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Event Sourcing your AngularJS applications
Event sourcing is a technique for data storage that involves storing the full history of data changes as a sequence of events. It sits at the highest level of a data storage maturity model above structured storage and CQRS. With event sourcing, all changes to data are stored as a sequence of events, and any updates result in a new event that is appended to the event log.
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Event Sourcing your AngularJS applications
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- 19.
Editor's Notes
- #3 Why? I wan to create better applications Most applications store the current state http://www.flickr.com/photos/celestinechua/9661913835
- #4 Levels of working with data Create Read Update Delete Command Query Responsibility Segregation Event-Sourcing
- #5 Data dumps and CRUD actions against database is very similar as seen from the front end
- #6 Most applications store the current state If you are lucky there is an audit trail of sorts http://www.flickr.com/photos/ell-r-brown/4011702143
- #7 http://www.flickr.com/photos/willowbl00/12459211923
- #8 http://www.flickr.com/photos/sukiweb/10223596316
- #9 The server is often just a simple gateway with just some validation logic
- #10 $resource and noSQL database make CRUD applications really easy
- #11 There is nothing wrong with a CRUD application if the problem domain is simple http://www.flickr.com/photos/juhansonin/5144239690
- #12 Command Query Responsibility Segregation
- #13 CQRS = Command Query Responsibility Segregation Use a different model to update information than the model you use to read information http://www.flickr.com/photos/usnavy/8220344431
- #14 Still storing just the current state Database structure is often normalized and optimized for updating Most application read far more frequently then update
- #15 Commands should be modeled after business actions A business user can understand command names and have a reasonable expectation of the outcome http://www.flickr.com/photos/micahdowty/4630801442
- #16 We are stil storing only the current state No trace of how we got there http://www.flickr.com/photos/danrocha/15602018982
- #17 Event sourcing doesn’t depend on CQRS but that structure is often used.
- #18 Event Sourcing is a very old idea that has become popular again over recent years. Events provide insight into how the system came to be in its current state http://www.flickr.com/photos/dragontomato/5174914835
- #19 Domain Event is something that has happened in the past The result of a Command to change something Very similar to the audit trail in a database http://www.flickr.com/photos/lendingmemo/11747440176/
- #20 No longer storing the current state but all event leading up to it The current state is a left fold of all events The projection parts are not really part of ES but CQRS and usually combined
- #21 Events are never erased An append only model http://www.flickr.com/photos/horiavarlan/4263326117
- #22 Events are projected out to the read model Observed facts = events Derived facts = projections http://www.flickr.com/photos/fotnmc/7172465908
- #23 Eventual consistency both good and bad Better scalability Harder to program the UI Block until done Fake it on the client Use long polling or push notifications http://www.flickr.com/photos/epsos/5732013768
- #24 Event Sourcing adds complexity Don’t do it where it doesn’t make sense It’s perfectly fine to use CRUD for static reference and ES for domain in the same app http://www.flickr.com/photos/10912969@N03/2046600021/
- #25 Sample application: https://github.com/mauricedb/Movies-GES Main technologies used: https://angularjs.org/ http://geteventstore.com/ http://redis.io/ http://www.asp.net/ https://www.flickr.com/photos/kevandotorg/6229660191
- #26 More info: Martin Fowler: http://martinfowler.com/eaaDev/EventSourcing.html Greg Young: http://goodenoughsoftware.net/ Daniel Whittaker: http://danielwhittaker.me/tag/event-sourcing/ João Bragança: https://github.com/thefringeninja/derp.inventory Damian Hickey: http://dhickey.ie/?tag=/Event-Sourcing https://www.flickr.com/photos/stevendepolo/4582437563/