Messaging Solutions in a Linux Environment

18 Messaging Solutions in a Linux Environment

򐂰 The client transport type allows an application program to run on a computer

separate from the computer where the queue manager is running. The queue

manager must have a server connection channel defined. This is done in a

synchronous fashion. The application program on Linux normally uses a

TCP/IP network connection to connect to the queue manager.

1.3.6 WebSphere MQ application programming interfaces

The three high-level APIs that are supported are the Message Queueing

Interface (MQI), Java Messaging Service (JMS) and the Application

Management Interface (AMI) that is a downloadable extension. The AMI is fully

supported by IBM but is no longer actively developed.

Introduction to the MQI

One of the enormous benefits of WebSphere MQ is that communicating between

applications can be done with a very small number of programming verbs across

multiple languages. These verbs are also the foundation for object-oriented

language support such as C++, WebSphere MQ for Java and JMS. There are 13

verbs in all but the most frequently used ones are pictured in Figure 1-4:

򐂰

MQCONN - for connecting a program to a queue manager

򐂰

MQOPEN - for opening a connection to an object such as a queue

򐂰

MQPUT - for placing a message in a queue

򐂰

MQGET- for retrieving a message from a queue

򐂰

MQINQ - for retrieving state information about an object such as a queue

򐂰

MQSET - for setting attributes on an object such as a queue

򐂰

MQCLOSE - for closing a connection to an object such as a queue

򐂰

MQDISC - for releasing a programs connection to a queue manager

Figure 1-4 MQI verbs

A

Put

Invoice-Q

Get

Invoice-Q

MQI

Invoice-Q

MQGET

MQOPEN

MQCLOSE

MQPUT1

MQBEGIN

MQCMT

MQBACK

MQPUT

MQCONN

MQCONNX

MQDISC

MQINQ

MQSET

B

Q

u

e

u

e

Chapter 1. Introduction to Linux and messaging 19

For programmatic control of transactions, these additional verbs in Figure 1-5 are

also supported:

򐂰

MQBEGIN - to notify a queue manager that a transaction is about to start

򐂰

MQCMIT - to commit the transaction with a queue manager

򐂰

MQBACK - to roll-back a transaction with a queue manager

Figure 1-5 MQI Transactional Verbs

For further information about programming with WebSphere MQ API’s can be

found in IBM publications:

򐂰 WebSphere MQ Application Programming Guide, SC34-6064-03

򐂰 WebSphere MQ Application Programming Reference, SC34-6062-03

Introduction to C++

The WebSphere MQ C++ classes encapsulate the MQI. There is a single header

file (imqi.hpp) that provides all of the available classes. For C++ applications

written using the C++ classes of WebSphere MQ to work on Linux, the following

compiler and libraries are required:

򐂰 g++ version 2.95.2 or a version 3 compiler

򐂰 libstdc ++ Version 3.0

For further information about programming with WebSphere MQ C++ classes

can be found in the IBM publication WebSphere MQ Using C++ (SC34-6067-02).

Up to date information about using C++ and the C++ classes of WebSphere MQ

on Linux can be found at:

http://www-306.ibm.com/software/integration/mqfamily/platforms/supported/

wsmq_for_linux_intel_5_3.html

...

CALL MQBEGIN

...

CALL MQGET within syncpoint

...

CALL MQPUT within syncpoint

...

EXEC SQL INSERT

...

CALL MQQMT

...

DB2