Page 82 - DCAP305_PRINCIPLES_OF_SOFTWARE_ENGINEERING

Principles of Software Engineering

Notes
Function Point Analysis was developed first by Allan J. Albrecht in the mid
1970s.

Ideal value of DRE must be 1 which means no defects found. The value other
than 1 assumed as software failure.

4.2 Software Architecture

It provides a high-level description of the goals of the architecture, the use cases support by
the system and architectural styles and mechanism that have been particular to most excellent
achieve the use cases. This structure then allows for the development of the design criteria and
documents that define the technical and domain standards in detail. It is these detailed design
documents that will guide the development of the actual MedBiquitous content in terms of
messages and services.
By analogy the architecture of a structure has to take into account the use of the building, what
are the people living/working in it expecting and then has to define the size, shape, structure
and so forth. The architecture has a set of guiding principles as well as known criteria and
constraints that shape the proposed architecture. The designers then have to develop detailed
specifications not only for the selection of materials but the placement of wiring, plumbing,
lighting and so forth.
Architecture is at the centre of our layered decision model (Figure 4.9), and at the centre of the
architecting activity. It is where the system structures are created, taking into account system
priorities and constraints, and ensuring that the system will achieve the system objectives and
architectural requirements. This work is informed and constrained by the decisions made in
the Meta-Architecture.
Within the architecture layer, we use different views to enhance the understand ability of the
architecture and to focus on particular concerns separately. We distinguish between Conceptual,
Logical and Execution views, as shown in Figure 4.10.

Figure 4.9: Software Architecture Decision Framework

guide Meta-Architecture
architects
• Architectural vision, principles, styles, key concepts and mechanisms
• Focus: high-level decisions that will strongly influence the structure of
the system; rules certain structural choices out, and guides selection
decisions an tradeoffs among others
Architecture Conceptual Architecture
• Structures and relationships, static and dynamic views,
assumptions and rationale Logical Architecture
• Focus: decomposition and allocation of responsibility,
interface design, assignment to processes and threads Execution Architecture
guide Architecture Guidelines and Policies
designers
• Use model and guidelines; policies, mechanisms and design patterns;
frameworks, infrastructure and standards
• Focus: guide engineers in creating design that maintain the integrity of
the architecture

4.2.1 Meta-architecture

The meta-architecture is a set of high-level decisions that will powerfully power the integrity and
structure of the system, but is not itself the arrangement of the system. The meta-architecture,
through style, patterns of composition or interaction, principles, and philosophy, rules certain

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