Compass provides OSEM technology for use with an applications Object domain model or XSEM when working with xml data structures. Compass also provides Resource Mapping technology for resources other than Objects/XML (that do not benefit from OSEM). The benefits of using Resources can be summarized as:

In order to work directly with a Resource, Compass needs to know the alias and the primary properties (i.e. primary keys in data-base systems) associated with the Resource. The primary properties are also known as id properties. This information is declared in Resource Mapping XML documents, so that Compass knows how to manage the Resource internally (this is needs especially for update/delete operations).

Here is an example of a Resource Mapping XML document:

<?xml version="1.0"?>
<!DOCTYPE compass-core-mapping PUBLIC
    "-//Compass/Compass Core Mapping DTD 2.0//EN"
    "http://www.compass-project.org/dtd/compass-core-mapping-2.0.dtd">

<compass-core-mapping>

  <resource alias="a">
    <resource-id name="id" />
  </resource>

  <resource alias="b">
    <resource-id name="id1" />
    <resource-id name="id2" />
  </resource>

  <resource alias="c">
    <resource-id name="id" />
    <resource-property name="value1" />
    <resource-property name="value2" store="yes" index="tokenized" />
    <resource-property name="value3" store="compress" index="tokenized" />
    <resource-property name="value4" store="yes" index="un_tokenized" />
    <resource-property name="value5" store="yes" index="no" converter="my-date" />
  </resource>
</compass-core-mapping>

Now that the Resource Mapping has been declared, you can create the Resource in the application. In the following code example the Resource is created with an alias and id property matching the Resource Mapping declaration.

ResourceFactory resourceFactory = compass.getResourceFactory();
Resource r = resourceFactory.createResource("a");
Property id = resourceFactory.createProperty("id", "1",
    Property.Store.YES, Property.Index.UN_TOKENIZED);
r.addProperty(id);
r.addProperty(resourceFactory.createProperty("mvalue", "property test",
    Property.Store.YES, Property.Index.TOKENIZED));

session.save(r);

The Resource Mapping file example above defines mappings for three resource types (each identified with a different alias). Each resource has a set of resource ids that are associated with it. The value for the resource-id tag is the name of the Property that is associated with the primary property for the Resource.

The third mapping (alias "c"), defines resource-property mappings as well as resource-id mappings. The resource-property mapping works with the Resource#addProperty(String name, Object value) operation. It provides definitions for the resource properties that are added (index, store, and so on), and they are then looked up when using the mentioned add method. Using the resource-property mapping, helps clean up the code when constructing a Resource, since all the Property characteristics are defined in the mapping definition, as well as auto conversion from different objects, and the ability to define new ones. Note that the resource-property definition will only work with the mentioned addProperty method, and no other addProperty method.

Here is an example of how resource-property mappings can simplify Resource construction code:

ResourceFactory resourceFactory = compass.getResourceFactory();
Resource r = resourceFactory.createResource("c");
r.addProperty("id", 1);
r.addProperty("value1", "this is a sample value");
r.addProperty("value5", new Date()); // will use the my-date converter (using the format defined there)
session.save(r);

All XML mappings should declare the doctype shown. The actual DTD may be found at the URL above or in the compass core distribution. Compass will always look for the DTD in the classpath first.

There are no compass-core-mapping attributes that are applicable when working with resource mappings.

<resource
      alias="aliasName"
      sub-index="sub index name"
      extends="a comma separated list of aliases to extend"
      analyzer="name of the analyzer"
/>
    all?,
    sub-index-hash?,
    resource-id*,
    (resource-analyzer?),
    (resource-boost?),
    (resource-property)*

<resource-contract
        alias="aliasName"
        extends="a comma separated list of aliases to extend"
        analyzer="name of the analyzer"
  />
      resource-id*,
      (resource-analyzer?),
      (resource-property)*
  

<resource-id
      name="idName"
/>

<resource-property
      name="property name"
      store="yes|no|compress"
      index="tokenized|un_tokenized|no"
      boost="boost value for the property"
      analyzer="name of the analyzer"
      reverse="no|reader|string"
      override="true|false"
      exclude-from-all="no|yes|no_analyzed"
      converter="converter lookup name"
>
</resource-property>

<resource-analyzer
      name="property name"
      null-analyzer="analyzer name if value is null"
      converter="converter lookup name"
>
</resource-analyzer>

<resource-boost
      name="property name"
      default="the boost default value when no property value is present"
      converter="converter lookup name"
>
</resource-boost>