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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.
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  • 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

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.
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  • 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.
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