Establishing an SPX connection

This section discusses the following topics:

• IPX/SPX parameters
• SPX addressing
• Using the SPX KEEPALIVE option
• Receiving on SPX

IPX/SPX parameters

In most cases the default settings for the IPX/SPX parameters will suit your needs. However, you may need to modify some of them in your environment to tune its use for WebSphere MQ. The actual parameters and the method of changing them varies according to the platform and provider of SPX communications support. The following sections describe some of these parameters, particularly those that may influence the operation of WebSphere MQ channels and client connections.

Please refer to the Novell Client for OS/2 documentation for full details of the use and setting of NET.CFG parameters.

The following IPX/SPX parameters can be added to the Novell NET.CFG file, and can affect WebSphere MQ SPX channels and client connections.

IPX

sockets (range = 9 - 128, default 64)

This specifies the total number of IPX sockets available. WebSphere MQ channels use this resource, so depending on the number of channels and the requirements of other IPX/SPX applications, you may need to increase this value.

SPX

sessions (default 16)

This specifies the total number of simultaneous SPX connections. Each WebSphere MQ channel or client connection uses one session. You may need to increase this value depending on the number of WebSphere MQ channels or client connections you need to run.

retry count (default = 12)

This controls the number of times an SPX session will resend unacknowledged packets. WebSphere MQ does not override this value.

verify timeout, listen timeout, and abort timeout (milliseconds)

These timeouts adjust the 'Keepalive' behavior. If an SPX sending end does not receive anything within the 'verify timeout' period, it sends a packet to the receiving end. It then waits for the duration of the 'listen timeout' for a response. If it still does not receive a response, it sends another packet and expects a response within the 'abort timeout' period.

SPX addressing

WebSphere MQ uses the SPX address of each machine to establish connectivity. The SPX address is specified in the following form:

        network.node(socket)

where

network

Is the 4-byte network address of the network on which the remote machine resides,

node

Is the 6-byte node address, which is the LAN address of the LAN adapter in the remote machine, and

socket

Is the 2-byte socket number on which the remote machine will listen.

The default socket number used by WebSphere MQ is 5E86. You can change the default socket number by specifying it in the queue manager configuration file qm.ini or the Windows systems registry. If you have taken the default options for installation, the qm.ini file for queue manager OS2 is found in c:\mqm\qmgs\os2. The lines in qm.ini might read:

SPX:
  SOCKET=n

For more information about values you can set in qm.ini, see Appendix C, Configuration file stanzas for distributed queuing.

The SPX address is later specified in the CONNAME parameter of the sender channel definition. If the WebSphere MQ systems being connected reside on the same network, the network address need not be specified. Similarly, if the remote system is listening on the default socket number (5E86), it need not be specified. A fully qualified SPX address in the CONNAME parameter would be:

 CONNAME('network.node(socket)')

but if the systems reside on the same network and the default socket number is used, the parameter would be:

 CONNAME(node)

A detailed example of the channel configuration parameters is given in MQSeries for OS/2 Warp configuration.

Using the SPX KEEPALIVE option

If you want to use the KEEPALIVE option you need to add the following entry to your queue manager configuration file (qm.ini) or the Windows systems registry:

SPX:
   KeepAlive=yes

You can use the timeout parameters described above to adjust the behavior of KEEPALIVE.

Receiving on SPX

Receiving channel programs are started in response to a startup request from the sending channel. To do this, a listener program has to be started to detect incoming network requests and start the associated channel.

You should use the WebSphere MQ listener.

Using the WebSphere MQ listener

To run the Listener supplied with WebSphere MQ, that starts new channels as threads, use the RUNMQLSR command. For example:

RUNMQLSR -t spx

Optionally you may specify the queue manager name or the socket number if you are not using the defaults.