SAP Processes
• Dialog process. This process handles user interaction initiated from the Presentation tier. Normally, there are multiple processes offering dialog services in each instance.
• Update process. SAP processes execute asynchronous changes on the database. There has to be at least one update process for each system. There can be instances without an update process. Usually one configures multiple Update processes as well.
• Batch process. This process handles long running, non-interactive jobs in the background, e.g. Payroll Calculation. SAP product tasks can be scheduled to run at a certain point in time or event based.
• Enqueue process. This process handles SAP logical locking management. There must be at least one Enqueue process for each SAP system. This process runs only on the SAP Central Instance and is a single point of failure. Therefore the efforts to use failover clustering for the SAP CI. In some cases, when there is a gap between a user confirmation and the end of an asynchronous update, a SAP object such as the Material or Customer needs to be locked before the database is accessed. In these cases, the Enqueue process handles the locking and unlocking of requests on the SAP NetWeaver Application Server Layer system-wide. This avoids extensive locking on the database level which could harm concurrency severely. The Enqueue process keeps the database from being flooded with locks and blocks objects not yet released. It is worth to note that the level of locking of the Enqueue is on Object basis. Such an object locked could translate into many database rows in different database tables.
• Spool process. This process enables print services for a SAP system. The process sends a print request to the Windows spool manager.
• Message server process. This process allows for communication between the different NetWeaver Application Server instances within one SAP system. The message server runs on the SAP CI and as well is a single point of failure.
• Gateway process. This process is responsible for external communication between NetWeaver Application Servers.
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Rajnikanth