How to Enable Web Services › How to Enable Web Services › Review Prerequisite Information › How Client Programs Access the API

How Client Programs Access the API

Web Services is a multithreaded application built with Java2 and the Apache AXIS2/JAVA component that enables client applications to communicate with a web service using the Simple Object Access Protocol (SOAP). The client and Web Services communicate using SOAP messages. The SOAP messages, requests and responses, are sent over TCP/IP between the client and the HTTP web server.

The following graphic shows the flow of information between the client, Web Services, and the CA Endevor SCM API.

As shown in the graphic, client applications access the CA Endevor SCM API through Web Services. Details of this process follow:

• The client application formats and sends a SOAP message to the HTTP server based on the definitions in the Web Services Description Language (WSDL) file. The request includes the name of the CA Endevor SCM data source that the client wants to access.
• Web Services matches the name of the data source requested by the client call to a configuration file. One or more configuration files are stored on the HTTP web server and enable access to the CA Endevor SCM API. A configuration file identifies the name and number of API STCs (the STC pool) available to pass requests to CA Endevor SCM. The CA Common Services CAICCI Spawn facility spawns the specified number of API STCs.

  To enable Web Services to process requests and communicate with the API, the z/OS environment where CA Endevor SCM is installed requires certain CA Common Services components, including the following:

  • CAICCI provides a common communications software layer that enables communication between Web Services and the API.
  • CAIENF must be configured to enable the CAICCI Spawn facility that lets CA Endevor SCM schedule, execute, and monitor a pool of STCs for Web Services requests.

This process uses the following standard technologies:

• XML language – The data format used by web service components. Communications between web service applications are written in XML format.
• Simple Object Access Protocol (SOAP) – An XML-based messaging protocol and encoding format for inter-application communication. SOAP messages are XML messages sent between applications. A SOAP message is a text file written in standard XML format that is enclosed in a SOAP structure. SOAP enables applications to know how to send and interpret the XML data.
• Web Services Description Language (WSDL) – A service description protocol. A web service's WSDL file is a dynamic XML file that serves as the interface between a client program and the web service. The Web Service WSDL file describes what CA Endevor SCM operations are available to the client program and the SOAP protocol bindings and message formats required to enable the client to interact with the web service.

  If you are using Web Services for a user-written client application, your web developer must create a client stub from the WSDL file. The client stub is responsible for conversion of parameters used in a function call and deconversion of results passed from the server after execution of the function. The client stub interacts with the web service stub. For more information see, User-Written Client Programs.