Identify Design Mechanisms

Identify Design Mechanisms is performed by the architect, once per iteration.

Purpose

+ To refine the analysis mechanisms into design mechanisms based on the constraints imposed by the implementation environment.

Input Artifacts

+ Supplementary Specifications

+ Software Architecture Document

+ Analysis Class

+ Design Model

Resulting Artifacts

+ Design Model elements

Classes

Packages

Subsystems

+ Software Architecture Document

Steps

- Categorize clients of analysis mechanisms

- Document architectural mechanisms

Pattern

Pattern

- Provides a common solution to a common problem in a context

Analysis/Design Pattern

+ Provides a solution to a narrowly scoped technical problem

+ Provides a fragment of a solution, or a piece of the puzzle

Framework

- Defines the general approach to solving the problem

- Provides a skeletal solution, whose details may be analysis/design patterns

Design pattern

Definition:

A design pattern provides a scheme for refining the subsystems or components of a software system, or the relationships between them. It describes a commonly-recurring structure of communicating components that solves a general design problem within a particular context.

Categorize Analysis Mechanisms

- Purpose

+ To refine the information gathered on the analysis mechanisms

- Steps

+ Identify the clients of each analysis mechanism

+ Identify characteristic profiles for each analysis mechanism

+ Group clients according to their use of characteristic profiles

+ Proceed bottom up and make an inventory of the implementation mechanisms that you have at your disposal

Persistency characteristics

- Granularity: What is the range of the persistent objects?

- Volume: How many objects must be kept persistent?

- Duration: How long must the persistent objects be kept?

- Access mechanism: How is a given object uniquely identified and retrieved?

- Access frequency: Are the objects more or less constant? Are they permanently updated?

- Reliability: Can the objects survive a crash of the process, the processor, or the whole system?

Combined Fragment

Definition:

A construct within an interaction that comprises an operator keyword and one or more interaction operands, each of which is a fragment of an interaction

Interaction Operand

Definition:

Each fragment comprises one or more interaction operands, each a subfragment of the interaction.

+ The number of operands depends on the type of combined fragment.

+ An operand is a nested fragment of an interaction. Each operand covers the lifelines covered by the combined fragment or a subset of them.

Interaction Expression

A specification of the range of number of iterations of a loop.

JDBC: Steps

Provide access to the class libraries needed to implement JDBC

Provide java.sql package

Create the necessary DBClasses

Assign one DBClass per persistent class

Incorporate DBClasses into the design

Allocate to package/layer

Add relationships from persistency clients

Create/Update interaction diagrams that describe:

Database initialization

Persistent class access: Create, Read, Update, Delete