Command Query Responsibility Segregation (CQRS) is the starting point of a change that will have a profound impact on system architecture, Dino Esposito claims in three articles in MSDN Magazine. It’s the first step in an evolution transitioning software architects from the idea of “models-to-persist” to the idea of “events-to-log” and about event-based data instead of data snapshots.
Looking at Command Query Responsibility Segregation (CQRS) in a larger architectural context there are other architectural styles available. There are database technologies solving the same problems but in a simpler way, Udi Dahan states looking into ways of approaching CQRS. There is also a way that fulfils a lot of the CQRS goals but with fewer moving parts when CQRS is really needed.
To make microservices awesome Domain-Driven Design (DDD) is needed, the same mistakes made 5-10 years ago and solved by DDD are made again in the context of microservices, David Dawson claimed in his presentation at this year’s DDD Exchange conference in London.
Improving on his understanding of the architecture and patterns involved in Command Query Responsibility Segregation (CQRS), Sacha Barber has created a complete CQRS demo application including event sourcing and an article with a cross examination of the inner workings.
Today’s applications are commonly unnecessarily complex or slow because of not using Command Query Responsibility Segregation (CQRS), Gabriel Schenker claims while stating he believes CQRS to be one of the most useful architectural patterns when used in the context of complex Line of Business (LOB) applications.
A service is a logical construct owning a business capability and made up of internal autonomous components or microservices that together fulfil the responsibilities of the service, Jeppe Cramon suggests continuing a previous series of blog posts clarifying his view on building services around business capabilities and bounded contexts.
Structuring data as a stream of events is an idea appearing in many areas and is the ideal way of storing data. Aggregating a read model from these events is an ideal way to present data to a user, Martin Kleppmann claims explains when describing the fundamental ideas behind Stream Processing, Event Sourcing and Complex Event Processing (CEP).
The World Wide Web Consortium (W3C) has published the Pointer Events standard as a recommendation for wide adoption, but its future is in doubt as Apple and Google are refusing to implement it.
The Chromium team announced back in August that Google is no longer working on implementing Pointer Events in Chrome in order to focus on Touch Events. Now they have given control to the Pointer Events polyfill library to jQuery which is hoping to “drive developer adoption of this unified event system” and eventually see “all browsers implement this standard natively.”
Hackathons are events where developers work together during a fixed period to collaboratively develop software. They provide learning opportunities and space for developers and organizations sponsoring the hackathons to network and have some fun.
Microservices are not new ideas and we will over the course of 3-5 years end up rebuilding WS-* the same way Web Services did rebuild all from CORBA unless we learn from our mistakes and improve to prevent them from being made again, Greg Young stated in a presentation at the Microservices Conference in London.
When using Domain-Driven Design (DDD) separating the concerns of a large system into bounded contexts with each context using its own data store there is often a need to share some common data. One way of doing that is to let each context publish events about changes, events that others can listen to, Julie Lerman recently explained in MSDN Magazine.
A common context for Command-Query Responsibility Segregation (CQRS) is a collaborative domain with multiple users working on the same set of data, it is less suitable in domains with only a single user working on a piece of data, Udi Dahan explained when discussing CQRS in an interview.
Leslie Lamport is the author of some of the most cited computer science papers and won a Turing Award in 2013 for his seminal work in distributed and concurrent systems. This is a summary of an interview that Lamport gave to Software Engineering Radio touching themes such as his early work in distributed systems and the importance of precise thinking in programming.
State transitions are an important part of our problem space and should be modelled within our domain, Greg Young states in a recent presentation focusing on basic event sourcing and how CQRS fits in.