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XCICS Web support includes some base components that are used for all XCICS Web support tasks, and some task-specific components which you select and configure for individual XCICS Web support tasks.
Base components
These are the basic components of the XCICS Web Support interface:
| • | TCP/IP support in XCICS is provided by the Unix/Linux and Windows operating systems |
| • | Secure Sockets Layer (SSL) support is used to provide security for the XCICS Web support implementation, and it is provided by OpenSSL packages (www.openssl.org). XCICS supports the Secure Sockets Layer (SSL) 3.0 protocol, and the Transport Layer Security (TLS) 1.0 protocol. |
| • | The Sockets listener task (CSOL) detects inbound TCP/IP connection requests, and invokes XCICS Web support by attaching the Web attach task. |
| • | Web attach tasks (CWXN, CWXU or an alias) receive data from the Web | client and deal with initial processing of requests, including URIMAP matching, code page conversion of the HTTP headers, analysis of the request, and code page conversion of the message body. The tasks also pre-process chunked and pipelined messages received from a Web client. If a static response is delivered (using a URIMAP definition), the Web attach task handles this processing as well. |
Resource definitions
These are the resources required for the XCICS Web Support interface execution:
| • | TCPIPSERVICE resource definitions are used to define each port that you use for XCICS as an HTTP server, including security options for connections on that port, and timeout and maximum size limits for inbound requests. They are not used for XCICS as an HTTP client. |
| • | URIMAP resource definitions match the URLs of requests from Web clients, or requests to an HTTP server, and provide XCICS with information on how to process the requests |
| • | TRANSACTION resource definitions are used to define alias transactions for HTTP request processing. XCICS supplies a resource definition for a default alias transaction, CWBA. When the Web attach task has completed initial processing for the request, if an application-generated response is to be produced, an alias transaction handles the remaining stages of processing. These include receiving the request, executing the application's business logic, construction of the HTTP response and code page conversion of the HTTP response. |
User application programs
The following type of user application programs may be used with the XCICS Web Support interface:
| • | Web-aware application programs can be designed for XCICS Web support, using the EXEC CICS WEB and EXEC CICS DOCUMENT application programming interfaces. For XCICS as an HTTP server, these programs can receive and analyze HTTP requests and provide application-generated responses to the Web client. For XCICS as an HTTP client, a user application program in XCICS can initiate an HTTP request to a server, and receive a response from it. |
| • | COMMAREA applications, programs which are designed to be linked to from another program using a COMMAREA interface, can be accessed using XCICS Web support with a converter program to convert their output into HTML for transmission to a Web client. Alternatively, you can write a Web-aware application program that links to a COMMAREA application and uses its output to provide HTTP responses. |
Programming interfaces
The XCICS Web Support interface is normally programmed by means of:
| • | The EXEC XCICS WEB application programming interface interprets and constructs HTTP requests and HTTP responses. Some commands are used for XCICS as an HTTP server, some for XCICS as an HTTP client, and some are for both forms of XCICS Web support. |
| • | The EXEC XCICS DOCUMENT application programming interface constructs XCICS documents to provide the body of a response or request that is sent out from XCICS. |
XCICS Web support utility programs
| • | Analyzer programs are associated with TCPIPSERVICE definitions. They are used to interpret an HTTP request if a URIMAP definition specifies the use of an analyzer program, or if no URIMAP definition is present. XCICS supplies a default analyzer program DFHWBAAX, which provides basic error handling, and an example analyzer program DFHWBADX, which supports requests using the URL format that XCICS Web support used
before CICS TS 3.1. Either of these analyzers can be used as a basis for your own analyzer program. |
| • | Converter programs can be used to decode an HTTP request and construct input to a user application program. Web-aware application programs do not normally require converter programs, but they might be needed by non-Web-aware applications that were not designed for XCICS Web support. XCICS does not supply a converter program. You can write a number of converter programs and select any converter program in your XCICS region to process a request. |
Document construction facilities
Response documents may be constructed by means of these facilities:
| • | UNIX/Linux or Windows files can be served as the body of a response to an HTTP request from a Web client. |
| • | Document template support enables message bodies to be built from fragments of HTML which are prepared offline. |
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