Copyright © 2016 M/Gateway Developments Ltd
EWD 3 Training Course
Part 27
JavaScript Abstraction of Global Storage:
The QEWD Session
Rob Tweed
Director, M/Gateway Developments Ltd
Twitter: @rtweed

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The QEWD Session
• Ephemeral storage that persists as long as
a user remains active
• Controlled / managed by the ewd-session
module
– This has a dependency on the
ewd-document-store module

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The QEWD Session
• The Session object contains some
information that is maintained by
ewd-session itself
– Used behind the scenes by QEWD
• session.data is available to the developer
for storage and retrieval of application-
specific session information

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The QEWD Session
• Session data is automatically garbage-
collected after the session expires

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Accessing the Session in QEWD
• Automatically made available to your
back-end message handler functions
myHandler: function(messageObj, session, send, finished) {…};

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session.data is a DocumentNode
Object
• session.data is an automatically-generated
DocumentNode object
– Points to the Session global storage for the
user whose message you're processing
– The developer can access and manipulate the
session.data contents by using the standard
DocumentNode APIs

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Accessing the Session in QEWD
myHandler: function(messageObj, session, send, finished) {..};
For example:
- session.data.$('mySessionVariable').value = 'bar';
- var foo = session.data.$('mySessionVariable').value;
- var someObj = session.data.$('mySessionObj').getDocument();
- session.data.$('mySessionObj').setDocument(someObj);

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Underlying Global Storage?
• By default it maps to a Global named
– CacheTempEWDSession
– On a Caché system, any Global prefixed CacheTemp
is mapped to in-memory storage and isn't journalled
• Highest performance
• You can over-ride this and define your own
Global name
– In the QEWD startup file
• config.sessionDocumentName

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QEWD startup file example
var config = {
managementPassword: 'keepThisSecret!',
serverName: 'New QEWD Server',
port: 8080,
poolSize: 1,
database: {
type: 'cache',
params: {
path: 'c:InterSystemsCache2015-2mgr’
},
sessionDocumentName: 'mySessionGlobal'
}};
var qewd = require('qewd').master;
qewd.start(config);