The
importance of CICS in VSE installations cannot be overstated. CICS
serves as data repository, interactive interface and as the focal
point of processing in most VSE shops. Recognizing the critical
nature of CICS in VSE/ESA and z/VSE, CSI International is proud
to introduce our latest TCP/IP for VSE enhancement--the
CICS Access Facility (CAF). The purpose of
CAF is to do just what the name implies: provide access to
CICS using TCP/IP facilities.
 What
do we mean by ‘access’?
• Access to CICS data directly from the Internet or intranet
by having web programs run under CICS Program Control.
• Access to active CICS data under CICD File Control via the TCP/IP
for VSE FTP client and FTP daemon.
These enhancements represent important advances in the functions
provided by TCP/IP for VSE. The following paragraphs explore
CAF’S
components.
back
to top
CAF
CGI Processor
Many VSE installations keep their live, production
data under control of CICS. In order to access that data with file
integrity, you need wed server applications that are also running
under control of CICS. The CAF CGI Processor runs as a CICS program
which communicates directly with the TCP/IP
for VSE Web Server.
Since it is executing as a true CICS program, it has access to
data that is defined to that CICS region and can therefore serve
that data to web browsers on the Internet or corporate intranet.
How does it work? TCP/IP for
VSE establishes a long-running
transaction within the CICS region. This long-running transaction
uses an internal socket queuing mechanism to communicate directly
with the TCP/IP partition. When a request comes in from the HTTP
Daemon, TCP/IP for VSE determines if the program is to
run under CICS and, if appropriate, directs the long-running task
to spawn a new CICS process that will link to the requested program.
That program has access to any CICS facility or file that is available
to any program running in the CICS environment. It can
be written in PL/1, COBOL or S/390 Assembler. The program can access
parameters (as passed by the browser in the URL) via the COMMAREA
and return a response by virtue of the EXEC CGI interface, a new
programming interface that allows bi-directional communication
between CICS and TCP/IP for VSE. The EXEC CGI interface
is used to pass HTML back to the HTTP Daemon using an internal
high-speed interface. These HTML lines will then be sent back to
the web browser for interpretation and display. The CAF CGI processor
can be used in conjunction with a two tier or three tier web-serving
solution.
back
to top
FTP
Support for the CICS File System
Everyone agrees that FTP is great, but wouldn't
it be really nice if it were possible to do your file transfers
against active CICS data without having to take CICS down. With
the CICS Access
Facility, this requirement is now satisfied. Because CAF accesses
data using CICS file control, VSE installations can read and update
CICS data directly using FTP. Let’s say, for example, that
there is a VSAM KSDS that you would like to update. You can prepare
the updates on the system of your choice and then FTP those updates
directly into your VSAM KSDS file. TCP/IP for VSE will
treat those updates as KSDA inserts, effectively providing a merge
function with active CICS data. With the inclusion of this statement,
all files that are open to CICS at the time of any request become
available to FTP. This is a very dynamic function. As files open
or close, they are made available or unavailable to FTP. Once
again, the function is implemented via a long-running transaction
running in the CICS partition. Because the files are accessed
under CICS file control, you have complete file integrity while
performing data transfer.
back
to top
Summary
The CICS Access Facility (CAF) provides functionality for interfacing your CICS system with your
TCP/IP network. With benefits including web-serving of CICS data with complete file integrity
and integrating the CICS file system with the file system provided
with TCP/IP
for VSE and
FTP, CAF is tailor-made for the VSE installation that wants to integrate
CICS into TCP/IP for VSE environment.
back
to top |
|
