34 Administering Oracle XML DB

Dynamic Protocol Registration of FTP and HTTP(S) Services with Local Listener

Oracle XML DB installation dynamically registers FTP and HTTP(S) services with the local listener. You can perform start, stop, and query with lsnrctl. For example:

• start: lsnrctl start

• stop: lsnrctl stop

• query: lsnrctl status

Post-Installation

After the manual installation, carry out these tasks:

1. Add the following dispatcher entry to the init.ora file:

   dispatchers="(PROTOCOL=TCP) (SERVICE=<sid>XDB)"
   

2. Restart the database and the listener to enable Oracle XML DB protocol access.

<xdbconfig> (Top-Level Element)

Element <xdbconfig> is the top-level element. Its structure is as follows:

<xdbconfig> 
    <sysconfig> ... </sysconfig> 
    <userconfig> ... </userconfig> 
</xdbconfig>

Element <sysconfig> defines system-specific, built-in parameters. Element <userconfig> lets you store new custom parameters.

<sysconfig> (Child of <xdbconfig>)

Element <sysconfig> is a child of <xdbconfig>. Its structure is as follows:

<sysconfig> 
    general parameters
    <protocolconfig> ... </protocolconfig> 
</sysconfig> 

Element <sysconfig> includes as content several general parameters that apply to all of Oracle XML DB, such as the maximum age of an access control list (ACL) and whether or not Oracle XML DB is case sensitive. Child <protocolconfig> contains protocol-specific parameters.

<userconfig> (Child of <xdbconfig>)

Element <userconfig> is a child of <xdbconfig>. It contains any parameters that you may want to add.

<protocolconfig> (Child of <sysconfig>)

Element <protocolconfig> is a child of <sysconfig>. Its structure is as follows:

<protocolconfig> 
  <common> ... </common> 
  <ftpconfig> ... </ftpconfig> 
  <httpconfig> ... </httpconfig> </protocolconfig> 

Under <common>, Oracle Database stores parameters that apply to all protocols, such as MIME-type information. Parameters that are specific to protocols FTP and HTTP(S) are in elements <ftpconfig> and <httpconfig>, respectively.

<httpconfig> (Child of <protocolconfig>)

Element <httpconfig> is a child of <protocolconfig>. Its structure is as follows:

<httpconfig>
  ...
  <webappconfig>
    ...
    <servletconfig>
      ...
      <servlet-list>
        <servlet> ... </servlet>
        ...
      </servlet-list>
    </servletconfig>
  </webappconfig>
  ...
  <plsql> ... </plsql>
</httpconfig>

Element <httpconfig> has the following child elements, in addition to others:

• <webappconfig> – used to configure Web-based applications. This includes Web application-specific parameters, such as icon name, display name for the application, and a list of servlets.

  Element <servletconfig> is a child of <webappconfig> that is used to define servlets. It has child <servlet-list>, which has child <servlet> (see "<servlet> (Descendant of <httpconfig>)").

• <plsql>^Foot 1  – used to define global configuration parameters when configuring the embedded PL/SQL gateway. Each global parameter is defined with a child element of <plsql>. The element name is the same as the global parameter name. The element content is the same as the parameter value.

  The recommended way to configure the embedded PL/SQL gateway is to use the procedures in PL/SQL package DBMS_EPG, not to edit file xdbconfig.xml.

<servlet> (Descendant of <httpconfig>)

An optional <plsql> element, child of <servlet>, configures the embedded PL/SQL gateway servlet. However, the recommended way to configure the embedded gateway is to use the procedures in PL/SQL package DBMS_EPG, not to edit file xdbconfig.xml.

Element <plsql> has a child element for each embedded PL/SQL DAD attribute^Foot 2  that is needed to configure the embedded gateway. All such children are optional. The element name is the same as the DAD attribute name. The element content is the same as the DAD-attribute value.

Element <servlet> is a descendent of <httpconfig> – see "<httpconfig> (Child of <protocolconfig>)". It is used to configure servlets, including Java servlets and embedded PL/SQL gateway servlets.

Oracle XML DB Configuration File Example

The following is a sample Oracle XML DB configuration file:

<xdbconfig xmlns="http://xmlns.oracle.com/xdb/xdbconfig.xsd" 
                 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
                 xsi:schemaLocation="http://xmlns.oracle.com/xdb/xdbconfig.xsd 
                                    http://xmlns.oracle.com/xdb/xdbconfig.xsd">
   <sysconfig>
      <acl-max-age>900</acl-max-age>
      <acl-cache-size>32</acl-cache-size> 
      <invalid-pathname-chars>,</invalid-pathname-chars>
      <case-sensitive>true</case-sensitive>       
      <call-timeout>300</call-timeout>
      <max-link-queue>65536</max-link-queue> 
      <max-session-use>100</max-session-use>
      <persistent-sessions>false</persistent-sessions> 
      <default-lock-timeout>3600</default-lock-timeout>
      <xdbcore-logfile-path>/sys/log/xdblog.xml</xdbcore-logfile-path>
      <xdbcore-log-level>0</xdbcore-log-level>
      <resource-view-cache-size>1048576</resource-view-cache-size> 
    
      <protocolconfig> 
          <common>
             <extension-mappings>
                <mime-mappings>
                  <mime-mapping>
                    <extension>au</extension>
                    <mime-type>audio/basic</mime-type>
                  </mime-mapping>
                  <mime-mapping>
                    <extension>avi</extension>
                    <mime-type>video/x-msvideo</mime-type>
                  </mime-mapping>
                  <mime-mapping>
                    <extension>bin</extension>
                    <mime-type>application/octet-stream</mime-type>
                  </mime-mapping>
                </mime-mappings> 

                <lang-mappings>
                  <lang-mapping>
                    <extension>en</extension>
                    <lang>english</lang>
                  </lang-mapping>
                </lang-mappings>

                <charset-mappings>
                </charset-mappings>

                <encoding-mappings>
                  <encoding-mapping>
                    <extension>gzip</extension>
                    <encoding>zip file</encoding>      
                  </encoding-mapping>
                  <encoding-mapping>
                    <extension>tar</extension>
                    <encoding>tar file</encoding>        
                  </encoding-mapping>
                </encoding-mappings>
             </extension-mappings>

             <session-pool-size>50</session-pool-size>
             <session-timeout>6000</session-timeout>
          </common>

          <ftpconfig>
            <ftp-port>2100</ftp-port>
            <ftp-listener>local_listener</ftp-listener>
            <ftp-protocol>tcp</ftp-protocol>
            <logfile-path>/sys/log/ftplog.xml</logfile-path>
            <log-level>0</log-level>
            <session-timeout>6000</session-timeout>
            <buffer-size>8192</buffer-size> 
          </ftpconfig>

          <httpconfig>
            <http-port>8080</http-port>
            <http-listener>local_listener</http-listener>
            <http-protocol>tcp</http-protocol>
            <max-http-headers>64</max-http-headers> 
            <session-timeout>6000</session-timeout>
            <server-name>XDB HTTP Server</server-name>
            <max-header-size>16384</max-header-size>
            <max-request-body>2000000000</max-request-body>
            <logfile-path>/sys/log/httplog.xml</logfile-path>
            <log-level>0</log-level>    
            <servlet-realm>Basic realm="XDB"</servlet-realm>
            <webappconfig>
              <welcome-file-list>
                <welcome-file>index.html</welcome-file>
                <welcome-file>index.htm</welcome-file>
              </welcome-file-list>
              <error-pages>
              </error-pages>
              <servletconfig> 
                <servlet-mappings>
                  <servlet-mapping>
                    <servlet-pattern>/oradb/*</servlet-pattern>
                    <servlet-name>DBURIServlet</servlet-name>
                  </servlet-mapping>
                </servlet-mappings>
                               
                <servlet-list>
                  <servlet>
                    <servlet-name>DBURIServlet</servlet-name>
                    <display-name>DBURI</display-name>
                    <servlet-language>C</servlet-language>
                    <description>Servlet for accessing DBURIs</description>
                    <security-role-ref>
                      <role-name>authenticatedUser</role-name>
                      <role-link>authenticatedUser</role-link>
                    </security-role-ref>
                  </servlet>
                </servlet-list>
              </servletconfig>
            </webappconfig>
          </httpconfig> 
      </protocolconfig>
    <xdbcore-xobmem-bound>1024</xdbcore-xobmem-bound> 
    <xdbcore-loadableunit-size>16</xdbcore-loadableunit-size> 
   </sysconfig>
</xdbconfig>

Oracle XML DB Configuration API

You can access the Oracle XML DB configuration file, xdbconfig.xml, the same way you access any other XML schema-based resource in the hierarchy. It can be accessed using FTP, HTTP(S), WebDAV, Oracle Enterprise Manager, or any of the resource and Document Object Model (DOM) APIs for Java, PL/SQL, or C (OCI).

For convenience, you can use PL/SQL package DBMS_XDB package for configuration access. It exposes the following functions and procedures:

• cfg_get – Returns the configuration information for the current session.

• cfg_refresh – Refreshes the session configuration information using the current configuration file. Typical uses of cfg_refresh include the following:

  • You have modified the configuration and now want the session to pick up the latest version of the configuration information.

  • It has been a long running session, the configuration has been modified by a concurrent session, and you want the current session to pick up the latest version of the configuration information.

• cfg_update – Updates the configuration information, writing the configuration file. A COMMIT is performed.

Example 34-2 updates parameters ftp-port and http-port in the configuration file.

DECLARE
  v_cfg XMLType;
BEGIN
  SELECT updateXML(DBMS_XDB.cfg_get(), 
                   '/xdbconfig/descendant::ftp-port/text()',
                   '2121', 
                   '/xdbconfig/descendant::http-port/text()', 
                   '19090')
    INTO v_cfg FROM DUAL;
  DBMS_XDB.cfg_update(v_cfg);
  COMMIT; 
END;
/ 

If you have many parameters to update, then it can be easier to use FTP, HTTP(S), or Oracle Enterprise Manager to update the configuration.

Configuring Default Namespace to Schema Location Mappings

Oracle XML DB identifies schema-based XMLType instances by pre-parsing the input XML document. If the appropriate xsi:schemaLocation or xsi:noNamespaceSchemaLocation attribute is found, then the specified schema location URL is used to consult the registered schema. If the appropriate xsi: attribute is not found, the XML document is considered to be non-schema-based.Oracle XML DB provides a mechanism to configure default schema location mappings. If the appropriate xsi: attribute is not specified in the XML document, the default schema location mappings is used. Element schemaLocation-mappings of the Oracle XML DB configuration XML schema, xdbconfig.xsd, can be used to specify the mapping between (namespace, element) pairs and the default schema location. If the element value is empty, the mapping applies to all global elements in the specified namespace. If the namespace value is empty, it corresponds to the null namespace.

The definition of the schemaLocation-mappings element is as follows:

 <element name="schemaLocation-mappings"
          type="xdbc:schemaLocation-mapping-type" minOccurs="0"/> 
 <complexType name="schemaLocation-mapping-type"><sequence>
      <element name="schemaLocation-mapping"
               minOccurs="0" maxOccurs="unbounded">
      <complexType><sequence>
        <element name="namespace" type="string"/>
        <element name="element" type="string"/>
        <element name="schemaURL" type="string"/>
      </sequence></complexType>
      </element></sequence> 
 </complexType> 

The schema location used depends on mappings in the Oracle XML DB configuration file for the namespace used and the root document element. For example, assume that the document does not have the appropriate xsi: attribute to indicate the schema location. Consider a document root element R in namespace N. The algorithm for identifying the default schema location is as follows:

1. If the Oracle XML DB configuration file has a mapping for N and R, the corresponding schema location is used.

2. If the configuration file has a mapping for N, but not R, the schema location for N is used.

3. If the document root R does not have any namespace, the schema location for R is used.

For example, suppose that your Oracle XML DB configuration file includes the following mapping:

      <schemaLocation-mappings>
         <schemaLocation-mapping>
            <namespace>http://www.oracle.com/example</namespace>
            <element>root</element>
            <schemaURL>http://www.oracle.com/example/sch.xsd</schemaURL>
         </schemaLocation-mapping>
         <schemaLocation-mapping>
            <namespace>http://www.oracle.com/example2</namespace>
            <element></element>
            <schemaURL>http://www.oracle.com/example2/sch.xsd</schemaURL>
         </schemaLocation-mapping>
         <schemaLocation-mapping>
           <namespace></namespace>
           <element>specialRoot</element>
           <schemaURL>http://www.oracle.com/example3/sch.xsd</schemaURL>
         </schemaLocation-mapping>
      </schemaLocation-mappings>
 

The following schema locations are used:

• Root element = root

  • Namespace = http://www.oracle.com/example

  • Schema URL = http://www.oracle.com/example/sch.xsd

  This mapping is used when the instance document specifies:

  <root xmlns="http://www.oracle.com/example/">
  

• Root element = null (any global element in the namespace)

  • Namespace = http://www.oracle.com/example2

  • Schema URL = http://www.oracle.com/example2/sch.xsd

  This mapping is used when the instance document specifies:

  <root xmlns="http://www.oracle.example2">
  

• Root element = specialRoot

  • Namespace = null (i.e null namespace)

  • Schema URL = http://www.oracle.com/example3/sch.xsd

  This mapping is used when the instance document specifies:

  <specialRoot>
  

Configuring XML File Extensions

Oracle XML DB Repository treats certain files as XML documents, based on their file extensions. When such files are inserted into the repository, Oracle XML DB pre-parses them to identify the schema location (or uses the default mapping if present) and inserts the document into the appropriate default table. By default, the following extensions are considered as XML file extensions: xml, xsd, xsl, xlt. In addition, Oracle XML DB provides a mechanism for applications to specify other file extensions as XML file extensions. The xml-extensions element is defined in the configuration schema, http://xmlns.oracle.com/xdb/xdbconfig.xsd, as follows:

 <element name="xml-extensions"
          type="xdbc:xml-extension-type" minOccurs="0"/> 
 
 <complexType name="xml-extension-type"><sequence>
      <element name="extension" type="xdbc:exttype"
               minOccurs="0" maxOccurs="unbounded">
      </element></sequence> 
  </complexType> 

For example, the following fragment from the Oracle XML DB configuration file, xdbconfig.xml, specifies that files with extensions vsd, vml, and svgl should be treated as XML files:

 <xml-extensions>
   <extension>vsd</extension>
   <extension>vml</extension>
   <extension>svgl</extension>
 </xml-extensions>