JavaTM Virtual Reality Applications and
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"Freedom" Service-Oriented Methodology
Object Design Process

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Principles -- Object Design

Analyze Behavior

The behavior tables for the current release group are updated to include PDL for internal behavior. The full (external plus internal) PDL behavior specifications are then analyzed to identify objects and operations on the objects needed to support the full behavior. The analysis comprises extending the behavior tables by adding objects and operations columns, which are used to record objects and operations mentioned in the PDL. The objects and their operations from all behavior tables in the release group are then combined into a composite list.


Create Object Model

An object model identifies all common service objects that must be implemented and their relationships to one another. The object model defines the design architecture of the system, which is a necessary prerequisite to object-oriented implementation. Freedom uses object model tables (OMTs) to record the object model rather than UML Class Diagrams because OMTs are less expensive to create and more amenable to completeness checking.

The objects identified in the extended behavior tables are copied into the OMT, and their relationships are defined. This leads to the identification of additional objects, which are also integrated into the OMT. The identification cycle is repeated until all objects so identified are already defined either in the OMT or in the reuse library. As with other tasks, the quality requirements are used to guide selection among competing architectural alternatives in the object model.


Identify Reusable Classes

When the common service objects needed to support the required response behavior of the current release group of requirements are identified via an object model, the object model table is examined for reusable common service objects. Any such objects found are flagged for implementation as reusable design components.


Create Interface Specifications

An interface specification defines the operations (i.e., Java methods) invocation protocols (arguments, return types, type value ranges, exceptions) and hidden information (field data, data value ranges) of each common service object to be implemented. An interface specification is created for each object (i.e., Java class) identified in the object model table for the release group. Interface specifications are most useful when used as input to tools for automatic generation of skeletal code, regression tests, API documentation, and skeletal user manual. As with other tasks, the quality requirements are used to guide selection among competing interface alternatives for interface specifications.


Create Behavior Tables for Classes with Complex Operations

Once the interface specifications have been defined, the full behavior (internal plus external behavior) of complex operations (Java methods) are specified. A complex operation is one for which the full behavior will likely require support services of other common service objects. The full behavior is recorded in an operation/method behavior table.

An operation/method behavior table is similar to a requirements behavior table except that each row in the table corresponds to an operation on the object (Java method) rather than a stimulus. The columns of an operation/method behavior table are the same as a requirements behavior table except there is no "new stimulus set" response column. The use of PDL is identical. As with other tasks, the quality requirements are used to guide selection among competing algorithmic alternatives when writing the PDL. One operation/method behavior table is created for each object in the object model table having complex operations.

The behavior of the complex operations is analyzed to identify additional objects and their operations by repeating the Object Design process starting with the Analyze Behavior task until no new objects are identified in the Create Object Model task.


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