Event-Sourcing your AngularJS applications
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Presentation on Event-Sourcing your AngularJS applications at enterJS 2015 in Darmstadt, Germany
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Event-Sourcing your AngularJS applications
- 1. Event-Sourcing your AngularJS applications MAURICE DE BEIJER - @MAURICEDB
- 2. Who am I? Maurice de Beijer The Problem Solver Microsoft Integration MVP Freelance developer DevelopMentor instructor Twitter:@mauricedb Blog: http://msmvps.com/blogs/TheProblemSolver/ Web: http://www.TheProblemSolver.nl E-mail: maurice.de.beijer@gmail.com
- 4. Data Storage Maturity Model 3 - Event Sourcing 2 - CQRS 1 - Structured storage 0 – Data Dump
- 5. Data Storage Maturity Model 3 - Event Sourcing 2 - CQRS 1 - Structured storage 0 – Data Dump
- 9. (Semi) Structured storage Database CRUD Server HTTP Browser
- 12. Data Storage Maturity Model 3 - Event Sourcing 2 - CQRS 1 - Structured storage 0 – Data Dump
- 13. Command Query Responsibility Segregation
- 14. Command Query Responsibility Segregation Database Query Service Browser Command Service Read Update
- 17. Data Storage Maturity Model 3 - Event Sourcing 2 - CQRS 1 - Structured storage 0 – Data Dump
Editor's Notes
- Why? I want to create better applications Most applications store the current state http://www.flickr.com/photos/celestinechua/9661913835
- Levels of working with data Create Read Update Delete Command Query Responsibility Segregation Event-Sourcing
- Data dumps and CRUD actions against database is very similar as seen from the front end
- 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
- http://www.flickr.com/photos/willowbl00/12459211923
- http://www.flickr.com/photos/sukiweb/10223596316
- The server is often just a simple gateway with just some validation logic
- $resource and noSQL database make CRUD applications really easy
- There is nothing wrong with a CRUD application if the problem domain is simple http://www.flickr.com/photos/juhansonin/5144239690
- Command Query Responsibility Segregation
- 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
- Still storing just the current state Database structure is often normalized and optimized for updating Most application read far more frequently then update
- 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
- We are stil storing only the current state No trace of how we got there http://www.flickr.com/photos/danrocha/15602018982
- Event sourcing doesn’t depend on CQRS but that structure is often used.
- 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
- 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/
- 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
- Events are never erased or updated An append only model http://www.flickr.com/photos/horiavarlan/4263326117
- Events are projected out to the read model Observed facts = events Derived facts = projections http://www.flickr.com/photos/fotnmc/7172465908
- 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
- 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/
- 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
- 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/