CSKL CICS Serves, Knowing Legacy is still making most profit for the organization.

1
CSKL - CICS Serves, Knowing Legacy (is still
making most profit for the organization).

• How Nat System switched from APPC over SNA to
  sockets over TCP/IP for the communication between
  client (Windows application) and server (CICS on
  z/OS), using the IBM-provided CSKL listener
  transaction by implementing a "child server"
  process, thereby leveraging its original
  three-tiered separation-of-concern approach.
  Advantages and drawbacks of short-living TCP
  connections used in this approach. Set-up and
  configuration of the CSKL.

2
Agenda

• Who am I and where do I come from?
• NatStar is just as dead as the mainframe -)
• CICS and TCP/IP
• What did we use it for and how?

3
GFI-Adelior
WELKOM - BIENVENUE - WELCOME
4
History
5
What we do

• Information systems designing and building,
  integration and implementation - the whole system
  life cycle
• Manage large and complex projects
• BPM
• Technologies Java, web services, web semantics,
  Client/Server...
• Infrastructure services Linux, Microsoft
• Business intelligence BO, Cognos
• Application software solutions accounting, time
  management...

6
NatStar Development Environment
7
Separation of concern
Application
uses
Operating System Services
Presentation Services
Data Services
Application Services
GUI Services
DBMS Services
Communication Services
8
Generation

• NCL for all Application Objects
• Generation of ANSI C code
• Specific to target platform
• Compilation on required targets

Code
Desktop to Mainframe
9
CICS TCP/IP

• Different flavours nowadays
• We use TCP/IP Socket Interface for CICS
• Vanilla TCP socket programming

10
Listener

• CSKL - The Concurrent Server
• Child Servers
• Take Socket

11
EBCDIC

• Extended Binary-Coded-Digit Interchange Code
• Code Pages
• Little/Big Endian
• Data Conversion is an issue

12
The way to the forum...
13
Short-living TCP connections

• Perfect match for short-living transactions
• Eliminates effect of user think-time
• Great for automatic fail-over
• Server is stateless
• Server is stateless
• Overhead of connection set-up
• TIME_WAIT

14
Set-up Configuration

• EZAC
• Define resources (mainly the listener)
• Tuning (RTFM!)
• Default values are not too bad

15
Some resources

• The listener
• CSKL Transaction
• EZACIC02 Program
• Configuration
• EZAC Transaction
• Operation
• EZAO Transaction
• netstat

16
Hints Tips

• Design is ever so important
• Know what to expect both ways
• RTFM!

17
The F...ine Manual

• Thats in the Communications Server Bookshelf

z/OS Communications Server IP CICS Sockets
Guide Version 1 Release 5 Document Number
SC31-8807-02 Program Number 5694-A01 and 5655-G52
18
Questions

• Questions?
• Comments?
• Remarks?
• Thoughts?
• Considerations?
• Issues?
• Anxieties?