How to create multiple dispatchers

[Former Member]

Is there a manual that describes how to create the scenario depicted at http://help.sap.com/saphelp_nw04/helpdata/en/7b/f9813712f7434be10000009b38f8cf/frameset.htm for Web AS 6.4?

I tried the <b>Create Server</b> command in MMC, but it's not what I want: to have several WAS instances/JVMs, each listening on a different port.

There is a reference to the Deploy Tool command <b>Create Dispatcher</b> at http://help.sap.com/saphelp_nw04/helpdata/en/e2/53547dc7c31a45b015f14bb2b4849d/frameset.htm . Perhaps the scope of this command is constrained to a single J2EE Project? I prefer to understand more before I try.

If anyone knows of a good description, please post a link. Thanks.

[viliana · Accepted solution]

Hi James,

Do you mean you want to install several dialog instances? In this case, you need to run the SAPInst and install the dialog instances. See the installation guides at service.sap.com/instguidesnw04.

See also: http://help.sap.com/saphelp_nw04/helpdata/en/fa/08f71489274f1e9d7cf5c610fbb0e6/frameset.htm

Hope that will help.

Best regards,

Viliana

[Former Member · Accepted solution]

Hi Viliana,

You pose a fair question. I don't know how to implement the topology, but here is what I hope:

to deploy three Web apps...

- running in different JVMs

- with different classpath and environment (Java parms and "classpath variables") and

- listening on different ports.

Note the distinct HTTP ports in this drawing http://help.sap.com/saphelp_nw04/helpdata/en/2e/611724f410254ca12a3f396ec5ae85/h-00100010000_image00...

What level of the Web AS hierarcy should I replicate to accomplish this? Are dialog instances easier to replicate than dispatchers? Is there yet another level that's better for this scenario. Thanks.

James Walkup

MomentumSI Inc.

Austin, Texas, USA

[Former Member · Accepted solution]

Viliana, thanks for the document reference. Based on this discussion , I suspect it's not necesary to install multiple Dialog Instances. My previous reply describes what I want to do.

I included the wrong link in the original question. Here are drawings of topologies that may work:

http://help.sap.com/saphelp_nw04/helpdata/en/2e/611724f410254ca12a3f396ec5ae85/h-00100010000_image00...

or

http://help.sap.com/saphelp_nw04/helpdata/en/00/bfb59803a84d6cae3f4ed300efa168/BCJAVA_S_image002.gif

(re new Java instances...

http://help.sap.com/saphelp_nw04/helpdata/en/00/bfb59803a84d6cae3f4ed300efa168/content.htm )

Dialog Instances are fine. I wonder if they necessary to have multiple JVMs listening on multiple ports?

[viliana · Accepted solution]

Hi James,

You can achieve what you want in two ways:

1. You install 3 J2EE Engine Instances; they are independent of each other; each instance consists of its own Java dispatcher and one or more server nodes; each dispatcher listens on a different HTTP port. You deploy each of your applications on its own instance. As this means that you will have three J2EE Engine installations, each will have its Central Services instance (consisting of Enqueue Server and Message Server) – thus, you will have three Message Servers and three Enqueue Servers. In this case your instances do not work in a cluster – they are independent.

2. The second way is to make a cluster consisting of three Java instances. Each instance consists of one Java dispatcher and one or more server nodes. Thus, you will again have three dispatchers, each dispatcher listens on its own HTTP port. The advantage here is that you will have only one Central Instance (that is, one Message Server and one Enqueue Server) instead of three.

In both scenarios, you can achieve what you want.

Installing multiple dispatchers in one instance is not possible – each instance can have only one dispatcher.

You can also consult the <a href="http://help.sap.com/saphelp_nw04/helpdata/en/e1/b5443e02a9ab4186a6e1240a9a2455/frameset.htm">J2EE Engine Architecture Manual</a>. It describes the architecture of the J2EE Engine in more detail.

Best regards,

Viliana

[Former Member · Accepted solution]

Viliana, Thanks for your very clear description! Now, I know just the topology to use for my project.

I just discovered these docs...

• Installation Guide - Additional Instances on UNIX

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https://websmp201.sap-ag.de/~sapidb/011000358700001695362004E

• Installation Guide - Additional Instances on Windows

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https://websmp201.sap-ag.de/~sapidb/011000358700001687272004E

• Installation Guide - Additional Instances on iSeries

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https://websmp201.sap-ag.de/~sapidb/011000358700002183142004E

Their links appear at https://websmp201.sap-ag.de/nw04installation: click "SAP Web AS 6.40 Installation and Related Documentation" then "Installation of Additional Instances".

James