04 Consuming Web Services

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Consuming a Web Service

Susanne Rothaug


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SAP AG2004 / Susanne Rothaug / Consuming a Web Service

Objectives

After completing this session you will be able to: Generate and deploy a Web service proxy

Create a Web service cl ient appl ication


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Creating a Web service client application consists of 3 major steps:

1) Retrieving the URL of the Web service. To do so, you have the following options:

- Search a UDDI registry. The link to the WSDL file is stored there.

Via URL (from server)

From local Server

From file system

From XI repository

- Look at the Web Service Homepage

2) Generate the Web service proxy.

3) Develop the client application.


Creating a Web Service Client Application

1

From UDDI Via URL (from server)

From local Server

From File System

From XI repository

2

Environment specific

Avai lab le for ABAP & Java

3 Focus on Business Application

SOAP / XML handling hidden by proxy

DevelopClient Application

GenerateWeb Service Proxy

Retrieve WSDL


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First, you need to create the Web service client proxy.

The first step to do so is to create a proxy project. ChooseFile New Project. Click on Web

Services and then choose Deployable Proxy Project. With the deployable proxy all information is

either generated during deployment or is retrieved at runtime. Therefore, deployable proxies are to a

certain degree protected from runtime changes. This also means that different client applications can use

this proxy later on. The other option would be a standalone proxy:, i.e., a Web service client that

generates stubs and runs without the J2EE Engine. This proxy can be used only with the SAP Web AS

release for which it has been generated.


Consuming a Web Service: Create Web Service ClientProxy - 1 -

Deployable vs.

standalone

proxy


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The new project is now displayed in the Client Explorer. Open the context menu and chooseNew

Client Proxy Definition.

You are asked to specify a package and a proxy name. Choose Local File System or URL as WSDL

source.

Select JAX-RPC Service Interface if you want JAX-RPC interface to be generated, and choose a WSDL

source among Local Server, Local File System or URL, and UDDI or URL to find the WSDL document

on which the WS proxy is to be based.

If you select Local Server, a list of deployed Web services on the J2EE Engine is displayed. Select the one

for which you are creating this proxy and choose Next.

If you select Local File System or URL, you have to specify the WSDL URL or browse the WSDL for the

file system.

If you select UDDI or URL, you have to specify the WSDL URL or search the WSDL in the UDDI

registry. Selecting UDDI opens the Search page of the UDDI client browser and by using its features you

can find the required WSDL. To use the UDDI client, you have to configure the HTTP proxy settings in

the Web Services Container Service of the Visual Administrator.


Consuming a Web Service: Create Web Service ClientProxy - 2 -

Package and

proxy name

Choose WSDL

source


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Now enter the URL of the WSDL of the Web service you want to create a client for.


Consuming a Web Service: Create Web Service ClientProxy 3 -

Enter WSDLURL


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In the Client Explorer you can view the files that have been created, such as the Logical Ports, the

Proxy Classes and Service Endpoint Interfaces etc.

Logical ports (LPs) contain the configuration of the client-side SOAP runtime, such as the access URL

or security settings. These are required if Web service calls are executed using proxies. To make

maintaining configuration data as flexible as possible, this data is not included in the Web service client

proxy definition, but can be entered or edited using the LPs created as part of the proxy definition in the

Client Explorer. So in short, when you move the proxy from one system to another (testing to

productive, f.ex.), all you have to do is change the target URL in the LP.

- The LPs provided correspond to the Web service configurations created for the Web service.

- Note: If a WS client was generated on the basis of a tModel, no LP is available. A LP can only be

generated from the WSDL document of the business service.

The Service Endpoint Interface (SEI) exposes the business methods provided by a particular Web

service. It is generated from the WSDL PortType and named after the PortType. The way the methods

are generated depends on the PortType and the JAX-RPC 1.0 conventions.

- For SAP Web Service Clients, an additional option is provided generation of RPC-style SEI for

document/literal-style WSDLs. In this case, for each generated method that has only one wrapper

parameter for the input, and one wrapper parameter for the output, an additional method is generated

that has the same name, but in whose signature the input and output parameters are unwrapped.


Consuming a Web Service: Create Web Service ClientProxy 4 -

Logical Port

Service

Endpoint

Interface


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Use the Web project that is already available in your Developer Studio. It would be too much effort to

write a whole client application, so we use this Web project. It contains, among a lot of other things, a jsp

the coding of which calls the credit limit check Web service.

Switch to the J2EE Explorer in the J2EE Development Perspective. The following steps need to be

executed:

Create an Ear project for the Web project.

Select the Web project and choose Add Web Service Client API Library. This enables you to use the

client API of the deployable proxy. Otherwise the IDE would not know while building the application

what a Web service proxy is. You have to do this only during design time. During runtime there are

other mechanisms.

Choose the proxy you just created from the list and click OK.


Consuming a Web Service: Create a client application - 1 -


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The second thing to do is to add the necessary JNDI mappings. They are necessary to find different objects

again that have been deployed to the J2EE engine.

Still in the J2EE Development perspective, expand the CreditLimitPrivateWeb project. In the context

menu of web-j2ee-engine.xml, choose Open. Choose the References tab.

To create new mappings, select jndi mapping and choose Add. Enter the required data:

1) Application local JNDI name this is the name under which the proxy is looked up in the application

- is in this example CreditLimitPrivateProxy.

2) Choose interface as the Server Component type.

3) Server Component JNDI name the name of the JNDI context under which the proxy is bound. The

following convention is used: /wsclients/proxies///.




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In the Enterprise Application project, double click on application-j2ee-engine.xml. Under the General

tab, selectReferences Add. Choose Select application in the reference target type popup and then

choose the proxy project you just created.




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Finally, select hard as the reference type.

Make sure that you deploy both the proxy and the client application to the J2EE engine.




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In short

The Enterprise Service Architecture (ESA), SAPs

approach for building services-oriented business

applications utilizes Web Services as vital part of itscommunication and integration strategy

SAPs rich business functionality, in conjunction with

state-of-the-art technology, enables you to establish

cross-company business processes as an integrated

part of your development efforts based on Web

Services

SAP Web Application Server 6.40 offers an easy,convenient way to build Web services


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Summary

Now you should be able to: Generate and deploy a Web service proxy

Create a Web service cl ient appl ication

Documents

04 Consuming Web Services