public interface MasterItemHandler
Modifier and Type | Method and Description |
---|---|
void |
dataUpdate(Map<String,Object> context,
DataItemValue.Builder value)
Called when data changed or the handler chain changed.
|
WriteRequestResult |
processWrite(WriteRequest request)
Handle a write request
|
void dataUpdate(Map<String,Object> context, DataItemValue.Builder value)
The call gets a context object provided which each handler can use to store context information of one calculation run. Each calculation run gets a fresh new context. The context is intended to pass data from one handler to the next.
Although the value parameter is a mutable type, the handler may only make changes inside the dataUpdate method.
context
- the context objectvalue
- the changed valueWriteRequestResult processWrite(WriteRequest request)
This method is called when a master item received a write request. It will then pass on the request to all MasterItemHandler in order to process or alter the write request. Each handler returns a result and then the next handler will received that altered write request.
If null is returned instead of a new write result, original write request is used and it is considered that the handler has done nothing.
request
- the write request to handleCopyright © 2016 Eclipse NeoSCADA Project. All rights reserved.