Doubts in web dispatcher and dialog instance

[Former Member]

Hi to everyone.

I´m new in SAP ad I have a doubts.

- What's the difference between central instance and dialog instance.

- Which are the processes of the Web Dispatcher and what makes each one

THANKS.

[Former Member]

Hi,

Basic differenc is,

central instance is messageserver+enqueue server.

dialog instance doesn't have message +enqueue server.it is just one more instance used for load balancing.

Engine can have one or more dailog instance but only one central instance.

webdispatcher is just a request handler,to distribute incoming client requests to available server process.

reward points if helpful

regards

usharani

[Former Member]

Hi,

The J2EE Engine 6.20 cluster consists of a central instance and one or more dialog instances. The central instance consists of a state controller (that manages the state of the whole cluster), a dispatcher node (that dispatches requests to application nodes), and one or more application nodes (that handle client requests). A dialog instance consists of a backup state controller (this is optional and only one is allowed in the cluster; it takes the responsibilities of the state controller in the case of failure), a dispatcher, and one or more application nodes.

The J2EE Engine 2004s cluster consists of one or more Java instances, the Central Services instance and a central database. Additionally, each Java instance consists of one dispatcher (that dispatches client requests to the server processes) and one or more server processes (that handle client requests).

A web dispatcher is a load balancer ,its the entry point for http requests into your system which consists of one or more web application server.it distributes the request to ensure an even distribution across the servers(load balancing).

Thanks

srinivas

[Former Member]

Hello Joel,

Central instance is that application server/instance on which the message server resides which along with dispatcher controls the work distribution to work process. Dialog instance is also an application server however it doesnot have message server.

Further central instance is the that instance on which enque workprocess(s) reside. Enque process is not present on dialog instances. It is responsible for locking mechanism.

Finally there is only central instance in an installation and it is a must. However you can have any number of dialog instances or may be if not needed not even one.

SAP Web Dispatcher is like a interface between internet and SAP applications.

For more info on SAP web dispatcher check this :

http://help.sap.com/saphelp_470/helpdata/en/42/5cfd3b0e59774ee10000000a114084/frameset.htm

If by process of SAP Web Dispatcher you are meaning dialog,background etc. work process which you find in normal SAP then the answer is that these process are not part of SAP Web Dispatcher.

SAP Web diaptcher helps in communication between internet and SAP. Apart from that it also does load balancing.

Please award points for useful answers.

Regards.

Ruchit.