CSC/ECE 517 Fall 2011/ch6 6e zj

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Introduction

The concept of heavier-weight methodology

Traditional methodology which is also known as Heavyweight development methodology that is based on a sequential series of steps, such as requirements definition, solution build, testing and deployment. Heavyweight development methodology mainly focuses detailed documentation, inclusive planning, and extroverted design.<ref name = "agile1">http://acm.web.auth.gr/2011/03/03/agile-methodology/</ref>

The concept of agile methodology

Agile methodology(Lightweight Methodology) is an approach to project management, typically used in software development. It helps teams respond to the unpredictability of building software through incremental, iterative work cadences, known as sprints. <ref name = "agile1"/>

Compare with the heavier-weight methodology and agile methodology

Heavier-weight methodology

Heavyweight methodology<ref>http://www.techrepublic.com/article/heavyweight-vs-lightweight-methodologies-key-strategies-for-development/5035285</ref>:

  • A heavyweight methodology which is compsited with rules, practices, and documents, that makes us discipline and time to follow correctly.
  • Heavyweight methodologies focus the in the greate detail of the project.
  • The specifications, reports, plans, schedules and checkpoints is required by the leads managers.
  • For the reason that the heavyweight methodology works when the thins start changing, so the project managers who use heavyweight methodologies will resist change.
  • Requirements definition, solution build, testing and deployment are always the basic steps for the heavyweight development methodology.
  • Rational Unified Process. is one of the widely used example of “heavyweight” methodology.
  • Heavyweight methodology is suitable for a project team which is larger than 10-20 people and work in several different locations.
  • If the project needs multiple teams working at several locations, and you need them to work tighter to develop some core parts of the project, in such condition heavyweight methodologies can be a better choice.

Advantage of heavier-weight methodology

  • It is a clear and powerful method for software development, many big corporations use this method to develop software. It clearly defines software development life cycle, which help a new developer better know how to develop the software.
  • Because we have clear stated what to do before the project actually start, this will save us time to do only those that we actually required. It always happen that a project team do a lot of effort to code and then later found out that it's not required at all. So using this method and adhering closely to documentation, It will avoid of those useless effort.
  • The project stakeholders are forced to clearly and correctly define the business requirements documentations. Also, developers are forced to completely understand the requirements before starting doing the high level design and coding. Without thoroughly understand the requirements, they will fail to meed the corresponding milestone and fail to continue the project.
  • Actually, making documentation at every state is an very essential step. It helps better understand the requirements, design the code , write code and design test on the software.

Disadvantage of heavier-weight methodology

The traditional project methodologies that many top corporations use, such as the SDLC approach, are considered to be bureaucratic or “predictive” in nature, and they’ve resulted in many unsuccessful projects. These “heavyweight” methodologies are becoming increasingly unpopular. They can be so laborious that the whole pace of design, development, and deployment actually slows down.
Heavyweight methodologies try to plan majority part of the project in great detail. Project managers need to predict predict every project milestones because they need those technical details, which result in a large number of documentation, such as plans, report, and schedules. However, we know, when doing a project, there are always a lot of changes, such as that the client may change their requirements, then all the schedules, checkpoints made for the project need to get changed. So making all the details for a project before actually starting the project is not an effective way.
Heavyweight development methodology is based on a sequential series of steps, such as requirements, solutions, testing and deployment, which means that every step could only be started with the finish of previous step, while the lightweight methodologies propose to execute the project steps in parallel.

Agile methodology

In 1970, Dr. Winston Royce presented a paper entitled “Managing the Development of Large Software Systems” which outlined his ideas on sequential development. In essence, his presentation asserted that a project could be developed much like an automobile on an assembly line, in which each piece is added in sequential phases. This means that every phase of the project must be completed before the next phase can begin. Thus, developers first gather all of a project’s requirements, then complete all of its architecture and design, then write all of the code, and so on. There is little, if any, communication between the specialized groups that complete each phase of work.<ref name = "agile3">http://agilemethodology.org/</ref>

Advantage of agile methodology

  • The most important characteristics of Agile methodology is that it is adaptive, making the team is able to respond to the change of requirements. We know that it is a quite common thing for requirements to get changed when developing a software.
  • The team does not have to invest time and effort and finally find that by the time they delivered the product, the requirement of the customer has changed.
  • The close communication from customer and the designer makes all the requirements clear and if somethings changed, the develop team could quickly respond to the change, there is no guesswork here.
  • No complicated and burdensome documentation, which saves a lot of time when developing software.
  • The outcome is always the software that best satisfy the customer, as they closely communicate during the developing proecess.


In a nutshell this means that you could quickly start a project, and project scope is flexible which means that you could properly manage the project scope during the developing process.

Disadvantage of agile methodology

It’s easy to see how this development agile methodology is far from optimized. First of all, it assumes that every requirement of the project can be identified before any design or coding occurs. Put another way, do you think you could tell a team of developers everything that needed to be in a piece of software before it was up and running? Or would it be easier to describe your vision to the team if you could react to functional software? Many software developers have learned the answer to that question the hard way: At the end of a project, a team might have built the software it was asked to build, but, in the time it took to create, business realities have changed so dramatically that the product is irrelevant. In that scenario, a company has spent time and money to create software that no one wants. Couldn’t it have been possible to ensure the end product would still be relevant before it was actually finished?

  • In case of some software deliverables, especially the large ones, it is difficult to access the effort required at the beginning of the software development life cycle.
  • There is lack of emphasis on necessary designing and documentation.
  • The project can easily get taken off track if the customer representative is not clear what final outcome that they want.
  • Only senior programmers are capable of taking the kind of decisions required during the development processes. Hence it has no place for newbie programmers, unless combined with experienced recourses.
  • Such development methodologies have also been criticized for their lack of strong planning and problems with applying them to the creation of larger software systems, especially in comparison to older, heavier weight methods like the spiral model.

Heavier-weight Methodology VS Agile Methodology

The Difference Between Heavier-weight Methodology and Agile Methodology

Differences Agile Methodology Heavier-weight Methodology
Customers Committed,knowledgeable,collocated,collaborative,representative,empowered Access to knowledgeable,collaborative,representative,empowered customers
Requirements Mainly emergent,rapid change. Knowable early, largely stable.
Architecture Designed for current requirements Designed for current and foreseeable requirements
Size Smaller Team and Products Larger Team and Products
Primary objective Rapid value High assurance
Developers Knowledgeable,collocated,collaborative Plan-driven,adequate skills,access to external knowledge.
Release cycle In phases (multiple cycles) Big bang (all functionality at once)

The Issue of Heavier-weight Methodology and Agile Methodology<ref name = "agile4">http://www.ijcsi.org/papers/IJCSI-8-4-1-441-450.pdf</ref>

Issue Agile Methodology Heavier-weight Methodology
Development life cycle Linear or incremental Incremental
Style of development Adaptive Anticipatory
Requirements Emergent–Discovered during the project. Clearly defined and documented
Documentation Light(replaced by face to face communication) Heavy/detailed Explicit knowledge
Team members Co-location of generalist senior technical staff Distributed teams of specialists
Client Involvement Onsite and considered as a team member Active/proactive Low involvement
Market Dynamic/Early market Mature/Main Street market
Measure of success Business value delivered Conformance to plan

Example

Heavier-weight methodology

Rational Unified Process

Indroduction of RUP

The Rational Unified Process (RUP),which comes from Rational Software and later by IBM, is a kind of heavy methodology which can be use to accomodate the change and adaptability during the development process. These are some features of RUP: it use the incremental iterations to build the software. The development disciplines like requirements, analysis, design, and implementation and testing can be parts of the interation. It help successful developing of the software by assign the tasks and responsibilities for the developing teams.

The Main Goal of RUP

RUP can product the high-quality software for its end-users in a predicatable shcedule and budget. RUP needs some guildlines for best pratices<ref name = "agile4" />:

  • Develop software iteratively
  • Manage requirements
  • Use component-based architectures
  • Visual model software
  • Verify software quality
  • Control changes to software
The Phases of RUP
The Phases of RUP
The Phases of RUP

RUP has a series of phases as follows:

  • Inception: In this phase, we should caculate some risks we may face in the future and the costs, eviroment, eviroment ect.
  • Elaboration: This phase require us know what needs us to build, and we also should know the detail, make sure the architecture will work in future.
  • Construction: In this phase we should build the product according to the documentation required and build the supporting documentation.
  • Transition: (Transition the Product to its Users) In this phase the product will release to the user for user tested, we should correct the bug in this phase for future deploying.


Notes:The picture cites from <ref name = "agile4" />

Usage of RUP Model
  • Distributed systems
  • Very large or complex systems
  • Systems combining several business areas
  • Systems reusing other systems
  • Distributed development of a system

Spiral Model

Indroduction of Spiral Model

Spiral Model is a software development process combining elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down and bottom-up concepts.This model is also known as Boehm's model, using his model, process is represented as a spiral rather than as a sequence of activities with backtracking.

Processes in Spiral Model
Spiral model
Spiral model

There are four processes in spiral model:

  • Objective setting: Specific objectives for the project phase are identified.
  • Risk assessment and reduction: Key risks are identified, analyzed and information is obtained to reduce these risks. The aim is that all risks are resolved.
  • Development and Validation: Once all possible risks have been identified the development of the software can begin, an appropriate model is chosen for the next phase of development.
  • Planning: The project is reviewed.


Usage of Spiral Model

Following are the usage of Spiral model:

  • Large and high budget projects.
  • When risk assessment is very critical.
  • Requirements are not very clearly defined and

complex.

  • When costs and risk evaluation is important
  • For medium to high-risk projects.
  • Long-term project commitment unwise because of potential changes to economic priorities.

Agile methodology

Extreme Programming(XP)

Indroduction of Extreme Programming(XP)

Extreme Programming(XP) is a lightweight design method developed by Kent Beck, Ward Cunningham, and others, XP has evolved from the problems caused by the long development cycles of traditional development models. The XP process can be characterized by short development cycles, incremental planning, continuous feedback, reliance on communication, and evolutionary design. With all the above qualities, XP programmers respond to changing environment with much more courage.

XP Terms and Practices
Life cycle of
Life cycle of

A summary of XP terms and practices is listed below:

  • The Planning Process:The desired features of the software, which are communicated by the customer, are combined with cost estimates provided by the programmers to determine what the most important factors of the software are. This stage is sometimes called the Planning Game.
  • Small Releases:The software is developed in small stages that are updated frequently, typically every two weeks.
  • Metaphor:All members on an XP team use common names and descriptions to guide development and communicate on common terms.
  • Simple Design:The software should include only the code that is necessary to achieve the desired results communicated by the customer at each stage in the process. The emphasis is not on building for future versions of the product.
  • Testing:Testing is done consistently throughout the process. Programmers design the tests first and then write the software to fulfill the requirements of the test. The customer also provides acceptance tests at each stage to ensure the desired results are achieved.
  • Refactoring:XP programmers improve the design of the software through every stage of development instead of waiting until the end of the development and going back to correct flaws.
  • Pair Programming:All code is written by a pair of programmers working at the same machine.
  • Collective Ownership:Every line of code belongs to every programmer working on the project, so there are no issues of proprietary authorship to slow the project down. Code is changed when it needs to be changed without delay.
  • Continuous Integration:The XP team integrates and builds the software system multiple times per day to keep all the programmers at the same stage of the development process at once.
  • 40-Hour Week:The XP team does not work excessive overtime to ensure that the team remains well-rested, alert and effective.
  • On-Site Customer:The XP project is directed by the customer who is available all the time to answer questions, set priorities and determine requirements of the project.
  • Coding Standard:The programmers all write code in the same way. This allows them to work in pairs and to share ownership of the code.


Crystal

Indroduction of Crystal

Crystal Methodologies is a family of methodologies((Crystal Clear, Crystal Yellow, Crystal Orange, etc.)developed by Alistair Cockburn. The word “Crystal” refers to the degree of hardness and the different colors of the methodology in much the same way that a crystal can have various degrees of hardness and variety of colors. The degree of hardness pertains to the use of rigor and ceremony i.e. as the hardness increases the amount of required documentation, processes and procedures increases.

Features and Restrictions of Crystal
Crystal
Crystal

Several of the key tenets of Crystal include teamwork, communication, and simplicity, as well as reflection to frequently adjust and improve the process. Like other agile methodologies, Crystal promotes early, frequent delivery of working software, high user involvement, adaptability, and the removal of bureaucracy or distractions.
Crystal methods are denoted by colors. The color of the methods as follows: Clear, Yellow, Orange, Orange Web, Red, Magenta, and Blue. Only three of the methods – Crystal Clear, Orange and Orange Web - have been constructed and actually used on projects.
One of the restrictions of the Crystal methods is that they only address collocated teams. Thus, the Crystal methods would not apply to distributed or offshore teams for which Cockburn offers no recommendation other than to locate the team together at one location.

Rules that are common to all the Crystal Methods
  • The project must use incremental development with increments of four months or less with a string preference of one to three months
  • The team must hold both pre- and post- reflection with a strong preference for mid-project reflection workshops

How to choose methodology?

What the best model is varies from project to project, but the creation of new models for software development that can strike a balance between extremes is an open question. The essential points you’ll need to consider when selecting a methodology are:

  • Budget
  • Team size
  • Project criticality
  • Technology used
  • Documentation
  • Training
  • Best practices/lesions learned
  • Tools and techniques
  • Existing processes
  • Software

When to Avoid the Agile Methodology

Some situations should avoid Agile Methodology if...

  • You have to formally document the requirements, design, code, and testing cases during each phase of the software life cycle.

This is usually the case when building an infrastructure application, rather than an application that supports a changeable business process. Infrastructure applications support an entire business unit over a long ROI period, with repeated updates and enhancements expected. These applications are likely to be managed by successive generations of application owners, who will need to inherit documentation from their predecessors, maintain it, and pass it on their successors.

  • Deliverables must pass through a chain of approvals and tollgates

Approvals and tollgates are mini-bottlenecks that can slow the momentum of a project, momentum that agile methods are supposed to support. Applications that require phase-end reviews or reviews of major deliverables by senior management, by a PMO, or even an Audit Committee may or may not be candidates for agile methods. Of course, the flip side to this is that agile methods can also help recover momentum lost to approvals and tollgates.

  • You have tools to create the software models but not to translate them to the low end software code.

Model-driven development tools that can generate code are proliferating, but the skills necessary to use them effectively are still relatively scarce. Unless you have both the tools AND the skills available, agile methods that depend on such tools need to be approached with caution.

  • You need to follow traditional Software management processes and Procedures.

"Traditional" usually means "comfortable". If the business sponsor and users are uncomfortable with anything but traditional ways of developing software, and remain unmoved by the value proposition for agile methods, don't bother.

  • Application users are NOT always accessible to you.

Agile management depends on an effective, day-to-day working partnership between the development team, the sponsor, and empowered users. If this partnership does not exist, or is likely to be weak, an agile project will face much higher risks than it should.

Conclusion

Agile methods demand that the customer is involved throughout; the customer is part of the team. It makes sense for the customer to want to be deeply involved in the product you are making them, however, there are a myriad of real world reasons why it might not be possible. With any process you deploy to solve a problem customer buy in is critical… The customer must understand what is required of them and be committed to deliver on that requirement. This cannot be forced and any attempts to make a customer buy into agile will result in difficulty. Sometimes, upfront analysis might just have to do...
It is possible to run an agile project on a fixed priced or time and materials basis. However, in both cases for the project to be agile the scope must be flexible. If the project is fixed scope, there is no benefit from using agile methods. If it’s fixed scope then more than likely the requirements will form part of the contract and thus be well defined (through upfront analysis). The point of agile is to allow change such that the developers are delivering software that will be used by the customer, essentially reduce the scary waste of 45% of functionality not being used!
Heavyweight methodologies sometimes that can be a better choice,for example that you have multiple teams working at different locations and you need tighter control to formalize key parts of the project.Since heavyweight methodologies require documentation at every stage this will help better understanding of the requirements the project. So we conclude that no one model is necessarily better or worse than another. As always the selection of a particular model is correct only in the context of the organization or the product under development. Correct selection is to a great degree dependant on having a clear understanding of the groups and types of development models. This is of further importance given that it's highly unlikely that any organization will follow a model strictly. Most organizations will opt to use a hybrid form that fits the capabilities of their staff and meets the needs of their business.

References

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