XP

Archived Posts from this Category

Executable Specifications – Presentation from AgilePalooza

Posted by on 06 Aug 2009 | Tagged as: Acceptance Testing, Agile, Architecture, DotNet, General, Java, Open Source, Scrum, Software Architecture, TDD, User Stories, XP

Earlier this year I did a presentation on Executable Specficiations for AgilePalooza conference. There is information about working with legacy code, commercial off-the-shelf (COTS) systems, and Acceptance Test-Driven Development (ATDD) using automated acceptance testing tools. Also, the presentation lists types of automated acceptance testing tools out there along with actual names of tools and what they are best used for on projects. Hope it is interesting to you.

Maintain One List of Work

Posted by on 12 Jun 2009 | Tagged as: Agile, Architecture, General, Leadership, Product Owner, Scrum, Software Architecture, User Stories, XP

During an interview at the Better Software conference this week, I mentioned that I thought maintaining a single list of work prioritized by the business was important for our industry to improve. The following text is an excerpt, in first draft form, from chapter 2, “Architecture Integrity”, of my upcoming book “Architecture in an Agile Organization” that is relevant to this topic.


In Scrum, the Product Backlog is a list of desired features prioritized by the Product Owner. Prioritization is done by the Product Owner to optimize value of the software delivered to the users. Instead of prioritizing within levels of importance such as high, medium, and low the Product Owner must prioritize in “stack-rank” order. This means that no Product Backlog item has the same priority as another item. This form of prioritization gives clear directions to development teams about what the most important feature is next to work on.

A healthy Product Backlog contains not only new features but also technical requirements to support the next Product Backlog items in priority. The development team is expected to review the Product Backlog frequently to provide cost estimates for Product Backlog items to help the Product Owner prioritize based on both cost and benefit. During the development team’s review they will suggest Product Backlog items that are missing from a technical point of view in the product definition. These technical Product Backlog items will be discussed with the Product Owner so they are able to prioritize them effectively. It is essential that the development team explain why each technical Product Backlog item is important to support other upcoming items. If this is not expressed the Product Owner could be inclined to demote those technical Product Backlog items because the value of them is not understood enough.

When issues are found in the software they usually come in three varieties:

  • Enhancement – a suggestion for improving the current state of the software from a user’s point of view
  • Defect – a system fault that occurs while using the software
  • Fire – a system fault that is inhibiting significant usage scenarios in the software and must be fixed immediately

Enhancements are requests for improvements to the software based on the perspective of the user. These improvements should be prioritized based on their value against all other Product Backlog items. An enhancement and defect issues are hard to distinguish from one another at times but that is fine. Defects are system faults that users are able to workaround but should not be happening from a user experience and/or technical perspective. Since we are able to work around these defects and the development team is able to provide a fix in the next iteration they are placed into the Product Backlog and prioritized against all other Product Backlog items. Fires are defects that cannot be worked around and cause serious problems for users of the software. In healthy software applications, fires should be a rare occurrence. It is important that a fix is implemented right away and may interrupt the work getting done in the current iteration.

issuetriage

Figure: This flow diagram describes how an identified issue is triaged in an iterative and incremental approach such as Scrum. If the issue is an enhancement or defect that can be worked around for now it goes into the Product Backlog and prioritized based on its value. If the issue is a “fire” or defect that cannot be worked around then it must be fixed immediately. The development will put the fire into their current list of work in the Sprint Backlog and figure out how it effects their commitment to deliver on their current iteration.

Defects are captured in bug databases in many organizations. Teams using the Scrum process to manage their software development find themsves in a predicament. Do we continue working from two lists, the Product Backlog of desired features and bug database? Or do we incorporate items from the bug database into the Product Backlog? I suggest all teams should incorporate defects into the Product Backlog. There are multiple reasons to do this:

  • Development team does not make priority decisions for the business stakeholders. If the development team decides to work on defects rather than desired features then they are deciding the defects are higher priority than the desired features without including the Product Owner in the decision-making process.
  • Minimizes the amount of hidden work done by the development team. By providing visibility into the defects, the development team is being transparent about the state of the software they are working on.
  • Provides the Product Owner with an opportunity to prioritize the defect lower. The Product Owner could decide the defect is not important enough to fix at this time.
  • Allows development team and Product Owner to design a solution for dealing with defects. From time to time the defect provides insight into a design flaw that the Product Owner would like to improve.

Ultimately, the development is able to maintain alignment with business priorities for the software. Priorities are decided based upon the full reality of the software, new features and defects included.

A single work queue, such as the Product Backlog, provides visibility to the development team about current expectations about upcoming work. The Product Owner should share the Product Backlog with the development team and discuss the direction of the product beyond the next iteration. As the development team gains knowledge about the direction of the product they will be able to provide input into the Product Backlog. This visibility is important so Product Backlog items do not surprise the development team when it is too late to prepare a proper solution.

Designing Through Programmer Tests (TDD)

Posted by on 27 May 2009 | Tagged as: Agile, General, Java, Scrum, TDD, Uncategorized, XP

To reduce duplication and rigidity of the programmer test relationship to implementation code, move away from class and methods as the definition of a “unit” in your unit tests. Instead, use the following question to drive your next constraint on the software:

What should the software do next for the user?

The following coding session will provide an example of applying this question. The fictitious application is a micro-blogging tool named “Jitter”. This is a Seattle-based fictitious company that focuses on enabling coffee injected folks write short messages and have common online messaging shorthand to be expanded for easy reading. The user story we are working on is:

So that it is easier to keep up with my kid’s messages, Mothers want to automatically expand their kid’s shorthand

The acceptance criteria for this user story are:

  • LOL, AFAIK, and TTYL are expandable
  • Able to expand lower and upper case versions of shorthand

The existing code already includes a JitterSession class that users obtain when they authenticate into Jitter to see messages from other people they are following. Mothers can follow their children in this application and so will see their messages in the list of new messages. The client application will automatically expand all of the messages written in shorthand.

The following programmer test expects to expand LOL to “laughing out loud” inside the next message in the JitterSession.

public class WhenUsersWantToExpandMessagesThatContainShorthandTest {

    @Test
    public void shouldExpandLOLToLaughingOutLoud() {
        JitterSession session = mock(JitterSession.class);
        when(session.getNextMessage()).thenReturn("Expand LOL please");
        MessageExpander expander = new MessageExpander(session);
        assertThat(expander.getNextMessage(), equalTo("Expand laughing out loud please"));
    }

}

The MessageExpander class did not exist so along the way I created a skeleton of this class to make the code compile. Once the assertion is failing, I then make the test pass with the following implementation code inside the MessageExpander class:

public String getNextMessage() {
    String msg = session.getNextMessage();
    return msg.replaceAll("LOL", "laughing out loud");
}

This is the most basic message expansion I could do for only one instance of shorthand text. I notice that there are different variations of the message that I want to handle. What if LOL is written in lower case? What if it is written as “Lol”? Should it be expanded? Also, what if some variation of LOL is inside a word? It probably should not expand the shorthand in that case except if the characters surrounding it are symbols, not letters. I write all of this down in the programmer test as comments so I don’t forget about all of these.

// shouldExpandLOLIfLowerCase
// shouldNotExpandLOLIfMixedCase
// shouldNotExpandLOLIfInsideWord
// shouldExpandIfSurroundingCharactersAreNotLetters

I then start working through this list of test cases to enhance the message expansion capabilities in Jitter.

@Test
public void shouldExpandLOLIfLowerCase() {
    when(session.getNextMessage()).thenReturn("Expand lol please");
    MessageExpander expander = new MessageExpander(session);
    assertThat(expander.getNextMessage(), equalTo("Expand laughing out loud please"));
}

This forced me to use the java.util.regex.Pattern class to handle case insensitivity.

public String getNextMessage() {
    String msg = session.getNextMessage();
    return Pattern.compile("LOL", Pattern.CASE_INSENSITIVE).matcher(msg).replaceAll("laughing out loud");
}

Now make it so mixed case versions of LOL are not expanded.

@Test
public void shouldNotExpandLOLIfMixedCase() {
    String msg = "Do not expand Lol please";
    when(session.getNextMessage()).thenReturn(msg);
    MessageExpander expander = new MessageExpander(session);
    assertThat(expander.getNextMessage(), equalTo(msg));
}

This forced me to stop using the Pattern.CASE_INSENSITIVE flag in the pattern compilation. Instead I tell it to match only “LOL” or “lol” for replacement.

public String getNextMessage() {
    String msg = session.getNextMessage();
    return Pattern.compile("LOL|lol").matcher(msg).replaceAll("laughing out loud");
}

Next we’ll make sure that if LOL is inside a word it is not expanded.

@Test
public void shouldNotExpandLOLIfInsideWord() {
    String msg = "Do not expand PLOL or LOLP or PLOLP please";
    when(session.getNextMessage()).thenReturn(msg);
    MessageExpander expander = new MessageExpander(session);
    assertThat(expander.getNextMessage(), equalTo(msg));
}

The pattern matching is now modified to use spaces around each variation of valid LOL shorthand.

return Pattern.compile("\\sLOL\\s|\\slol\\s").matcher(msg).replaceAll("laughing out loud");

Finally, it is important that if the characters around LOL are not letters it still expands.

@Test
public void shouldExpandIfSurroundingCharactersAreNotLetters() {
    when(session.getNextMessage()).thenReturn("Expand .lol! please");
    MessageExpander expander = new MessageExpander(session);
    assertThat(expander.getNextMessage(), equalTo("Expand .laughing out loud! please"));
}

The final implementation of the pattern matching code looks as follows.

return Pattern.compile("\\bLOL\\b|\\blol\\b").matcher(msg).replaceAll("laughing out loud");

I will defer refactoring this implementation until I have to expand additional instances of shorthand text. It just so happens that our acceptance criterion for the user story asks that AFAIK and TTYL are expanded, as well. I won’t show the code for the other shorthand variations in the acceptance criteria. However, I do want to discuss how the focus on “what should the software do next” drove the design of this small component.

Driving the software development using TDD focusing on what the software should do next helps guide us to only implement what is needed and with 100% programmer test coverage for all lines of code. For those who have some experience with object-oriented programming will implement the code with high cohesion, modules focused on specific responsibilities, and low coupling, modules that make few assumptions about other module they interact with will do. This is supported by the disciplined application of TDD. The failing programmer test represents something that the software does not do yet. We focus on modifying the software with the simplest implementation that will make the programmer test pass. Then we focus on enhancing the software’s design with the refactoring step. It has been my experience that refactoring refactoring represents most of the effort expended when doing TDD effectively.

AgilePalooza in San Francisco May 29th

Posted by on 19 May 2009 | Tagged as: Acceptance Testing, Agile, Architecture, General, Leadership, Open Source, Product Owner, Scrum, Software Architecture, TDD, Travel, User Stories, XP

AgilePalooza is a one day Agile conference on Friday May 29th at the San Francisco State University downtown campus. There will be two tracks: Learning Agility and Advancing Agility.

“Learning Agility” will be presentation style whereas “Advancing Agility” will use the open space format.

Speakers include David Hussman (DevJam), Chris Sterling (SolutionsIQ), Luke Hohmann (Enthiosys), Lee Henson (VersionOne Services) with special guests Ainsley Nies (open space co-facilitator) and Ian Culling (VersionOne CTO). When not presenting for the “Learning Agility” track speakers will participate in the open space.

Space is limited and the cost is low so please register soon if you would like to attend. For more information or to register please visit www.AgilePalooza.com.

Where?

San Francisco State University Downtown Campus, 835 Market Street, San Francisco. (Powell street BART station in the Westfield Center) – Map/Directions

When?

9am-5pm (check-in and continental breakfast starts at 8am)

Cost?

$69

Register here: www.AgilePalooza.com

Survey for Software Quality Attributes – Where Should We Focus?

Posted by on 17 May 2009 | Tagged as: Agile, Architecture, General, IASA, Leadership, Product Owner, Scrum, Software Architecture, XP

I have been using a tool for some time with clients and teams to find out what software quality attributes the product development team should focus on in the project. ISO standard 9621 describes the quality attributes found in software. The following image shows the 6 categories and specific attributes contained within them.

ISO 9621 Software Quality Attributes

ISO 9621 Software Quality Attributes

Before I knew about this standard I would discuss how different quality attributes are in conflict with each other. For instance, if we write code that is focused on performance we lose some maintainability. It will be more difficult to read code focused on performance because readability will be sacrificed to some extent.

Now that I’ve known about ISO 9621 for many years, I made a simple spreadsheet tool to interview Product Owners, stakeholders, and software development team members with. Here is the Excel spreadsheet form of this tool:

Software Quality Attributes Rating Tool

Although a bunch of smart people have come up with ISO 9621, I found that modifying the software quality attributes rated in the tool worked more effectively with interviewees. This tool is not to decide what software attributes will be present in the software product getting developed. It is used to identify which software quality factors the team should put more emphasis on when making trade-off decisions during the project. Here is a list of the software quality attributes used in the tool:

  • Suitability – Functionality is suitable to all end users
  • Interoperability – Functionality interoperates with other systems easily
  • Compliance – Functionality is compliant with applicable regulatory guidelines
  • Security – System is secure: confidentiality, integrity, availability, accountability and assurance
  • Maturity – System components are proven stable by others
  • Fault Tolerance – System continues operating properly in the event of failure by one or more of its components
  • Recoverability – System recovers from failures in surrounding environment
  • Understandability – Able to use system with little training
  • Learnability – Supports learning of system functionality with little external interfacing
  • Operability – Ability to keep a system in a functioning and operating condition
  • Performance – Perceived response is immediate
  • Scalability – Able to handle increased usage on the appropriate amount of resources
  • Analyzability – Ability to figure out how the system functions
  • Changeability – Ability to change the system components to meet new business needs
  • Testability – Ability to create repeatable and specific tests of the system and potential for some to be automated
  • Adaptability – Ability to change out system component functionality quickly
  • Installability – Ease of installation and reinstallation
  • Conformance – Conformance to industry and operational standards
  • Replaceability – Ability to replace system in the future

Using the tool is quite simple:

  1. Emphasis Ranking: Have the Product Owner score each of the software quality factors from 1-5 (1 being less applicable and 5 being more applicable) in terms of the software product.
  2. Business Stakeholders identify 3 Must Haves – Ask the business stakeholders what are the 3 software quality factors they want most and stack rank them from 1 to 3
  3. Software Development Team 3 Must Haves – Ask the software development team what are the 3 software quality factors they want most and stack rank them from 1 to 3
  4. Capture Notes about Decisions – Use the notes column to capture any specific decisions about the software quality factors that would help the entire software product team come to consensus.
  5. Discuss Must Haves across Groups – Get the Product Owner, business stakeholders, and software development team members together to discuss and come to consensus on which software quality attributes they will focus on for this project.

Please let me know how you use this tool. There have been many teams that have taken up this tool and found it to be helpful for communicating what is most important from a software quality attibutes point of view in the project. Hope it does the same for you.

When Is Team Velocity Affected?

Posted by on 07 Apr 2009 | Tagged as: Agile, General, Leadership, Product Owner, Scrum, XP

For some time I have described team velocity as a:

function of (sprint length, team makeup, sizing nomenclature, product)

Given these parameters to team velocity, how can each affect team velocity when modified?

Sprint Length

It is common for teams when they first implement Scrum to have difficulty with short sprint length. They are probably not used to delivering potentially shippable code every 2 weeks or whatever their initial sprint length is. When a team is having difficulties many of them believe that lengthening the sprint length will alleviate the problems. When a team is thinking about doing this, I now share a phrase that I heard from Chet Hendrickson at a technical debt workshop we both attended:

Lower the threshold of pain

Instead of changing the sprint length I want to facilitate teams in identifying what is the root cause of their difficulties. Many times I have found that the problems are either technical or external difficulties. Technical difficulties such as:

  • executing manual testing takes too long
  • not enough support from QA department for testing each sprint
  • build takes too long to validate and deploy
  • too much technical debt

are something that the team can start to work on. A team must work with their Product Owner to understand the technical issues and what they will get in return for fixing the most important ones. External difficulties may come in the form of:

  • sign off takes too long from external person in organization
  • cannot deploy into external environments easily
  • not able to get key people with special skill sets on team

and can cause the team problems in getting to potentially shippable code each sprint. It is my opinion that a team should weaken their Definition of Done and identify impediments to getting as close to potentially shippable code as they had hoped. If it is technical then they must get items in the Product Backlog. If it is external then the ScrumMaster must shepherd the impediments to resolution or make step-wise progress on addressing them. Take care of the impediments and the sprint length will become less of a problem.

Team Makeup

If the team makeup is changed then the velocity will change. There are many factors that cause this to happen:

  • skill set differences
  • bringing new person up to speed
  • reduction in team size
  • personality problems

The most effective Scrum teams that I have witnessed have worked together, at least a core group, for some time. If your organization is having difficulty keeping teams together then there is an organizational impediment that must be addressed. What about the way work flows to the teams causes them to continually get broken up and reconfigured? Organizations that can give work to teams rather than reconfiguring teams to match the work will have more success with Scrum.

Sizing Nomenclature

Although this is part of the function of team velocity, in my experience it is rare that teams modify their sizing nomenclature. Usually this happens when they first start Scrum where they change from duration-based estimation to estimating size and then deriving duration after executing a number of sprints. If the sizing nomenclature is changed from 2n to Fibonacci sequence there could be a significant change in velocity numbers. Fibonacci sequence produces a curve that rises at a much shorter slope than 2n. 2n is used by teams who have significant risk in technology knowledge on the team, such as in using new platform or R&D. The technical knowledge may lessen over time and they might decide to change their sizing nomenclature to Fibonacci instead. This will have an effect but, again, this has been rare in my experience.

Product

It can’t be said enough but:

Team velocity cannot be compared across teams! – Take NOTE managers!

If teams are working on different products, and therefore different Product Backlogs, then they will have to consider different contextual issues when deriving their velocity for planning efforts. Velocity is most useful when all parts of the team velocity function above is staying consistent. Teams should understand this and if they start working on a different product such as:

  • another project
  • new initiative
  • or an actual different product

then they should understand that their team velocity will be affected.

Conclusion

Consider the items described in this article that can affect team velocity usefulness in your own projects. Team velocity is a:

function of (sprint length, team makeup, sizing nomenclature, product)

If any part of this function is modified then it will affect your team velocity. Bring this up amongst the team and management so that it can be discussed honestly and dealt with in a reasonable way.

My Talk @ SD West 2009 on “Managing Software Debt”

Posted by on 27 Mar 2009 | Tagged as: Acceptance Testing, Agile, Architecture, Distributed Computing, DotNet, General, IASA, Java, Jini/JavaSpaces, Leadership, Maven, Open Source, Podcasts, Product Owner, Ruby, Scrum, Software Architecture, TDD, User Stories, XP

I have uploaded the talk I did at SD West 2009 on Yahoo! Video and here it is:

It’s BeyondAgile: people making software that works

Posted by on 25 Mar 2009 | Tagged as: Acceptance Testing, Agile, Architecture, DotNet, General, Leadership, Product Owner, Scrum, TDD, User Stories, XP

The hopefully-not-anticlimatic second event of the still-pretty-new BeyondAgile is happening on Thursday:

“Agile Challenges Clinic/Swap Meet”
Thursday, 26 March 2009
6:30 to 8:30 p.m.
Locations on the Eastside and Seattle!
Read on for agenda and location information, or visit our Google Group at
http://groups.google.com/group/beyondagile

The Blurb
At the first event, everyone (over forty people) created a backlog of ideas, suggestions, and work items. Among them were two suggestions that gave rise to this event’s focus: “a bring-a-problem” session where everyone helps everyone with their challenges. We’ve extended the idea of a clinic, where you bring a problem to an expert and get help, to a swap meet (or potluck), were everyone brings something and gets something. So come if you think you’re brimming over with answers and expertise, and come if you’re wanting other perspectives or advice on how to tangle with the problems that bedevil your days.

We’ll also form a program team, a group that’ll work proactively to plan interesting and exciting events in sufficient time for the blurb-writer–that’s me–to write and distribute the blurb a few weeks before the event. If you’re wondering who’d be good at doing that, go look in a mirror—it’s you we need!

Second Event Agenda

  • Welcome and Announcements (10 min.)
  • Formation of Program Team (10 min.)
  • “Agile Clinic/Swap Meet (85 min.)
  • Giveaway Drawing (5 min.)
  • Meeting Retrospective (10 min.)
  • Socializing and Breakout/Breakup/Beer

Event Locations

Eastside: SolutionsIQ
First Floor Training Center
10785 Willows Road NE, Suite 250
Redmond, WA
NOTE: directions and picture of building at http://www.solutionsiq.com/about-us/contact-us.php?Look for the tent signs and the blue BeyondAgile logo

Seattle: Amdocs Digital Commerce Division (formerly QPass)
Greece Room
2211 Elliott Ave Suite 400
Seattle, WA

Questions?
Contact us at beyondagile@taoproductions.com, or visit our Google Group, or contribute to the nascent Wiki at beyondagile.org.

Why come?
Here’s your chance to be in on the beginning of an exciting new collaboration of the Puget-Sound area (and beyond!) agile-interested. And if that’s not enough, we’ll hold a drawing to win exciting and valuable prizes!

What’s BeyondAgile?
It’s the combination and follow-on to a number of the agile-oriented user and interest groups that have operated in the Puget Sound area. Representatives of the Seattle XP User Group and Seattle Scrum came together in December to try and combine the efforts of all of us who care about and use agile methods.

Why does BeyondAgile exist?
o Find best practices among all agile processes
o Build a bigger agile community
o Take advantage of overlaps between existing groups
o Expand beyond meetings and provide a place to collaborate
o Align software development and business
o Explore cutting-edge ideas and techniques

What is BeyondAgile like?
That, in large part, is up to you. A primary reason for consolidating our efforts is to broaden our base of support, capability, and leadership. We envision a more active, multi-faceted organization that does more than just host talking heads. We’ll gather at least once a month on the 4th Thursday of the month, and probably more often, once you figure out what other events you’d like.

Where do BeyondAgile events happen?
Our goal is to have many answers to this. As a result, we’ve worked to remove the impediment offered by bridges and commuting: for our monthly meetings, we hold our events in both Eastside and Seattle locations, through the semi-magic of videocasting. We’re experimenting: we’ve thought of trying to alternate the “real” physical meeting between sides of the lake. At this point, we’re only at the stage of using a semi-okayish video link between the two locations, and try *very* hard to make the meeting balanced between locations. That’s harder than it seems; come and help us work it out! We’re still dreaming of enabling people anywhere to attend through streaming video, even after the meeting’s already happened, but we need more knowledge, resources, and volunteers before that’s going to happen.

I have question for you.
Great! Visit the Google Group (BeyondAgile) or send a message to beyondagile@taoproductions.com

What is Architecture?

Posted by on 19 Jan 2009 | Tagged as: Agile, Architecture, General, IASA, Leadership, Product Owner, Scrum, Software Architecture, TDD, XP

Talk about a loaded term. Even the term itself, “architecture”, when used in the Agile community can start a heated discussion. When I was coordinator of the International Association of Software Architects Puget Sound chapter, the discussions about “what is architecture” caused passionate debate. I am sure this entry will get some interesting comments, as well.

I don’t believe that this entry will solve the question but I hope to at least give some focus for teams who are dealing with the structural integrity of their applications. First off, a definition of “architecture”:

architecture: noun – “the art or practice of designing and constructing…” or “the complex or carefully designed structure of something” or “the conceptual structure and logical organization of a computer or computer-based system”

Each of these definitions interests me but to put them to practice is quite difficult. They are left to interpretation about what is design, construction, structure, conceptual, and logical. Earlier interpretations of this term interpreted these to mean the high-level structure, architectural style, and finally the stuff that is too expensive to get wrong.

It seems to me that my interpretation is a bit different. Working with tools, practices, and processes over the past 15 years has guided me to a different conclusion. I believe that architecture is how it is SAID:

Structure – how the pieces (components) create a solution (application)
Alignment – the degree to which the application or enterprise structures align to current business objectives and strategy
Integrity – the components that provide stability to the structure (application or enterprise) (ie. automated tests and builds, service-level agreements, network infrastructure, etc…)
Design – a way to conceptually communicate the planned or implemented structure of a component, application, or enterprise (ie. system of names, XP practice of Metaphor, information radiators, etc…)

Using these as the basic building blocks for teams to focus their efforts can be helpful.

The structure is the reality of the solution’s construction. If the structure is too brittle or complex to support future needs then the structure is not sound. If you have been in the software development industry for even short period of time you have probably seen applications that are too brittle or complex.

If the application or enterprise structures are not aligned with current business needs then the value of those structures have deteriorated. We sometimes keep a specific architecture and force-fit new business needs into it because it once was the right architecture to have or we paid a bunch of money for it. Continual restructuring of our architecture to meet today’s business needs is important.

Providing supports to our structure allows for it withstand changes in the environment such as new business needs and updates in technology. Automated tests and builds help us keep the structural integrity of our applications intact while these changes are introduced into our applications and enterprise.

Communicating the conceptual structure of a component, application, or enterprise is important because it is common for new people to work on them and for those structures to interact with other components and applications. Getting someone up to speed on a component or application involves verbal, tactile, written, and visual examples. Much of what is needed can be kept in or close to the codebase along with conversations with existing developers. It is important to understand how components and applications are currently structure conceptually so we can discuss their interactions with other components and applications. For instance, should we connect via library, SOAP, RPC, or REST?

When I think of application architecture I want to focus on just a few principles:

  • Application architecture is about changeability, not longevity
  • Application architecture decisions should be made closest to where they are implemented as possible
  • Application architecture design is not only about our ability to design a solution but also knowing what components, applications, and solutions already exist
  • The value for change in a component’s, application’s, or enterprise’s architecture is directly proportional to the cost of not addressing

If the structure is not able to change as the needs of our business change then the solution will become a liability. If someone other than those who are constructing components and applications are deciding on architecture decisions then there will be important information lost in translation between the two. If we keep using the same design hammer (ie. always using 3-tier or IoC for everything) then we are not allowing the strongest solutions to emerge. The value of architecture can usually be described by the cost incurred if it is not taken care of.

Well, let the onslaught of comments commence. I have put out my ideas on architecture. There are many more out there to discuss and I am sure I will hear some of them. I will finish this entry with a quote from Martin Fowler’s “Who Needs an Architect?” article:

“I define architecture as a word we use when we want to talk about design but want to puff it up to make it sound important.”

See You at SD West 2009

Posted by on 15 Jan 2009 | Tagged as: Acceptance Testing, Agile, Architecture, General, Leadership, Open Source, Product Owner, Scrum, Software Architecture, TDD, Travel, User Stories, XP

I’d like to invite you to join me at …

SD West 2009 Conference & Expo
March 9–13
Santa Clara Convention Center, Santa Clara, CA
http://www.SDExpo.com/

I’m pleased to announce that I’ll be teaching the following session at SD West 2009:

“Managing Software Debt: Continuing to Deliver High Value as Systems Age” on Friday, March 13th from 3:30-5:00pm

SD West is where the software development community gathers to learn about the latest business-critical technologies, network with peers, connect with innovative vendors and get inspiration from industry visionaries. The comprehensive conference program covers today’s most important topics including cloud computing, concurrent programming, dynamic languages, agile processes, security, testing and much more.

Super early bird conference discounts of up to $400 expire Friday, January 16.  As a speaker, I can also offer you an additional $100 off the VIP Pass. Simply register at http://www.SDExpo.com with the code 9ESPK to get your discount.

Check out all the excellent educational opportunities SD West 2009 has to offer at http://www.SDExpo.com.

I look forward to seeing you in Santa Clara!

Next Page »