy and you want to call an external service, then you should configure your proxy in the SAP NetWeaver Administrator, in Web Services Configuration  → WS Global Settings.	Enter a string that defines the WSDL URL and press GO.
Case 2: Logical Destination Select
Logical Destination	You use this option when you want to: ·        Choose from a set of previously defined WSDL files ·        Access and execute Web services that need authentication ·        Browse for a Web service in a UDDI Services Registry ·        Access and execute ABAP web services	To open the configuration screen, choose Select. ...                             a.      From the In dropdown box, select a logical destination.                             b.      In the Search for field, enter a search pattern.                             c.      Choose Search. The list with the logical destination interfaces appears in the Result table below.                             d.      Select an interface and choose Accept.

       4.      On the Web Service Properties screen, select one of the following:

○       A port from the Interface Port Name dropdown box

○       A logical destination (if any)  from the Logical Destination Endpoint dropdown box.

       5.      From the list with the available interface operations, choose an operation.

The operation parameters are displayed in the right-hand part of the screen.

For each particular Web service, different operations are available, for example:

■       StartProcess is an operation defined for the GPProcessDiscoveryWSIL Web service. It creates an instance of a process template.

More information: Consuming the GPProcessDiscovery Web Services

■       CompleteAction is defined for the GPActionDiscoveryWSIL Web service and completes a process step.

More information: Consuming the GPActionDiscoveryWSIL Web Service

       6.      To open the Define Input screen, choose Next

The input parameters of the web service are automatically detected.

       7.      To open the Define Output screen, choose Next.

The output parameters of the web service are automatically detected

       8.      Choose Next, and then Finish and Open.

The callable object design time opens. You can edit the object definition here.

In case of changes in the definition of the Web service you have exposed, you can update the existing callable object through the GP design time. On the Object Definition tab page, choose Update to update input, output, configuration parameters, result states, and exceptions defined for the selected operation.

To check for parameter compatibility, choose Check.

       9.      To activate the object, choose (Activate). 

Example

For an example of exposing a Web service as a callable object, see Importing a Web Service in Guided Procedures.