The protocol handler receives data from a transport handler and prepares it for the data handler or receives data from the data handler and prepares it for the transport handler. A simple protocol is a comma separated list (CSV).
To create a new protocol handler AbstractProtocolHandler must be extended (or IProtocolHandler implemented)
/**
* Creates a new protocol handler
* @param direction is this handler used in a source (IN) or in a sink (OUT)
* @param access which kind of access pattern is supported ( PUSH, PULL, ROBUST_PUSH, ROBUST_PULL)
* @param options set of options as key value pairs
* @param dataHandler the data handler thats connected to the protocol handler
* @return
*/
public IProtocolHandler<T> createInstance(ITransportDirection direction, IAccessPattern access,
Map<String, String> options, IDataHandler<T> dataHandler);
The following method could be overwritten:
- open(): This method is called, when the query is started.
Important: When overwriting this method, getTransportHandler().open() must be called, too. - close(): This method is called, when der query is stopped.
Important: When overwriting this method, getTransportHandler().close() must be called, too.
Pullbased
- boolean hasNext(): must be overwritten, to state if a new element is available for processing
- T getNext(): must be overwritten to deliver the next element
- boolean isDone(): can be overwritten to state if a source will not deliver anymore elements
Pushbased
For pushbased access the methods from the Interface ITransportHandlerListener need to be overwritten:
/**
* Is called when a new connection with the transport handler is established
* @param caller
*/
void onConnect(ITransportHandler caller);
/**
* Is called when an existing connection to the transport handler is interrupted
* @param caller
*/
void onDisonnect(ITransportHandler caller);
/**
* Implement this method to process the message
* @param message as ByteBuffer
*/
void process(ByteBuffer message);
/**
* Implement this method to process the message
* @param message as String Array
*/
void process(String[] message);
/**
* Implement this method to process the message
* @param message as T
*/
void process(T m);
Typically, these methods are called from the underlying transport handler