jump to navigation

Requirements Analysis Overview August 26, 2005

Posted by Coolguy in Business Analysis.
Tags:
trackback

Introduction

  • Its all the tasks that go into the instigation, scoping and definition of a new or altered computer system
  • Successfully completing a “requirements analysis” task is a challenge
  • In the first place, it is not easy to identify all the stakeholders, give them all an appropriate form of input, and document all their input in a clear and concise format
  • Studies of previous projects reveal that costs and technical risks can be reduced through rigorous and thorough up-front requirements engineering

General problems

  • The right people with adequate experience, technical expertise, and language skills may not be available to lead the requirements engineering activities
  • The initial ideas about what is needed are often incomplete, wildly optimistic, and firmly entrenched in the minds of the people leading the acquisition process
  • the difficulty of using the complex tools and diverse methods associated with requirements gathering may negate the hoped for benefits of a complete and detailed approach


Stakeholder issues

  • Users don’t understand what they want
  • Users won’t commit to a set of written requirements
  • Users insist on new requirements after the cost and schedule have been fixed
  • Communication with users is slow
  • Users often do not participate in reviews or are incapable of doing so
  • Users are technically unsophisticated
  • Users don’t understand the software development process


Developer issues

  • Software developers and the end user often have different vocabularies. Consequently, they can believe they are in perfect agreement until the finished product is supplied.
  • Software developers often try to make the requirements fit an existing system or model, rather than develop a system specific to the needs of the client
  • Analysis is often carried out by programmers, rather than business analysts. It is often the case that programmers lack the people skills and the real world knowledge to understand a business process properly


Solutions

  • One of the solutions to this problem has been recognising that requirements analysis is a specialist field best carried out by experts, i.e. business or system analysts, who could bridge the gap between the business and IT (Information Technology) worlds
  • Modern techniques introduced in the 1990s like Prototyping, UML, use cases, and Agile software development seem to offer more promise

Main Techniques

  • Requirements analysis can be a long and arduous process
  • The requirements specialists do their work by talking to people, documenting their findings, analyzing the collected information to discover inconsistencies and oversights, and then talking to people again
  • This process can go on for a while, and may continue throughout the life cycle of a system.
  • New systems change the environment and relationships between people, so it is important to identify all the stakeholders, make sure you take into account all their needs; and ensure they understand the implications of the new systems
  • Frequently, this objective is not met because:
  • there is not enough talking, and important needs are overlooked when the system is implemented; and/or
  • there is not enough descriptive feedback, and the users are disappointed by the new system’s characteristics
  • Analysts can employ several techniques to get the requirements from the customer:
  1. Interviews
  2. Requirements workshops
  3. Creating requirements lists.
  4. Prototyping
  5. Use cases

Stakeholder interviews

  • Stakeholder interviews are obviously necessary in requirement specification
  • However, in any large system a number of individuals need to be interviewed, which increases the time and cost; but more importantly almost always this reveals major discrepancies with regard to how the existing business process works and how it should work in the future
  • Also different users might have differing or even contradictory requirements.

Requirement workshops

  • Therefore where systems are complex the usual method is to use requirement workshops, where the analyst brings the main stakeholders in the system together in order to analyse the system and develop the solution
  • Such workshops are ideally carried out off site, so that the stakeholders are not distracted. They usually have a facilitator to keep the process focused, a scribe to document the discussion, and usually make use of a projector and diagramming software. Often multiple workshops are required to bring the process to a successful conclusion
  • Requirements workshops are considered to be a very useful technique which can save significant time. However, it can be hard to get all the required stakeholders together at one time.
  • A more general weakness is that some stakeholders do not contribute forcefully enough in workshops and their requirements will not receive the appropriate attention, inevitably producing a limited solution
  • Additionally, while requirement workshops are an excellent technique for modelling the existing system, they are not so useful for defining the nature of the solution

Contract style requirement lists

  • The most common way of documenting requirements has been contract style requirement lists.
  • In a complex system such requirements lists can run to hundreds of pages
  • Strengths:
  • Provides a checklist of requirements.
  • Provide a contract between the project sponsor(s) and developers.
  • For a large system can provide a high level description
  • Weaknesses:
  • Such lists can run to hundreds of pages. It is virtually impossible to read such documents as a whole and have a coherent understanding of the system.
  • Such requirements lists abstract all the requirements and so there is little context
  • This abstraction makes it impossible to see how the requirements fit together.
  • This abstraction makes it difficult to identify which are the most important requirements.
  • This abstraction means that the more people who read such requirements the more different visions of the system you get.
  • This abstraction means that it’s extremely difficult to be sure that you have the majority of the requirements. Necessarily, these documents speak in generality; but the devil as they say is in the details.
  • These lists create a false sense of mutual understanding between the stakeholders and developers.
  • These contract style lists give the stakeholders a false sense of security that the developers must achieve certain things. However, due to the nature of these lists, they inevitably miss out crucial requirements which are identified later in the process. Developers use these discovered requirements to renegotiate the terms and conditions in their favour.
  • These requirements lists are no help in system design, since they do not lend themselves to application.

Prototypes

  • Prototypes are mock ups of the screens of an application which allow users to visualize the application that isn’t yet constructed.
  • Prototypes help users get an idea of what the system will look like, and make it easier for users to make design decisions without waiting for the system to be built.
  • Problems:
  1. Managers once they see the prototype have a hard time understanding that the finished design will not be produced for some time
  2. Designers often feel compelled to use the patched together prototype code in the real system, because they are afraid to ‘waste time’ starting again.
  3. Prototypes principally help with design decisions and user interface design. However, they can’t tell you what the requirements were originally
  4. Designers and end users can focus too much on user interface design and too little on producing a system that serves the business process
  • Prototypes can be flat diagrams (referred to as ‘wireframes’) or working applications using synthesized functionality
  • Wireframes are made in a variety of graphic design documents, and often remove all colour from the software design (ie use a greyscale colour palette) in instances where the final software is expected to have graphic design applied to it

Use cases

  • A use case is a technique for capturing the potential requirements of a new system or software change
  • Each use case provides one or more scenarios that convey how the system should interact with the end user or another system to achieve a specific business goal
  • Use cases typically avoid technical jargon, preferring instead the language of the end user or domain expert
  • Use cases are often co-authored by software developers and end users.
  • Each use case focuses on describing how to achieve a single business goal or task
  • From a traditional software engineering perspective a use case describes just one feature of the system.
  • The degree of formality of a particular software project and the stage of the project will influence the level of detail required in each use case.
  • A use case defines the interactions between external actors and the system under consideration to accomplish a business goal
  • Actors are parties outside the system that interact with the system; an actor can be a class of users, roles users can play, or other systems.
  • Use cases treat the system as a “black box”, and the interactions with system, including system responses, are as perceived from outside the system
  • This is deliberate policy, because it simplifies the description of requirements, and avoids the trap of making assumptions about how this functionality will be accomplished
  • A use case should:
  • describe a business task to serve a business goal
  • have no implementation-specific language
  • be at the appropriate level of detail
  • be short enough to implement by one software developer in single release.
  • Use cases can be very good for establishing the functional requirements; however they are not suited to capturing non-functional requirements.

Stakeholder identification

  • In the early days systems were built for the projects sponsor(s), who were usually management types
  • Many systems have been designed by managers with little or no contributions from the eventual users; these systems have tended to fail horrendously
  • It is increasingly recognised that stakeholders do not just exist in the organisation the analyst is hired by
  • Other stakeholders will include:
  1. those organisations that integrate (or should integrate) horizontally with the organisation the analyst is designing the system for
  2. any back office systems or organisations
  3. higher management

Advertisements

Comments»

No comments yet — be the first.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: