Object Derivation Analysis
Objectives
The goal of this task is to define a migration path from a process driven
paradigm into an object oriented paradigm based on legacy systems analysis. The
approach is premised on the need to expedite the analysis process while
concurrently defining a migration path from legacy architectures.
Legacy systems were developed using a variety of process driven techniques.
Abstracting these processes is a highly analytical and, therefore, risk prone
process. On the other hand, the capture and abstraction of data definitions from
legacy architectures is a more automated process. This premise underlies the
approach expressed within this task.
Object Derivation Analysis defines how to take an entity relationship model
derived from one or more legacy systems and create an object model. If the goal
is to create an object model from scratch, then top-down object modeling
techniques should be pursued. However, where legacy object derivation,
architecture transition or integrity checking of a top-down object model is the
goal, this approach outlines a path forward.
One last point should be considered. For a variety of reasons, object
oriented systems have been primarily implemented using relational databases (RDBMS).
According to most experts, this will be the case for some time forward. Object
developers, therefore, are required to retrofit object oriented designs into a
RDBMS.
The approach outlined here supports development synchronization of relational
data and object oriented designs using the Legacy Transition Meta-model (LTM).
LTM is defined in the TIM Appendix section. The model driven
client/server migration scenario offers more insight into transition management
based on the use of this and related TIM tasks.
Specific objectives of the Object Derivation Analysis task include the
following:
· Capture and represent legacy objects in a formal object model
· Abstract existing objects from legacy based entity relationship view
· Refine this model based on process encapsulation techniques
· Deliver a completed object model reflecting key objects for both the current environment and target requirements
· Optionally synchronize the evolution of relational DBMS and corresponding object oriented system using LTM
Entrance Criteria
This task, as much as any TIM task, is linked to techniques defined in
other development methods. Object modeling, within the context of this task, is
based on the Martin/Odell Object Oriented Analysis (OOA) model.
This and other prerequisite entrance criteria are listed below:
· Acceptance and availability of object modeling techniques as defined in the Martin/Odell model
· A corresponding object oriented, event driven development methodology that defines notations and techniques under an integrated approach
Note: The following entrance criteria may be derived from Subject Area/Entity
Type Analysis task or similar effort. Results of this task are highly dependent
upon the completeness and quality of the input model.
· Completion of entity relationship modeling effort via subject area/entity type analysis task or similar effort
Note: Logical Data Analysis provides an integrated, relational data model
derived from legacy systems and target requirements. This is an optional but
useful entrance criterion as identified below.
· Completion of interaction analysis via Inventory/Analysis business function/entity type analysis task
· Optionally, completion of the TIM logical data analysis task or similar effort providing a normalized data model
Note: The following supports process encapsulation step.
· Optionally, availability of populated LTM linking function and processes with data entity types
· Optionally, availability of interaction matrix of processes and entity types as specified in the Transformation interaction analysis task or similar approach
Roles/Skills
The personnel and skill requirements necessary to meet the object derivation
analysis task objectives are identified below.
· Redevelopment Expert
- Ability to navigate data models and systems as defined within this task and derive an object model
· Data Modeling Expert
- Expertise in object modeling and object oriented development using object oriented CASE tools
· Current Systems Expert
- Knowledge of the functionality of current data utilization
- Knowledge of the functionality of current data utilization
· Target System Functional Expert
- Knowledge of target data requirements
Input Requirements
The system components and related inputs required to initiate and complete
the object derivation analysis task are listed below.
Note: See Entrance Criteria section for notes regarding the optional nature
of certain input requirements.
· Entity relationship model or models derived during subject area/entity type analysis task
· Entity Type/Function Matrix developed during business function/entity type analysis task
· Optionally, normalized logical data model input from logical data analysis task
· Optionally, LTM repository populated with entity types, attributes, relationships and corresponding associations to functions and programs and other legacy objects
· Optionally, Entity Type/Process Matrix developed during interaction analysis task
Tool/Technology Support
Technologies supporting the object derivation analysis task include object
modeling and open systems repository tools. These tools are used to represent
information as required by this task.
Object modeling tool
Tool requirements focus on modeling the objects within a business area of the
organization. This tool should support basic object modeling requirements
according to the Martin/Odell Object Oriented Analysis (OOA) object diagramming
method. It should, as a minimum, include the following diagramming techniques:
This tool should also make objects available to event and business rule
diagramming facilities based on the Martin/Odell OOA and support process
encapsulation.
Additional features may include the ability to immediately prototype results
of object model modifications or to extend modeling notations based on other
requirements.
Open systems repository
An open repository provides an important, yet optional, capability to link
entity types with object types. This is important if analysts require backward
mapping of objects to entity types in order to implement the object oriented
system using an RDBMS.
Requirements include the ability to reflect objects, entities, attributes and
relationships as repository objects and link them based on the transformations
that occur within this task. A recommended legacy transition meta-model is shown
in the TIM Appendix section.
Task Steps
The object derivation analysis task is comprised of the following task steps:
