GEM METADATA DEVELOPMENT

Xiaoping Wang, Macrosearch

Allen Macklin, PMEL and Bernard Megrey, AFSC

TOPICS

• Introduction about EML metadata standard• GEM metadatabase development• Advantages of Oracle Database

GOAL

Generate EML-compliant metadata documents for the datasets that are in the interests of GEM (Gulf of Alaska Ecosystem Monitoring, a program of the Exxon Valdez Oil spill Trustee Council).

WHAT IS EML

• Stands for Ecological Metadata Language.• Exists as a set of XML Schema documents.• Allows for the structural expression of

metadata elements.

ADVANTAGES OF EML

• Includes almost all metadata elements covered by other metadata standards.

• Can be used in a modular and extensible manner.

• Can be used to describe:- Dataset- Literature- Software- Protocol

USE OF DATASET MODULE

• Data table• Spatial raster• Spatial vector• Stored procedure• Other entity

METADATA ELEMENTS(1) General Information

• Dataset title, abstract and purpose• Data creator(s), metadata provider(s) and

contact information• Keywords• Data maintenance• Data distribution• Geographic/time coverage

METADATA ELEMENTS(2) Research Project Information

• Project title and description• Participants and their roles• Funding sources• Study area description• Design description

METADATA ELEMENTS(3) Method Information

• Method description• Sampling• Instruments• Software

METADATA ELEMENTS(4) Data Information

• Table name and description• Attribute name and definition• Attribute domain code and definition• Data unit• Data precision• Missing value code• Accuracy

METADATABASE DEVELOPMENT(1) Database Table Design

• Main table – One row for each dataset• Other tables – One or multiple rows for each

dataset.- Keywords- Personnel- Data tables - Table attributes- Attribute domain codes- Instruments.

METADATABASE DEVELOPMENT(2) Integrity Constraints

• Primary key – dataset record ID in main table• Foreign key – dataset record ID in other tables• Check constraints – allowed values of EML

elements• NOT Null constraints – mandatory EML

elements

METADATABASE DEVELOPMENT(3) Stored Procedures

• Handle repeated database operations• Input large text files

METADATA FILE GENERATION

• Java Program development– Read data from metadatabase– Generate EML-compliant metadata files

• Validate metadata files against EML– no XML errors – no EML errors

ORACLE DATABASE

• Advantages– Can be used on multiple platforms

(Windows, Unix, and Linux…)– Has the best security features– Has the highest availability and reliability– Has a powerful language (PL/SQL) for data

query and manipulation• Disadvantage

– More expensive

FUNDAMENTAL DATA SECURITY REQUIREMENTS

• Confidentiality - users can see only the data that they are supposed to see.

• Integrity - data is protected from deletion and corruption.

• Availability - data is available to authorized users without delay.

DATA AVAILABILITY(1) Real Application Clusters

DATA AVAILABILITY(2) Replication

DATA AVAILABILITY(3) Data Guard

DATA AVAILABILITY(4) Stream

DATA MANAGEMENT

• Database management - Data storage • Metadata management - Data documentation • Data availability - Online data share