Sunday, 12 October 2014

Evolving & Emerging Architecture: Agile-EA

Going into companies is always an interesting experience. You get to view the way they work and in agile organisations using physical boards, you can walk the floor and view how the work is progressing. That is well known in the agile project management arena, product owner roles etc. but it's also an extremely useful technique in the Agile Enterprise Architecture world (Agile-EA). Before going into why, we need to recap a couple of definitions.

1. Conway's Law

In 1968, Melvin Conway provided this now tried and tested gem.

"organizations which design systems ... are constrained to produce designs which are copies of the communication structures of these organizations"

This is a huge revelation for some companies, but it got hidden by process oriented techniques, which masked the problem for decades.  

In the agile space, it's a very different story. The reliance on teams to develop their own processes, and having the greatest expressive power within them as opposed to across them has resulted in this being more applicable than ever. You can turn this to your advantage and having elements of a workflow which make up the greatest proportion of it, contained within teams really improves the rate of delivery of work, as I have covered in previous posts and is a much better facilitator of outcome than having a distributed development team. This also means that cross-team communication encourages the development of a system through that communication channel.

2. Consumer Driven Contracts

A consumer driven contract can be considered a Kanban pull signal. This pulls a feature from another team and in software development spaces, this also includes a sub-suite of tests from the consuming team. When a feature provided by another team is needed, a cross-team card, often of a different colour is placed on the team board who are to provide that functionality (at Laterooms,com for example, they used rainbow coloured cards at one point). That team then pick the card up and code against the tests to make them pass. 

Consumer driven contracts are pretty much the most central concept in true just in time, cross team software delivery. They often have a subtask link to the source board and effectively provide an architectural link between application components or business features.

This provides opportunities for architects in both the enterprise and/or solution sphere to see how their estate is evolving by simply going to all stand-up meetings, and building a picture of the emerging architecture or estate by following the chain of tickets. Once such a ticket appears, this introduces an architectural dependency and over time, more and more tickets appears which fill the space between things that architecture lives in.

Walking the Floor

Architects live between things. As architects we should aim to get to every stand-up within our sphere. When we do, we should look out for these cross team tickets, or features being played which we are aware touch something else or perhaps could leverage a feature elsewhere in our estate. 

Imagine we go to the stand-ups and see the following boards after, iteration/sprint 10. 

Sprint 10 board states

Sprint 11 sees a purpose ticket appear on team board 1, required by team board 2 (who are pulling it). The purple ticket represents a cross-team 'pull' (indicated in team 2's 'X' ticket for convenience) since it requires a feature from team 2. The dotted line now represents the relationship between the two teams, which remember by Conway's law represents a link between the system or business features:

Sprint 11 emerges an architectural link

This continues to be played and supposing by the end of Sprint 11 it and its compatriot pull are both done. This ticket is now complete and the architectural link has been delivered. So the architecture of the estate now looks like the following (Arrowed lines represent a dependency):

Sprint 11 Architecture - Note, no Team 4 features live, so architect doesn't care

Sprint 12 and two purple tickets appear. One from team 3 to 1 and one 4 to 2. The solid line represents the delivered link from Sprint 11:

Sprint 12 Architecture
When this is delivered, the architecture then looks like:

Architecture after Sprint 12
And so the cycle continues. 


Each one of the dotted lines represents a communication flow between two teams and brings them closer for that phase of the development. When it's done, the link still exists in the system (solid line), but they can separate and form relationships with other teams, as team 1 did with team 3, after team 1 finished with team 2. Of course, there are times when the platform will need to delete those links, removing them from the estate, but the communication still happens regardless. 

As an architect, attending the stand-ups is a great way to see how the system evolves. You can walk the boards looking for these special cards and draw out the architecture as you proceed. Indeed, if you're an active contributor (and you should be) you can and should facilitate the teams to make decisions which are systemically optimal and forming links when the team could otherwise expend a lot of effort would save them and the company time and money. As the organisation matures and the role of software architect embeds in the teams (as roles over job descriptions), it is these individuals who will go to other team stand-ups and hence, facilitate the creation, updating or destruction of these architectural links.


Post a Comment

Whadda ya say?