In previous blog postings I've defined Discipline Agile Delivery (DAD)
but I haven't shared the lifecycle (although I have done so in a couple of white papers, most recently Scaling Agile: An Executive Guide
) in this blog. Until now.
The DAD method combines strategies and practices from several software methods, including Scrum
, Extreme Programming (XP)
, Agile Modeling
, Agile Data
, and the Open Unified Process (OpenUP)
. One aspect of this "process idea reuse" is that the DAD extends the Scrum lifecycle to be a full-fledged delivery lifecycle. Figure 1 overviews the Scrum lifecycle, which addresses the construction aspects of agile delivery quite well. It depicts the product backlog which is a basic prioritized requirements stack
; the concept of delivering incrementally in consistent time boxes (what Scrum calls sprints and other methods such as DAD call iterations); holding a daily coordination meeting; and demoing your work at the end of the sprint/iteration/timebox to get feedback from key stakeholders. These are all great ideas, which is why the DAD method adopts and enhances them.Figure 1: The Scrum lifecycle. The focus is on the construction part of the lifecycle (click on the diagram for details).
Several years ago I wrote about the Agile lifecycle
and the need to extend it beyond construction, and this thinking is reflected in the DAD lifecycle of Figure 2. The DAD lifecycle extends the Scrum lifecycle in several important ways:
- It includes explicit phases. Sacrilege! Rhetoric aside, there are in fact serial aspects to agile software development. Project teams go through an initiation effort - called "warm up" in Eclipse Way, Inception in Unified Process, Sprint 0 in Scrum, and Iteration 0 in other methods - at the beginning of a project. Eventually the team will go through a release phase - called the "end game" in Eclipse Way
- It includes project initiation. During the Inception phase you perform basic project initiation activities such as requirements envisioning, architecture envisioning, initial release planning, getting funding for the project, and starting to build the team (among other tasks). In the summer of 2009 I ran the 2009 Agile Project Initiation survey which revealed that the average agile team spent 4 week on initiation activities such as this, that 89% did some sort of up-front requirements work, and that 85% did some sort of up-front architecture work.
- It includes release activities. The DAD lifecycle also includes a Transition phase where you release your solution into production or the marketplace. These activities typically include final testing and hardening of your solution, training end users, pilot/beta testing, finalizing documentation, running the solution in parallel with the system(s) being replaced, and so on.
- It explicitly indicates production activities. Many agile delivery teams are responsible for supporting the existing version(s) of their system which are currently running in production. Because there are existing versions, the team will be getting enhancement requests and defect reports from their operations and support people. Many of these requests can simply be treated as new requirements to be prioritized and put on the work item stack. Some need to be addressed right away, particularly "severity 1" defects, which requires the delivery team to "stop the line", address the problem, release a patch or hot fix, then reintegrate the changes into the version they're currently working on. My experience is that it's critical to include a production phase in your delivery lifecycle to make it explicit to the team that they need to take operations and support concerns into account.
- It explicitly enhances the product backlog. The product backlog has evolved into a work item list (or work item stack if you prefer). Disciplined agile teams put more than just requirements on the stack, as you read above it is common to treat defect reports as you do requirements.
- It explicitly includes critical milestone points. An important aspect of the DAD method is that not only does it support self organization such as Scrum but it does so within an appropriate governance framework. Disciplined agile teams recognize that they exist within a larger organization, that they should follow common development guidelines, that they should strive to leverage and build out the shared enterprise infrastructure, that they must report common metrics to senior management (hopefully automatically via the use of instrumented tooling such as we see on the Jazz platform).
One of the advantages of the DAD method over Scrum is that it doesn't require you to figure these common things out for yourself. Figure 2. The Disciplined Agile Delivery (DAD) lifecycle (basic). The focus is on the delivery portion of the system lifecycle, from starting a project to releasing the solution into production (click on the diagram for details).
Figure 3 depicts the advanced form of the DAD lifecycle. This form of the lifecycle occurs on experienced teams that have originally adopted the basic, Scrum-based lifecycle of Figure 2 and evolved it over time to be leaner. One of the implications of continuous improvement and continuous learning, key recommendations of the DAD process framework, is that your lifecycle will evolve. Primary changes that you see between Figure 2 and Figure 3 are the adoption of a work item pool
instead of a work item stack
and the abandonment of iterations (the critical observation is that practices such as detailed planning, demos, retrospectives and so on do not need to be on the same cadence, hence iterations disappear).
Figure 3. The Disciplined Agile Delivery (DAD) lifecycle (advanced). Over time you will improve your strategy towards a leaner approach (click on the diagram for details).
Figure 4. An older version of the basic DAD lifecycle using Scrum terminology. Use whatever terminology you're comfortable with, there is no "standard" (click on the diagram for details).
One of the differences that you may have noticed between the Scrum lifecycle of Figure 1 and the DAD lifecycle of Figure 2 is different terminology is used. For example, iteration is used instead of sprint. Work item list is used instead of product backlog. Although I believe that the terminology used in Figure 2 is more accurate, it really doesn't matter because it's easy to use Scrum terminology with DAD if you like. You can see this clearly in Figure 4. What is important is that you choose the terminology which you are most comfortable with, and be prepared to translate back and forth between terms as there are no standards and there never will be. As an aside, you might find Translating Scrum Terminology
to be of interest.
DAD is still a process framework that you'll need to tailor to meet your unique needs. More on this in future blog postings.
Modified by ScottAmbler
For several years now I've written various articles and newsletters on the topics of estimating and funding strategies for software development projects, and in particular for agile software development projects. Whenever I talk to people about agile software development, or coach them in how to succeed at it, some of the very first questions that I'll be asked, particularly by anyone in a management role, is how to fund agile software development projects. Apparently a lot of people think that you can only apply agile strategies on small, straightforward projects where it makes sense to do a time and materials (T&M) approach. In fact you can apply agile strategies in a much greater range of situations, as the various surveys
that myself and others are showing time and again. My goal with this blog posting is to summarize the various strategies for, and issues surrounding, the funding of agile software development projects.
There are three basic strategies for funding projects, although several variations
clearly exist. These strategies are:
- "Fixed price". At the beginning of the project develop, and then commit to, an initial estimate based on your up-front requirements and architecture modeling efforts. Hopefully this estimate is given as a range, studies have shown that up-front estimating techniques such as COCOMO II or function points are accurate within +/- 30% most of the time although my July 2009 State of the IT Union survey found that on average organizations are shooting for +/- 11% (their actuals come in at +/- 19% on average, but only after doing things such as dropping scope, changing the estimate, or changing the schedule). Fixed-price funding strategies are very risky in practice because they promote poor behavior on the part of development teams to overcome the risks foisted upon them as the result of this poor business decision. It is possible to do agile on a fixed budget but I really wouldn't recommend it (nor would I recommend it for traditional projects). If you're forced to take a fixed-price approach, and many teams are because the business hopes to reduce their financial risk via this approach not realizing that it actually increases their risk, then adopt strategies that reduce the risk.
- Stage gate. Estimate and then fund the project for given periods of time. For example, fund the project for a 3-month period then evaluate it's viability, providing funding for another period of time only to the extent that it makes sense. Note that stages don't have to be based on specific time periods, they could instead be based on goals such as to intiate the project, prove the architecture with working code, or to build a portion of the system. Disciplined agile methods such as Open Unified Process have built in stage-gate decision points which enable this sort of strategy. When the estimation technique is pragmatic, the best approaches are to have either the team itself provide an estimate for the next stage or to have an expert provide a good gut feel estimate (or better yet have the expert work with the team to develop the estimate). Complex approaches such as COCOMO II or SLIM are often little more than a process facade covering up the fact that software estimating is more of an art or a science, and prove to be costly and time consuming in practice.
- Time and materials (T&M). With this approach you pay as you go, requiring your management team to actually govern the project effectively. Many organizations believe a T&M strategy to be very risky, which it is when your IT governance strategy isn't very effective. An interesting variation, particularly in a situation where a service provider is doing the development, is an approach where a low rate is paid for their time which covers their basic costs, the cost of materials is paid out directly, and delivery bonuses are paid for working software. This spreads the risk between the customer/stakeholder and the service provider. The service provider has their costs covered but won't make a profit unless they consistently deliver quality software.
The point is that there are several strategies for funding agile software development projects, just like there are several strategies for funding traditional software development projects. My experience is that fixed-price funding strategies are incredibly poor practice which increases the risk of your software development projects dramatically. I recognize how hard it can be to change this desire on the part of our business stakeholders, but have also had success changing their minds. If you choose to perservere, which is a difficult decision to make, you can help your organization's decision makers to adopt more effective strategies. Like you they want to improve the effectiveness of your IT efforts.Further reading: (In recommended order)
- Something's Gotta Give: Argues for a flexibly approach to funding, schedule, and/or scope.
- Agile on a Fixed Budget: Describes in detail how to take a fixed-price approach on agile projects.
- The Dire Consequences of Fixed-Price IT Projects: Describes in detail the questionable behavior exhibited by IT teams when forced to take a fixed-price approach.
- Is Fixed-Price Software Development Unethical?: Questions the entire concept of fixed-price IT projects, overviewing some of the overwhelming evidence against this really poor practice.
- Reducing the Risk of Fixed-Price Projects: Describes viable strategies for addressing some of the problems resulting from the decision of fixed-price projects.
- Strategies for Funding Software Development Projects: Describes several variations on the strategies described above.
- Lies, Great Lies, and Software Development Project Plans: Summarizes some results from the July 2009 State of the IT Union survey which explored issues related to project funding (among many).
I just wanted to share with you the Manifesto for Software Craftsmanship
which extends the Agile Manifesto
. The Manifesto for Software Craftsmanship states:As aspiring Software Craftsmen we are raising the bar of professional software development by practicing it and helping others learn the craft. Through this work we have come to value:
- Not only working software, but also well-crafted software
- Not only responding to change, but also steadily adding value
- Not only individuals and interactions, but also a community of professionals
- Not only customer collaboration, but also productive partnerships
That is, in pursuit of the items on the left we have found the items on the right to be indispensable.
I view this manifesto as an important step in the maturation of software development. More on this in a future blog posting.[Read More
The Scrum community has adopted a different set of terms than the other agile methodologies. This is done on purpose to help people realize that Agile approaches are different than traditional approaches, which can help in their adoption, but it can also hinder people's understanding because some of the terminology is not only non-standard it really doesn't make much sense. Because of this I'm often asked by people that I'm coaching to convert back and forth between terms, and recently wrote a detailed article on the subject. The following summarizes the mapping:
- Daily Scrum Meeting ==> Daily Stand-up Meeting
- Product Backlog ==> Work Item List
- Scrum Master ==> Team Lead or Team Coach
- Sprint ==> Iteration or Time Box
For more details read my article Translating Scrum Terminology
which includes explanations of a wider range of Scrum terms and discussions of why some of them really are questionable. Further reading:
I'm often asked by customers for case studies of successful agile adoptions or agile projects in general. This is definitely a valid request, and yes, such case studies exist. But I'm often concerned that the people making these requests don't appreciate the implications of what they're asking for. My concerns with case studies are:
- The juicy information is rarely included. The information that you really want to find out, such as what went wrong and why it went wrong, is rarely discussed. If problems, oops I mean "challenges", are discussed at all they're typically glossed over in favor of focusing in on the positives. Although many people want to write up the juicy bits this information is invariably edited out through the company's vetting process. In short, my advice is to take case studies with a grain of salt.
- Some case studies are more fiction than fact. Although this isn't a problem with IBM case studies due to the governance efforts of my good friends in IBM's legal department (we love you folks, really) it can be an issue with some case studies.
- The case study may no longer be true today. Stuff happens. Perhaps the case study was mostly true at the time it was written, but now that time has passed problems have appeared that weren't apparent earlier, thus the effort wasn't as nearly as successful as it was written up. For example, a few years ago I ran into the manager of a team that I had read about in one case study, only to find out that once the study was published the key team members left the company to become consultants in that subject area. Having lost these people, who were all very highly skilled, his system proved to be unmaintainable by the rest of his staff who weren't so highly skilled and had to be rewritten. Over time the success story turned into an abject failure.
- Waiting for case studies puts you in the position of follower. For every case study that gets written, dozens, if not hundreds of similar efforts didn't get written up. Writing case studies is hard, takes time, and the writer seldom gets much benefit from doing so. The lag time between the project completing and the case study being published can be many, many months and sometimes years. The implication is that by the time you wait for several case studies that are similar to your situation you've pretty much lost all opportunity for competitive advantage and are now merely trying to catch up to the organizations who are clearly ahead of you (the writers of the case studies).
- What has the requester given back to the community? I often hear people lament that there isn't enough case studies, or isn't something close enough to their situation. Yet, when I ask them how many case studies they've written and the answer is usually none. If you want to get you also need to give. ;-)
So, next time you think you need a case study before making a decision, recognize that you may be paying a fairly high opportunity cost for information that is questionable at best.Further reading:
Contrary to popular belief, agile development teams do in fact model and yes, they even do some up front requirements and architecture modeling. Two of the best practices of Agile Modeling are Requirements Envisioning
and Architecture Envisioning
where you spend a bit of time at the beginning of the project doing enough initial modeling to get you going in the right direction. The strategy is to take advantage of modeling, which is to communicate and think things through without taking on the risks associated with detailed specifications written early in the lifecycle
. In this blog posting I will focus on requirements envisioning, in a future posting I'll cover architecture envisioning.
The goal of initial requirements envisioning is to identify the scope of your effort. You need to do just enough modeling early in the project to come to stakeholder concurrence and answer questions such as what you're going to build, roughly how long it's going to take (give a range), and roughly how much it's likely to cost (once again, give a range). If you can get the right people together in the room, which can sometimes be a logistics challenge but not one that you couldn't choose to overcome, there are very few systems (I suspect less than 5%) that you couldn't initially scope out in a few days or a week. I also suspect that most of the remaining systems could be scoped out with less than 2 weeks of modeling, and if not then I'd take that as an indication that you're taking on too large of a project. I'm not saying that you'll be able to create big detailed specifications during this period, and quite frankly given the problems associated with "Big Requirements Up Front (BRUF)
" you really don't want to, but I am saying that you could gain a pretty good understanding of what you need to do. The details, which you'll eventually need, can be elicited throughout the lifecycle when you actually need the information. A common saying in the agile community is that requirements analysis is so important for us that we do it every single day, not just during an initial phase. I'll discuss just in time (JIT) approaches to requirements modeling in a future posting.
To envision the requirements for a business application, you might want to consider creating the following models:
- High-level use cases (or user stories). The most detail that I would capture right now would be point form notes for some of the more complex use cases, but the majority just might have a name. The details are best captured on a just-in-time (JIT) basis during construction.
- User interface flow diagram. This provides an overview of screens and reports and how they're inter-related. You just need the major screens and reports for now.
- User interface sketches. You'll likely want to sketch out a few of the critical screens and reports to give your stakeholders a good gut feeling that you understand what they need. Sketches, not detailed screen specifications, are what's needed at this point in time.
- Domain model. A high-level domain model, perhaps using UML or a data modeling notation, which shows major business entities and the relationships between them, can also be incredibly valuable. Listing responsibilities, both data attributes and behaviors, can be left until later iterations.
- Process diagrams. A high-level process diagram, plus a few diagrams overviewing some of the critical processes, are likely needed to understand the business flow.
- Use-case diagram. Instead of a high-level process diagram you might want to do a high-level use case diagram instead. This is a matter of preference, I likely wouldn't do both.
- Glossary definitions. You might want to start identify key business terms now, although I wouldn't put much effort into settling on exact definitions. I've seen too many teams run aground on "analysis paralysis" because they try to define exact terminology before moving forward. Don't fall into this trap.
For small teams simple tools such as whiteboards and paper are usually sufficient for requirements envisioning. But what happens at scale? What if you're working on a large agile team, say of 50 people, 200 people (IBM has delivered software into the marketplace with agile teams of this size), or even 500 people (IBM currently has teams of this size applying agile techniques)? What if your team is distributed? Even if you have people working on different floors of the same building, let alone working from home or working in different cities or countries, then you're distributed (see my postings about distributed agile development
). Suddenly whiteboards and paper-based tools (index cards, sticky notes, ...) aren't sufficient. You're still likely to use these sorts of tools in modeling sessions with stakeholders, but because of one or more scaling factors you need to capture your requirements models electronically.
In January Theresa Kratschmer and I gave a webcast entitled Agile Requirements: Collaborative, Contextual, and Correct
which overviewed agile approaches to requirements elicitation and management, including requirements envisioning. We also showed how Rational Requirements Composer (RRC)
can be used to electronically capture critical requirements information, enabling you to address the needs of large and/or distributed agile teams, while still remaining lightweight and flexible. I suspect that you'll find the webcast to be very illuminating and RRC something that you want to take a look at (the link leads to a trial version). Of course RRC can be used in other situations as well, but that's not what I'm focused on right now.
Teams which find themselves in regulatory environments will likely need to do more than just use RRC, as might very large teams. Regulatory compliance often requires more complex requirements documentation, which in turn requires more sophisticated tools such as DOORS or Requisite Pro, and I would consider using those tools in the types of situations that warrant it. One of the things that people often struggle to understand about agile approaches is that you need to tailor your strategy to reflect the situation at handle. One process size does not fit all, so you will end up using different tools and creating different artifacts to different extents in different situations. Repeatable results, not repeatable processes
, is the rule of the day. Further reading:
Modified by ScottAmbler
This article has been replaced by an official "Disciplined Agile Manifesto".
The text of the original article remains below.
I've recently been working with Mark Lines of UPMentors and we've had some interesting discussions around evolving the Agile Manifesto which I thought I would share here to obtain feedback. Note that this is not any sort of official position of IBM, nothing in my blog is by the way (unless explicitly stated so), nor is it some sort of devious plot to take over the agile world (although if we did have some sort of devious plot, we'd make the exact same claim). What we hope to accomplish is to put some ideas out there in the hopes of getting an interesting conversation going.
Over the past decade we’ve applied the ideas captured in the Agile Manifesto and have learned from our experiences doing so. What we’ve learned has motivated us to suggest changes to the manifesto to reflect the enterprise situations which we have applied agile and lean strategies in. We believe that the changes we’re suggesting are straightforward:
Where the original manifesto focused on software development, a term which too many people have understood to mean only software development, we suggest that it should focus on solution delivery.
Where the original focused on customers, a word that for too many people appears to imply only the end users, we suggest that it focus on the full range of stakeholders instead.
Where the original manifesto focused on development teams, we suggest that the overall IT ecosystem and its improvement be taken into consideration.
Where the original manifesto focused on the understanding of, and observations about, software development at the time there has been some very interesting work done within the lean community since then (and to be fair there was very interesting work done within that community long before the Agile Manifesto was written). We believe that the Agile Manifesto can benefit from lean principles.
Our suggested rewording of the Agile Manifesto follows, with our suggested changes in italics.
Updating the Values of the Agile Manifesto
We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value:
Individuals and interactions over processes and tools
Working solutions over comprehensive documentation
Stakeholder collaboration over contract negotiation
Responding to change over following a plan
That is, while there is value in the items on the right, we value the items on the left more.
Updating the Principles behind the Agile Manifesto
Our highest priority is to satisfy the customer through early and continuous delivery of valuable solutions.
Welcome changing requirements, even late in the solution delivery lifecycle. Agile processes harness change for the stakeholder’s competitive advantage.
Deliver working solutions frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale.
Stakeholders and developers must work together daily throughout the project.
Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done.
The most efficient and effective method of conveying information to and within a delivery team is face-to-face conversation.
Quantified business value is the primary measure of progress.
Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.
Continuous attention to technical excellence and good design enhances agility.
Simplicity--the art of maximizing the amount of work not done--is essential.
The best architectures, requirements, and designs emerge from self-organizing teams.
At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.
Leverage and evolve the assets within your organizational ecosystem, and collaborate with the people responsible for those assets to do so.
Visualize workflow to help achieve a smooth flow of delivery while keeping work in progress to a minimum.
The organizational ecosystem must evolve to reflect and enhance the efforts of agile teams, yet be sufficiently flexible to still support non-agile or hybrid teams.
We’re agile – things evolve, including manifestos. Looking forward to your feedback (add a comment).
Updates Since this Was First Published:
Test-driven development (TDD) is a common agile programming technique which has both specification and validation aspects. With TDD, you specify your software in detail on a just-in-time (JIT) basis via executable tests that are run in a regression manner to confirm that the system works to your current understanding of what your stakeholders require.
TDD is the combination of test-first development (TFD) and refactoring. With TFD, you write a single test (at either the requirements level with customer/acceptance tests or the design level with developer tests) and then you write just enough software to fulfill that test. Refactoring is a technique where you make a small change to your existing code to improve its design without changing its semantics.
TDD offers several benefits:1. It enables you to take small, safe steps during development, increasing programmer productivity.2. It increases quality. Agile developers are doing more testing, and doing it more often, than ever before. We're also fixing the problems that we find right on the spot.3. It helps to push validation activities early in the lifecycle, decreasing the average cost to fix defects (which rises exponentially the longer it takes you to detect them).4. Through single sourcing information, by treating tests as both specifications and as tests, we reduce the work required, increasing productivity.5. We leave behind valuable, up-to-date, detailed specifications for the people who come after us. Have you ever met a maintenance programmer who wouldn't want a full regression test suite for the code that they're working with?
But TDD isn't perfect. Although TDD is great at specifying code at a fine-grain level, tests simply don't scale to address higher level business process and architectural issues. Agile Model Driven Development (AMDD) enables you to scale TDD through initial envisioning of the requirements and architecture as well as just-in-time (JIT) modeling at the beginning and during construction iterations. To scale requirements-level TDD, you must recognize that customer tests are very good at specifying the details, but not so good at providing overall context. High-level business process models, conceptual domain models, and use cases are good at doing so, and these work products are often created as part of your initial requirements envisioning and iteration modeling activities. Similarly, to scale design-level TDD you must recognize that developer tests are very finely grained but once again do not provide overall context. High-level architecture sketches created during envisioning activities help set your initial technical direction. During each construction iteration, you'll do more detailed design modeling to think through critical issues before you implement them via TDD.
You also need to scale the validation aspects of TDD. TDD is in effect an approach to confirmatory testing where you validate the system to the level of your understanding of the requirements. The fundamental challenge with confirmatory testing, and hence TDD, is that it assumes that stakeholders actually know and can describe their requirements. Therefore you need to add investigative testing practices which explore issues that your stakeholders may not have thought of, such as usability issues, system integration issues, production performance issues, security issues, and a multitude of others.
For further reading, I suggest:1. My article "Introduction to TFD/TDD" at http://www.agiledata.org/essays/tdd.html which overviews TDD.2. My February 2008 column in Dr. Dobb's Journal entitled "Scaling TDD" at http://www.ddj.com/architect/205207998 which explores this issue in detail. 3. Andrew Glover's article "In pursuit of code quality: Adventures in behavior-driven development" at http://www.ibm.com/developerworks/java/library/j-cq09187/ which describes a new-and-improved take on TDD called BDD.[Read More
Modified by ScottAmbler
An imporant step in scaling your agile strategy is to adopt a Disciplined Agile Delivery (DAD)
approach instead of one which is just focused on agile construction. One aspect of adopting a DAD approach it to mature your focus from just producing software to instead providing a solution which meets the needs of its stakeholders within the appropriate economic, cultural, and technical constraints. The fundamental observation is that as IT professionals we do far more than just develop software. Yes, this is clearly important, but in addressing the needs of our stakeholders we will often:
Provide new or upgraded hardware
Change the business/operational processes which stakeholders follow
Change the organizational structure in which our stakeholders work
Update supporting documentation
And yes, develop high-quality software
Although delivery of high-quality, working software is important it is even more important that we deliver high-quality working solutions to our stakeholders. Minimally IT professionals should have the skills and desire to produce good software, but what they really need are the skills and desire to provide good solutions. We need strong technical skills, but we also need strong "soft skills" such as user interface design and process design to name just two.
The shift to a solution-oriented focus from a software-oriented focus requires your agile teams to address some of the software-oriented prejudices which crept into the Agile Manifesto
. The people who wrote the manifesto (which I fully endorse) were for the most part software developers, consultants, and in many cases both. It is little wonder that this group would allow a bias towards software development creep into the language of their manifesto.
A common question that I keep running into with customers is whether you can take an agile approach to service oriented architecture (SOA). The quick answer is yes, because Agile is orthogonal to the implementation technologies used. You can take an agile approach developing COBOL applications running on mainframes, fat-client Java applications, multi-tier J2EE applications, and yes, even services. Granted, it's easier to do with some technologies than others, either because of the nature of the technology or because of the supporting tools.
The long answer is "yes, but". You don't adopt an SOA approach for the sheer joy of doing so, instead you very likely want to improve the level of reuse within your organization. To succeed at SOA-driven reuse you need an enterprise focus, something that doesn't appear to be very common on many agile teams. Therein lies the challenge. Several strategies for improving your chances with Agile SOA, and SOA in general, follows:1. Invest in some initial enterprise architecture modeling. You don't need to identify all of the details up front, that would take too long and actually put the effort at risk, but you do need to set a starting point to guide development teams. Identifying the technical architecture is critical, and identifying a few basic services which would provide immediate business value to one or more teams is critical. Involve people from several application project teams to ensure that you get a wide range of input. See http://www.agiledata.org/essays/enterpriseArchitecture.html for a streamlined approach to enterprise architecture modeling. Creating big, detailed models often proves to be a waste of time because development teams are rarely motivated to read mounds of documentation.2. Build out the initial infrastructure on a real application development project. This proves that your SOA strategy actually works and puts the technical foundation in place for future teams. During this period you'll be tempted to try to support several development teams, which is feasible but dramatically increases your risk. It's also tempting to focus simply on getting the infrastructure in place without delivering any business functionality, but this risks producing an ivory-tower architecture that nobody is interested in.3. Spread the service architects out onto application development teams. The people that formulated and then proved your SOA should be actively involved on the development teams that are working with it to ensure that the teams use it appropriately and to ensure that the architects get concrete feedback which they can use to evolve the architecture. When working on agile teams, these people will need to work in a collaborative and evolutionary approach just like other team members.4. Fund reuse separately. I've lost track of the number of organizations that I've run into that fail at reuse because their development teams never have the resources to develop reusable assets. That's simply the nature of the beast -- project teams will always be more interested in addressing their own specific requirements than they are in investing the time and effort to make something reusable. The real problem here is that you expect them to act differently. A better strategy is to have a separate reuse engineering team that has the resources to monitor existing projects to look for potentially reusable assets. When they find said assets this team does the work to harvest the asset, to reengineer it to make it reusable, and then to integrate back into the original source project. The goal is to make it as painless as possible to produce reusable assets such as services. If you expect project teams to do this work out of the goodness of their hearts then you're effectively punishing them when they do the right thing. That's not a very good governance strategy, IMHO.5. The reuse team now owns the asset. Any reusable asset, including services, will need to be maintained, evolved over time, and supported. This isn't free nor is it viable for project teams to do so.
If you're interested, I provide agile strategies for both enterprise architecture and strategic reuse in the book "Enterprise Unified Process". Although written under the assumption that you're taking a RUP-based approach to development, the reality is that the EUP can extend any evolutionary/agile software development process so that it addresses the larger-scale needs of modern IT organizations.
- Scott[Read More