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EWD 3 Training Course Part 2: EWD 3 Overview

The document provides an overview of the EWD 3 training course, focusing on the EWD-Qoper8 module, which is a high-performance Node.js message queue designed to process requests using worker processes. It supports modularization, allowing integration with various databases like Redis, Caché, and GT.M, without core dependencies on specific databases. The document explains the architecture, including the master process handling queues, worker processes for handling messages, and the integration with Express.js for routing HTTP requests.

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Copyright © 2016 M/Gateway Developments Ltd EWD 3 Training Course Part 2 Overview of EWD 3 Rob Tweed Director, M/Gateway Developments Ltd Twitter: @rtweed
Copyright © 2016 M/Gateway Developments Ltd EWD 3 Design Aims • Modularising previous-generation (EWD.js) into independent components • Mix and match "buffet" of components • Interoperable with other Node.js modules, eg Express • No core dependence on particular databases • Redis, Caché and GT.M can be used as embedded multi- model databases • But any other Node.js-interfaced database can be used too
Copyright © 2016 M/Gateway Developments Ltd Core EWD 3 Component • ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 • Very high-performance Node.js Message Queue • Master Node.js process: • Queue & dispatch mechanism • Pool of persistent Worker Node.js processes • These process the requests that are put on the queue
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 • Creates an isolated run-time environment for each handler function • Each worker process only handles a single request at a time • Comparable to AWS Lambda's run-time container • Concurrency is handled by the master process only • Its sole purpose is to queue and dispatch incoming requests to an available worker process, and handle the response/results from the worker
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 • Worker processes are persistent – Started on demand – When a worker process finishes processing a request, it is returned to the available pool, ready to process another request – No startup / tear-down cost
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 • Master process API – this.addToQueue(messageObject) • Adds a message to the queue – this.on('response', function(responseObject, workerPid) {..} • Handles the response from worker – Usually simply returning the response to the client that sent the original request message to the master process
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 • What the worker does to process a message is up to you • You define a custom worker module • Worker API: – this.on('message', function(messageObject, send, finished) {..} • finished(responseObject): – Mandatory function – Sends final response to master process – Releases Worker process back to available pool • send(responseObject): – Optional function – Sends a response to master process – Worker process remains unavailable
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Node.js Worker Process Node.js Worker Process
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher addToQueue(obj)
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module Unavailable Node.js Worker Process Custom Worker Module ewd-qoper8 Begin processing message
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module Unavailable worker.on('message', function(messageObj) { // process message }); Node.js Worker Process Custom Worker Module ewd-qoper8 Begin processing message
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Unavailable / processing addToQueue(obj) Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Node.js Worker Process Custom Worker Module ewd-qoper8 Worker pool size not exceeded:
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Worker pool all busy: Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 New request remains in queue
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 As soon as a worker is available again: Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Available Node.js Worker Process Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Worker pool all busy: Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Finished Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 finished(responseObject);
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Finished this.on('response', function(responseObj) { // do something with the response }); Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Available Node.js Worker Process Custom Worker Module ewd-qoper8 Worker automatically returned to the available pool NB: Workers are NOT destroyed after use Removes overhead of continually starting worker processes
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Available Node.js Worker Process Custom Worker Module ewd-qoper8 Worker processes only handle a single request at a time Completely isolated run-time environment for your handler functions Worker process becomes immediately available for the next queued request when processing completed
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 is a building block • Not really useful on its own • Completely generic, general-purpose message queue • Core piece of infrastructure on which the rest of EWD 3 is built – ewd-qoper8 can also be used independently of the other EWD 3 modules and integrated with any other Node.js modules, databases etc
Copyright © 2016 M/Gateway Developments Ltd Express + ewd-qoper8 • Express is the standard Node.js web server – REST, Web Services, interactive applications – Express is a Node.js module – Customised by defining middleware – ewd-qoper8 can be configured as Express middleware • Requests sent to Express by client • Routed to ewd-qoper8 • ewd-qoper8 queues and processes them • ewd-qoper8 response returned via Express to client
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + Express Queue Queue processor/ dispatcher Express HTTP(S) Interface WebSocket socket.io Interface addToQueue(req) Node.js Worker Process Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + Express + ewd-qoper8-express Queue Queue processor/ dispatcher Express HTTP(S) Interface Automates and simplifies the use of ewd-qoper8 with Express for HTTP requests Adds special Express router function app.use('/qoper8', qx.router()); ewd-qoper8-express ewd-qoper8- express Node.js Worker Process Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + Express + ewd-qoper8-express Queue Queue processor/ dispatcher Express HTTP(S) Interface Message constructed from Express req object – all information needed for back-end processing by Worker: -path -method -headers -query -body -etc ewd-qoper8-express ewd-qoper8- express Node.js Worker Process Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 Database Dependency? • ewd-qoper8 itself does not have a dependency on a database – In-memory queue – Master and Workers are just Node.js processes * see later parts of this course for details on how to add queue backup / resilience
Copyright © 2016 M/Gateway Developments Ltd Using ewd-qoper8 with Caché • Use a separate module: – ewd-qoper8-cache • Normally used by worker processes • Makes use of cache.node interface module – cache.node is a proprietary InterSystems module that is included with Caché – Allows access from JavaScript/Node.js to: » Caché extrinsic functions » Global storage » Caché Objects & methods – JavaScript API defined by InterSystems » Low-level
Copyright © 2016 M/Gateway Developments Ltd Using ewd-qoper8 with GT.M • Use a separate module: – ewd-qoper8-gtm • Normally used by worker processes • Makes use of NodeM interface module – NodeM is an Open Source module for use with GT.M, which implements the cache.node APIs – Allows access from JavaScript/Node.js to: » GT.M extrinsic functions » Global storage – JavaScript API originally defined by InterSystems » Low-level
Copyright © 2016 M/Gateway Developments Ltd Using ewd-qoper8 with Redis • Use a separate module: – ewd-qoper8-redis • Normally used by worker processes • Makes use of ewd-redis-globals module – ewd-redis-globals is an Open Source module for use with Redis, which: » Implements Global Storage functionality » implements the cache.node APIs – Allows access from JavaScript/Node.js to: » Global storage » Uses the tcp-netx module to connect to Redis – JavaScript API originally defined by InterSystems » Low-level
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module cache.node ewd-qoper8-cache Caché ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module nodem ewd-qoper8-gtm GT.M ewd-qoper8 Equivalent module for use with GT.M Uses David Wicksell’s NodeM module which emulates cache.node for GT.M
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx ewd-qoper8-redis Redis ewd-qoper8 Equivalent module for use with Redis Redis behaves as a Global Storage Database via the same cache.node APIs ewd-redis-globals
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché function Custom Worker Module ewd-qoper8 For legacy Mumps or Caché ObjectScript Function integration
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M function Custom Worker Module ewd-qoper8 For legacy Mumps Function integration
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché Globals Custom Worker Module ewd-qoper8 Basic low-level Mumps-centric API
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M Globals Custom Worker Module ewd-qoper8 Basic low-level Mumps-centric API
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx ewd-qoper8-redis Redis ewd-qoper8 ewd-redis-globals Globals Basic low-level API
Copyright © 2016 M/Gateway Developments Ltd JavaScript-centric database access • ewd-qoper8-cache, ewd-qoper8-gtm and ewd-qoper8-redis auto-install ewd- document-store • ewd-document-store provides a JavaScript-oriented abstraction of Global Storage database: – "persistent JavaScript Objects" – Document database • Fine-grained storage of JSON
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals Persistent JavaScript Objects & Fine-grained Document Database Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M ewd-document-store Globals Persistent JavaScript Objects & Fine-grained Document Database Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx Redis ewd-qoper8 ewd-redis-globals Globals ewd-qoper8-gtm ewd-document-store Persistent JavaScript Objects & Fine-grained Document Database
Copyright © 2016 M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” myDocument = { a: 123, b: { c1: 'foo', c2: 'foo2' } d: { e1: { f1: 'bar1', f2: 'bar2' }, e2: { f1: 'bar1', f2: 'bar2', f3: 'bar3' } } }
Copyright © 2016 M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” var f3node = new this.documentStore.DocumentNode('myDocument', ['d', 'e2', 'f3']);
Copyright © 2016 M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” var value = f3Node.value; // 'bar3'
Copyright © 2016 M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” var value = f3Node.parent.$('f2').value; // 'bar2'
Copyright © 2016 M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” myDocument = { a: 123, b: { c1: 'foo', c2: 'foo2' } d: { e1: { f1: 'bar1', f2: 'bar2' }, e2: { f1: 'bar1', f2: 'bar2', f3: 'bar3' } } } var docOnDisk = new this.documentStore.DocumentNode('myDocument'); var localDoc = docOnDisk.getDocument();
Copyright © 2016 M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” myDocument = { a: 123, b: { c1: 'foo', c2: 'foo2' } d: { e1: { f1: 'bar1', f2: 'bar2' }, e2: { f1: 'bar1', f2: 'bar2', f3: 'bar3' } } } var docOnDisk = new this.documentStore.DocumentNode('myDocument'); docOnDisk.setDocument(localDoc);
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals This powerful & intuitive abstraction requires synchronous access ewd-qoper8 provides the isolated run-time container to make this possible Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M ewd-document-store Globals Custom Worker Module ewd-qoper8 This powerful & intuitive abstraction requires synchronous access ewd-qoper8 provides the isolated run-time container to make this possible
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx Redis ewd-qoper8 ewd-redis-globals Globals ewd-qoper8-gtm ewd-document-store This powerful & intuitive abstraction requires synchronous access ewd-qoper8 provides the isolated run-time container to make this possible
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 for synchronous database access • A worker process only handles one request object at a time • Any blocking database (or other) I/O has no impact on the processing of other requests – Each request independently handled, isolated in its own worker
Copyright © 2016 M/Gateway Developments Ltd Sessions • EWD 3 uses a stateless model for web access • Each request from a client may be processed by a different ewd-qoper8 worker process • Usually you need to maintain state information across a sequence of client requests • EWD Sessions provide this capability • The ewd-session module allows you to create and maintain Sessions – Sessions are automatically mapped to ewd-document DocumentNode objects
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Session storage projected as DocumentNode objects Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M ewd-document-store Globals ewd-session Session storage projected as DocumentNode objects Custom Worker Module ewd-qoper8
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx Redis ewd-qoper8 ewd-redis-globals Globals ewd-qoper8-gtm ewd-document-store ewd-session Session storage projected as DocumentNode objects
Copyright © 2016 M/Gateway Developments Ltd ewd-session APIs • sessions.create(applicationName) – Creates a new session, associated with the specified application – Returns a session token • Randomly-generated uuid string • sessions.authenticate(token) – Checks that token is valid and has not yet expired – returns the session object for the token, or an error
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache*+ ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session var session = sessions.create('vista'); Send back session.token Custom Worker Module ewd-qoper8 * Applies also to ewd-qoper8-gtm and ewd-qoper8-redis
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache* + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session var result = sessions.authenticate(token); Returns result.session if successful / result.error if not Custom Worker Module ewd-qoper8 * Applies also to ewd-qoper8-gtm and ewd-qoper8-redis
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache* + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Session object extends GlobalNode object Adds session-specific properties & methods Custom Worker Module ewd-qoper8 * Applies also to ewd-qoper8-gtm and ewd-qoper8-redis
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store + ewd-session + Express Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Express HTTP(S) Interface WebSocket socket.io Interface Custom Worker Module ewd-qoper8 Functions
Copyright © 2016 M/Gateway Developments Ltd Pre-packaged super-modules • QEWD (formally known as ewd-xpress) – Quick and Easy Web Development platform for: • Interactive browser-based applications – Web-sockets or Ajax • Web and REST services • Embedded persistent JSON store / session cache using: – Caché, GT.M or Redis • Compatible with all modern JavaScript front-end frameworks • ewd-qoper8-vistarpc – REST interface to VistA RPCs • ewd-feder8 – Federation / integration platform • Extension of QEWD – Lightweight enterprise service bus functionality
Copyright © 2016 M/Gateway Developments Ltd QEWD (using Caché) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-xpress cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Express HTTP(S) Interface WebSocket socket.io Interface browserewd-client Custom Worker Module ewd-qoper8 Functions
Copyright © 2016 M/Gateway Developments Ltd QEWD (using GT.M) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-xpress nodem ewd-qoper8-gtm GT.M ewd-document-store Globals ewd-session Express HTTP(S) Interface WebSocket socket.io Interface browserewd-client Custom Worker Module ewd-qoper8 Functions
Copyright © 2016 M/Gateway Developments Ltd QEWD (using Redis) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-xpress ewd-redis-globals ewd-qoper8-redis Redis ewd-document-store Globals ewd-session Express HTTP(S) Interface WebSocket socket.io Interface browserewd-client Custom Worker Module ewd-qoper8 tcp-netx
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8-vistarpc (using Caché) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-qoper8- vistarpc cache.node ewd-qoper8-cache ewd-document-store Globals ewd-session Express HTTP(S) Interface REST RPCs Interface function Caché & VistA Symbol Table Custom Worker Module ewd-qoper8 Symbol Table Function
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8-vistarpc (using GT.M) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-qoper8- vistarpc nodem ewd-qoper8-gtm ewd-document-store Globals ewd-session Express HTTP(S) Interface REST RPCs Interface function GT.M & VistA Symbol Table Custom Worker Module ewd-qoper8 Symbol Table Function
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8-vistarpc • Login: (POST) – Access & verify codes – XUS SIGNON SETUP – XUS AV CODE – Returns error or greeting object – If successful: • Creates new Session • Symbol table saved to Session – Contains DUZ etc – No direct access by REST client – Only Indirect access via Authorization token • Return Session Token & VistA greeting 20 – 30ms round trip
Copyright © 2016 M/Gateway Developments Ltd ewd-qoper8-vistarpc • If logged in - runRPC: – Use Session token in Authorization header – POST: • RPC name • RPC arguments object – Symbol table restored from Session • Contains DUZ etc • Determines whether user can run RPC – Standard Mumps-side "business as usual" logic – Return RPC result – Save Symbol table to Session
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-feder8 cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Express HTTP(S) Interface Custom Worker Module ewd-qoper8 REST/ Web Service Client ewd-xpress Also works with GT.M and Redis
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client Worker Process ewd-feder8 ewd-qoper8 REST Server REST Server REST Server Web Service Server Web Service Server cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client Worker Process ewd-feder8 ewd-qoper8 REST Server REST Server REST Server Web Service Server Web Service Server cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Named Group
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Copy of request sent to all servers in group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Responses Received asynchronously Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Last response Received Aggregate response object created Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client Worker Process ewd-feder8 Custom Worker Module ewd-qoper8 REST Server REST Server REST Server Web Service Server Web Service Server cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Named Group Aggregate response Returned to client via Master process
Copyright © 2016 M/Gateway Developments Ltd Aggregate response { Server_1_name: {responseObject}, Server_2_name: {errorObject}, Server_3_name: {responseObject} }
Copyright © 2016 M/Gateway Developments Ltd Interception / Customisation • ewd-feder8 emits events: – When it receives a request from a client – When it receives a response from an end- point server – When an aggregate response is ready for return to a client • These can be used to: – Intercept the flow through ewd-feder8; and – Customise the behaviour of ewd-feder8
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Intercept response Possibly modify it And/or determine action based on response
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Forward new request to group of servers
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Intercept aggregate Response Decide what to do
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Send new request
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Intercept response Create final response
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Return final response to client
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Cache can be Used to store/ build up final response during "dance"
Copyright © 2016 M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session EWD Sessions can also be used – potentially easier to use and manage

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EWD 3 Training Course Part 2: EWD 3 Overview

  • 1.
    Copyright © 2016M/Gateway Developments Ltd EWD 3 Training Course Part 2 Overview of EWD 3 Rob Tweed Director, M/Gateway Developments Ltd Twitter: @rtweed
  • 2.
    Copyright © 2016M/Gateway Developments Ltd EWD 3 Design Aims • Modularising previous-generation (EWD.js) into independent components • Mix and match "buffet" of components • Interoperable with other Node.js modules, eg Express • No core dependence on particular databases • Redis, Caché and GT.M can be used as embedded multi- model databases • But any other Node.js-interfaced database can be used too
  • 3.
    Copyright © 2016M/Gateway Developments Ltd Core EWD 3 Component • ewd-qoper8
  • 4.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 • Very high-performance Node.js Message Queue • Master Node.js process: • Queue & dispatch mechanism • Pool of persistent Worker Node.js processes • These process the requests that are put on the queue
  • 5.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 • Creates an isolated run-time environment for each handler function • Each worker process only handles a single request at a time • Comparable to AWS Lambda's run-time container • Concurrency is handled by the master process only • Its sole purpose is to queue and dispatch incoming requests to an available worker process, and handle the response/results from the worker
  • 6.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 • Worker processes are persistent – Started on demand – When a worker process finishes processing a request, it is returned to the available pool, ready to process another request – No startup / tear-down cost
  • 7.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 • Master process API – this.addToQueue(messageObject) • Adds a message to the queue – this.on('response', function(responseObject, workerPid) {..} • Handles the response from worker – Usually simply returning the response to the client that sent the original request message to the master process
  • 8.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 • What the worker does to process a message is up to you • You define a custom worker module • Worker API: – this.on('message', function(messageObject, send, finished) {..} • finished(responseObject): – Mandatory function – Sends final response to master process – Releases Worker process back to available pool • send(responseObject): – Optional function – Sends a response to master process – Worker process remains unavailable
  • 9.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Node.js Worker Process Node.js Worker Process
  • 10.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher addToQueue(obj)
  • 11.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher
  • 12.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher
  • 13.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module ewd-qoper8
  • 14.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8
  • 15.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module Unavailable Node.js Worker Process Custom Worker Module ewd-qoper8 Begin processing message
  • 16.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module Unavailable worker.on('message', function(messageObj) { // process message }); Node.js Worker Process Custom Worker Module ewd-qoper8 Begin processing message
  • 17.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Unavailable / processing addToQueue(obj) Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8
  • 18.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Node.js Worker Process Custom Worker Module ewd-qoper8 Worker pool size not exceeded:
  • 19.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Worker pool all busy: Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 New request remains in queue
  • 20.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 As soon as a worker is available again: Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Available Node.js Worker Process Custom Worker Module ewd-qoper8
  • 21.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Worker pool all busy: Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 Unavailable / processing Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8
  • 22.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Finished Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8 finished(responseObject);
  • 23.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Finished this.on('response', function(responseObj) { // do something with the response }); Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module Node.js Worker Process Custom Worker Module ewd-qoper8
  • 24.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Available Node.js Worker Process Custom Worker Module ewd-qoper8 Worker automatically returned to the available pool NB: Workers are NOT destroyed after use Removes overhead of continually starting worker processes
  • 25.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Master Node.js Process Queue Queue processor/ dispatcher Available Node.js Worker Process Custom Worker Module ewd-qoper8 Worker processes only handle a single request at a time Completely isolated run-time environment for your handler functions Worker process becomes immediately available for the next queued request when processing completed
  • 26.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 is a building block • Not really useful on its own • Completely generic, general-purpose message queue • Core piece of infrastructure on which the rest of EWD 3 is built – ewd-qoper8 can also be used independently of the other EWD 3 modules and integrated with any other Node.js modules, databases etc
  • 27.
    Copyright © 2016M/Gateway Developments Ltd Express + ewd-qoper8 • Express is the standard Node.js web server – REST, Web Services, interactive applications – Express is a Node.js module – Customised by defining middleware – ewd-qoper8 can be configured as Express middleware • Requests sent to Express by client • Routed to ewd-qoper8 • ewd-qoper8 queues and processes them • ewd-qoper8 response returned via Express to client
  • 28.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + Express Queue Queue processor/ dispatcher Express HTTP(S) Interface WebSocket socket.io Interface addToQueue(req) Node.js Worker Process Custom Worker Module ewd-qoper8
  • 29.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + Express + ewd-qoper8-express Queue Queue processor/ dispatcher Express HTTP(S) Interface Automates and simplifies the use of ewd-qoper8 with Express for HTTP requests Adds special Express router function app.use('/qoper8', qx.router()); ewd-qoper8-express ewd-qoper8- express Node.js Worker Process Custom Worker Module ewd-qoper8
  • 30.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + Express + ewd-qoper8-express Queue Queue processor/ dispatcher Express HTTP(S) Interface Message constructed from Express req object – all information needed for back-end processing by Worker: -path -method -headers -query -body -etc ewd-qoper8-express ewd-qoper8- express Node.js Worker Process Custom Worker Module ewd-qoper8
  • 31.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 Database Dependency? • ewd-qoper8 itself does not have a dependency on a database – In-memory queue – Master and Workers are just Node.js processes * see later parts of this course for details on how to add queue backup / resilience
  • 32.
    Copyright © 2016M/Gateway Developments Ltd Using ewd-qoper8 with Caché • Use a separate module: – ewd-qoper8-cache • Normally used by worker processes • Makes use of cache.node interface module – cache.node is a proprietary InterSystems module that is included with Caché – Allows access from JavaScript/Node.js to: » Caché extrinsic functions » Global storage » Caché Objects & methods – JavaScript API defined by InterSystems » Low-level
  • 33.
    Copyright © 2016M/Gateway Developments Ltd Using ewd-qoper8 with GT.M • Use a separate module: – ewd-qoper8-gtm • Normally used by worker processes • Makes use of NodeM interface module – NodeM is an Open Source module for use with GT.M, which implements the cache.node APIs – Allows access from JavaScript/Node.js to: » GT.M extrinsic functions » Global storage – JavaScript API originally defined by InterSystems » Low-level
  • 34.
    Copyright © 2016M/Gateway Developments Ltd Using ewd-qoper8 with Redis • Use a separate module: – ewd-qoper8-redis • Normally used by worker processes • Makes use of ewd-redis-globals module – ewd-redis-globals is an Open Source module for use with Redis, which: » Implements Global Storage functionality » implements the cache.node APIs – Allows access from JavaScript/Node.js to: » Global storage » Uses the tcp-netx module to connect to Redis – JavaScript API originally defined by InterSystems » Low-level
  • 35.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module cache.node ewd-qoper8-cache Caché ewd-qoper8
  • 36.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module nodem ewd-qoper8-gtm GT.M ewd-qoper8 Equivalent module for use with GT.M Uses David Wicksell’s NodeM module which emulates cache.node for GT.M
  • 37.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx ewd-qoper8-redis Redis ewd-qoper8 Equivalent module for use with Redis Redis behaves as a Global Storage Database via the same cache.node APIs ewd-redis-globals
  • 38.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché function Custom Worker Module ewd-qoper8 For legacy Mumps or Caché ObjectScript Function integration
  • 39.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M function Custom Worker Module ewd-qoper8 For legacy Mumps Function integration
  • 40.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché Globals Custom Worker Module ewd-qoper8 Basic low-level Mumps-centric API
  • 41.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M Globals Custom Worker Module ewd-qoper8 Basic low-level Mumps-centric API
  • 42.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx ewd-qoper8-redis Redis ewd-qoper8 ewd-redis-globals Globals Basic low-level API
  • 43.
    Copyright © 2016M/Gateway Developments Ltd JavaScript-centric database access • ewd-qoper8-cache, ewd-qoper8-gtm and ewd-qoper8-redis auto-install ewd- document-store • ewd-document-store provides a JavaScript-oriented abstraction of Global Storage database: – "persistent JavaScript Objects" – Document database • Fine-grained storage of JSON
  • 44.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Custom Worker Module ewd-qoper8
  • 45.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals Persistent JavaScript Objects & Fine-grained Document Database Custom Worker Module ewd-qoper8
  • 46.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M ewd-document-store Globals Persistent JavaScript Objects & Fine-grained Document Database Custom Worker Module ewd-qoper8
  • 47.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx Redis ewd-qoper8 ewd-redis-globals Globals ewd-qoper8-gtm ewd-document-store Persistent JavaScript Objects & Fine-grained Document Database
  • 48.
    Copyright © 2016M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” myDocument = { a: 123, b: { c1: 'foo', c2: 'foo2' } d: { e1: { f1: 'bar1', f2: 'bar2' }, e2: { f1: 'bar1', f2: 'bar2', f3: 'bar3' } } }
  • 49.
    Copyright © 2016M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” var f3node = new this.documentStore.DocumentNode('myDocument', ['d', 'e2', 'f3']);
  • 50.
    Copyright © 2016M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” var value = f3Node.value; // 'bar3'
  • 51.
    Copyright © 2016M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” var value = f3Node.parent.$('f2').value; // 'bar2'
  • 52.
    Copyright © 2016M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” myDocument = { a: 123, b: { c1: 'foo', c2: 'foo2' } d: { e1: { f1: 'bar1', f2: 'bar2' }, e2: { f1: 'bar1', f2: 'bar2', f3: 'bar3' } } } var docOnDisk = new this.documentStore.DocumentNode('myDocument'); var localDoc = docOnDisk.getDocument();
  • 53.
    Copyright © 2016M/Gateway Developments Ltd ewd-document-store myDocument “a” 123 “b” “c2” “foo2” “d” “c1” “foo” “e2” “e1” “f2” “bar2” “f1” “bar1” “f2” “bar2” “f1” “bar1” “f3” “bar3” myDocument = { a: 123, b: { c1: 'foo', c2: 'foo2' } d: { e1: { f1: 'bar1', f2: 'bar2' }, e2: { f1: 'bar1', f2: 'bar2', f3: 'bar3' } } } var docOnDisk = new this.documentStore.DocumentNode('myDocument'); docOnDisk.setDocument(localDoc);
  • 54.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals This powerful & intuitive abstraction requires synchronous access ewd-qoper8 provides the isolated run-time container to make this possible Custom Worker Module ewd-qoper8
  • 55.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M ewd-document-store Globals Custom Worker Module ewd-qoper8 This powerful & intuitive abstraction requires synchronous access ewd-qoper8 provides the isolated run-time container to make this possible
  • 56.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis + ewd-document-store Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx Redis ewd-qoper8 ewd-redis-globals Globals ewd-qoper8-gtm ewd-document-store This powerful & intuitive abstraction requires synchronous access ewd-qoper8 provides the isolated run-time container to make this possible
  • 57.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 for synchronous database access • A worker process only handles one request object at a time • Any blocking database (or other) I/O has no impact on the processing of other requests – Each request independently handled, isolated in its own worker
  • 58.
    Copyright © 2016M/Gateway Developments Ltd Sessions • EWD 3 uses a stateless model for web access • Each request from a client may be processed by a different ewd-qoper8 worker process • Usually you need to maintain state information across a sequence of client requests • EWD Sessions provide this capability • The ewd-session module allows you to create and maintain Sessions – Sessions are automatically mapped to ewd-document DocumentNode objects
  • 59.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Session storage projected as DocumentNode objects Custom Worker Module ewd-qoper8
  • 60.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-gtm + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher nodem ewd-qoper8-gtm GT.M ewd-document-store Globals ewd-session Session storage projected as DocumentNode objects Custom Worker Module ewd-qoper8
  • 61.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-redis + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher Custom Worker Module tcp-netx Redis ewd-qoper8 ewd-redis-globals Globals ewd-qoper8-gtm ewd-document-store ewd-session Session storage projected as DocumentNode objects
  • 62.
    Copyright © 2016M/Gateway Developments Ltd ewd-session APIs • sessions.create(applicationName) – Creates a new session, associated with the specified application – Returns a session token • Randomly-generated uuid string • sessions.authenticate(token) – Checks that token is valid and has not yet expired – returns the session object for the token, or an error
  • 63.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache*+ ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session var session = sessions.create('vista'); Send back session.token Custom Worker Module ewd-qoper8 * Applies also to ewd-qoper8-gtm and ewd-qoper8-redis
  • 64.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache* + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session var result = sessions.authenticate(token); Returns result.session if successful / result.error if not Custom Worker Module ewd-qoper8 * Applies also to ewd-qoper8-gtm and ewd-qoper8-redis
  • 65.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache* + ewd-document-store + ewd-session Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Session object extends GlobalNode object Adds session-specific properties & methods Custom Worker Module ewd-qoper8 * Applies also to ewd-qoper8-gtm and ewd-qoper8-redis
  • 66.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8 + ewd-qoper8-cache + ewd-document-store + ewd-session + Express Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Express HTTP(S) Interface WebSocket socket.io Interface Custom Worker Module ewd-qoper8 Functions
  • 67.
    Copyright © 2016M/Gateway Developments Ltd Pre-packaged super-modules • QEWD (formally known as ewd-xpress) – Quick and Easy Web Development platform for: • Interactive browser-based applications – Web-sockets or Ajax • Web and REST services • Embedded persistent JSON store / session cache using: – Caché, GT.M or Redis • Compatible with all modern JavaScript front-end frameworks • ewd-qoper8-vistarpc – REST interface to VistA RPCs • ewd-feder8 – Federation / integration platform • Extension of QEWD – Lightweight enterprise service bus functionality
  • 68.
    Copyright © 2016M/Gateway Developments Ltd QEWD (using Caché) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-xpress cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Express HTTP(S) Interface WebSocket socket.io Interface browserewd-client Custom Worker Module ewd-qoper8 Functions
  • 69.
    Copyright © 2016M/Gateway Developments Ltd QEWD (using GT.M) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-xpress nodem ewd-qoper8-gtm GT.M ewd-document-store Globals ewd-session Express HTTP(S) Interface WebSocket socket.io Interface browserewd-client Custom Worker Module ewd-qoper8 Functions
  • 70.
    Copyright © 2016M/Gateway Developments Ltd QEWD (using Redis) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-xpress ewd-redis-globals ewd-qoper8-redis Redis ewd-document-store Globals ewd-session Express HTTP(S) Interface WebSocket socket.io Interface browserewd-client Custom Worker Module ewd-qoper8 tcp-netx
  • 71.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8-vistarpc (using Caché) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-qoper8- vistarpc cache.node ewd-qoper8-cache ewd-document-store Globals ewd-session Express HTTP(S) Interface REST RPCs Interface function Caché & VistA Symbol Table Custom Worker Module ewd-qoper8 Symbol Table Function
  • 72.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8-vistarpc (using GT.M) Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-qoper8- vistarpc nodem ewd-qoper8-gtm ewd-document-store Globals ewd-session Express HTTP(S) Interface REST RPCs Interface function GT.M & VistA Symbol Table Custom Worker Module ewd-qoper8 Symbol Table Function
  • 73.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8-vistarpc • Login: (POST) – Access & verify codes – XUS SIGNON SETUP – XUS AV CODE – Returns error or greeting object – If successful: • Creates new Session • Symbol table saved to Session – Contains DUZ etc – No direct access by REST client – Only Indirect access via Authorization token • Return Session Token & VistA greeting 20 – 30ms round trip
  • 74.
    Copyright © 2016M/Gateway Developments Ltd ewd-qoper8-vistarpc • If logged in - runRPC: – Use Session token in Authorization header – POST: • RPC name • RPC arguments object – Symbol table restored from Session • Contains DUZ etc • Determines whether user can run RPC – Standard Mumps-side "business as usual" logic – Return RPC result – Save Symbol table to Session
  • 75.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 Node.js Worker Process Master Node.js Process Queue Queue processor/ dispatcher ewd-feder8 cache.node ewd-qoper8-cache Caché ewd-document-store Globals ewd-session Express HTTP(S) Interface Custom Worker Module ewd-qoper8 REST/ Web Service Client ewd-xpress Also works with GT.M and Redis
  • 76.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client Worker Process ewd-feder8 ewd-qoper8 REST Server REST Server REST Server Web Service Server Web Service Server cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
  • 77.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client Worker Process ewd-feder8 ewd-qoper8 REST Server REST Server REST Server Web Service Server Web Service Server cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Named Group
  • 78.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
  • 79.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Copy of request sent to all servers in group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
  • 80.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Responses Received asynchronously Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
  • 81.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Last response Received Aggregate response object created Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
  • 82.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 Master Process Express REST/ Web Service Client Worker Process ewd-feder8 Custom Worker Module ewd-qoper8 REST Server REST Server REST Server Web Service Server Web Service Server cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Named Group Aggregate response Returned to client via Master process
  • 83.
    Copyright © 2016M/Gateway Developments Ltd Aggregate response { Server_1_name: {responseObject}, Server_2_name: {errorObject}, Server_3_name: {responseObject} }
  • 84.
    Copyright © 2016M/Gateway Developments Ltd Interception / Customisation • ewd-feder8 emits events: – When it receives a request from a client – When it receives a response from an end- point server – When an aggregate response is ready for return to a client • These can be used to: – Intercept the flow through ewd-feder8; and – Customise the behaviour of ewd-feder8
  • 85.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session
  • 86.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Intercept response Possibly modify it And/or determine action based on response
  • 87.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Forward new request to group of servers
  • 88.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Intercept aggregate Response Decide what to do
  • 89.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Send new request
  • 90.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Intercept response Create final response
  • 91.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Return final response to client
  • 92.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session Cache can be Used to store/ build up final response during "dance"
  • 93.
    Copyright © 2016M/Gateway Developments Ltd ewd-feder8 "dance" Master Process Express REST/ Web Service Client REST Server REST Server REST Server Web Service Server Web Service Server Named Group Worker Process ewd-feder8 ewd-qoper8 cache.node ewd-qoper8-cache Caché ewd-document-store ewd-session EWD Sessions can also be used – potentially easier to use and manage