James On Programming

The second day of µCon proved to be as interesting as the first. I have another huge list of things to investigate, and there are some things I need to get underway at work tomorrow. As I said in my  post about day 1, the most important thing about microservices is, for me, the discussion of the problems and patterns of modern web-development. Pretending that monolithic applications work is no longer an option.

• The relationship of microservices to SOA came up several times, with people questioning whether this was just a re-branding or rehabilitation of SOA.
• Another good question emerging from microservices is why we still can’t produce satisfactory architecture after all this time (Conway’s Law dates back to 1968).  We have a cycle of new techniques becoming common, then standardised, then growing bloated and cluttered until someone takes a clean-sheet approach and we start again.
• The concept of cohesion is one that I haven’t paid enough attention to; (micro)services should be ‘loosely coupled, highly cohesive’. It was also good to be reminded that logical and physical architecture do not need to be the same. I don’t think we pay enough attention to things as simple as package structure.
• Jeppe Cramon pointed out that “a service that only deals with data is a database,” and we already have APIs for that. Why wrap that in REST?
• One thing that’s difficult for me personally is getting out of the database transaction mindset. Cross-service transactions are a bad thing, but are likely to become prevalent as large software providers make it easier for people to do things the wrong way.
• Jakub Korab had an important lesson for developers working with monoliths: if you touch any external system then you’re working with distributed computing. Monolithic architecture is an assumption that has worked (more-or-less) for a long time, but it’s not really true. All developers should have an awareness of the CAP framework and the Fallacies of Distributed Computing.

The only major problem I had with µCon was the lack of female presenters. If a subject has no female practitioners with something to say, then the topic may not be ready for a conference. Otherwise it was an excellent two days. I’ve already booked a ticket for the 2015 event.

I spent today in London, attending the first day of µCon, a conference dedicated to microservices. A lot of delegates seemed to be in the same position as me – working with a monolithic application that needs separating. Microservices are certainly not the answer to my problems, but many of the techniques and architectures will help me. The most relevant session was Chipping Away at a Monolith by Mark Landeryou and Steve McDonald from SagePay, which gave me a lot to think about.

Some other immediate responses:

• There was a great deal of pragmatism. As enthusiastic as people were about microservices, there was an air of caution rather than triumphalism. This is a good solution in some situations but certainly not a silver bullet.
• The question of technical debt came up a lot. I’ve read several things recently questioning the use of the term ‘technical debt‘, and some of the speakers took a similar view. I’m often seeing it used thoughtlessly and dangerously.
• Many microservice architectures have focussed on HTTP/REST, but some of the other options (pub/sub messaging, thrift) are interesting.
• Conway’s Law is a constant reference point, and I need to sit down and read the original paper. I find myself wondering recently why we even organise programmers into IT departments rather than place them in the business where they are needed.
• The Unix Philosophy came up a lot too, with one speaker describing Unix pipes as the most perfect API ever invented.
• My main concern with microservices is that they are an ideal. Most people have good intentions but still somehow find themselves dealing with difficult codebases. Greenfield development is rare and temporary. Maybe we need conferences focussed on monolith programming – but I expect that would be a hard sell

Another early start tomorrow for day 2. It’s going to take me a few days to read through the notes I made properly (21 pages so far), but I’m looking forward to another day of talks.