<xsd:schema xmlns="http://www.ics.uci.edu/pub/arch/xArch/pladiff.xsd" 
    xmlns:types="http://www.ics.uci.edu/pub/arch/xArch/types.xsd" 
    xmlns:archinstance="http://www.ics.uci.edu/pub/arch/xArch/instance.xsd" 
    xmlns:options="http://www.ics.uci.edu/pub/arch/xArch/options.xsd" 
    xmlns:variants="http://www.ics.uci.edu/pub/arch/xArch/variants.xsd" 
    xmlns:xlink="http://www.w3.org/1999/xlink" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
    targetNamespace="http://www.ics.uci.edu/pub/arch/xArch/pladiff.xsd" 
    elementFormDefault="qualified" attributeFormDefault="qualified">
    
    <!-- Import namespaces used -->
    <xsd:import namespace="http://www.ics.uci.edu/pub/arch/xArch/instance.xsd" 
        schemaLocation="http://www.isr.uci.edu/projects/xarchuci/core/instance.xsd" />
    <xsd:import namespace="http://www.ics.uci.edu/pub/arch/xArch/types.xsd" 
        schemaLocation="http://www.isr.uci.edu/projects/xarchuci/ext/types.xsd" />
    <xsd:import namespace="http://www.ics.uci.edu/pub/arch/xArch/options.xsd" 
        schemaLocation="http://www.isr.uci.edu/projects/xarchuci/ext/options.xsd" />
    <xsd:import namespace="http://www.ics.uci.edu/pub/arch/xArch/variants.xsd" 
        schemaLocation="http://www.isr.uci.edu/projects/xarchuci/ext/variants.xsd" />
    <xsd:annotation>
        <xsd:documentation>
            xArch Diff XML Schema 2.0

            The following elements are used to define how to
            represent a change between Product Line Architectures.
            This schema can be used to show when an element
            (connector, etc.) was removed or added to a
            preexisting architecture.

            Depends on: {types.xsd, instance.xsd, options.xsd, variants.xsd}

            Change Log:
			   2004-05-02: Ping Chen, Chris Van der Westhuizen:
				 Changed the schema to be unique for product line architecture
				 in order to be differentiated from runtime diff and merge
               2003-10-26: Ping Chen, Matt Critchlow, Akash Garg, Chris Van
                 der Westhuizen:
                 Changed the Add Subarchitecture to contain only the description
                 of the subarchitecture.
               2003-05-12: Ping Chen, Matt Critchlow, Akash Garg, Chris Van
                 der Westhuizen:
                 Cleaned up the document.  Fixed up some naming inconsistencies
               2003-05-08: Ping Chen, Matt Critchlow, Akash Garg, Chris Van
                 der Westhuizen:
                 Augmented addLink and addSignatureInterfaceMapping with
                 information about the endpoints they are connected to.
                 Also added ability to add/remove optionals.
               2003-04-22: Ping Chen, Matt Critchlow, Akash Garg, Chris Van
                 der Westhuizen:
                 Re-wrote the schema for the diff document to become
                 hierarchical.  Now allows for fine-grained diffing of
                 elements such as interfaces, variants, and signatures.
                 Finally, added support for sub-structures.
               2002-07-23: Eric M. Dashofy [edashofy@ics.uci.edu]:
                 Changed location of core (xArch) schema in the import
                 statement to a more stable URL.
               2002-01-28: Eric M. Dashofy [edashofy@ics.uci.edu]:
                Upgraded to 2001 XML Schema standard and validated
                 with XML Spy 4.2.  Only changes were to the namespace
                 declaration for 'xsd' in the header.
               2001-04-12: Eric M. Dashofy [edashofy@ics.uci.edu]:
                 Cleanup and validation by XML Spy 3.5.
               2001-04-09: Christopher van der Westhuizen 
                 [vanderwe@uci.edu]:
                 Initial development and internal release.
        </xsd:documentation>
    </xsd:annotation>
    <!--
      Element: PLADiff

      The root element of any PLA diff; it sits under the xArch element in an
      xArch document.
    -->
    <xsd:element name="plaDiff" type="PLADiff" />
    <!--
      TYPE: PLADiff

      This type describes the difference between one PLA
      and another.  It describes what was removed and added by
      describing the root DiffPart.  This DiffPart describes all the
      changes that should be made at the root level (the level in the
      structural hierarchy that we are starting the diff process at).
    -->
    <xsd:complexType name="PLADiff">
        <xsd:sequence>
            <xsd:element name="diffPart" type="DiffPart" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
      TYPE: DiffPart

      This element contains a description of the context of this diff,
      or the location that these diff instructions should be applied at.
      It also contains the list of additions and removals that should be
      applied as well as a diff part for substructures.
      Conceptually, a diff part represents all the differences at one
      particular level in the hierarchy (substructure or variant types).
      This diff part can contain more diff parts to represent
      another level of substructure within the current structure.
    -->
    <xsd:complexType name="DiffPart">
        <xsd:sequence>
            <xsd:element name="diffLocation" type="DiffLocation" />
            <xsd:element name="add" type="Add" minOccurs="0" 
                maxOccurs="unbounded" />
            <xsd:element name="remove" type="Remove" minOccurs="0" 
                maxOccurs="unbounded" />
            <xsd:element name="diffPart" type="DiffPart" minOccurs="0" 
                maxOccurs="unbounded" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
      Type: DiffLocation

      This element contains the description of the location
      in which the diff instruction should be applied.
      It could either represent:
      1. A description of an element - The diff should be applied to the
            subarchitecture within that element (component or connector)
            - the type of that component.
      2. A description of a variant - The diff should be applied to the
            type that the variant with this description (guard) points to.
    -->
    <xsd:complexType name="DiffLocation">
        <xsd:sequence>
            <xsd:element name="location" type="archinstance:Description" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
      TYPE: Add

      This element lists an addition to an architecture.
      This would include the addition of a component,
      connector, link, substructures, variants...
      The list of adds is broken down into 2 basic groups,
      1. Adds to the substructure of a type (arch structure entities)
      2. Adds to the type itself (type entities).
    -->
    <xsd:complexType name="Add">
        <xsd:choice>
            <xsd:element name="addStructuralEntity" type="AddStructuralEntity" />
            <xsd:element name="addTypeEntity" type="AddTypeEntity" />
        </xsd:choice>
    </xsd:complexType>
    <!--
      TYPE: AddStructuralEntity

      This element lists an addition to an ArchStructure
      element, i.e. component, connectors, links, and interfaces, optional.
    -->
    <xsd:complexType name="AddStructuralEntity">
        <xsd:choice>
            <xsd:element name="component" type="types:Component" />
            <xsd:element name="connector" type="types:Connector" />
            <xsd:element name="addLink" type="AddLink" />
            <xsd:element name="addInterface" type="AddInterface" />
            <xsd:element name="addOptional" type="AddOptional" />
        </xsd:choice>
    </xsd:complexType>
    <!--
     TYPE: AddLink

     This element lists an addition of a link to a structure.
    -->
    <xsd:complexType name="AddLink">
        <xsd:sequence>
            <xsd:element name="link" type="types:Link" />
            <xsd:element name="interfaceEndPoint" type="InterfaceEndPoint" 
                minOccurs="2" maxOccurs="2" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
     TYPE: InterfaceEndPoint

     This element describes the endpoint to a link or signature interface 
     mapping in terms of its connected interface's description and the connected 
     component/connector.
    -->
    <xsd:complexType name="InterfaceEndPoint">
        <xsd:sequence>
            <xsd:element name="interfaceDescription" 
                type="archinstance:Description" />
            <xsd:element name="connectingElementDescription" 
                type="archinstance:Description" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
     TYPE: AddInterface

     This element lists the addition of an Interface.
     It is broken down into two parts: the description of the element
     that contains this interface, and the interface itself.
     The description of the element is required so that we can easily
     find the element that holds this interface
    -->
    <xsd:complexType name="AddInterface">
        <xsd:sequence>
            <xsd:element name="elementDescription" 
                type="archinstance:Description" />
            <xsd:element name="interface" type="types:Interface" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
     TYPE: AddOptional

     This element lists the addition of an optional..
     It is broken down into two parts: the description of the element
     that contains this optional, and the optional itself.
     The description of the element is required so that we can easily
     find the element that holds this optional
    -->
    <xsd:complexType name="AddOptional">
        <xsd:sequence>
            <xsd:element name="elementDescription" 
                type="archinstance:Description" />
            <xsd:element name="optional" type="options:Optional" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
      TYPE: AddTypeEntity

      This element lists an addition to an actual Type
      element, i.e. variants, signatures,
      substructures-, and signature interface mappings.
      We also included the name of the element (diff location) that
      these additions should be applied to.  This way, we can easily
      locate where to add the signature (or whatever else).
    -->
    <xsd:complexType name="AddTypeEntity">
        <xsd:sequence>
            <xsd:element name="diffLocation" type="DiffLocation" />
            <xsd:choice>
                <xsd:element name="signature" type="types:Signature" />
                <xsd:element name="variant" type="variants:Variant" />
                <xsd:element name="subArchitecture" 
                    type="archinstance:Description" />
                <xsd:element name="addSignatureInterfaceMapping" 
                    type="AddSignatureInterfaceMapping" />
            </xsd:choice>
        </xsd:sequence>
    </xsd:complexType>
    <!--
     TYPE: AddSignatureInterfaceMapping

     This element lists an addition of a signature interface mapping to a 
     structure.  It is augmented with the description of the two endpoints this 
     connects.
    -->
    <xsd:complexType name="AddSignatureInterfaceMapping">
        <xsd:sequence>
            <xsd:element name="signatureInterfaceMapping" 
                type="types:SignatureInterfaceMapping" />
            <xsd:element name="signatureEndPoint" type="SignatureEndPoint" />
            <xsd:element name="interfaceEndPoint" type="InterfaceEndPoint" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
     TYPE: SignatureEndPoint

     This element describes an endpoint at either side of a signature in 
     terms of its connected signature interface mapping's description and 
     the connected component/connector.
    -->
    <xsd:complexType name="SignatureEndPoint">
        <xsd:sequence>
            <xsd:element name="signatureDescription" 
                type="archinstance:Description" />
            <xsd:element name="outerElementDescription" 
                type="archinstance:Description" />
        </xsd:sequence>
    </xsd:complexType>
    
    <!--
      TYPE: Remove

      This element indicates a removal of an element
      from an architecture.  This includes the removal
      of a structural or type entity.
    -->
    <xsd:complexType name="Remove">
        <xsd:choice>
            <xsd:element name="removeStructuralEntity" 
                type="RemoveStructuralEntity" />
            <xsd:element name="removeTypeEntity" type="RemoveTypeEntity" />
        </xsd:choice>
    </xsd:complexType>
    <!--
      TYPE: RemoveStructuralEntity

      This element lists a removal to an ArchStructure
      element, i.e. component, connector, link, or interface.
    -->
    <xsd:complexType name="RemoveStructuralEntity">
        <xsd:choice>
            <xsd:element name="component" type="archinstance:Description" />
            <xsd:element name="connector" type="archinstance:Description" />
            <xsd:element name="link" type="archinstance:Description" />
            <xsd:element name="removeInterface" type="RemoveInterface" />
            <xsd:element name="removeOptional" type="RemoveOptional" />
        </xsd:choice>
    </xsd:complexType>
    <!--
     TYPE: RemoveInterface

     This element lists a removal of an Interface.
     Similar to the AddInterface, it includes
     the description of the element (component/connector) that
     contains this interface.
    -->
    <xsd:complexType name="RemoveInterface">
        <xsd:sequence>
            <xsd:element name="elementDescription" 
                type="archinstance:Description" />
            <xsd:element name="interfaceDescription" 
                type="archinstance:Description" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
     TYPE: RemoveOptional

     This element lists a removal of an optional.
     Similar to the AddOptional, it includes
     the description of the element (component/connector) that
     contains this optional.
    -->
    <xsd:complexType name="RemoveOptional">
        <xsd:sequence>
            <xsd:element name="elementDescription" 
                type="archinstance:Description" />
            <xsd:element name="optionalDescription" 
                type="archinstance:Description" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
      TYPE: RemoveSignatureInterfaceMapping

      This element lists a removal of a SignatureInterfaceMapping.
      Since signature-interface-mappings doesn't have descriptions
      of their own, we describe them by the description of its 2
      endpoints (the outer signature and the inner interface).
    -->
    <xsd:complexType name="RemoveSignatureInterfaceMapping">
        <xsd:sequence>
            <xsd:element name="outerSignatureDescription" 
                type="archinstance:Description" />
            <xsd:element name="innerInterfaceDescription" 
                type="archinstance:Description" />
        </xsd:sequence>
    </xsd:complexType>
    <!--
      TYPE: RemoveTypeEntity

      This element lists a removal to an actual Type
      element, i.e. componentType, connectorType, or
      an interfaceType.
      We also included the name of the element (diff location) that
      these removals should be applied to.  This way, we can easily
      locate where to remove the signature (or whatever else).
    -->
    <xsd:complexType name="RemoveTypeEntity">
        <xsd:sequence>
            <xsd:element name="diffLocation" type="DiffLocation" />
            <xsd:choice>
                <xsd:element name="signature" type="archinstance:Description" />
                <!--
                    This description doesn't mean anything since
                    we don't need a type for the removeSubArchitecture
                    element. Only one subArchitecture anyways.
                -->
                <xsd:element name="subArchitecture" 
                    type="archinstance:Description" />
                <xsd:element name="variant" type="archinstance:Description" />
                <xsd:element name="removeSignatureInterfaceMapping" 
                    type="RemoveSignatureInterfaceMapping" />
            </xsd:choice>
        </xsd:sequence>
    </xsd:complexType>
</xsd:schema>