John Bywater - Event Sourcing in Python - Event-oriented Analysis and Design with Applications

Event-oriented analysis and design with applications.

By John Bywater

Copyright 2020 John Bywater

All rights reserved. No part of this book may be reproducedor transmitted in any form or by any means, electronic ormechanical, including photocopying, recording, or by anyinformation storage and retrieval system, without permissionin writing from the publisher.

Thank you for reading this book. We have covered a lot of ground. The bookwas mainly about event-sourced models, applications and systems. But the questionof how generally applicable is event sourcing brought us to Whiteheads processphilosophic scheme: the idea that the actual world is built up from actual occasionsof experience, with human occasions of experience being of an especially high grade.Understanding Whiteheads scheme made it very apparent that Christopher Alexanderspattern language scheme is a creative application of Whiteheads scheme: patternlanguage was intended to describe events. Alexanders patterns correspond toWhiteheads actual occasions, and Alexanders pattern language corresponds toWhiteheads structured living societies. Alexanders remark that the world is builtup of events and nothing else echoes Whiteheads remark that everything thatexists is derived by abstraction from actual occasions. Alexanders remarkthat pattern languages teach you to be receptive to what is real echoesWhiteheads view that there is no going behind actual occasions to findanything more real. At the centre of all of this are the actual occasions,which are both a creative process of feeling and a decision that bringsmany feelings into a unity of feeling; things that both come to exist andthat can be explained and expressed in terms of their interconnections anddecisions. The notion of an event is then understood as an interrelated setof actual occasions (a social nexus, or society) with the limiting type beinga nexus that has only one member.

In adopting Whiteheads scheme, we respond to the question of how generallyapplicable is event sourcing by acquiring an understanding that all domainsare inherently constituted by what happens in that domain. In adopting Alexandersscheme, we acquire a technique for describing and conditioning creative occasionsof design. The patterns of event-sourced applications presented in the main chaptersof this book are generally applicable for these two reasons: firstly we can alwaystackle the complexity in a domain by building supportive event-sourced applications;secondly, when we build event-sourced applications we can condition our occasions ofdesign by following the patterns in this book.

The patterns in this book are intended to be used in a particular set ofhuman occasions of experience: occasions of designing event-sourced softwareapplications and event-driven systems. Software code can be exciting andbut isnt in itself alive, and however fascinating can be tiring to work withand understand. We have been through quite a lot of software code in the previousfifteen chapters. And so I wanted to end this book on a warmer note, by returningto the human level, and saying something more about the application of Whiteheadsscheme in the world of human personal experience and human relationships,by discussing more fully the psychology topics that were mentioned in the prologue:Carl Rogers person-centred theory, and Marshall Rosenbergs nonviolent or collaborativecommunication.