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load balancing: web dispatcher vs. message server

Franz
Explorer
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I couldn't find a sufficient answer, why I should use the web dispatcher.

Is it because of the enhanced functionality ?

Or is there trouble in using the message server for dispatching http-requests?

Thanks,

Franz

Accepted Solutions (1)

Accepted Solutions (1)

nelis
Active Contributor
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To quote SAP:

You can use HTTP load balancing on the SAP Message Server for stateless applications only. For stateful Web applications with a state in the back end (such as BSP applications), you require the Web Dispatcher.

You can only use the SAP message server for HTTP load distribution if the browser is the direct client of the message server. If another component lies between the client (browser) and the message server, (for example, the portal), you cannot use the message server to distribute the load.

Nelis

Franz
Explorer
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Thank you, Nelis, I'm not quite sure, if the Service which is registered in SICF really is a BSP. I quess only the developer knows, if it is stateless or not ? What is the difference, if the browser connects directly to the application server (besides load balancing) ? Does this work with stateful sessions ?

nelis
Active Contributor
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I quess only the developer knows, if it is stateless or not ?

Yes, you should ask your developers if their applications will require state.

What is the difference, if the browser connects directly to the application server (besides load balancing) ? Does this work with stateful sessions ?

Yes this should work fine because there is no redirection from the message server. The Web Dispatcher stores your ip address in a table to maintain the state of the connection.

Nelis

rhviana
Active Contributor
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Hi Nelis,

I know that this thread was opened a long time ago.

But I Have question regard mensage server:

" If another component lies between the client (browser) and the message server, (for example, the portal), you cannot use the message server to distribute the load."

If I user SAP PI as middleware layer, I can use mensage server instead of webdispatcher ?

Kind regard,

Ricardo Viana.

Former Member
0 Kudos

Yes you could although in general SAP recommends to use Web Dispatcher for load balancing instead of the HTTP message server. See SAP note 1040325 for details. Notice that for PI additional tuning might be necessary to achieve proper load balancing, see SAP note 1596109 for details. What kind of services are you planning to call from your PI system?

rhviana
Active Contributor
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Thanks Samuli.

Answers (1)

Answers (1)

Former Member
0 Kudos

Hello Franz,

Refer to the following page for short decription of the main SAP Web Dispatcher functions:

http://help.sap.com/saphelp_nw04/helpdata/en/42/5cfd3b0e59774ee10000000a114084/content.htm

Functions

The SAP Web dispatcher performs the following tasks:

· Selects an appropriate application server (persistence with stateful applications, load balancing, ABAP or Java server), see Server Selection and Load Balancing Using the SAP Web Dispatcher.

· Filters URLs u2013 you can define URLs that are to be rejected, see SAP Web Dispatcher as a URL Filter

· Depending on the SSL configuration, forwards, terminates, and (re)encrypts requests. See SAP Web Dispatcher and SSL

The message server could do only starless-session load balancing.

Regards,

Ventsi Tsachev