Download - GEM METADATA DEVELOPMENT Xiaoping Wang, Macrosearch Allen Macklin, PMEL and Bernard Megrey, AFSC
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