Logical Data Analysis

Objectives

This task supports the analysis and redesign of data definitions based on bottom-up derived definitions and, if applicable, the integration with top-down derived models. Bottom-up models can be refined for the purposes of creating a relational representation of the current system(s). They may also be merged with top-down models in order to refine and validate new designs.

Specific objectives include the following:

· Redesign the existing application data architecture

· Develop a bottom-up entity relationship model based on captured data from current system(s) of interest

· Refine and normalize bottom-up, captured model, as required to redesign current data representations

· Merge bottom-up model with top-down model and refine as required to validate the integrity of top-down model

Entrance Criteria

The entrance criteria for the logical data analysis task are listed below.

· Completion of Inventory/Analysis, data definition analysis task

· Completion of Inventory/Analysis, subject area/entity type analysis

· Completion of Positioning, data definition rationalization task for data definitions of interest

· Completion of Positioning, literal analysis and removal task

· Completion of target (top-down) Entity Relationship (ER) model

· Population of LTM repository model as completed in entrance criteria tasks

Roles/Skills

The personnel and skill requirements necessary to meet the logical data analysis task objectives are identified below.

· Redevelopment Expert

- Ability to determine best mix of top-down/bottom-up analysis and how to integrate these techniques

- Expertise in capturing, building, merging bottom-up models & integrating those models with top-down views

· Current Systems Expert

- Knowledge of existing system source environment

- Knowledge of the functionality of current data utilization

· Target System Functional Expert

- Knowledge of target data requirements

· Data Modeling Expert

- Expert at building bottom-up and top-down data models

· User Requirements Analyst

- Ability to provide input to strategic model

Input Requirements

The system components and related inputs required to initiate and complete the logical data analysis task are listed below.

· Entity relationship model or models derived during subject area/entity type analysis task

· Rationalized representation of primary I/O record definitions (layouts) from data definition rationalization

· Current physical systems environment including access to program, Copy or DDL source code

· Access to active data dictionaries defining record, segment and schema definition

· Target application, top-down normalized logical relational model

· Functional assessment Form 005 - data entity mapping factors

· Legacy transition meta-model (LTM) populated with all system components and relationships based on use in prior TIM tasks

Tool/Technology Support

Technologies supporting the logical data analysis task include data reverse engineering, I-CASE modeling, and open systems repository tools. These tools are used to represent information as required by this task.

Data Reverse Engineering Tool

Tools for this task focus on the capture, import and manipulation of data definitions (and in some cases physical data) with the intent of deriving a logical model. This is typically in the form of an entity relationship model for this task. Features include:

Note: Various capture tools support COBOL, PL/I, IDMS Schema, IMS DBD and PSB, and DB/2 DDL as input to process.

· Ability to capture existing data definitions including source program layouts (COBOL, PL/I, etc.), relational tables, schema and other formats

· Ability to represent records as entities and elements as attributes in a tool encyclopedia

The following features are technically optional but, in practicality, required for any efforts other than trivial systems redevelopment. Step level tool guidelines reflect this requirement.

· Ability to apply artificial intelligence to captured data representations to create an ER model

· Ability to merge multiple models (bottom-up and/or top-down)

· Ability to assist in producing a normalized data model from an ER model

Optional - based on tool availability.

· Ability to capture record layouts and input physical data value to derive an ER model

I-CASE modeling tool

I-CASE analysis workstations provide a mechanism for specifying current and target process action diagrams. While automated input facility is not available in all formats for this type of model, captured rules may be respecified into bottom up/top down process action diagrams with this technology.

Open systems repository

A repository provides an important, yet optional, capability to link business areas, systems and components using the legacy transition meta-model. In this task, repository is used to trace current entities and attributes to physical data structures as well as to link current entities to target entities and attributes.

Task Steps

The logical data analysis task is comprised of the following task steps:

	Load & Merge Bottom-Up ER Model(s)
	Refine Bottom-Up Derived ER Model<
	Merge Top-Down & Bottom-Up ER Models
	Normalize Merged ER Model
	Review and Sign-Off Normalized Data Model