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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
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
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
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.
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
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
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)
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