Daemon for Real-Time Data Acquisition
Background process that processes the InfoPackages and data transfer processes assigned to it at regular intervals.
The daemon controls and monitors the transfer process for real-time data acquisition. The daemon performs the following tasks depending on the scenario used:
If you are transferring data from an SAP source system, the daemon starts the transfer of data into the PSA using an InfoPackage (using service API).
It controls the status of the data transfer.
It starts with a data transfer process for posting the data into the InfoProvider.
It closes and opens requests when threshold values are reached.
It triggers the subsequent process chains.
The daemon receives information from the InfoPackage and the data transfer process about the data to be transferred or further updated, the PSA tables or InfoProviders to be filled, and when a request should be closed and a new one opened.
How it Works
When you extract data, the daemon works on the basis of the list of DataSources assigned to it in the InfoPackages, extracts the data from the source systems, and transfers it to the PSA table. It informs the service API in the source system when the data for the target system has been updated. When a PSA request has been closed, and a new one opened, the updated data is deleted from the delta queue in the source system.
When you post data from the PSA to the InfoProvider, the daemon works on the basis of the list of sources (DataSources) and targets (InfoProviders) assigned to it in the data transfer processes. It transfers the data to the InfoProviders. If these InfoProviders are independent DataStore objects or DataStore objects of a HybridProvider, the system activates the data automatically and writes it to the change log.
Operating Mode
The daemon runs in a permanent background job and switches to idle mode, during which the background job continues execution, between extraction processes. If you are using the service API to transfer data, the RFC connection to the source system remains open. This implies that a permanent RFC connection is required between each source system and the BW for real-time data acquisition using the service API. To prevent the system from using too much main memory and to avoid keeping the RFC connection open for too long, the daemon stops independently on a regular basis and reschedules itself. As a result, the main memory can be released and a new RFC connection is opened. This happens without having to close the requests for real-time data acquisition.
See the information about the behavior of the daemon when stopping and starting systems using the soft shutdown or report RS_SYSTEM_SHUTDOWN. For more information, see the documentation about the basic administrative tasks in SAP NetWeaver BW.
Error Behavior
The daemon writes each successfully executed step to a control table. If the extraction or update is terminated, the daemon restarts itself and continues the process from the point at which it was terminated. It repeats the entire substep with the granularity of a data package. For example, if execution of the DTP is terminated, the daemon gets the new data from the source and loads it into the InfoProvider together with the data packages that terminated previously. You define the maximum allowed number of such repetitions when the daemon loads or closes requests in the InfoPackage.
More information: Creating InfoPackages for Real-Time Data Acquisition