Added support for prefix to namespace bindings for use in Metapath mo…

…dules and external constraints for supporting multiple models and Metapath types and functions with colliding names that are in different namespaces. This better aligns Metapath with the XPath 3.1 specification.
usnistgov · Jul 24, 2024 · 5ec4066 · 5ec4066
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diff --git a/schema/metaschema/metaschema-module-constraints.xml b/schema/metaschema/metaschema-module-constraints.xml
@@ -5,42 +5,64 @@
     <context>
         <metapath target="/METASCHEMA"/>
         <constraints>
-            <let var="all-imports" expression="recurse-depth(.,'doc(resolve-uri(import/@href))/METASCHEMA')"/>
-            <index id="metaschema-short-name-unique" target="(.|$all-imports)" name="metaschema-metadata-short-name-index">
-                <formal-name>Unique Module Short Names</formal-name>
+            <let var="all-imports" expression="recurse-depth('doc(resolve-uri(import/@href))/METASCHEMA')"/>
+            <index id="module-short-name-unique" target="(.|$all-imports)" name="metaschema-metadata-short-name-index">
+                <formal-name>Index Module Short Names</formal-name>
                 <description>Ensures that the current and all imported modules have a unique short name.</description>
                 <key-field target="@short-name"/>
             </index>
+            <expect id="module-top-level-version-required" target=".[not(@abstract) or @abstract='yes']" test="@version">
+                <formal-name>Require Version for Top-Level Modules</formal-name>
+                <description>A top-level module, a module that is not marked as @abstract='yes', must have a version specified.</description>
+                <message>Unless marked as @abstract='yes', a Metaschema module (or an imported module) should have a version.</message>
+            </expect>
+            <expect id="module-top-level-root-required" target=".[not(@abstract) or @abstract='yes']" test="define-assembly/root-name">
+                <formal-name>Require Root Assembly for Top-Level Modules</formal-name>
+                <description>A top-level module, a module that is not marked as @abstract='yes', must have at least one assembly with a root-name.</description>
+                <message>Unless marked as @abstract='yes', a Metaschema module (or an imported module) should have at least one assembly with a root-name.</message>
+            </expect>
+            <is-unique id="module-namespace-unique-entry" target="namespace">
+                <formal-name>Require Unique Namespace Entries</formal-name>
+                <description>Ensures that all declared namespace entries are unique.</description>
+                <key-field target="@prefix"/>
+                <key-field target="@uri"/>
+            </is-unique>
+            <is-unique id="module-namespace-unique-prefix" target="namespace">
+                <formal-name>Require Unique Namespace Entry Prefixes</formal-name>
+                <description>Ensures that all declared namespace entries have a unique prefix.</description>
+                <key-field target="@prefix"/>
+            </is-unique>
         </constraints>
-        <context>
-            <metapath target=".[not(@abstract) or @abstract='yes']"/>
-            <constraints>
-                <expect id="metaschema-top-level-version-required" target="." test="@version">
-                    <formal-name>Require Version for Top-Level Modules</formal-name>
-                    <description>A top-level module, a module that is not marked as @abstract='yes', must have a version specified.</description>
-                    <message>Unless marked as @abstract='yes', a Metaschema module (or an imported module) should have a version.</message>
-                </expect>
-                <expect id="metaschema-top-level-root-required" target="." test="define-assembly/root-name">
-                    <formal-name>Require Root Assembly for Top-Level Modules</formal-name>
-                    <description>A top-level module, a module that is not marked as @abstract='yes', must have at least one assembly with a root-name.</description>
-                    <message>Unless marked as @abstract='yes', a Metaschema module (or an imported module) should have at least one assembly with a root-name.</message>
-                </expect>
-            </constraints>
-        </context>
         <context>
             <metapath target="import"/>
             <constraints>
-                <expect id="metaschema-import-href-available" target="." test="document-available(resolve-uri(import/@href))">
+                <expect id="module-import-href-available" target="." test="document-available(resolve-uri(import/@href))">
                     <formal-name>Import is Resolvable</formal-name>
                     <description>Ensure each import has a resolvable @href.</description>
                     <message>Unable to access a Metaschema module at '{{ resolve-uri(@href) }}'.</message>
                 </expect>
-                <expect id="metaschema-import-href-is-module" target="." test="doc(resolve-uri(import/@href))/METASCHEMA ! exists(.)">
+                <expect id="module-import-href-is-module" target="." test="doc(resolve-uri(import/@href))/METASCHEMA ! exists(.)">
                     <formal-name>Import is Resolvable</formal-name>
                     <description>Ensure each import is a Metaschema module.</description>
                     <message>Unable the resource at '{{ resolve-uri(@href) }}' is not a Metaschema module.</message>
                 </expect>
             </constraints>
         </context>
     </context>
+    <context>
+        <metapath target="/metaschema-meta-constraints"/>
+        <constraints>
+            <is-unique id="meta-constraints-namespace-unique-entry" target="namespace">
+                <formal-name>Require Unique Namespace Entries</formal-name>
+                <description>Ensures that all declared namespace entries are unique.</description>
+                <key-field target="@prefix"/>
+                <key-field target="@uri"/>
+            </is-unique>
+            <is-unique id="meta-constraints-namespace-unique-prefix" target="namespace">
+                <formal-name>Require Unique Namespace Entry Prefixes</formal-name>
+                <description>Ensures that all declared namespace entries have a unique prefix.</description>
+                <key-field target="@prefix"/>
+            </is-unique>
+        </constraints>
+    </context>
 </metaschema-meta-constraints>
diff --git a/schema/metaschema/metaschema-module-metaschema.xml b/schema/metaschema/metaschema-module-metaschema.xml
@@ -52,6 +52,9 @@
                     <description>A relative or absolute URI for retrieving an out-of-line Metaschema definition.</description>
                 </define-flag>
             </define-assembly>
+            <assembly ref="metapath-namespace" max-occurs="unbounded">
+                <group-as name="namespace-bindings" />
+            </assembly>
             <choice-group max-occurs="unbounded">
                 <group-as name="definitions" in-json="ARRAY"/>
                 <discriminator>object-type</discriminator>
@@ -183,6 +186,21 @@
         </constraint>
     </define-assembly>
 
+    <define-assembly name="metapath-namespace">
+        <formal-name>Metapath Namespace Declaration</formal-name>
+        <description>Assigns a Metapath namespace to a prefix for use in a Metapath expression in a lexical qualified name.</description>
+        <use-name>namespace-binding</use-name>
+        <define-flag name="uri" as-type="uri" required="yes">
+            <formal-name>Metapath Namespace URI</formal-name>
+            <description>The namespace URI to bind to the prefix.</description>
+        </define-flag>
+        <define-flag name="prefix" as-type="token" required="yes">
+            <formal-name>Metapath Namespace Prefix</formal-name>
+            <description>The prefix that is bound to the namespace.</description>
+        </define-flag>
+    </define-assembly>
+
+
     <define-assembly name="inline-define-assembly">
         <formal-name>Inline Assembly Definition</formal-name>
         <use-name>define-assembly</use-name>
@@ -1238,6 +1256,11 @@
                     <description>A relative or absolute URI for retrieving an out-of-line Metaschema constraint definition.</description>
                 </define-flag>
             </define-assembly>
+
+            <assembly ref="metapath-namespace" max-occurs="unbounded">
+                <group-as name="namespace-bindings" />
+            </assembly>
+
             <define-assembly name="scope" min-occurs="1" max-occurs="unbounded">
                 <group-as name="scopes" in-json="ARRAY"/>
                 <define-flag name="metaschema-namespace" as-type="uri" required="yes"/>
@@ -1302,6 +1325,10 @@
         <description>Defines constraint rules to be applied to an existing set of Metaschema module-based models.</description>
         <root-name>metaschema-meta-constraints</root-name>
         <model>
+            <assembly ref="metapath-namespace" max-occurs="unbounded">
+                <group-as name="namespace-bindings" />
+            </assembly>
+
             <define-assembly name="definition-context">
                 <define-flag name="name" as-type="token" required="yes"/>
                 <define-flag name="namespace" as-type="uri" required="yes"/>

diff --git a/schema/xml/metaschema-meta-constraints.xsd b/schema/xml/metaschema-meta-constraints.xsd
@@ -11,6 +11,7 @@
     <xs:element name="metaschema-meta-constraints">
         <xs:complexType>
             <xs:sequence>
+                <xs:element name="namespace-binding" type="NamespaceBindingType" minOccurs="0" maxOccurs="unbounded"/> 
                 <xs:element name="context" type="ModelContextType" maxOccurs="unbounded"/>
             </xs:sequence>
         </xs:complexType>

diff --git a/schema/xml/metaschema.xsd b/schema/xml/metaschema.xsd
@@ -45,6 +45,8 @@
 
         <xs:element name="import" type="MetaschemaImportType" minOccurs="0" maxOccurs="unbounded"/>
 
+		<xs:element name="namespace-binding" type="NamespaceBindingType" minOccurs="0" maxOccurs="unbounded"/> 
+
         <xs:choice minOccurs="0" maxOccurs="unbounded">
           <xs:element name="define-assembly" type="GlobalAssemblyDefinitionType"/>
           <xs:element name="define-field" type="GlobalFieldDefinitionType"/>
@@ -80,6 +82,22 @@
     </xs:attribute>
   </xs:complexType>
 
+  <xs:complexType name="NamespaceBindingType">
+  	<xs:annotation>
+      <xs:documentation>Assigns a Metapath namespace to a prefix for use in a Metapath expression in a lexical qualified name.</xs:documentation>
+  	</xs:annotation>
+	<xs:attribute name="prefix" type="TokenDatatype" use="required">
+      <xs:annotation>
+        <xs:documentation>The prefix that is bound to the namespace.</xs:documentation>
+      </xs:annotation>
+	</xs:attribute>
+	<xs:attribute name="uri" type="URIDatatype" use="required">
+      <xs:annotation>
+        <xs:documentation>The namespace URI to bind to the prefix.</xs:documentation>
+      </xs:annotation>
+	</xs:attribute>
+  </xs:complexType>
+
   <xs:group name="DefinitionMetadataGroup">
     <xs:sequence>
       <xs:element name="formal-name" minOccurs="0">
@@ -1303,6 +1321,7 @@
             </xs:attribute>
           </xs:complexType>
         </xs:element>
+        <xs:element name="namespace-binding" type="NamespaceBindingType" minOccurs="0" maxOccurs="unbounded"/> 
         <xs:element name="scope" maxOccurs="unbounded">
           <xs:complexType>
             <xs:choice maxOccurs="unbounded">