Types of Messages & Message Header details.

Types of Messages: 

4 Types of messages:

1. Request: A message for which a reply is expected.

2. Reply: A reply to a request message.

3. Datagram: A message for which no reply is expected.

4. Report: Is an occurrence of an issue or an error.

About Messages

A message consists of two parts:

1. Data that is sent from one program to another

2. The message descriptor or message header

The message descriptor identifies the message (message ID) and contains control information,

also called attributes, such as message type, expiry time, correlation ID, priority, and the name ofthe queue for the reply.

A message can be up to 4 MB or 100 MB long, depending on the MQSeries version you use.

MQSeries Version 5 (for distributed platforms) supports a maximum message length of 100 MB.

The Message Descriptor

The table below contains some interesting attributes of the message descriptor. We mention them

here because they explain some of the functions the queue manager provides for you

put: Writing a message into a queue. This is similar to inserting a record into a DB2 table.

get: Reading or getting a message from a queue. This is similar to selecting a record from a DB2 table.

MQI (Message Queuing Interface): 

It is the interface between an MQ application program and MQ Queue Manager or Server. MQI provides set of calls thru that application program can put and get messages to and from the queue.

Note: The default message get in MQ is destructive, if you want a message to be get in browse mode the application program has to set the options for the Browse get in the get message options structure.

SQL: It is interface between an application program and the physical relational database (it can be DB2 or Oracle).

Programming languages used for as Interface to connect MQ

Ex:

MQ COBOL (Mainframe or AS/400 MQ application development)

MQ C

 

MQ has two types of software’s:

1. MQ Server: If you installed MQ Server s/w on a machine an MQ service will run on the machine and you can define all the WebSphere MQ objects(for example, Queue Manager, Queues etc.,). 15-20 min

2. MQ Client:If you intall MQ client S/W on a machine, there will be no service run that machine, it is a set of libraries used to communicate with MQ Server running on the Server machine). 

MQ: 

32+ platforms: AS/400, Z/OS, all UNIX flavors (LINUX, SOLARIS SPARC, SOLARIS INTEL, IBM AIX and HP_UX), Windows and ISERIES.

Languages: COBOL, C, JAVA, ASSEMBLER, .NET, JMS