Item Resubscription
So we open a session for subscription for an item say AAPL.OQ, get some refresh and updates, then close the subscription using CloseMsg with below params:
closeMsg.clear();
encodeIterator.clear();
closeMsg.msgClass(MsgClasses.CLOSE);
closeMsg.containerType(DataTypes.NO_DATA);
closeMsg.flags(CloseMsgFlags.ACK);
byteBuffer.clear();
encodeBuffer.clear();
encodeBuffer.data(byteBuffer);
encodeIterator.setBufferAndRWFVersion(encodeBuffer, Codec.majorVersion(), Codec.minorVersion());
Now within the same session, I want to resubscribe to AAPL.OQ, I see that though my request for subscription is sent to TREP, I don't get any responses (refresh messages) back.
How to resubscribe after unsubscription within the same session
To close a stream, you need to specify the streamID of the closed item.
closeMsg.clear(); closeMsg.msgClass(MsgClasses.CLOSE); closeMsg.streamId(streamId()); closeMsg.domainType(domainType); closeMsg.containerType(DataTypes.NO_DATA);
After that, you can send a new request message to subscribe to that item.
You can refer to the com.thomsonreuters.upa.examples.consumer example in the Elektron SDK package regarding closing and requesting items.
Depending on your use case / requirements - you may want to explore the Pause / Resume functionality available with the Elektron APIs.
As the name suggests, you can pause an event stream and resume it as required - for some scenarios this can be more efficient than close and resubscribe.