The purpose de.metas.async is to queue up and process tasks on the server side.
To outline how it works, let’s look at the tables that are involved:
C_Queue_WorkPackage for each single task, there is one work package record, so the workpackage table makes up the actual queue elements. Among other things, the workpage’s priority is set directly in these records.
There are three “sub-tables” which all reference one workpackage each. Each workpackage can be referenced by any number of “sub-records”. The tables are:
C_Queue_Element records each reference one metasfresh record to work with via AD_table_ID and Record_ID columns. Examples include invoice candidates, shipment candidates etc.C_Queue_WorkPackage_Param records can specify parameters to be used when the workpackage is processed.C_Queue_WorkPackage_Log records contain audit/log informations that were collected while the work pacage was processedC_Queue_PackageProcessor records specify the business logic that can be applied to a given workpackage. More specifically, the package processor table has a column named Classname
which references a java class that in turn implements the interface IWorkpackageProcessor.
Each workpackage references one package processor that is in charge of processing it.
When processing a workpackage, the package-processor’s customer business logic accesses the workpackage’s elements and parameters to do the job, and write audit messages to the work package’s log.C_Queue_Processor records reference one or many package processors. They basically constitue a queue.
This means metasfresh does not need to have one queue for each workpackage-processor, but can also have one queue for different kinds of workpackages.Here is an experimental ascii-Diagram i started working on. Thx to http://stable.ascii-flow.appspot.com/
+-------------------+
| C_Queue_Processor |<--+
|-------------------| |
| | | +---------------------------+
| | | +-+| C_Queue_Element |
+-------------------+ |n:n | |---------------------------|
| | | C_Queue_WorkPackage_ID |
| | | AD_Table_ID |
n:1 +--------------------------+ | | | Record_ID |
+-->| C_Queue_PackageProcessor |<--+ | +---------------------------+
| |--------------------------| |
| | ClassName | |
| | | | +---------------------------+
| +--------------------------+ | | C_Queue_WorkPackage_Param |
| +---------------------+ 1:n | |---------------------------|
| | C_Queue_WorkPackage |<------+--+ C_Queue_WorkPackage_ID |
| +-----------------------------+ 1:n |---------------------| | | |
| | C_Queue_Block |<---+----| C_Queue_Block_ID | | +---------------------------+
| |-----------------------------| | Prio | |
+---+ C_Queue_PackageProcessor_ID | | ReadyForProcessing | |
| | | Processed | | +---------------------------+
+-----------------------------+ | Error | | | C_Queue_WorkPackage_Log |
| ... | | |---------------------------|
+---------------------+ +--+ C_Queue_WorkPackage_ID |
| |
+---------------------------+