Metadata

Metadata

1.Metadata defined

Data about data, It contains

Location and description of dw

Names, definition, structure and content of the dw

Identification of data sources

Integration and transformation rules to populate dw and end user

Information delivery information

Data warehouse operational information

Security authorization

Metadata interchange initiative

It is used for develop the standard specifications to exchange metadata

2 Metadata Interchange initiative

It used for develop the standard specifications for metadata interchange format it will allow Vendors to exchange common metadata for avoid difficulties of exchanging, sharing and Managing metadata

The initial goals include

Creating a vendor-independent, industry defined and maintained standard access mechanism and standard API

Enabling individual tools to satisfy their specific metadata for access requirements, freely and easily within the context of an interchange model

Defining a clean simple, interchange implementation infrastructure

Creating a process and procedures for extending and updating

Metadata Interchange initiative have define two distinct Meta models

The application Metamodel- it holds the metadata for particular application

The metadata Metamodel- set of objects that the metadata interchange standard can be used

to describe

The above models represented by one or more classes of tools (data extraction, cleanup, replication)

Metadata interchange standard framework

Metadata itself store any type of storage facility or format such as relational tables, ASCII files ,fixed format or customized formats the Metadata interchange standard framework will translate the an access request into interchange standard syntax and format

Metadata interchange standard framework - Accomplish following approach

Procedural approach-

ASCII batch approach-ASCII file containing metadata standard schema and access parameters is reloads when over a tool access metadata through API

Hybrid approach-it follow a data driven model by implementing table driven API, that would support only fully qualified references for each metadata

The Components of the metadata interchange standard frame work.

The standard metadata model-which refer the ASCII file format used to represent the metadata

The standard access framework-describe the minimum number of API function for communicate metadata.

Tool profile-the tool profile is a file that describes what aspects of the interchange standard metamodel a particular tool supports.

The user configuration-which is a file describing the legal interchange paths for metadata in the users environment.

3. Metadata Repository

It is implemented as a part of the data warehouse frame work it following benefits

It provides a enterprise wide metadata management.

It reduces and eliminates information redundancy, inconsistency

It simplifies management and improves organization control

It increase flexibility, control, and reliability of application development

Ability to utilize existing applications

It eliminates redundancy with ability to share and reduce metadata

4. Metadata management

The collecting, maintain and distributing metadata is needed for a successful data warehouse implementation so these tool need to be carefully evaluated before any purchasing decision is made

5. Implementation Example

Implementation approaches adopted by platinum technology, R&O, prism solutions, and logical works

5.1 PLATINUM REPOSITORY

It is a client /server repository toolset for managing enterprise wide metadata, it provide a open solutions for implementing and manage the metadata

The toolset allows manage and maintain heterogeneous, client/server environment

Platinum global data dictionary repository provides functionality for all corporate information

It designed for reliable, system wide solutions for managing the metadata.

5.2 R&O: The POCHADE repository

It is a client/server based application that has document management.

The advantages

Performance-sub-second response time

Scalability-it runs on anywhere from laptop to a main frame.

Capacity-it support very large repository implementations

5.3 Prism solutions

It offered by prism directory manager it integrate and manage all Metadata definition The directory manager can

Import business model from CASE TOOLS

Import metadata definitions from prism warehouse manager.

Export metadata into catalogs

The directory manager consist of three components

Information directory-containing appropriate entries

Directory builder-customize views, imports and exports metadata

Directory navigator-navigate the metadata and launches quires into the warehouse. Prism directory manager answers user question about

What data exists in the data warehouse?

Where to find data.

What the original source of data

How summarizations where created

What transformations were used?

Who is responsible for correcting errors?

Prism directory manager import metadata from several sources for build the information directory

Collect the technical metadata by prism warehouse manager

It exchange the metadata through metal ink

The directory manager enhances data warehouse use in several ways

User can identify and retrieve relevant information for analysis with easy poin-and click navigation

Customized navigational paths for different groups of user

5.4 Logical works universal directory

It is a recent group of metadata repository tools it act as the hub of all data warehouse activity The activities are

Inventorying source data

Designing the data warehouse

Mapping source to target data

Populating data warehouse

Analyzing in the data warehouse

Evolving the data warehouse.

Increasing the quality of business decisions

Universal directory consist of two components

Universal Explorer.

Directory administrator

6. Metadata trends

The process of integrating external and external data into the warehouse faces a number of challenges

Inconsistent data formats

Missing or invalid data

Different level of aggregation

Semantic inconsistency

Different types of database (text, audio, full-motion, images, temporal databases, etc..)

The above issues put an additional burden on the collection and management of common metadata definition this is addressed by Metadata Coalition’s metadata interchange specification (mentioned above)