Embed Size (px)
Citation preview
EWD.js Architecture
Rob TweedM/Gateway Developments Ltd
Twitter: @rtweedEmail: [email protected]
Tuesday, 18 February 14
EWD.js Architecture
2
Tuesday, 18 February 14
EWD.js Architecture
3
Child Process removed from available poolas soon as a request is sent to it
Tuesday, 18 February 14
EWD.js Architecture
4
Child Process returned to available pool as soonas processing is completed
Tuesday, 18 February 14
EWD.js Architecture
5
Each Child process handles only one request at a time
Tuesday, 18 February 14
EWD.js Development
6
100%JavaScript
Tuesday, 18 February 14
EWD.js Messaging
7
EventOccurs
Tuesday, 18 February 14
EWD.js Messaging
8
JSONMessageCreated
Tuesday, 18 February 14
EWD.js Messaging
9
MessageSent
Tuesday, 18 February 14
EWD.js Messaging
10
MessageReceived
atback-end
Tuesday, 18 February 14
EWD.js Messaging
11
MessageHandler
fired
Tuesday, 18 February 14
EWD.js Messaging
12
_setDocument()
Tuesday, 18 February 14
EWD.js Messaging
13
_getDocument()
Tuesday, 18 February 14
EWD.js Messaging
14
Messagesentby
back-end
Tuesday, 18 February 14
EWD.js Messaging
15
MessageReceived
bybrowser
Tuesday, 18 February 14
EWD.js Messaging
16
JSONMessage
EventHandler
Fires
Tuesday, 18 February 14
EWD.js Messaging
17
ModifyUI
Tuesday, 18 February 14
Send message from browser
18
EWD.sockets.sendMessage({ type: "sendHelloWorld", params: { text: 'Hello World!', sender: 'Rob', date: new Date().toUTCString() } });
Tuesday, 18 February 14
Back-end Module
19
module.exports = { onMessage: { sendHelloWorld: function(payload, ewd) { // do whatever is required with payload return {received: true}; // or any JSON } }};
Tuesday, 18 February 14
Back-end Module
20
module.exports = { onMessage: { sendHelloWorld: function(payload, ewd) { // eg save payload to JSON store var store = new ewd.mumps.GlobalNode('myStore', [1]); store._setDocument(payload); return {savedInto: ‘myStore’}; } }};
Tuesday, 18 February 14
Browser-side Handler
21
onMessage { sendHelloWorld: function(msgObject) { // do whatever you need to do with the incoming message, eg: var text = 'Your message was successfully saved into ' + messageObj.message.savedInto; toastr.clear(); toastr.info(text); } };
Tuesday, 18 February 14
No Polling!
• With WebSockets, the back-end can send a message at any time to:– a specific browser– all browsers running a specific EWD.js
application– all currently-connected browsers
22
Tuesday, 18 February 14
Back-end can send a message
23
var savedMsg = new ewd.mumps.GlobalNode('myMessage', []); ewd.sendWebSocketMsg({ type: 'savedMessage', message: savedMsg._getDocument() });
Tuesday, 18 February 14
Node.js, but Synchronous Code!
• Your back-end code runs in a Node.js Child Process
• An EWD.js Child Process only handles a single request at a time so it can afford to use blocking, synchronous I/O
• If all Child Processes are busy, incoming requests are queued in the fully asynchronous master Node.js process
• Child Process pool size is configurable to match demand
24
Tuesday, 18 February 14
Node.js, but Synchronous Code!
• Database connector interfaces used by EWD.js are synchronous
• Your back-end JavaScript logic can be written in easy-to-maintain, intuitive synchronous style
• No “callback hell” or pseudo-synchronous syntax
• Result: faster development, maintainable JavaScript logic
25
Tuesday, 18 February 14
Built-in secured Web Services
• Any back-end EWD.js JavaScript method can also be exposed as a JSON Web Service
• Access is automatically secured– HMAC-SHA256 digital signatures required for
every HTTP request– The same security used by Amazon Web
Services• Lightweight peer-to-peer access between
EWD.js systems 26
Tuesday, 18 February 14
Secured Linked Systems
27
Tuesday, 18 February 14
EWD.js requirements
• Ideally browsers that support HTML5 WebSockets– however, EWD.js uses Node.js socket.io
library• emulates websockets using other techniques if not
available• even works with old versions of Internet Explorer!
28
Tuesday, 18 February 14
