From 0a0d3f616c9531c7931c365e1912cbcf6358441b Mon Sep 17 00:00:00 2001 From: Bill Erickson Date: Mon, 3 Mar 2014 09:42:03 -0500 Subject: [PATCH] LP#1268619: websocket : more JS api docs Signed-off-by: Bill Erickson Signed-off-by: Galen Charlton --- src/javascript/opensrf_ws_shared.js | 103 +++++++++++++++++++++++++++++------- 1 file changed, 83 insertions(+), 20 deletions(-) diff --git a/src/javascript/opensrf_ws_shared.js b/src/javascript/opensrf_ws_shared.js index fe63a2a..4b90dc8 100644 --- a/src/javascript/opensrf_ws_shared.js +++ b/src/javascript/opensrf_ws_shared.js @@ -13,23 +13,54 @@ * GNU General Public License for more details. * ----------------------------------------------------------------------- */ + +/** + * Shared WebSocket communication layer. Each browser tab registers with + * this code all inbound / outbound messages are delivered through a + * single websocket connection managed within. + * + * Messages take the form : {action : my_action, message : my_message} + * actions for tab-generated messages may be "message" or "close". + * actions for messages generated within may be "message" or "error" + */ + var WEBSOCKET_URL_PATH = '/osrf-websocket-translator'; -var WEBSOCKET_PORT = 7680; +var WEBSOCKET_PORT = 7680; // TODO: remove. all traffic should use SSL. var WEBSOCKET_PORT_SSL = 7682; +var WEBSOCKET_MAX_THREAD_PORT_CACHE_SIZE = 1000; -// set of shared ports (i.e. browser tabs) +/** + * Collection of shared ports (browser tabs) + */ var connected_ports = {}; + +/** + * Each port gets a local identifier so we have an easy way to refer to + * it later. + */ var port_identifier = 0; -// maps osrf message threads to a port index in connected_ports +// maps osrf message threads to a port index in connected_ports. +// this is how we know which browser tab to deliver messages to. var thread_port_map = {}; -// our shared websocket +/** + * Browser-global, shared websocket connection. + */ var websocket; -// pending messages awaiting a successful websocket connection +/** + * Pending messages awaiting a successful websocket connection + * + * instead of asking the caller to pass messages after a connection + * is made, queue the messages for the caller and deliver them + * after the connection is established. + */ var pending_ws_messages = []; +/** + * Deliver the message blob to the specified port (tab) + */ function send_msg_to_port(ident, msg) { console.debug('sending msg to port ' + ident + ' : ' + msg.action); try { @@ -42,19 +73,25 @@ function send_msg_to_port(ident, msg) { } } -// send a message to all listeners +/** + * Send a message blob to all ports (tabs) + */ function broadcast(msg) { for (var ident in connected_ports) send_msg_to_port(ident, msg); } -// opens the websocket connection -// port_ident refers to the requesting port +/** + * Opens the websocket connection. + * + * If our global socket is already open, use it. Otherwise, queue the + * message for delivery after the socket is open. + */ function send_to_websocket(message) { if (websocket && websocket.readyState == websocket.OPEN) { - // websocket connection is viable. send our message. + // websocket connection is viable. send our message now. websocket.send(message); return; } @@ -96,11 +133,11 @@ function send_to_websocket(message) { websocket.onmessage = function(evt) { var message = evt.data; - // this is a hack to avoid having to run JSON2js multiple - // times on the same message. Hopefully match() is faster. - // We can't use JSON_v1 within a shared worker for marshalling - // messages, because it has no knowledge of application-level - // class hints in this environment. + // this is sort of a hack to avoid having to run JSON2js + // multiple times on the same message. Hopefully match() is + // faster. Note: We can't use JSON_v1 within a shared worker + // for marshalling messages, because it has no knowledge of + // application-level class hints in this environment. var thread; var match = message.match(/"thread":"(.*?)"/); if (!match || !(thread = match[1])) { @@ -130,26 +167,50 @@ function send_to_websocket(message) { * (see above). Only the port expecting a message with the given * thread will honor the message, all other ports will drop it * silently. We could just broadcastfor every messsage, but this - * is more efficient. + * is presumably more efficient. + * + * If for some reason this fails to work as expected, we could add + * a new tab->ws message type for marking a thread as complete. + * My hunch is this will be faster, since it will require a lot + * fewer cross-tab messages overall. */ - if (Object.keys(thread_port_map).length > 1000) + if (Object.keys(thread_port_map).length > + WEBSOCKET_MAX_THREAD_PORT_CACHE_SIZE) { + console.debug('resetting thread_port_map'); thread_port_map = {}; + } } + /** + * Websocket error handler. This type of error indicates a probelem + * with the connection. I.e. it's not port-specific. + * Broadcast to all ports. + */ websocket.onerror = function(evt) { var err = "WebSocket Error " + evt + ' : ' + evt.data; - // propagate to all ports so it can be logged, etc. broadcast({action : 'error', message : err}); - throw new Error(err); + websocket.close(); // connection is no good; reset. + throw new Error(err); } + /** + * Called when the websocket connection is closed. + * + * Once a websocket is closed, it will be re-opened the next time + * a message delivery attempt is made. Clean up and prepare to reconnect. + */ websocket.onclose = function() { console.debug('closing websocket'); websocket = null; + thread_port_map = {}; } } -// called when a new port (tab) is opened +/** + * New port (tab) opened handler + * + * Apply the port identifier and message handlers. + */ onconnect = function(e) { var port = e.ports[0]; @@ -169,7 +230,9 @@ onconnect = function(e) { } if (messsage.action == 'close') { - // TODO: add me to body onunload in calling pages. + // TODO: all browser tabs need an onunload handler which sends + // a action=close message, so that the port may be removed from + // the conected_ports collection. delete connected_ports[port_ident]; console.debug('closed port ' + port_ident + '; ' + Object.keys(connected_ports).length + ' remaining'); -- 2.11.0