Fork channels: support state transfer ------------------------------------- Key: JGRP-1941 URL: https://issues.jboss.org/browse/JGRP-1941 Project: JGroups Issue Type: Feature Request Reporter: Bela Ban Assignee: Bela Ban Fix For: 3.6.5 Currently state transfer is not supported for ForkChannels: {{ForkChannel.getState()}} throws an exception. State transfer could be implemented by catching events {{STATE_TRANSFER_OUTPUTSTREAM}} (get-state) and {{STATE_TRANSFER_INPUTSTREAM}} (set-state) in {{FORK}}. When {{getState()}} is called (on the main or fork channel), the state provider gets a get-state in {{FORK}}. It then asks the main channel and all fork channels to write their states to the output stream, as follows: {noformat} | main-channel | state | fork-channel1 | state | fork-channel2 | state | ... {noformat} This is a list of \{channel-name | state\} pairs, where each state is prefixed with the name of the channel. This can be implemented by simply passing the {{STATE_TRANSFER_OUTPUTSTREAM}} event up the main stack and each of its fork stacks. On the state requester, the {{STATE_TRANSFER_INPUTSTREAM}} event is caught by {{FORK}}. Each \{channel | state\} pair is parsed for the channel name and then the input stream is passed to the corresponding channel for {{setState(InputStream)}} to be invoked. This whole thing is designed as a one-shot state transfer, to be called *once* after the main channel and all fork-channels have been created. It is not meant to be called repeatedly (although this works).