1. Communication Method Group Name: ARC Source: Jiaxin Yin, Huawei Technologies Co., Ltd., yinjiaxin@huawei.com Meeting Date: 2015-8-12 Agenda Item: TBD

2. Background Currently we support three modes of communication – blocking synchronous – non-blocking synchronous – non-blocking asynchronous Determined by the ORIGINATOR by setting the Response type parameter in the Request. blocking-synchronousnon-blocking synchronousnon-blocking asynchronous OriginatorReceiver Request Handling Response (result) OriginatorReceiver Request Handling Response (ACK) Request(Retrieve result) Response (result) OriginatorReceiver Request Handling Response (ACK) Notify(result) Response

3. Issue Case 1: – The originator initiates blocking request, but it takes longer than usual for the receiver to respond. – The originator has to terminate the connection after all the time waiting without any result Case 2: – The originator expects the request may take long time, thus initiates the request using non-blocking. – However the receiver happens to be quite efficient, the result is ready almost immediately – Instead of piggyback the result, the originator has to start an ADDITIONAL request to retrieve the result Case 3: – Part of the result is available immediately. – It takes longer to wait for the other parts of the result. – The value of the margin result become less and less, however, time spent on those result is still growing.

4. Cause of the issue The information between the client and the server is asymmetrical – Client never know if the server is heavily loaded or not – The server is unable to guess the intention of the client – The server itself is hard to tell how long it will take to handle this request. Current communication method only provides solution at the two end points. – Either blocking or non-blocking – Either prepare the whole result or nothing

5. Proposal Besides the current mechanism Introduce one mode between blocking and non- blocking: flex – If the server finds himself heavy loaded, ACK the request and deal with the request at some other time. – If the server is OK at the moment, piggyback the result directly. Introduce one mode between whole resource and nothing: partial – Piggyback the quickest result in blocking mode but also let the originator know how to retrieve the other following result – The retrieval of the other result is in non-blocking mode.

6. Questions and comments?