The Requirement

What is Inception? What is the vision and business case for this project? –not to define all the requirements Feasible? Buy and/or build? Rough unreliable range of cost Should we proceed or stop?

Requirement Beginning of project life cycle Occur troughout the Inception and Elaboration What you are going to build?

Metamodel Small triangle indicates that the package contains a model The anchor icon indicates that contain the thing at the other end of the line

Metamodel Metamodel contains 2 model that are differrence. The requirement model contain –functional requirements (what the system should) –Non-functional requirements (constraints on the system) The use case model contain –Use cases (specifications of system functionality) –Actors (external roles that interact directly with the system)

Defining requirement model Requirement tell us ? (what or how) we should build. Two types of requirement (functional and non- functional) Well-formed

ATM What the system should do? 1.The ATM system shall check the validity of the inserted ATM card. 2.The ATM system shall validate the PIN number entered by the customer. A constraint placed on the system 1.The ATM system shall be written in C++ 2.The ATM system shall validate an ATM card in three seconds or less

Techniques Interviews Questionnaires workshops

Use case modeling Proceeds as follows. –Find a candidate system boundary. –Find the actors. –Find the use cases. –Iterate until stable. Output –System boundary Edge or boundary of the system. –Actors Roles played by people or things that use the system. –Use cases Things that the actor can do with the system. –Relationships Relationships between actors and use cases.

Looking at the input Business model –Best source of requirement Requirement model –Functional requirement suggest use cases and actors –Non-functional suggest things you may keep in mind when constructing the use case model

The subject-System boundary First thing when build a system is decide where the boundaries of the system –What is part of your system –What is external to your system The subject(uml2.0) is drawn as a box –Label with the name –Actors drawn outside –Use cases inside

What are actors Actor specifies a role (entity) that interact with your system directly It may represent a user role Or a role played by another system or piece of hardware Actors are always external to the system

Indentifying actors Who or what uses the system What roles do they play in the interaction Who install the system Starts and shutdown the system Who maintains the system What other systems interact with this system Who or what gets and provides information to the system Does anathing happen at a fixed time

What are use cases A use case is something an actor wants the system to do. Always started by an actor.

Identifying use cases Best way is start with the list of actors,consider how each actor is going to use the system. Descriptive name that is a verb phrase. Find some new actors !!! Helpful list of questions –What functions that actor want from the system? –Does the system store and retrieve information?(which actor trigger this behavior) –What happens when the system changes state(start,stop)? –Do any external events affect the system? –Does the system interact with any external system? –Does the system generate any report?

diagram

Specification