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How does the dispatcher make the syste understand about the workprocesses

Former Member
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There the backgroung,foreground,spool,update etc processes,how does teh application server understand which way it shud adotp to process.fro exanple if i say foreground or back ground the systemprocess it in the same place the only diff is that it's nto seen in background an seen in fore ground,how the sytem understands this and if u knwo anything more please explain.All this doen by dispatcher .hwo tecnically system deos understand this.


Former Member
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There is one special kind of work process called <i>Dispatcher</i>. The control wll always go to this work process initially. This decides whether the program processing should be done by a <i>Dialog Work Process</i> (in the foregorund mode) or a <i>Background Work Process</i>.

Refer to the following link in the Documentation -


Anand Mandalika.

Former Member
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SAP has something called as Message servers ,Message servers handle communication between servers and processes within the SAP system.

Dialog Work Process/Server

Each Dialog work process handles one dialog step of a user transaction, then becomes available to process another dialog step. A Dialog server consists of a Dispatcher and a fixed number of Dialog work processes which are available exclusively to handle dialog requests.

Batch Server

Batch processing allows a program to be run at a scheduled time in the background. A background scheduler is responsible for starting jobs at the requested times. Jobs are processed as if they were entered by a user, so they must pass through the same dialog steps; this ensures the integrity of the system.

Update Server

Since the Update server must make changes to the database, it is usually on the same physical system as the database. When an update is requested, the job is separated into a dialog portion and an update portion. First, the dialog portion creates a log file, which is then used by the update work process to perform the actual changes.

Enqueue Server

Rather than relying on the database to control access to the data, SAP implements its own system for controlling access, called the Enqueue server. The Enqueue server uses lock tables to manage access to the data, ensuring only one user at a time has the ability to make changes to the same data.

Spool Server

When a Spool request is generated, the data is placed in TEMporary SEquential objects, and information related to the request is stored in the database. When the request is ready to be printed, it is handled by the Spool work process, which formats it and passes it to the operating system's spooler. The operating system spooler may be on the user's workstation, or on a separate system altogether.