The parent currently uses a fixed-size 100000 byte buffer to receive
messages. Even with a tile size of 256x256 pixels, that is not enough for some
tiles that compress badly as PNG. Add a nextmessage: message that gives the
size of the immediately following message. Send a such before each tile:
message, and handle it appropriately. The nextmessage: message is used only
from child to parent process, it is never sent to the Websocket client.
Once Poco 1.6.1 is released, this will not be necessary.
The JS code always passes in 0 for now. The server parses the parameter and
calls LibreOfficeKitDocument::setPart() before calling paintTile().
Probably also the status, key, mouse and selection messages will need a part
number. The intent is after all that the protocol is as stateless as
possible. (So maybe we should also pass the document URL in each message?)
Having a 'close' would mean being able to do a new 'open', too, which
introduces unneeded complexity, at least at this stage.
Just start a fresh WebSocket connection for each document.
