DS-COMPOSITE datastream
Content Models may contain this reserved datastream. It lists the datastreams that must exist in subscribing data objects, and the few requirements on them.
DSCompositeSchema
The old schema for the datastream can be seen below.
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<dsCompositeModel
xmlns="info:fedora/fedora-system:def/dsCompositeModel#">
<dsTypeModel ID="DC">
<form MIME="text/xml"/>
</dsTypeModel>
<dsTypeModel ID="ORIGIN">
<form MIME="text/xml"/>
</dsTypeModel>
</dsCompositeModel>
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Optional datastreams
First, we will ammend the schema to support the property "optional" to datastream declarations. The JIRA issue for this is http://fedora-commons.org/jira/browse/FCREPO-531
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<xsd:schema
targetNamespace="info:fedora/fedora-system:def/dsCompositeModel#"
xmlns="info:fedora/fedora-system:def/dsCompositeModel#"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<xsd:element name="dsCompositeModel">
<xsd:complexType>
<xsd:sequence>
<xsd:element minOccurs="0" maxOccurs="unbounded" ref="dsTypeModel"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="dsTypeModel">
<xsd:complexType>
<xsd:sequence>
<xsd:element minOccurs="0" maxOccurs="unbounded" ref="form"/>
</xsd:sequence>
<xsd:attribute name="ID" use="required" type="xsd:NCName"/>
<xsd:attribute name="optional" use="optional" type="xsd:boolean" default="false"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="form">
<xsd:complexType>
<xsd:attribute name="FORMAT_URI" use="optional" type="xsd:anyURI"/>
<xsd:attribute name="MIME" use="optional"/>
</xsd:complexType>
</xsd:element>
</xsd:schema>
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Allowing extensions in DS-COMPOSITE
Since Fedora already use DS-COMPOSITE to declare the existence of datastreams, it is the natural location to specify restrictions on the contents of datastreams. Unfortunately, the schema for the DS-COMPOSITE datastream does not allow for any extra content, To that effect, we have made a small change to the schema.
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What is noteworthy here is that the <dsTypeModel> and the <form> elements are left unchanged. The Fedora code, working with DS-COMPOSITE only looks for these tags, so the new schema will not cause conflicts, and the extensions will be quietly ignored. This is exactly as we want, this change should not make our objects incompatible with an older Fedora.
Reserved extensions in DS-COMPOSITE
We have reserved two extention names.
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<dsCompositeModel
xmlns="info:fedora/fedora-system:def/dsCompositeModel#"
xmlns:schema="http://ecm.sourceforge.net/types/dscompositeschema/0/1/#">
<!-- The DC datastream is declared. It's mime type must be text/xml. It must adhere to the xml schema residing in the DC_SCHEMA datastream in this content model. -->
<dsTypeModel ID="DC">
<form MIME="text/xml"/>
<extension name="SCHEMA">
<reference type="datastream" value="DC_SCHEMA"/>
</extensions>
</dsTypeModel>
<!-- The ORIGIN datastream is declared. It's mime type must be text/xml. It must adhere to the xml schema residing in the ORIGIN_SCHEMA datastream in this content model-->
<dsTypeModel ID="ORIGIN">
<form MIME="text/xml"/>
<extension name="SCHEMA">
<reference type="datastream" value="ORIGIN_SCHEMA"/>
</extensions>
</dsTypeModel>
</dsCompositeModel>
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Schema Extension
There are three kinds of datastreams in a Fedora object:
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