HistHook API Reference

The HistHook API allows a developer to hook into all History-related events before they are processed by the History subsystem. To facilitate this, the HistHook is made public. The hook receives data related to the event and provides you the option to return the custom SQL that will be processed by the database. By providing this custom SQL, you can do the following:

• Implement your own Batch History database by overwriting the Histhook.dll to the desired functionality.

  Note: This is a complicated task and should be thoroughly considered before attempting.
  If you use the hook to return custom SQL, you will most likely NOT be able to use the AVEVA Batch Management History Administration interface or the AVEVA Batch Management Reporting interface. This would depend on the type and amount of changes made to the custom SQL.

• Capture Historical events (such as End of Batch) and use them as triggers for other integration purposes.

  Note: You need to be extremely fast in your operations. The whole AVEVA Batch Management System can get delayed if these hooks take additional time to execute. Also, be aware that the data is not in the History Database yet, when the hook is called.

You can perform the following administrative tasks for the history server.

• Create user accounts for the History Administration pages.

• Administer the history error queue.

The following are the two different functional areas of the HistHook API:

• The HistHook interface: This is called by Batch applications such as the Batch Manager and few other Batch applications, before sending the data (through the History Queue, via the HistQMngr) to the HistQReader on the Batch History Server.

• The HistQReader interface: This is called by the History Queue Reader on the Batch History Server when it is trying to process the Error Queue messages. The interface allows you to add your own custom ErrorQ table that can support the CRUD (Create, Retrieve, Update, or Delete) operations. The HistQReader interface also provides the ability to connect to a different database server than the one on the Batch History Server node.