Schema Cache

The XML Editor provides a schema cache located in the %InstallRoot%\Xml\Schemas directory. The schema cache is global to all users on your computer and includes standard XML Schemas that are used for IntelliSense and XML document validation.

The XML editor can also find schemas located in the solution, schemas specified in the Schemas field of the document Properties window, and schemas identified by the xsi:schemaLocation and xsi:noNamespaceSchemaLocation attributes.

The following table describes the schemas that are installed with the XML Editor.

Updating Schemas in the Cache

The editor loads the schema cache directory when the XML editor package is loaded and watches for any changes while running. If a schema has been added, it is automatically loaded into an in-memory index of known schemas. If a schema has been removed, it is automatically removed from the in-memory index. If a schema has been updated, it automatically invalidates the in-memory cache of this schema.

The XML editor also supports any number of schema catalog files in the schema cache directory. Schema catalogs can point to other locations for schemas that you always want the editor to know about. The catalog.xsd file defines the format for the catalog file and is included in the schema cache directory. The catalog.xml file is the default catalog and it contains links to other schemas in the %InstallDir%. The following is a sampling of the catalog.xml file:

<SchemaCatalog xmlns="https://schemas.microsoft.com/xsd/catalog">
  <Schema href="%InstallDir%/help/schemas/Favorites.xsd" targetNamespace="urn:Favorites-Schema"/>
  <Schema href="%InstallDir%/help/schemas/Links.xsd" targetNamespace="urn:Links-Schema"/>
  <Schema href="%InstallDir%/help/schemas/MyHelp.xsd" targetNamespace="urn:VSHelp-Schema"/>
</SchemaCatalog>

The href attribute can be any file path or http URL pointing to the schema. The file path can be relative to the catalog document. The following variables, delimited by %%, are recognized by the editor and will be expanded in the path:

• InstallDir

• System

• ProgramFiles

• Programs

• CommonProgramFiles

• ApplicationData

• CommonApplicationData

• LCID

  The catalog document can include a Catalog element, which points to other catalogs. You can use the Catalog element to point to a central catalog shared by your team or company, or an online catalog shared with your business partners. The href attribute is the file path or http URL for the other catalogs. The following is an example of the Catalog element:

<Catalog href="file://c:/xcbl/xcblCatalog.xml"/>

The catalog can also control how schemas are associated with XML documents using the special Association element. This element associates schemas that have no target namespace with a particular file extension, which can be useful because the XML Editor does not do any auto-association of schemas that do not have a targetNamespace attribute. In the following example the Association element associates the dotNetConfig schema with all files that have the "config" file extension:

<Association extension="config" schema="%InstallDir%/xml/schemas/dotNetConfig.xsd"/>

Localized Schemas

In many cases the catalog.xml file does not contain entries for localized schemas. You can add additional entries to the catalog.xml file that point to the localized schema directory.

In the following example a new Schema element has been created that uses the %LCID% variable to point to the localized schema.

<Schema href="%InstallRoot%/Common7/IDE/Policy/Schemas/%LCID%/TDLSchema.xsd"
  targetNamespace="https://www.microsoft.com/schema/EnterpriseTemplates/TDLSchema"/>

Changing the Location of the Schema Cache

You can customize the location for the schema cache using the Miscellaneous options page. If you have a directory of favorite schemas, the editor can be configured to use those schemas instead.

To change the schema cache location

1. From the Tools menu, select Options.

2. Expand Text Editor, expand XML, and then click Miscellaneous.

3. Click the Browse button on the Schemas field.

4. Select the folder for the schema cache and click OK.

To add another directory of common schemas

1. Edit the catalog.xml file in the XML editor schema cache directory.

2. Add a new <Catalog href="…"/> element that points to the directory of additional schemas.

3. Save your changes.

   The catalog is automatically reloaded.

See Also

XML Editor