EWD 3 Training Course Part 2: EWD 3 Overview

2. 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

4. 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

5. 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

6. 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

7. 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

8. 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

14. 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

15. 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

16. 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

17. 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

18. 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:

19. 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

20. 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

21. 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

22. 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);

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. 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

32. 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

33. 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

34. 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

35. 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

36. 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

37. 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

38. 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

39. 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

40. 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

41. 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

42. 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

43. 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

44. 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

45. 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

46. 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

47. 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

48. 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' } } }

49. 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']);

50. 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'

51. 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'

52. 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();

53. 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);

54. 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

55. 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

56. 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

57. 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

58. 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

59. 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

60. 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

61. 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

62. 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

63. 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

64. 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

65. 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

66. 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

67. 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

68. 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

69. 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

70. 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

71. 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

72. 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

73. 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

74. 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

75. 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

76. 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

77. 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

78. 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

79. 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

80. 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

81. 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

82. 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

84. 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

85. 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

86. 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

87. 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

88. 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

89. 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

90. 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

91. 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

92. 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"

93. 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