Authentication

The implementation of Metadata Service authentication is an integration of the Java Authentication and Authorization Service, the core API of J2SE 1.4, and the LDAP Login Module that connects to JPL Directory Server.

Authorization

The Metadata Service authorization is a simple user-based authorization. All users are permitted to the search and browse functions. An authenticated user can add, modify, and remove metadata objects. However, only an owner of the metadata objects is permitted to modify and remove functions.

RMI Interfaces

In addition to the CORBA protocol, the Metadata Registry also supports the RMI protocol. The syntax for all method interfaces stay unchanged except for the server name. Usually, the CORBA server is named "urn:eda:corba:JPL.EDM.MetadataRegistry" and the RMI server is named "urn:eda:rmi:JPL.EDM.MetadataRegistry". The property name, "jpl.eda.metadata.registry.urn", can be configured at the global property area to specify the server name. Running the client progr ams via the command line, the users will need to know the server name to connect to.

Permissible Values Enhancement

In the previous version of the Element Registry, the users could only enter a vector of values as the element's permissible values. This release allows the users to setup the enumerated permissible values in which each value may be attached with a meaning and a description for the value. Please check out the data dictionary schema, dataDictionary.dtd or dataDictionary.xsd, for its xml syntax to add the value meanings and descriptions to your data dictionaries.

Compliant to ISO/IEC 11179 standard for a data element, the Element Registry has included two additional attributes to the permissible value set to meet the requested requirement from the users especially the JPL Core Metadata Group. The following table lists the new attributes and their description and usage.

The following text contains an example for a data element, 'Document State', from JPL Core Metadata traslated and represented in MDR dictionary XML syntax:

...
<permitVal>
<value>0</value>
<valueMeaning>In Preparation</valueMeaning>
<valueDesc>insert description for this value here</valueDesc>
</permitVal>
<permitVal>
<value>1</value>
<valueMeaning>Invisible draft</valueMeaning>
<valueDesc>insert description for this value here</valueDesc>
</permitVal>
<permitVal>
<value>2</value>
<valueMeaning>Draft</valueMeaning>
<valueDesc>insert description for this value here</valueDesc>
</permitVal>
...
	

New Metadata Attributes

In addition to the Dublin Core Element Set, the Metadata Registry (MDR) has introduced a few attributes to the metadata set to meet the requested requirements from the users. The following table lists the added attributes and their description and usage.

Version Control

The newly added attribute, "Version", allows the users to perform version control at the user's level. The user can label the schema or dictionary resource with his/her own versioning scheme. At the system level, the MDR internally provides every registration action a sequence number, "Registry Identifier", which is increased by 1 for every transaction.

Web Directory Hierarchy

This feature allows web accessible to all versions of a registered schema or dictionary file in an organized directory hierarchy. The directory structure depends on the metadata attributes, "Identifier", "Registry Identifier", and "Version".

Users can organize their directory hierarchy for a schema or dictionary file through attributes "Identifier" and "Version". The MDR first looks at attribute "Identifier" and considers symbol "." as "/" to create subdirectories. Then, it creates a subdirectory with the text from attribute "Version" and places a copy of the schema or dictionary there. The attribute "URI" is set to this location.

For example, given "Identifier" with value of "MDR.Dictionary.DTD", "Version" with value of "1.0", and file name of "dataDictionary.dtd", the MDR generates a directory hierarchy of "$ROOTDIR/MDR/Dictionary/DTD/1.0/dataDictionary.dtd". The URI is set to "http://metadata/schema/MDR/Dictionary/DTD/1.0/dataDictionary.dtd".

The MDR also keeps a copy of the schema or dictionary file at another location determined by the attributes "Identifier" and "Registry Identifier". In the similar way, with the above example, the MDR places a copy in "$ROOTDIR/MDR/Dictionary/DTD/34/dataDictionary.dtd" providing "Registry Identifier" with a sequence number of 33.

In case of the attribute "Version" is left blank by the user, the subdiretory with value of "Version" is not created. The URI is set to the directory path composed with "Registry Identifier" instead. With the above example, the URI is set to "http://metadata/schema/MDR/Dictionary/DTD/33/dataDictionary.dtd".

When the user decides to promote the schema or dictionary registry, a copy of the file is placed at a higher level of the directory hierarchy depending only on attribute "Identifier". With the above example, the file's location is "$ROOTDIR/MDR/Dictionary/DTD/dataDictionary.dtd" and the URI is "http://metadata/schema/MDR/Dictionary/DTD/dataDictionary.dtd".

Promotion of Registry

This capability allows users to pro mote or release a dictionary or schema registered. The attribute "Status" is used to distinguish if the registry is published as an official document. The status is assigned by the MDR depending on the user's command. The value "REGISTERED" is set when a dictionary or schema is registered successfully. The value "RELEASED" is set when the user decides to promote or release it. A further study of approval policy is suggested. With the "promote" command, not only the status is switched to "RELEASED", the physical file is copied to a higher level in the web directory hierarchy and the URI is updated. See the Web Directory Hierachy section for detail.

Validation of Schema

This release includes the validation of a schema file during the registration process. The schema file can be in dtd syntax format or xml compliant syntax such as .xsd or .xsl files. The MDR reports errors encountered while it tries to register the schema file.

Validation of an Instance XML Document

This capability allows users to validate an instance xml file againsta dtd or xml schema reference embedded in the file. Do not confuse this capability with the validation of schema file.

General Manipulation

Some general manipulation features have been added to this release. Users are now able to cleanup the undesired registration of dictionary/schema or correct the typos in the metadata.

More on Profile Support

The resLocation in profile generated for a schema or dictionary registry is set to their URI.