Page 20 - DCAP304_DCAP515_SOFTWARE_PROJECT_MANAGEMENT

Software Project Management

Notes 1. Feasibility Study: The feasibility study comprise of one single stage, which involves
conducting a high level analysis of a business area to decide whether a system can cost
effectively support the business requirements. In the Feasibility Study an overview Data
Flow Diagram (DFD) is produced together with a high level Logical Data Structure (LDS).
At this phase the DFD will represent the existing system and the LDS may be incomplete
and contain unresolved many-to-many relationships.
2. Requirements Analysis:

 Investigation of the current environment: All through this stage the systems requirements
are identified and the present business environment is modeled in terms of the
processes carried out and the data structures involved. In this DFDs and LDSs are
used to produce detailed logical models of the current system.
 Business Systems Options (BSO): All through this stage up to six business system
options are produced and presented. As a result, one of these options is adopted and
polished. DFDs and LDSs are produced to support each business system option and
the last chosen option. The transition from the former stage to this stage is a key part
of SSADM: this is where we move from a logical model of the current system to a
logical model of the required system. This means that here the DFDs and LDSs have
to be refined to cater to new or changed requirements.

3. Requirements Specification: The Requirements Specification comprises of a single stage
which involves further developing the work carried out in the Requirements Analysis:
detailed functional and non-functional requirements are recognized and new techniques
are introduced to define the required processing and data structures.
4. Logical System Specification:

 Technical system options: In this phase up to six technical options (specifying the
development and implementation environments) are formed, one being selected.
 Logical design: In this phase the logical design of update and enquiry processing and
system dialogues (menus, etc.) is carried out.
5. Physical Design: The Physical Design contains of a single stage in which the logical system
specification and technical system specification is employed to create a physical database
design and a set of program specifications.
SSADM revolves around the use of three key techniques:

1. Logical Data Modelling (LDM): This is the procedure of identifying, modelling and
documenting the data requirements of a business information system. A LDM consists of
a LDS and the associated documentation. LDSs represent Entities (things about which a
business needs to record information) and Relationships (necessary associations between
entities).
2. Data Flow Modelling (DFM): This is the procedure of identifying, modeling and
documenting how data flows around a business information system. A Data Flow Model
consists of a set of integrated DFDs supported by suitable documentation. DFDs represent
processes (activities which transform data from one form to another), data stores (holding
areas for data), external entities (things which send data into a system or receive data from
a system) and finally data flows (routes by which data can flow).

3. Entity/Event Modelling (EM): This is the procedure of identifying, modeling and
documenting the business events which influence each entity and the sequence in which
these events occur. An EM consists of a set of Entity Life Histories (ELHs) (one for each
entity) and appropriate supporting documentation.

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