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Yuval Yeret

Creating an Agile Culture to Drive Organizational Change - 1 views

www.borland.com/...creating-an-agile-culture.html

agile enterprise adoption culture

shared by Yuval Yeret on 15 May 09 - Cached
  • It is critical that everyone has the same understanding of, and commitment to, the desired outcome: a business that is reliable through predictable technology processes that deliver business agility. To do this, there needs to be a management commitment to develop a focused, on-going practice around the pursuit of organizational maturity. As part of this, gaps in skills and capabilities should be identified and positive action – training, coaching, process improvement and tools deployment – taken in order to close the gap
  • the work force needs to understand the business drivers for Agility. They need to be challenged to improve their quality, improve their cycle times, to improve the frequency of releases and the value they deliver to the customer. They need to know how these things fit within the bigger picture and why improvement is their responsibility.
  • To change a culture it's important to recognize that every knowledge worker makes decisions and takes actions that affect the performance of the business. The culture in the organization is the reflection of those decisions and actions.
  • ...14 more annotations...
  • all the people understand and internalize the concepts and ideals behind the Agile movement
  • translated into concepts that can be widely applied to the many day-to-day decisions each of them will make
  • internalize and live three principles: making progress with imperfect information; existing in a high trust, high social capital culture; and shortening cycle times. These ideas need to be infused into the workforce at every opportunity.
  • it should spread virally. It can start with just one manager, who educates his immediate direct reports on the concepts and then takes the time to reflect and show how each decision is aligned the principles
  • work-in-progress as a liability rather than an asset.
  • . Every member of the team should be educated to understand it, and to be capable of demonstrating how their decisions and actions are concomitant with it. The Decision Filter is
  • The Agile Decision Filter
  • Delivering quickly can provide immediate value while delay can result in obviated functionality of little value or missing a more lucrative opportunity while completing existing work-in-progress
  • Are we making progress with imperfect information? Or are we trying to be perfect before we start? Does this decision add or maintain trust in our organization and with our partners? Or does it remove trust and breed fear? Are we treating work-in-progress as it if were a liability? Or are we treating it like an asset?
  • the team can start to modify their practices one decision at a time and drive towards a goal of business agility
  • The "transition" to Agile will happen slowly, and supporting the change will require training, coaching and tools – but change will be real and long-lasting.
  • By changing your culture using the simple principles captured in The Agile Decision Filter, teams will adopt Agile. Give it a little time and magic will happen. They will voluntarily change their behaviors and adopt Agile practices. They will behave in a fashion aligned with the principles and values behind The Agile Manifesto. They will not resist because they had a say in the changes, which are tailored specifically to their environment and their needs.
  • this approach may seem less prescriptive and straightforward than an "Agile Change Initiative" project plan. And yes, taking on a management-led Agile Transition Initiative looks faster and cheaper,
  • However, it is all wishful thinking, and the only way to get the payoff is to invest the time and show the courage to lead true Agile change. True Agile change requires you to change the culture. To change the culture, teach all your people how to use the Agile Decision Filter and hold them accountable for every decision they make.
Yuval Yeret

InfoQ: Ensuring Success for Self Organizing Teams - 0 views

www.infoq.com/...lf-organization-success-factor

agile management self_org

shared by Yuval Yeret on 08 Jul 09 - Cached
  • Helicopter Managers – who step in too soon to rescue thereby depriving the team to think and solve problems together.
  • Absentee Managers – who would not step in at all irrespective of whether the team has all the necessary skills to tackle the problem.
  • If the team has sufficient skills to solve the problem then give them space else ask questions to help them get unstuck. This would help in building the skills eventually.
  • ...7 more annotations...
  • When time is not of the essence give the team time to work the issue. This would improve the team feeling and collaboration.
  • If the solution space is limited in scope and impact, or the decision is reversible, give the team space to solve the problem, even it there's a good chance they'll get it wrong the first time.
  • Tolerate mistakes and allow time for learning – management should not jump in at the first problem. They should allow the team to learn from their mistakes and take corrective action on their own.
  • Clearly define the boundaries – Without this the team is lost on how much they can manage themselves and when should they invoke management help. Without the definition of boundaries, teams err on side of caution and do not take any decision without seeking permission.
  • Keep the team challenged, yet not frustrated- The manager should be aware of the team’s skill level and limitations. He should be able to provide the team with enough challenges to keep them in a state of learning and growth.
  • emphasis on the balanced involvement of management with the team
  • It is important for the managers to be aware of the skill level of the team to step in or stay back at the right moment and act as a catalyst for the team to reach a state of self organization
Yuval Yeret

Agile PMO Role - 0 views

www.gantthead.com/...articlesPrint.cfm

agile pmo

shared by Yuval Yeret on 20 Jul 09 - Cached
  • Institute an agile transition team, and have the agile PMO play a significant role on that team. If you are starting on the journey, establishing an agile transition team can be a critical factor in your success. The agile transition team plans and implements the strategy for the organization’s agile transition (using a backlog, iterations, planning meetings, retrospectives and, in general, responding to change) This group monitors and communicates results throughout the organization, and is responsible for removing organizational level impediments. The PMO representative can act as ScrumMaster for the agile transition team. Members should be leaders representing different departments and functions that are impacted by the agile transition. For example, having leaders from development, QA, product development and the PMO is an excellent practice.
  • Establish a “Meta Scrum” that is tasked with mapping projects and features to corporate strategy. As part of optimizing the whole, it is important for there to be a big picture view across products and features. In general, product managers are tasked with defining, prioritizing and communicating the vision and features for their products. When you have a program that encompasses multiple products with multiple product owners and project teams, keeping everything in line with the corporate vision can sometimes be overlooked.   Unlike the Scrum of Scrums--which is tactical, i.e. focused on execution--the Meta Scrum is focused on the strategic planning and decisions guiding the program or programs as a whole. Establishing a Meta Scrum with the PMO representative acting as ScrumMaster to plan and facilitate meetings (as well as reporting and tracking decisions and action items) can add significant value in having a program able to rapidly respond to change while staying true to the corporate strategy and objectives.
  • I like using story points to establish the velocity of individual teams. From a program point of view, however, story points are difficult to use across multiple teams. The nut there is that one team’s story point is not equivalent to another team’s story point. To crack that nut, I use agileEVM to “normalize” to standard project management metrics like the Cost Performance Index and the Schedule Performance Index, as well as the Estimate At Complete in integrated dollars. These metrics can be aggregated across teams to establish progress against the plan for the entire program.
  • ...1 more annotation...
  • Establish an agile CoachingCenter. It is important from an organizational perspective to continue to provide coaching and training to agile teams. Team development and facilitation needs continue after the initial shift to agile methods is completed. In addition, new team members are hired, new practices discovered and implemented. Establishing an agile coaching center of excellence can meet this need.   In order to be successful, the center needs to be a legitimate organization with an assigned budget, staff and objectives. The center can be a located within the agile PMO. The center can develop and manage a central agile library, produce various lunch ‘n’ learns and other programs to infuse agile values and knowledge across the organization, and provide proficient, independent facilitators to teams for various retrospectives and other needs. In addition, the center can help the team gather metrics on their agility and health so that the team can take action if the decide to.
Yuval Yeret

Is Design Dead? - 0 views

www.martinfowler.com/...designDead.html

eng-practices-list

shared by Yuval Yeret on 10 Dec 14 - Cached
  • In its common usage, evolutionary design is a disaster. The design ends up being the aggregation of a bunch of ad-hoc tactical decisions, each of which makes the code harder to alter. In many ways you might argue this is no design, certainly it usually leads to a poor design. As Kent puts it, design is there to enable you to keep changing the software easily in the long term. As design deteriorates, so does your ability to make changes effectively. You have the state of software entropy, over time the design gets worse and worse. Not only does this make the software harder to change, it also makes bugs both easier to breed and harder to find and safely kill. This is the "code and fix" nightmare, where the bugs become exponentially more expensive to fix as the project goes on
  • the planned design approach has been around since the 70s, and lots of people have used it. It is better in many ways than code and fix evolutionary design. But it has some faults. The first fault is that it's impossible to think through all the issues that you need to deal with when you are programming. So it's inevitable that when programming you will find things that question the design. However if the designers are done, moved onto another project, what happens? The programmers start coding around the design and entropy sets in. Even if the designer isn't gone, it takes time to sort out the design issues, change the drawings, and then alter the code. There's usually a quicker fix and time pressure. Hence entropy (again).
  • One way to deal with changing requirements is to build flexibility into the design so that you can easily change it as the requirements change. However this requires insight into what kind of changes you expect. A design can be planned to deal with areas of volatility, but while that will help for foreseen requirements changes, it won't help (and can hurt) for unforeseen changes. So you have to understand the requirements well enough to separate the volatile areas, and my observation is that this is very hard. Now some of these requirements problems are due to not understanding requirements clearly enough. So a lot of people focus on requirements engineering processes to get better requirements in the hope that this will prevent the need to change the design later on. But even this direction is one that may not lead to a cure. Many unforeseen requirements changes occur due to changes in the business. Those can't be prevented, however careful your requirements engineering process.
  • ...6 more annotations...
  • The fundamental assumption underlying XP is that it is possible to flatten the change curve enough to make evolutionary design work. This flattening is both enabled by XP and exploited by XP. This is part of the coupling of the XP practices: specifically you can't do those parts of XP that exploit the flattened curve without doing those things that enable the flattening. This is a common source of the controversy over XP. Many people criticize the exploitation without understanding the enabling. Often the criticisms stem from critics' own experience where they didn't do the enabling practices that allow the exploiting practices to work. As a result they got burned and when they see XP they remember the fire.
  • XP's advice is that you not build flexible components and frameworks for the first case that needs that functionality. Let these structures grow as they are needed. If I want a Money class today that handles addition but not multiplication then I build only addition into the Money class. Even if I'm sure I'll need multiplication in the next iteration, and understand how to do it easily, and think it'll be really quick to do, I'll still leave it till that next iteration.
  • You don't want to spend effort adding new capability that won't be needed until a future iteration. And even if the cost is zero, you still don't want to add it because it increases the cost of modification even if it costs nothing to put in. However you can only sensibly behave this way when you are using XP, or a similar technique that lowers the cost of change.
  • My advice to XPers using patterns would be Invest time in learning about patterns Concentrate on when to apply the pattern (not too early) Concentrate on how to implement the pattern in its simplest form first, then add complexity later. If you put a pattern in, and later realize that it isn't pulling its weight - don't be afraid to take it out again.
  • begin by assessing what the likely architecture is. If you see a large amount of data with multiple users, go ahead and use a database from day 1. If you see complex business logic, put in a domain model. However in deference to the gods of YAGNI, when in doubt err on the side of simplicity. Also be ready to simplify your architecture as soon as you see that part of the architecture isn't adding anything.
  • XP design looks for the following skills A constant desire to keep code as clear and simple as possible Refactoring skills so you can confidently make improvements whenever you see the need. A good knowledge of patterns: not just the solutions but also appreciating when to use them and how to evolve into them. Designing with an eye to future changes, knowing that decisions taken now will have to be changed in the future. Knowing how to communicate the design to the people who need to understand it, using code, diagrams and above all: conversation.
Yuval Yeret

Negotiation Tactics - 0 views

changingminds.org/...tactics.htm

negotiation

shared by Yuval Yeret on 15 Sep 14 - Cached
  • In negotiation, there are many tactics that you may meet or use. They can be fair, foul or something in between, depending on the competitive or collaborative style of the people involved and the seriousness of the outcomes.
  • Behavior Labeling
  • Cards on the Table: State your case, clearly and completely.
  • ...3 more annotations...
  • Go For A Walk: Take time out to change.
  • Fair Criteria: Set decisions criteria such that is is perceived as fair.
  • Expanding the Pie: Ensuring there's more for everyone.
  • Yuval Yeret on 15 Sep 14
     
    Cards on the Table:
Yuval Yeret

Challenging Why (not if) Scrum Fails | NetObjectives - 0 views

www.netobjectives.com/...questioning-why-scrum-fails

shared by Yuval Yeret on 22 May 09 - Cached
  • I do believe for Scrum to work beyond the team you need more than Scrum
  • what to add to Scrum making it more effective when it won't readily work
  • lack of team agility is not always the major impediment to Enterprise Agility
  • ...12 more annotations...
  • While starting at the team level with Scrum is often good, you often need to start with the product management team - that is, where product enhancements to be worked on are selected
  • Even when Scrum works at the team level, organizations very often report little impact to the bottom line.  While this is better than nothing (if the teams are happier, that's good), it usually doesn't justify a huge investment
  • in many contexts in which Scrum does not work readily, Scrum has no power to improve the context in which it is in.  In other words, the impediments that one must fix are often outside of the scope of what Scrum helps you do.
  • These impediments are often not even seen or if they are, are often viewed as "just the way it is."
  • certain Scrum attitudes often makes things worse
  • Scrum does little to let management to know how the team works or what impact management decisions have on the team
  • There is almost a religious zeal that Scrum tells you little of what to do
  • While SoS works well for certain types of work, it does not work well when the different teams have different motivations. 
  • the high failure rate is due to the fact that Scrum works in certain contexts but has little ability to change the contexts in which it doesn't work wel
  • One needs to pay attention to where to start as well as see how to change the context.  Separating the team from management doesn't help.  Focusing on only the team part of the value stream - giving little guidance both up and downstream of the team also doesn't help.  Lean provides guidance here (meaning Scrum with the aid of Lean could provide insights),
  • look into using Lean as a context for any improvement in your software development organization
  • While Scrum may be an appropriate choice in many circumstances, other methods may be better (e.g., Kanban Software Development).  Scrum's rapid ascension probably has more to do with its success in the places it easily fits.  Now that it is past the early adopter phase, we may see it having even a harder time as people attempt to scale it.
Yuval Yeret

Kanban development oversimplified: a simple explanation of how Kanban adds to the ever-... - 0 views

agileproductdesign.com/...kanban_over_simplified.html

lean kanban

shared by Yuval Yeret on 03 Jun 09 - Cached
  • It’s a lot easier to estimate a story that’s small — which can lead to more accurate estimates, and better predictability.
  • It’s easier to plan with smaller stories. With big stories — stories that might take weeks for a developer to implement — it becomes difficult to plan a development time-box — particularly when the iterations are only a couple of weeks. It seems that only a couple stories fit — and there’s often room for half a story — but how do you build half a story? Splitting them into smaller stories makes it easier to plan those time-boxes.
  • Shrinking stories forces earlier elaboration and decision-making. Where product owners could write their stories fairly generally and consider many of the details later, now breaking them down into smaller stories forces more thinking earlier in a planning lifecycle.
  • ...36 more annotations...
  • Managing little stories forces us to keep better track of how they fit together. Product owners are often asked to break down stories to a level where a single story becomes meaningless. To keep track of what’s meaningful to them and other stakeholders, they often need to keep track of bigger items such as the features of the product and how many stories contribute to building up that feature.
  • The result of these herniated time-box activities is a cycle that’s actually 3-4 times longer than our time-box. To get work done, we’ll use a time-box to elaborate stories, one to develop them, another to more thoroughly test them, and if there are bugs, possibly another to fix them.
  • During an ideal Agile time-box we’ll have frequent discussions between developers, testers, and those on a product owner team — like business analysts, user experience people, and business people. We’ll do this to understand what we need to build and describe what we’ll do to validate the story was really done. When time-boxes are short, there’s less time for this conversation. It’s common to move many of the conversations to detail the story and describe acceptance to the time-box before so we can be ready to really get moving with development when the time-box starts.
  • It’s difficult to fit thorough validation of the story into a short time-box as well. So, often testing slips into the time-box after. Which leaves the nasty problem of what to do with bugs� which often get piped into a subsequent time-box.
  • Anyone who’s attended an Agile planning meeting knows they can often last about an hour longer than you can stand it
  • As time-boxes shrink those on the product owner team and testers find themselves in a constant mode of getting ready for a next time-box and evaluating past time-boxes
  • work long hours, attend lots of meetings, and seem to have less time to be available to help developers with the current time-box. Since their focus is on a future or past time-box, questions about this time-box seem like interruptions. Collaboration decreases and tensions increase. Their work load is heavy, bumpy, not smooth or even.
  • Kanban cards are used to limit the amount of inventory the factory builds. It doesn’t do the Toyota factory any good to build doors faster then they can assemble cars. It just wastes money on excess doors, and parts of doors. Excess work in progress is considered to be waste in Lean manufacturing. (It’s probably waste in non-Lean manufacturing too.) In the above completely made up example, you’ll never have more than 15 finished doors hanging around. (Mudha is Japanese for waste. Learn it to impress your Lean friends.)
  • “Kan” means visual, and “ban” means card or board.
  • Kanban thinking in software development attempts to do a similar thing. We want to limit unnecessary work in progress to be no higher than it needs to be to match the throughput of the team.
  • In Kanban development: time-boxed development is out stories are larger and fewer estimation is optional or out completely velocity is replaced by cycle time
  • Exactly what’s left of Agile if we get rid of time-boxes, change the meaning of stories, and stop measuring velocity. And, exactly what do car doors and Kanban cards have to do with software development? Don’t get hung up on process. Remember, agile development isn’t a process.
  • You might have a column where business analysts spend time tracking down technical details that developers need to understand to write code.
  • These columns aren’t set. You should discuss with your team the phases that stories go through to be completed. Some organization may use columns for writing documentation, or preparing customer service people to support the feature in production.
  • The top is used for stories currently in progress in that phase. The bottom is the buffer. When work for that phase of the story is completed, it moves from “in progress” to the “buffer” where it’ll wait to be pulled into the next phase.
  • When we set limits for work in progress, we’ll set a total number for the process step that includes both “in process” and the “finished buffer” for that process step.
  • Stories must be minimal marketable features
  • To be marketable the feature needs to be large enough to be useful — probably larger than the teeny stories that take a couple days to build and seem to be best practice in Agile development today. A MMF may take weeks to build. But the important thing isn’t how long it takes to build, but that it be understandable and valuable to those who’ll receive it. To identify a MMF some folks ask the question “Would I announce it in my company’s product blog?” If it’s too tiny to mention, then it’s not a MMF.
  • To be lean, we’ll limit the number of stories we allow onto the board. A common formula is to add up all the members of the team in all roles and divide by two. All roles includes developers, analysts, user interfaced designers, testers, deployment people — anyone immediately responsible for getting features to market. For example, if team members total 20, we might limit the number of MMF-style stories on the board to 10.
  • Today developers have finished a story, and s they walk to the Kanban board to move it out of development, they notice their single buffer slot is full — and the “testing in progress” column is filled to its limit. What now? The developers talk to the testers. “We’re really struggling to keep up here. It’ll be till tomorrow morning before we can get some of these stories moved out.” “Hmm�” says a developer “Can we help test?” “Of course you can!” says the tester. “With your help we can get these cleared out by the end of the day.“ The tester grins “I just don’t want you validating a story you implemented.”
  • For the limits of the story process steps, the limit is often half the number of people that can perform the work for that phase of development. For instance if you have 6 developers, you might limit the development in progress column to 3. Now, this will force developers to work together on stories. I do find in practice that this may not work out for all teams — so I often see limits that equal the number of developers (or those that can perform the process step) or often 1.5 * the number of people in a role. Of course if you do this, it’ll raise the overall work in progress — and as you might expect, items will take longer to finish.
  • When a column in a Kanban board is full, we know that group is at capacity. We also know that if this keeps happening that that process step is likely where a bottleneck is.
  • If you’ve ever waited in line for the Pirates of the Caribbean in Disneyland you might remember signs along the way that say “Your wait time from here is 30 minutes” — something like that. Now you can post your own wait times on your Kanban board. At the bottom of your story queue post the average cycle time with wait time. It’ll say something like “Your wait time for a story here is approximately 18 days.” At the top of the queue post the average working cycle time. It might say “your wait time from here is 14 days.”
  • When you place focus on how quickly you can get functionality done, and have the ability to measure just that, then the estimates don’t much matter. In fact, many using a Kanban approach have simply stopped estimating at all. Yes story sizes vary, but being able to give a wait time plus or minus a few days is sufficient for many organizations’ concerns.
  • But, since there’s no development time-box in Kanban development, we’ll measure story-by-story how long they took to complete — the “cycle time” of the story.
  • Some do still estimate stories. Then use those estimates in conjunction with cycle time. Using a spreadsheet we can calculate the average cycle time for stories with a given estimate. If you do this, consider placing a handy chart next to your Kanban board showing estimate in one column, and wait times in adjacent columns. With this you’re answering the real question stakeholders are asking for when they get estimates: “when am I going to see this functionality in the software?”
  • If your stakeholders are like mine, they don’t want to know when they’re going to get this functionality, the want to know when they’re going to get all this functionality. I find that if I place stories into a spreadsheet with start and end dates, and calculate cycle time, if I select an arbitrary time period — say a two or three week time period — I can see how many stories where completed during this time period. For instance I might see the team finished 22 stories in 3 weeks — that’s about 7.3 stories per week. Given a backlog of 100 stories I can reasonably infer that it’ll take between 13 and 14 weeks (100/7.3). That’s yesterday’s weather for Kanban — at least the way I calculate it.
  • If I know that during three week time period there where 15 working days and that 5 developers worked the entire time, that’s 75 developer days. Knowing that lets me calculate the average number of developer days per story: 3.4 (75/22) — Which is darn close to pi — which makes me believe it has to be right. ;-) This number, 3.4, is what XP practitioners referred to as load factor.
  • Evaluation cycles, not development time-boxes
  • The only difference is the cycles aren’t used to plan and commit to stories any longer.
  • The daily standup or daily scrum meeting occurs as normal, but now it occurs in front of the Kanban board. Instead of the regular meeting ritual of checking in with each person to find out what they worked on yesterday and will work on today, the discussion revolves around the Kanban board and what will likely move on and off the board today, where “traffic” seems the heaviest, and what we could do to clear bottlenecks.
  • Reflect every few weeks
  • Lean practices help teams increase throughput. They don’t make developers type faster, rather they draw attention to bottlenecks that slow things down, help you see them and respond to them quicker. Using a Kanban board lets you easily visualize work in progress across different roles and lets you see when someone is taking on too much work simultaneously.
  • Demonstrate every few weeks
  • A task board as it’s commonly used in an agile approach can give you the visualization too. But, widening the task board to separate testing from development from acceptance or other process steps helps me better visualize where things are clogging up — helps me better diagnose problems. And, setting hard limits for process steps and respecting them really makes me deal with the problem in a way that dropping a pile of stories into a sprint or iteration didn’t. But, maybe it’s just me who’s lazy and avoids dealing with tough problems. I’m sure you’d never run into a situation where you and your team let lots of finished development work pile up waiting to be tested.
  • There’s no one as zealous as the newly converted There’s a lot of folks pretty excited about Kanban out there. I am too. Sometimes that zeal takes the form of telling people practicing common agile time-boxed development that they’re wrong. But, I guess I’m crusty enough to know that there’s lots of right ways to succeed and anyone who believes they’ve found the best ways is likely wrong. Don’t let those voicing opinions strongly for, or against, Kanban approaches stop you for digging in deeper and understanding the ideas behind it.
  • Yuval Yeret on 03 Jun 09
     
    one of the best articles about Kanban and its relation to Agile I've encountered so far - focusing on Feature development (not maintenance)
Yuval Yeret

James Shore: The Art of Agile Development: Simple Design - 0 views

www.jamesshore.com/...simple_design.html

james shore art development

shared by Yuval Yeret on 13 Jan 15 - No Cached
  • Simple Design AudienceProgrammers Our design is easy to modify and maintain
  • Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away. —Antoine de Saint-Exupéry Any intelligent fool can make things bigger, more complex and more violent. It takes a touch of genius and a lot of courage to move in the opposite direction. —Albert Einstein
  • When writing code, agile developers often stop to ask themselves, "What is the simplest thing that could possibly work?" They seem to be obssessed with simplicity. Rather than anticipating changes and providing extensibility hooks and plug-in points, they create a simple design that anticipates as little as possible, as cleanly as possible. Unintuitively, this results in designs that are ready for any change, anticipated or not.
  • ...10 more annotations...
  • I don't think XP and patterns are conflicting. It's how you use patterns. The XP guys have patterns in their toolbox, it's just that they refactor to the patterns once they need the flexibility
  • You Aren't Gonna Need It (YAGNI) This pithy XP saying sums up an important aspect of simple design: avoid speculative coding. Whenever you're tempted to add something to your design, ask yourself if it supports the stories and features you're currently delivering. If not, well... you aren't gonna need it. Your design could change. Your customers' minds could change.
  • We do this because excess code makes change difficult. Speculative design, added to make specific changes easy, often turns out to be wrong in some way, which actually makes changes more difficult. It's usually easier to add to a design than to fix a design that's wrong. The incorrect design has code that depends on it, sometimes locking bad decisions in place.
  • Once and Only Once
  • avoid duplication. "Once and only once" is the Extreme Programming phrase. The authors of The Pragmatic Programmer [Hunt & Thomas] use "don't repeat yourself," or the DRY principle.
  • Self-Documenting Code Simplicity is in the eye of the beholder. It doesn't matter much if you think the design is simple; if the rest of your team or future maintainers of your software find it too complicated, then it is.
  • What if we know we're going to need a feature? Shouldn't we put in a design hook for it? In XP, the plan can change every week. Unless you're implementing the feature that very week, don't put the hook in. The plan could change, leaving you stuck with unneeded code.
  • Results When you create simple designs, you avoid adding support for any features other than the ones you're working on in the current iteration. You finish work more quickly as a result. When you use simple design well, your design supports arbitrary changes easily. Although new features might require a lot of new code, changes to existing code are localized and straightforward.
  • Simple design requires continuous improvement through refactoring and incremental design and architecture. Without it, your design will fail to evolve with your requirements. Don't use simple design as an excuse for poor design. Simplicity requires careful thought. As the Einstein quote at the beginning of this section says, it's a lot easier to create complex designs than simple ones. Don't pretend "simple" means "fastest" or "easiest.
  • Until recently, the accepted best practice in design followed the advice Erich Gamma now disavows: "The key to maximizing reuse lies in anticipating new requirements and changes to existing requirements, and in designing your systems so they can evolve accordingly."
Yuval Yeret

James Shore: The Art of Agile Development: Incremental Design and Architecture - 1 views

www.jamesshore.com/...incremental_design.html

eng-practices-list james shore evolutionary design agilearchitecture

shared by Yuval Yeret on 10 Dec 14 - No Cached
  • when you first create a design element—whether it's a new method, a new class, or a new architecture—be completely specific. Create a simple design that solves only the problem you face at the moment, no matter how easy it may seem to solve more general problems
  • Waiting to create abstractions will enable you to create designs that are simple and powerful.
  • The second time you work with a design element, modify the design to make it more general—but only general enough to solve the two problems it needs to solve. Next, review the design and make improvements. Simplify and clarify the code. The third time you work with a design element, generalize it further—but again, just enough to solve the three problems at hand. A small tweak to the design is usually enough. It will be pretty general at this point. Again, review the design, simplify, and clarify. Continue this pattern. By the fourth or fifth time you work with a design element—be it a method, a class, or something bigger—you'll typically find that its abstraction is perfect for your needs. Best of all, because you allowed practical needs to drive your design, it will be simple yet powerful.
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  • This is difficult! Experienced programmers think in abstractions. In fact, the ability to think in abstractions is often a sign of a good programmer. Coding for one specific scenario will seem strange, even unprofessional.
  • Continuous Design Incremental design initially creates every design element—method, class, namespace, or even architecture—to solve a specific problem. Additional customer requests guide the incremental evolution of the design. This requires continuous attention to the design, albeit at different time-scales. Methods evolve in minutes; architectures evolve over months. No matter what level of design you're looking at, the design tends to improve in bursts. Typically, you'll implement code into the existing design for several cycles, making minor changes as you go. Then something will give you an idea for a new design approach, requiring a series of refactorings to support it. [Evans] calls this a breakthrough (see Figure). Breakthroughs happen at all levels of the design, from methods to architectures.
  • Don't let design discussions turn into long, drawn-out disagreements. Follow the ten-minute rule: if you disagree on a design direction for ten minutes, try one and see how it works in practice. If you have a particularly strong disagreement, split up and try both as spike solutions. Nothing clarifies a design issue like working code.
  • Risk-Driven Architecture Architecture may seem too essential not to design up front. Some problems do seem too expensive to solve incrementally, but I've found that nearly everything is easy to change if you eliminate duplication and embrace simplicity. Common thought is that distributed processing, persistence, internationalization, security, and transaction structure are so complex that you must consider them from the start of your project. I disagree; I've dealt with all of them incrementally [Shore 2004a]. Two issues that remain difficult to change are choice of programming language and platform. I wouldn't want to make those decisions incrementally!
    • Yuval Yeret
      Yuval Yeret on 12 Jan 15
       
      Possible exercise - Try to come up with various things that are risky to YAGNI. And then order them according to level of risk. Use the examples here to seed the list
  • Limit your efforts to improving your existing design
  • To apply risk-driven architecture, consider what it is about your design that concerns you and eliminate duplication around those concepts
  • Your power lies in your ability to chooose which refactorings to work on. Although it would be inappropriate to implement features your customers haven't asked for, you can direct your refactoring efforts towards reducing risk. Anything that improves the current design is okay—so choose improvements that also reduce future risk.
  • design is so important in XP that we do it all the time
  • Don't try to use incremental design without a commitment to continuous daily improvement (in XP terms, merciless refactoring.) This requires self-discipline and a strong desire for high-quality code from at least one team member. Because nobody can do that all the time, pair programming, collective code ownership, energized work, and slack are important support mechanisms.
  • Test-driven development is also important for incremental design. Its explicit refactoring step, repeated every few minutes, gives pairs continual opportunities to stop and make design improvements. Pair programming helps in this area, too, by making sure that half of the team's programmers—as navigators—always have an opportunity to consider design improvements.
  • Alternatives If you are uncomfortable with XP's approach to incremental design, you can hedge your bets by combining it with up-front design. Start with an up-front design stage and then commit completely to XP-style incremental design. Although it will delay the start of your first iteration (and may require some up-front requirements work, too), this approach has the advantage of providing a safety net without incurring too much risk.
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