Creating a Metadata Service

Creating a Metadata Service

Like Image and Feature Services, a Metadata Service starts with an ArcXML configuration file; however, you can't create or modify a Metadata Service's ArcXML configuration file using ArcIMS Author. To help you create your Metadata Service, a sample file is installed with ArcIMS that you can edit in a text editor.

ArcIMS relies on the capabilities of ArcSDE and a relational database to store, search for, retrieve, and index metadata documents. Before starting your first Metadata Service, discuss configuring a relational database for XML columns with your database administrator. You should also work with the database administrator to schedule when updated documents should be indexed and how often the service's text indexes are optimized.

Changing some the default values for the XML DBTUNE parameters lets you customize storage and indexing properties and may improve your Metadata Service’s performance over time. You should also review the database's text indexing documentation; you may want to adjust some of the text indexing settings using the DBTUNE parameters. DBTUNE changes take effect the next time you create a Metadata Service. You can't apply these changes to an existing Metadata Service. After creating a new Metadata Service with a custom DBTUNE keyword you can migrate your documents from your existing service to the new one using the MDExport and MDImport commands.

Changing some additional ArcSDE initialization parameters such as MAXBLOBSIZE may help when publishing large documents to a Metadata Services, or importing and exporting large documents to and from the service with MDImport and MDExport.

After deciding on the settings you will use for your Metadata Service, reflect those settings in the ArcXML configuration file.

ArcSDE connection information—You must provide the appropriate ArcSDE connection information for the user who will own the Metadata Service. This user must be granted sufficient permissions to create data in the geodatabase as well as any additional permissions required for ArcSDE XML columns in your relational databases.

Table name prefix—The prefix used to name the objects created in the database by ArcIMS; "imsmetadata" by default. If the tables identified by the prefix already exist in the database, the Metadata Service will attempt to use the existing tables when starting the service. To create a different Metadata Service that contains a different set of documents or has different storage and indexing parameters specify a different prefix.

ArcSDE configuration—The ArcSDE DBTUNE configuration keyword that will be used to determine the storage location of the data, the text indexing properties, and so on when the Metadata Service's tables and indexes are created in the database. If a configuration keyword is not specified, the DEFAULTS keyword will be used. If you are creating a Gazetteer Metadata Service and you are using Oracle or DB2, specify the IMS_GAZETTEER keyword instead. Alternatively, specify a custom DBTUNE keyword. For SQL Server, ideally you should create and use a custom IMS_GAZETTEER keyword when creating a Gazetteer Metadata Service to associate its index with a separate full text catalog.

Learn more about DBTUNE configuration parameters for ArcSDE XML columns

Compressed documents—All documents are compressed in the database by default to reduce storage size and improve performance. Documents can be stored uncompressed to support custom applications with all relational databases except Informix.

Validation—Documents can be validated to see if they contain the information required by Metadata Services to support basic searches in Metadata Explorer and ArcCatalog. This value is set to "true" in the sample Metadata Service ArcXML configuration file to better support accessing and searching the service using the Metadata Explorer application. If a value is not provided, the default value "false" is used. With validation, documents lacking the required information should not be published; validation is expected to be performed by the client application and the client is expected to take appropriate action if validation fails. If the client does not validate documents and reject documents that don't pass, the Metdata Service will publish the document but you may never be able to find the document with a search. Validation is not expected to ensure that document content conforms to a metadata standard.

Updating text indexes—When set to "automatic", the default, text indexes will be updated immediately after each document is published; this leads to fragmented indexes and decreased performance over time. Index_words can be left as "automatic" for SQL Server. While useful when starting out, set change this value to "manual" for Oracle or DB2 once you know your Metadata Service is working properly. With the manual setting, the database’s text indexes must be updated periodically, by running the aimsmetaindx command as part of your nightly schedule or scheduling text index updates in the database.

Searching individual metadata elements—An ArcSDE XPath index definition file can be used to specify which XML elements in the published documents will be indexed so their contents can be searched. The default XPath index definition file is <ArcIMS Install Location>/Metadata/Commands/index_def.txt file, which supports all of the ArcCatalog search criteria and the default searches available with the CSW Connector, Metadata Explorer, and the GIS Portal Toolkit. If you provide a custom index definition file instead, it must reside on the machine where ArcIMS is installed.

Administrative table—Used to manage published documents with a custom application. Administrative tables must be created before starting a Metadata Service.

After editing the configuration file, you can start the Metadata Service using Administrator. However, before publishing documents, you must enable authentication and define user names and passwords for accessing the service.

Editing the MetadataServer.axl file

  1. In a text editor, edit the MetadataServer.axl file in the AXL directory created on installation. On Windows, this file is located by default at C:\ArcIMS\AXL\Metadata.

  2. Edit the SDEWORKSPACE element and type in the appropriate information to connect to ArcSDE.

  3. Set TABLE_NAME prefix to a unique name for the Metadata Service objects in the database. The default value is imsmetadata. This name should not contain spaces or be more than 14 characters in length.

  4. Set CONFIG_PARAMETER keyword to an appropriate ArcSDE DBTUNE configuration keyword. The DEFAULTS keyword will be used if another keyword is not provided. If the Metadata Service will contain gazetteer places and the RDBMS is Oracle, DB2, or SQL Server, use the IMS_GAZETTEER keyword.

  5. Set CONFIG_PARAMETER compress to true or false. When set to true, XML documents are compressed when stored in the database.

  6. Set METADATA_CONTENT validate to true or false. When set to true, documents should be validated before they are published to ensure they contain the five pieces of information required for Metadata Explorer and ArcCatalog.

  7. Set METADATA_CONTENT index_words to “automatic” or “manual”. When set to manual, use the aimsmetaindx command or a scheduled database job to update the database’s text indexes with content from recently published documents.

  8. Set INDEX_DEFINITION index_file to the location of an ArcSDE XPath index definition file; the full path to the file must be provided. By default, the index_def.txt file installed with ArcIMS at <ArcIMS Install Location>\Metadata\Commands will be used.

Starting a Metadata Service

  1. Start Administrator and click Services in the left panel to display the currently running services.

  2. Click the New Service button.

  3. Type the Name for your Metadata Service. This is the name people will see when they access your Metadata Service.

  4. Before starting your first Metadata Service, read ArcSDE and database configuration.

  5. Locate the Metadata Service configuration file that you’ve created. The sample file is MetadataServer.axl.

  6. Click the Virtual Server dropdown arrow and click MetadataServer1.

  7. Type the Directory Location where ArcIMS will store the output XML files returned when a user searches or browses your Metadata Service.

  8. Type the HTTP Location associated with the directory location specified in the step above.

  9. Click OK.

Creating a new Metadata Service

Related topics

Setting up your Metadata Service

Adding an administrative table to a service

 



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