During my London staying, I had also the chance to attend Simon Brown's in-the-brain event, which turned out to be more two-way than mine, with Simon softly facilitating a really open discussion. As it is often the case, interesting ideas emerged. Here are some of my side notes, mixed with some of my following ruminations.
Communicating the architecture
One of the biggest challenges seems to be finding the right way to effectively communicate the architecture. It turned out that architecture documents are not the best way to convey architecture information alternative and possibly more creative ways are needed, spanning from Wikis, to podcasts, to live sessions. Honestly, the Google Chrome Comics is a great way to deliver an architectural view. But maybe it's not a viable option for common teams.
Also, a prototype could bring so much information and is particularly efficient in edge situations, where the team is not properly trained or skilled and needs to produce some code anyway. Bad as it may sound, also cut&paste information propagation (the worst case scenario) might be preferable to paralysis or anarchy.
Championing the architecture
Without an active championing role, the architecture is at risk of being twisted or thwarted. Without an active role, an architectural specification is just a piece of paper.
Non Functional requirements
Managing non functional requirements seems to be a hot spot for many agile teams: requirements do not naturally show up as user stories, so their emergency has to be somehow facilitated. Also, automatic tests on nonfunctional requirements are necessary.
Strictly tying delivered software to business value might eventually put non functional requirements aside, but having a fully operating passed load test delivers both business value and confidence.
A pragmatic strategy to define if an occasional need needs to be transformed into an Architecture requirement is to count the number of times you've been hit by the need to refactor a given thing, with 'three' as a threshold for a rule of thumb. Before getting to the threshold one should "resist to the temptation" of refactoring the code to a more elegant solution.
Personal note: it's interesting to notice that this works only in teams where you have an efficient information flow within the team. If development process does not facilitate this sort of information exchange (es. no daily scrum meetings), your counting might reach '20' before the need for a given refactoring is communicated to the architect-in-charge (whatever that means).
I also advocated the cause of "sustainable architectures": putting too much stuff on an architecture definition might result valueless if the team isn't able to grasp it. Sometimes it's better keep everything as simple as possible, or to step back and start with a less sophisticated solution, and invest in training or improving the team technical skills (or the architect communication ones) before building and obscure cathedral.
A key point is that architecture is about things that are expensive to change in software applications. Interestingly, a too sophisticated architecture (architects love to create frameworks) is more frequent than the need to heavily refactor an existing one. Honestly, I think that in many cases, simply defining a clean layering architecture might be enough, to allow a clean solution of emerging architectural requirements.
Personal note: also, the cost of change has largely dropped: if we compare heavyweight frameworks that were popular some years ago, with what can be achieved with Spring and AOP in terms of pluggable, orthogonal requirements, it's clear that the scenario has changed radically, at least in the JEE landscape.
Should architects be part of the team?
It turned out that architects are sitting on the borderline of the team. There are architects that are definitely not in the team (and absolutely do not code), and some which are more willing to pair with developers, improving team skills and gaining feedback on the correctness of the architectural choices. At the end of the day, developers are architecture primary users, and, as an architect, I really would have my choices tested and challenged by a real feedback. On the other hand, an architect should preserve its ability to think long term, so can't be fully involved in coding, especially tasks which are on the critical path. Moreover, they might be external roles, hired on a short term basis, or with reduced availability, so being part of a fully involved Scrum team might be problematic. Doing Scrum by the book, the Team might ask for an external architecture support as long as the team thinks they need it.
Project start effect (personal note)
As a consultant, I might have a slightly biased perspective, but in many times, the architecture definition has just been the result of a "resource allocation incident". Sometimes, the team was just set and ready-to-code, so there wasn't really much time to have them wait for a good architecture specification to start coding. Sometimes, I joined a project when development had already started, so I had to impose an architecture over a (barely) existing another. Finally, some other projects would not even start before an "architectural view" documentation is developed, as this is part of the project budget negotiation by the management (SOA is a typical example of this case); so when the project starts you have more or less a "specification" already in place. In other words, the early days really influenced the whole project direction, and this rarely has to do with architecture, per se.