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What are the difference between Agile and iterative and incremental development? Is Agile considered as iterative and incremental? Some info shown the Agile is the latest of iterative and incremental. I need a clear clarification on this.
Iterative - you don't finish a feature in one go. You are in a code >> get feedback >> code >> ... cycle. You keep iterating till done.
Incremental - you build as much as you need right now. You don't over-engineer or add flexibility unless the need is proven. When the need arises, you build on top of whatever already exists. (Note: differs from iterative in that you're adding new things.. vs refining something).
Agile - you are agile if you value the same things as listed in the agile manifesto. It also means that there is no standard template or checklist or procedure to "do agile". It doesn't overspecify.. it just states that you can use whatever practices you need to "be agile". Scrum, XP, Kanban are some of the more prescriptive 'agile' methodologies because they share the same set of values. Continuous and early feedback, frequent releases/demos, evolve design, etc.. hence they can be iterative and incremental.
Incremental development means that different parts of a software project are continuously integrated into the whole, instead of a monolithic approach where all the different parts are assembled in one or a few milestones of the project.
Iterative means that once a first version of a component is complete it is tested, reviewed and the results are almost immediately transformed into a new version (iteration) of this component.
So as a first result: iterative development doesn't need to be incremental and vice versa, but these methods are a good fit.
Agile development aims to reduce massive planing overhead in software projects to allow fast reactions to change e.g. in customer wishes. Incremental and iterative development are almost always part of an agile development strategy. There are several approaches to Agile development (e.g. scrum).
Iterative development implies revisiting usual waterfall model steps over the course of product lifetime. The stages can even overlap, i.e. while doing end-to-end testing you could already start preparing new requirements.
Incremental development means you roadmap your features and implement them incrementally.
Agile aims at creating "potentially shippable product" after every sprint. How you achieve it is a different story. Agile tries to employ "best" techniques from various fields (e.g. extreme programming). Agile does not exclude running neither incremental nor iterative development.
Some important and successfully executed software projects like Google Chrome and Mozilla Firefox are fine examples of both iterative and incremental software development.
I will quote fine ars technica article which describes this approach: http://arstechnica.com/information-technology/2010/07/chrome-team-sets-six-week-cadence-for-new-major-versions/
According to Chrome program manager Anthony Laforge, the increased pace is designed to address three main goals. One is to get new features out to users faster. The second is make the release schedule predictable and therefore easier to plan which features will be included and which features will be targeted for later releases. Third, and most counterintuitive, is to cut the level of stress for Chrome developers.
Laforge explains that the shorter, predictable time periods between releases are more like "trains leaving Grand Central Station." New features that are ready don't have to wait for others that are taking longer to complete—they can just hop on the current release "train." This can in turn take the pressure off developers to rush to get other features done, since another release train will be coming in six weeks. And they can rest easy knowing their work isn't holding the train from leaving the station.<<
Agile is mostly used technique in project development.In agile technology peoples are switches from one technology to other ..Main purpose is to remove dependancy.
Like Peoples shifted from production to development,and development to testing.
Thats why dependancy will remove on a single team or person..
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could someone explain to me the iterative development methodology and the benefits/limitations for using it in developing a web application?
Also, I've been researching it but I am confused, is it part of Agile or not? Some sources say that it is and some don't?
Thanks all.
Iterative is opposed to waterfall development. As you know, you should go through a couple of different phases for delivering a software product.
Requirements Engineering/Elicitation
Analysis & Design
Implementation
Testing & Verification
Deployment & Maintenance
At the end of each phase, you will have some Artifacts or deliverable results. In waterfall strategies, once you finish a phase, everything is done, and you will not come back to that phase again.
In iterative approaches, you will go through these phases repeatedly. In each cycle you repeat all of or part of these phases and at the end of each cycle you will deliver a working product.
Iterative approaches let you to develop your software incrementally and you will be able to establish and then further extend your product step by step. You may deliver just a skeleton of your web application at the end of first cycles and thenafter in each cycle, you will revisit your requirements, design, implementation, and your testing plans. You will find bugs and fix them. At the same time, you will receive feedback from your end-customers and change your product accordingly.
Agile methodologies like scrum, are mainly about how to eliminate unnecessary extensive processes like heavy documentation, formal meetings, etc. So, you can focus on your product and code instead and iterate through your cycles much faster. Agile neither enforce waterfall nor iterative approaches, but the fact is that waterfall is now outdated and it is not going be used any more in industry.
Iterative development has been around quite a while. It certainly predates agile, though you could argue it is ancestor of the agile development approach.
There are some non-agile development approaches that include iterations, such as RUP, so it is not exclusively an agile practice.
There are also a lot of ways to use the iterative approach. You could, for example, do up-front gathering of requirements and design and then use iteration during the development phase only.
Agile frameworks like XP and Scrum take iterations a bit further and look to have a 'releasable' product at the end of each iteration.
Benefits of the agile iterative approach:
The product is releasable at an earlier stage in development
Progress is often easier to measure (released code is a great measure of progress)
The iterative approach allows teams to more easily respond to change
Limitations of the agile iterative approach:
It can be a challenge to fit things like UAT and regulatory compliance in to iterations
There can be an overhead associated with frequent releases and frequent re-planning
You could think of having a releasable product at the end of each iteration as a pure form of iterative development. Not every team uses this approach. For example, some may leave the user testing until after several iterations. The downside with this is that you are never really sure the work is 'done', because potentially user feedback could change things.
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I'm very positive towards agile development, and have worked on agile projects on and off for about 13 years. But I have a concern that I've never really been able to address. It doesn't always seem to manifest, but it has bitten me a few times.
Agile seems to be in some sense a 'greedy algorithm'. Start with the highest value story, optimise the system to precisely fulfil that story, and repeat.
Actual greedy algorithms are prone to suffering from converging to locally optimal solutions, while missing a globally optimal solution.
Has this been people's experience?
Is it actually a problem?
If so, what techniques do you use to avoid such local optima and yet remain agile?
Actual greedy algorithms are prone to suffering from converging to locally optimal solutions, while missing a globally optimal solution.
This holds true if EPIC technical User Story and guideline is not established, along with the normal business EPIC user story.
Has this been people's experience?
At times yes, it has been my experience. One instance was when the user stories we worked on were broken down too much, and the solution was to broaden them to get a more global outlook at our designs. And at times it was different enterprise scrum teams in the same projectt, conflicting with different technical framework uses and approaches.
Is it actually a problem?
It is only a problem, if you ignore the technical EPIC user story or guideline.
If so, what techniques do you use to avoid such local optima and yet remain agile?
Here is one Agile approach to solving this:
During Agile Release planning, instead of just coming up with a Business EPIC User Story, also come up with a Technical EPIC User Story. The Technical EPIC User story would have the product vision from a technical stand point, in terms of technical architecture, application framework, quality standards, and global design considerations etc. These could be broken down into smaller technical user stories, and have a Scrum Team which works on getting those user stories working. An example of a user story could be: "As a Technical Project Manager, I want the whole enterprise project using A, B, C framework, and coding as per X,Y,Z coding standards, so that there is uniformity in project development work.
If you don't want to form a scrum team separately for this, then just keep them as reminder cards next to backlogs for development teams to use as guidelines.
As a testing guideline, we used to have successful integration testing as a done criteria for each backlog. A global test was conducted in an integration environment, on all working software deployed from all enterprise teams, to deem it shippable. So right from inception to end of the backlog, the theme is set for global working software and not just local working software.
Finally, Agile development involves keeping a constant eye on quality, and one of the quality issues could be bad design or a too localized design. As and when this is discovered, it should be redesigned within that backlog itself, and followed going forward for other Backlogs.
I've been on a project which has had this problem, and has not dealt with it effectively.
The local quality of the code - over the scale of a package, say - was not bad. But there were problems at larger scales; things like duplication of logic (but not code) between packages, use of batch recomputation jobs where we should be using event-driven approaches, splitting the system into separate services at the wrong place, etc.
None of these problems could be fixed by refactoring a single class or package. As a result, they never happened in the normal course of events. We did refactorings at smaller scale - when adding a feature, we'd refactor in that area before starting, and again after we finished (as well as making some effort to write good code as we were going). But that never led to refactoring larger, architectural concerns.
We were all conscious of the problems, we just didn't have anything in our process that let us fix them.
One notable victory we did have was where there was duplication between two distantly related module. Essentially, there was code to render a web page showing the results of some set of calculations, and also a background job to generate reports doing similar calculations. The calculation code was shared, but the code to set up the calculations was not; one was driven by a user's view preferences, whereas the other was driven by a configured reporting job. We had a feature to implement that would have involved adding a new aspect to the calculations, which would have meant adding more items to both kinds of configuration, and then adding business logic to both sets of calculation setup code. We managed to get the product manager (our customer proxy) to agree to budget enough time for the work that we could refactor to unite the ideas of user view preferences and configured reporting job, so throwing away one of the sides of the duplication, then implement the feature. This took longer than just implementing it twice, but the product manager was wise enough to realise that this would let us implement future features spanning both pages and reports more quickly.
The mechanism in the process by which we did this was writing stories for the job of refactoring. Essentially, something like "As a product manager, i want pages and reports to use common calculation setup code, so that i can get features added more quickly". This is absolutely not a proper kind of story, but it fitted in the system, and it did the job.
I think that if the running of this project had been a bit healthier, then there would have been a steady stream of stories like this. We would acknowledge that we had a lot of architectural debt, and that work to pay it off had value, and allocate a fixed fraction of our time to it, perhaps about 20% (which would really mean one pair at a time). We could then have generated features/epics, stories, and tasks just as we did for customer-oriented work. These would originate from the team themself, rather than the product managers.
Sadly, there wasn't quite enough communication and trust between the development and product management sides that this was feasible; we could say to product that we had a problem, it was important, and that it would take so long to fix, and they couldn't know if that was true or not. As such, they were generally unwilling to schedule time to do it. The sad thing was that everyone was in agreement that there were problems and it would be good to fix them, we just had an impasse over actually doing it.
in my experirence, if you´re working a project context with fixed time/requirements then yes, most of the times Agile leads to local optima.
But my point is that in a complex endeavour, the requirements, the team itself and even the goals change. Agile is also about embracing changes.
Then, paradoxically, this greedy strategy arrises as a reasonable option for global optimization when dealing with moving targets.
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I have been interested in agile methods of late and have found a lot of prescriptions and minute descriptions of a lot of practices.
Still, I remember my best projects as run-to-completion spikes followed by some debugging and minimal testing before going live.
I have been asking myself, did Flickr use agile methods? Does Facebook practice TDD? Was Gmail made in 25 minute spans followed by 5 minutes of daydream?
In other words, before I listen further to all the preaching and jump into the manuals, what evidence do I get that this is the way to be successful in a successful project in a successful company?
Of course, I am asking this because I want to read the answers, not because I want to dismiss an argument.
A related question is, how many non-Agile (Waterfall, "Big Design Up Front", etc) projects are successful? In my experience, not many. In fact, I just rolled off a two-phase project in which the first phase was traditional Waterfall and failed pretty significantly, but the second phase was iterative in nature and yielded substantially better results (on time, far fewer defects, end result was closer to client's actual needs than the original spec).
I've been doing Agile development for a few years now and, overall, have found it to be superior to the alternative. A few things I've noticed:
Agile != "no process". Agile is about having only as much process as you need and continually refining that process.
Agile requires discipline. You not only have to have a process, you have to follow it.
Agile won't turn a failing project into a success. It can help you identify that the project is failing sooner rather than later, and help you figure out why it's failing. It's about shortening the feedback loop so that you have a chance to get back on course before it's too late.
Microsoft Research recently posted an article in which they empirically evaluate some Agile methods. It's well worth a read and might provide some of the information you're looking for.
Here's a successful project of mine: http://www.sky.com
Went live after a few months.
Delivered new functionality to the CMS and servers behind the site weekly - with deployments typically every week or so.
All done with all the extreme programming disciplines.
Weekly demos to the customer to go with the weekly iterations.
Here's another agile project (also done strictly with XP), also a big success: http://showbiz.sky.com/
I've also worked on two other successful XP projects:
Banking A system for cleaning up and distributing fixed income data across investment bank sites in NY, London, Paris and Tokyo. I believe the whole project only had one production incident over the course of a few years.
Mobile Data A system for configuring mobile phones and PDAs for mobile networks and handset manufacturers. We built the core product incrementally over a number of years and co-ordinated the work over three sites across the world. All done using extreme programming. Customers were some of the largest companies in the mobile business. Our apps provided global support for some of these clients.
I really wouldn't go back to the old way of doing things - and neither would the customers that sponsored the projects I've mentioned above.
In most of the big companies (IBM for instance), the methodology is not always the same, Agile or Rational or Waterfall. That depends in a lot of the history of the projects and the experience of the current People and Project Managers.
If you plan to develop on something is always good to check on all the sides before deciding what suits best for your plan.
So the short answer is: It depends.
My product (the Sophos Email Appliance) is developed using agile methods. Industrial Extreme Programming, as espoused by Joshua Kerievsky, was used for the first several years of development. Recently I have started to move the team more towards Kanban, visualizing work flow and using pull-based scheduling instead of time-boxed iterations.
In other words, before I listen further to all the preaching and jump into the manuals, what evidence do I get that this is the way to be successful in a successful project in a successful company?
There is empirical evidence that most IT projects are not successful (where success means on time, on budget and fully functional here). Given this evidence, it seems reasonable to wonder if a deterministic approach (the waterfall) is well suited for software projects.
"The definition of insanity is doing the same thing over and over and expecting different results." --Albert EinsteinRita Mae Brown1
If a deterministic process produces failures over and over, we are likely not applying the right process for software development projects and Agile methods are an alternative. The theory behind these methods is that most software projects are not deterministic, they are creative (like in art) and complex (as defined by Ralph Stacey) projects and we can't predict everything. So, instead of trying to predict everything and then fighting against change, we should use an adaptive process. And this is what Agile methods are about.
Now, using an Agile method will never guarantee systematic success (and someone claiming the inverse is a liar) but they'll give you better control over the risks. And, if your project has to fail, it will at least fail fast.
Update: 1 Actually, this quotation seems to be misattributed to Albert Einstein. The earliest known occurrence, and probable origin, cites to Rita Mae Brown.
I believe Doublefine just produced Brutal Legend using Scrum.
From what I understand StackOverflow is a successful website built with agile practices and TDD.
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After learning about source control the first thing I did is do a project with svn. After learning about git I used it in a personal project. After learning about UML/Design Patterns/Design Principles/TDD I applied them to a personal project. How can I do the same to agile development? Is agile just for teams and big projects? How do I set up these iteration things?
I think Agile is definitely not just for team projects. Agile advocates a set of values that apply equally well to many types of projects, even personal ones. I was in exactly your situation a while ago, trying to apply agile development to a personal university project, and learned a lot in the process. Some useful things that the agile mindset can give you include:
Work on stuff that adds value to the final product. Make yourself a backlog of features and prioritize them as though you were the customer. Then discipline yourself to work on features based on their value to the product rather than what you want to do right now. This might save you from a lot of unnecessary, over-designed code that you won't use. If you have a deadline, it's even more important.
Have an evolutionary design: start with The Simplest Thing That Could Possibly Work and Refactor Mercilessly.
Postpone decisions until the Last Responsible Moment.
Timebox yourself into sprints or iterations (VERY important on university projects).
...
If you go over some of the agile methodologies again, I think you'll find plenty of values and practices that you could apply by yourself.
While writing this answer, at least 3 other answers came up and beat me to it. I agree with all of them. :)
Make list of tasks and features that you want in your application. Take those tasks and put them on a card wall.
You can't really have a meeting by yourself, but in the morning decide what you will do for the day and what you successfully did yesterday. Take those tasks, do them and then move to the next. Make sure at every point you are delivering continuously integrated, working software and you update your backlog. You might have "bug bash days" where you just fix bugs. That would be a one man scrum. :)
It's hard to truly apply agile coding to one-man projects because many of its benefits are aimed at small teams where you can quickly collaborate on focussed areas.
That said, you can adopt some of the techniques:
Release often
Focus on your users' needs
Feel free to deviate from major version plans - you can change direction whenever you feel the need
Spend less time in setting up major frameworks and get something working as soon as possible. Then go back and refactor to accomplish your original needs (if they still apply)
Other than pair developing, you can do the remainder of the practices if you are willing to play multiple roles. If you have someone who is willing to work with you, you can also do pair developing.
First you would build a product backlog. This would be a prioritized list of features or story cards you wish to develop. No card should be bigger than the work you can complete in a single iteration or sprint. If your sprints are a week or two, that will determine the size of the features or story cards on your prioritized product backlog. As the product owner, you can change the priority of the product backlog for each iteration. From the product backlog, you could build your iteration and release plans.
Since you are playing multiple roles, you will need to allow time for you to author the story card. The story card should sketch the GUI, describe the primary and secondary workflows and most importantly have acceptance criteria.
Once you sign off the written story card, you can begin development on the card. You would use TDD (test driven development) to write the test first, then the code. You would repeat until the card is done. The acceptance criteria would help you decide what unit tests to write.
Once the developed of the card is done, you would write the automated functional tests. You could use Quick Test Pro, FIT, Cucumber or some other favorite automated unit test tool. I would stay away from any play and record features as that can drive up rework in the future as you refactor.
Once the unit test is completed and the card passes, it can be added to all other automated functional test and can be run at least daily if not at every check in.
At the end of the iteration and prior to moving your working software to production, you can perform the User Acceptance Testing.
As the developer you should use continuous integration, automated builds kicked off with each of the frequent check in to your source code control system.
After the story card has been written and prior to developing the cards for the iteration, you can task them out (i.e,. provide estimates for each of the tasks required to develop the card). You can determine if any refactoring needed can be completed within your estimate or if you need to create a new story card that captures the technical debt you identified.
As you can see, you can take a single member agile team very far. Given that the agile management practices help collaboration and identify what is important, you can benefit from those practices also. Given that the engineering (XP) practices enable the code to remain healthy thus supports sustainable pace, you code will remain flexible, contain a strong unit and functional automated test harness and allow you to continue development at a sustainable pace indefinitely.
Is possible to use Scrum for one man projects.
Create backlog
Optimal time for one sprint is half day
At Friday create plan for next week and every half day update burndowns for each projects.
For example, don't be afraid to refactor your own code, even if it works, if the result is more flexible and robust.
A few thoughts on this:
Iterations are as long as you'd like them to be
IPMs are still possible where you pick what you want to do over that length of time
Demos at the end are still useful to see working functionality in a somewhat professional manner rather than your own little debugging area that may not be as clean or orderly
Retrospectives are still useful to see what is and isn't working for yourself at a point where you can see the forest for the trees in a sense
It is quite possible to be Agile in a personal one-man project, IMO.
All of the advice here is good, but there is one important aspects of Agile that usually goes unmentioned: monitoring.
Agile asks you to take a look at what you have done, what you are doing, where you are going, and make appropriate course corrections if needed.
I think Big Visible charts and Burndown/Burnup charts are so useful, I wrote a program, Task Analytics, to make these charts easily. It's perfect for small or one man projects.
Good luck.
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Maybe my understanding of agile development isn't as good as it should be, but I'm curious how an agile developer would potentially use off-the-shelf (OTS) software when the requirements and knowledge of what the final system should be are changing as rapidly as I understand them to (often after each iteration of development).
I see two situations that are of particular interest to me:
(1) An OTS system meets the initial set of requirements with little to no modification, other than potential integration into an existing system. However, within a few iterations of development, this system no longer meets the needs without rewriting the core code. The developers must choose to either spend additional time learning the core code behind this OTS software or throw it away and build from scratch. Either would have a drastic impact on development time and project cost.
(2) The initial needs are not like any existing OTS system available, however, in the end when the customer accepts the product, it ends up being much like existing solutions due to requirement additions and subtractions. If the developers had more requirements and spent more time working on them up front, this solution could have been used instead of building again. The project was delivered, but later and at a higher cost than necessary.
As a software engineer, part of my responsibilities (as I have been taught), are to deliver high-quality software to the customer on time at the lowest possible cost (among other things). Agile development allows for high-quality software, but in some cases, it might not be apparent that there are better alternatives until it is too late and too much money has been spent.
My questions are:
How does off-the-shelf software fit in with agile development?
How do the agile manager and agile developer deal with these cases?
What do the agile paradigms say about these cases?
Scenario1:
This can occur regardless off the OTS nature of the component. Agile does not mean near-sighted.. you'd need to know the big chunks.. the framework bits and spend thinking time on it beforehand. That said, you can only build to what you know .. Delay only till the last responsible moment.Then you need to pick one of the alternatives and start on it. (I'd Avoid third party application unless the cost of developing it in-house is infeasible.. but that's just me). Prototype multiple solutions to check feasibility with list of known requirements. Keep things loosely coupled (replacable), easy to change and full tested. If you reach the fork of keep hacking or rewrite, you'd need to think of which has better value for the business and pick that option. It's comes down 'Now that we're here, what's the best we can do now?'
Scenario2:
This can happen although the chances are slim compared to the team spending 2-3 months trying to get the requirements 'finalized' only to find that the market needs or customer minds have changed and 'Now we want it this way'. Once again, its a question of what is the point of time till which you are prepared to investigate and explore before committing on a path of action. Decide wisely with whatever information you have upto that point.. Hindsight is always 20-20 but the customers wont wait forever. You can't wait till the point of time where the requirements coalesce to fit a known OTS component :)
Agile says Do whatever makes sense and strip out the non-value-adding activities :) Agile is no magic bullet. just my 2 agile cents :)
Not a strict answer per se, but I think that using off the shelf software as a component in a software solution can be very beneficial if:
It's data is open, e.g. an open database or a web service to interact with it
The off the shelf system can customised easily using a similar programming paradigm to the rest of your solution
It can be seamlessly adapted to the rest of your work-flow
I'm a big fan of not re-inventing the wheel, and using your development skills to design the 'glue' between off-the-shelf solutions can be a big win.
Remember 'open' is the important part, and a vendor will often tout their solution as open when it isn't really.
I think I read somewhere that if during an iteration you discover that you have more than 20% more work that you initially thought then you should abandon the sprint and start planning a new one taking into account the additional work.
So this would mean replanning with the business to see if they still want to go ahead with the original requirements now that you know more.
At our company we also make use of prototyping before the sprint to try and identify these kind of situations before they arise on a sprint. Although of course that still may not identify the kind of situation that you describe.
C2 wiki discussion: http://c2.com/cgi/wiki?BuyDontBuild