Application Requirements

There are two sets of documents containing requirements for applications:

• Business Requirements outline the Business Case for the required application, in other words what the business will do with the application. This will include the Return on Investment for the application as well as all related improvements to the business. Business requirements will also include the Service Level Requirements as defined by the service customers and users.
• Application Requirements documents are based on the Business Requirements and specify exactly how the application will meet those requirements. In short, Application Requirements documents gather information that will be used to commission new applications or changes to existing applications, for example:
• To design the architecture of the application (specification of the different components of the system, how they relate to one another and how they will be managed)
• To specify a Request for Proposal (RFP) for a Commercial Off the Shelf (COTS) application
• To initiate the design and building of an application in-house.

Requirements documents are normally owned by a project leader, either of a development project team, or for a team drawing up specifications for an RFP. Requirements documents are subject to document control for the project as they form part of the overall scope of the project.

Four different types of Application Requirements need to be defined (for more detailed information, please refer to the ITIL Service Design and Service Transition publications):

• Functional Requirements describe the things an application is intended to do, and can be expressed as services, tasks or functions the application is required to perform.
• Manageability Requirements are used to define what is needed to manage the application or to ensure that it performs the required functions consistently and at the right level. Manageability requirements also identify constraints on the IT system. These requirements serve as a basis for early system sizing and estimates of cost, and can support the assessment of the viability of the proposed IT system. Most importantly, they drive design of the operational models and performance standards used in IT Operations Management.
• UsabilityRequirements are normally specified by the users of the application and refer to its ease of use. Any special requirements for handicapped users also need to be specified here.
• Test Requirements specify what is required to ensure that the test environment is representative of the operational environment and that the test is valid (i.e. that it actually tests what it is supposed to).

Date: 2014-12-29; view: 910