Resource Managers
1. Introduction
A resource manager is an Orbeon PresentationServer (OPS) component
responsible for reading and writing XML and other resources like binary and text
documents. A resource manager abstracts the actual mechanisms used to store
resources. An important benefit of using such an abstraction is that it is possible
to store all your application files in a sandbox which can be moved at will within a
filesystem or between storage mechanisms. For instance, resources can be stored:
-
As files on disk (using your operating system's file system)
-
As resources within a WAR file
-
As resources within one or more JAR files
-
In a WebDAV server
A resource manager is both used:
This chapter describes the different types of resource managers and explains their
configuration.
2. General Configuration
A single resource manager is initialized per OPS web application. Configuration is
handled in the web application descriptor (web.xml ) by setting a number
of context parameters. The first parameter indicates the resource manager factory:
<context-param> <param-name>oxf.resources.factory</param-name> <param-value>org.orbeon.oxf.resources.DefaultResourceManagerFactory </param-value> </context-param>
Other properties depend on the resource manager defined by the factory. These
properties are described in the following sections.
3. Filesystem Resource Manager
Purpose |
Loading resources from a filesystem |
Factory |
org.orbeon.oxf.resources.FilesystemResourceManagerFactory
|
Properties |
oxf.resources.filesystem.sandbox-directory
|
The Filesystem resource manager loads resources from a filesystem. This is
especially useful during development, since no packaging of resources is necessary.
The oxf.resources.filesystem.sandbox-directory property can be used to
define a sandbox, and if used must point to a valid directory on a filesystem. If
not specified, no sandbox is defined, and it is possible to access all the files on
the filesystem.
Using the Filesystem resource manager without a sandbox is particularly useful for
command-line applications.
3.1. Example
<context-param> <param-name>oxf.resources.factory</param-name> <param-value>org.orbeon.oxf.resources.FilesystemResourceManagerFactory </param-value> </context-param> <context-param> <param-name>oxf.resources.filesystem.sandbox-directory</param-name> <param-value>/home/user/oxf/myapp/resources</param-value> </context-param>
4. ClassLoader Resource Manager
Purpose |
Loading resources from a JAR file in the classpath |
Factory |
org.orbeon.oxf.resources.ClassLoaderResourceManagerFactory
|
Properties |
None |
The class loader resource manager can load resource from a JAR file or from a
directory in the classpath. This resource manager is required to load internal
resources for OPS.
4.1. Example
<context-param> <param-name>oxf.resources.factory</param-name> <param-value>org.orbeon.oxf.resources.ClassLoaderResourceManagerFactory </param-value> </context-param>
5. WebApp Resource Manager
Purpose |
Loading resources from a WAR file or deployed Web Application |
Factory |
org.orbeon.oxf.resources.WebAppResourceManagerFactory
|
Properties |
oxf.resources.webapp.rootdir
|
This resource manager is useful when you want to package an application into a
single WAR file for distribution and deployment. The configuration property
indicates the path prefix of the resources directory inside a WAR file. It is
recommended to store resources under the WEB-INF directory to make sure that the
resources are not exposed to remote clients.
5.1. Example
<context-param> <param-name>oxf.resources.factory</param-name> <param-value>org.orbeon.oxf.resources.WebAppResourceManagerFactory </param-value> </context-param> <context-param> <param-name>oxf.resources.webapp.rootdir</param-name> <param-value>/WEB-INF/resources</param-value> </context-param>
6. URL Resource Manager
Purpose |
Loading resources from a URL |
Factory |
org.orbeon.oxf.resources.URLResourceManagerFactory
|
Properties |
oxf.resources.url.base
|
This resource manager is able to load resources form any URL (http or ftp). It can
be used if your resources are located on a web server or a content management
system with an HTTP interface.
6.1. Example
<context-param> <param-name>oxf.resources.factory</param-name> <param-value>org.orbeon.oxf.resources.URLResourceManagerFactory</param-value> </context-param> <context-param> <param-name>oxf.resources.url.base</param-name> <param-value>http://www.somwhere.com/base/</param-value> </context-param>
7. WebDAV Resource Manager
Purpose |
Loading resources from a WebDAV repository |
Factory |
org.orbeon.oxf.resources.WebDAVResourceManagerFactory
|
Properties |
oxf.resources.webdav.base
oxf.resources.webdav.username
oxf.resources.webdav.password
|
This resource manager is able to load resources form a WebDAV repository through
HTTP. Examples of WebDAV repositories include:
For more information about WebDAV, please consult WebDAV Resources.
7.1. Example
<context-param> <param-name>oxf.resources.factory</param-name> <param-value>org.orbeon.oxf.resources.WebDAVResourceManagerFactory </param-value> </context-param> <context-param> <param-name>oxf.resources.webdav.base</param-name> <param-value>http://www.somwhere.com/base/</param-value> </context-param> <context-param> <param-name>oxf.resources.webdav.username</param-name> <param-value>joe</param-value> </context-param> <context-param> <param-name>oxf.resources.webdav.password</param-name> <param-value>password</param-value> </context-param>
Warning
The WebDAV resource manager is considered experimental.
8. Priority Resource Manager
Purpose |
Chains several resource managers in order |
Factory |
org.orbeon.oxf.resources.PriorityResourceManagerFactory
|
Properties |
oxf.resources.priority.1
oxf.resources.priority.2
oxf.resources.priority.n
|
With the priority resource manager you can chain several resource managers. It is
crucial to be able to load resources from multiple sources since some resources are
bundled in the OPS JAR file. Thus, the class loader resource
manager must always be in the priority chain. It usually has the lowest priority so
the application developer can override system resources.
There can be any number of chained resource managers. They are configured by adding
a oxf.resources.priority.n property, where n is an
integer.
Warning
The priority resource manager is more efficient when most resources are found
in the first resource manager specified.
8.1. Example
<context-param> <param-name>oxf.resources.factory</param-name> <param-value>org.orbeon.oxf.resources.PriorityResourceManagerFactory </param-value> </context-param> <context-param> <param-name>oxf.resources.webapp.rootdir</param-name> <param-value>/WEB-INF/resources</param-value> </context-param> <context-param> <param-name>oxf.resources.priority.1</param-name> <param-value>org.orbeon.oxf.resources.WebAppResourceManagerFactory </param-value> </context-param> <context-param> <param-name>oxf.resources.priority.2</param-name> <param-value>org.orbeon.oxf.resources.ClassLoaderResourceManagerFactory </param-value> </context-param>
9. Caché Database Resource Manager
Purpose |
Loading resources from the Caché database |
Factory |
org.orbeon.oxf.resources.CacheResourceManagerFactory
|
Properties |
oxf.resources.cache.url
oxf.resources.cache.username
oxf.resources.cache.password
|
This resource manager loads XML documents from InterSystems Caché Object Database.
eXtc provides a W3C DOM
interface to Caché and allows OPS to store and retrieve XML
documents. This section assumes Caché and eXtc are already installed on your
system.
Note
To enable this Resource Manager, you must copy CacheDB.jar from
Caché distribution into OPS WEB-INF/lib directory.
Warning
The Caché Resource Manager only supports XML document. To serve other
document types (like text, images), you must cascade a second resource manager
with the help of the Priority Resource Manager.
9.1. Importing XML Files into Caché
OPS ships with CacheImport to populate the
database with resource from a directory. Set your CLASSPATH
environment variable to include the following JAR files to run
CacheImport :
- ops.jar
- CacheDB.jar
- commons-cli.jar
- xercesImpl-2_2_1_orbeon.jar
- xml-apis-2_5_1.jar
- dom4j-1_4.jar
The options below are available:
Option |
Meaning |
-u,--url arg |
Caché URL |
-l,--login arg |
Caché Login |
-p,--password arg |
Caché Password |
-r,--root arg |
Resource Root |
You run CacheImport with the following command:
java org.orbeon.oxf.resources.CacheImport
9.2. Example
<context-param> <param-name>oxf.resources.factory</param-name> <param-value>org.orbeon.oxf.resources.CacheResourceManagerFactory </param-value> </context-param> <context-param> <param-name>oxf.resources.cache.url</param-name> <param-value>jdbc:Cache://localhost:1972/OXF</param-value> </context-param> <context-param> <param-name>oxf.resources.cache.username</param-name> <param-value>_SYSTEM</param-value> </context-param> <context-param> <param-name>oxf.resources.cache.password</param-name> <param-value>sys</param-value> </context-param>
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