The DANSrvAE customization plug-in is a .Net assembly with a set of methods that are called from the generic server and a set of generic server callback methods.
The plug-in assembly contains the application specific handling for DA and AE functionality.
For the DA server these methods are in the GenericServer class. For the event server they are in the EventServer/EventSubscription classes.

The AE handling is split into two parts:

• NSPluginNet4.dll contains the AE configuration with the event sources/types and a dummy implementation of the OPC AE specified client interface handling.
• In NSPluginAEbaseNet4.dll are methods with a standard implementation of the OPC AE methods. Theses methods override the dummy implementation in NSPluginNet4.dll.
  If preferred, then the methods can be fully implemented in NSPlugin.dll instead of using the overrides in NSPluginAEbase.dll.

 

The generic server calls some customization methods at startup and some when a client calls certain functions. The DA server configuration methods are always called, even when the server is started from AE client.

 

 

 

 

A set of callback functions allow the customization plug-in to get status information from the generic server or change data in the generic server. The most important callback methods are AddItem and SetItemValue.

Typically the customization plugin has Thread the reads values from the device and updates the item cache in the generic server.
The Professional Edition allows the item update to be optimized for items that are currently actually accessed by clients. In application with thousands of items this increases performance considerably.

The Professional Edition ConfigBuilder class reads the item configuration from an XML file, which can be created and maintained with the ConfigBuilder Windows application.

The customization module can be implemented in widely different ways to accommodate the application.
Item declaration can be statically, defined at startup or dynamically when the client first accesses the item.
The signal update handling depends much on the 'device' communication. If quick access to single items is possible, as e.g. when the 'device' is a data base then the customization part does not need to implement a data buffer. It can access the device whenever the generic server module calls the RefreshItems function.

If the item value changes from the device are event driven, then the values can be written into the generic server cache in the event handler and the RefreshItems methods need not be implemented.