![Copyright ยฉ 2016 M/Gateway Developments Ltd
Document Store Event Handling
Example of afterSet node object
{
"documentName":"CacheTempEWDSession",
"path":["session","72","foo"],
"before":{
"value":"bar",
"exists":true
},
"value":"bar"
}](https://image.slidesharecdn.com/ewd3-course-26-160901093026/85/EWD-3-Training-Course-Part-26-Event-driven-Indexing-8-320.jpg)
![Copyright ยฉ 2016 M/Gateway Developments Ltd
Document Store Event Handling
{
"documentName":"CacheTempEWDSession",
"path":["session","72","foo"],
"before":{
"value":"bar",
"exists":true
},
"value":"bar"
}
Tells you the DocumentNode
that may need indexing / re-indexing](https://image.slidesharecdn.com/ewd3-course-26-160901093026/85/EWD-3-Training-Course-Part-26-Event-driven-Indexing-9-320.jpg)
![Copyright ยฉ 2016 M/Gateway Developments Ltd
Document Store Event Handling
{
"documentName":"CacheTempEWDSession",
"path":["session","72","foo"],
"before":{
"value":"bar",
"exists":true
},
"value":"bar"
}
Tells you the previous contents,
if any, of the DocumentNode, prior
to the afterSet event](https://image.slidesharecdn.com/ewd3-course-26-160901093026/85/EWD-3-Training-Course-Part-26-Event-driven-Indexing-10-320.jpg)
![Copyright ยฉ 2016 M/Gateway Developments Ltd
Document Store Event Handling
{
"documentName":"CacheTempEWDSession",
"path":["session","72","foo"],
"before":{
"value":"bar",
"exists":true
},
"value":"bar"
}
Tells you the new value of the
DocumentNode, as a result of
the afterSet event](https://image.slidesharecdn.com/ewd3-course-26-160901093026/85/EWD-3-Training-Course-Part-26-Event-driven-Indexing-11-320.jpg)
EWD 3 Training Course Part 26: Event-driven Indexing
- 1. Copyright ยฉ 2016 M/Gateway Developments Ltd EWD 3 Training Course Part 26 JavaScript Abstraction of Global Storage: Event-Driven Indexing Rob Tweed Director, M/Gateway Developments Ltd Twitter: @rtweed
- 2. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Indexing โข When a document node is created, changed or deleted, we may want to maintain a corresponding set of index document nodes โข How can this be done in a modular and automatically-invoked way?
- 3. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Indexing โข When a document node is created, changed or deleted, we may want to maintain a corresponding set of index document nodes โข How can this be done in a modular and automatically-invoked way? โ Events
- 4. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Events โข Emitted automatically by: โ value property (when used to set/change a value) โ setDocument() method (for each node created) โ increment() method โ delete() method โข Allows you to write handlers to maintain indices
- 5. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Events โข beforeSet โข afterSet โข beforeDelete โข afterDelete โ You'll probably use the after* events most frequently
- 6. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Event Handling โข this.documentStore.on(eventName, function(obj) {..}); โข eg: this.documentStore.on('afterSet', function(nodeObj) { // do something with the changed node });
- 7. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Event Handling โข this.documentStore.on(eventName, function(obj) {..}); โข eg: this.documentStore.on('afterSet', function(nodeObj) { // do something with the changed node }); Tells you what node was changed, what value it had previously (if any) and what new value it has now
- 8. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Event Handling Example of afterSet node object { "documentName":"CacheTempEWDSession", "path":["session","72","foo"], "before":{ "value":"bar", "exists":true }, "value":"bar" }
- 9. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Event Handling { "documentName":"CacheTempEWDSession", "path":["session","72","foo"], "before":{ "value":"bar", "exists":true }, "value":"bar" } Tells you the DocumentNode that may need indexing / re-indexing
- 10. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Event Handling { "documentName":"CacheTempEWDSession", "path":["session","72","foo"], "before":{ "value":"bar", "exists":true }, "value":"bar" } Tells you the previous contents, if any, of the DocumentNode, prior to the afterSet event
- 11. Copyright ยฉ 2016 M/Gateway Developments Ltd Document Store Event Handling { "documentName":"CacheTempEWDSession", "path":["session","72","foo"], "before":{ "value":"bar", "exists":true }, "value":"bar" } Tells you the new value of the DocumentNode, as a result of the afterSet event
- 12. Copyright ยฉ 2016 M/Gateway Developments Ltd Where to handle Document Store Events? โข Your QEWD application-specific back-end handler module โ Use its optional init() function โข If defined in your module, this function is invoked when the module is initially loaded by a worker process โข You can define the handlers you need within this function โข Filter the document names you're interested in indexing within your application module
- 13. Copyright ยฉ 2016 M/Gateway Developments Ltd Handling Document Store Events โข eg C:qewdnode_modulesdemo1.js module.exports = { init: function() { this.documentStore.on('afterSet', function(docNode) { console.log('*** afterSet event triggered by ' + JSON.stringify(docNode)); }); }, handlers: { testButton: function(messageObj, session, send, finished) { session.data.$('foo').value = 'bar'; send({ type: 'intermediate', foo: 'bar', date: new Date().toString() }); finished({ ok: 'testButton message was processed successfully!' }); } };
- 14. Copyright ยฉ 2016 M/Gateway Developments Ltd Handling Document Store Events โข eg C:qewdnode_modulesdemo1.js module.exports = { init: function() { this.documentStore.on('afterSet', function(docNode) { if (docNode.documentName === 'myDoc') { // delete previous index document node // create new index node // remember that this will, itself, invoke more events for index document nodes! } }); }, handlers: { // etcโฆ } };