X-Path Queries on XML Document | BizTalk Server

Here, in this article I would brief about querying XML Document Node values using X-path 

XPath is used to navigate through elements and attributes in an XML document. It is a major element in W3C's XSLT standard. XPath uses path expressions to navigate in XML documents 
It contains a library of standard functions and is a major element in XSLT; without XPath knowledge you will not be able to create XSLT documents. 

XPath Terminology 

Nodes 

In xpath, there are seven kinds of nodes: element, attribute, text, namespace, processing-instruction, comment, and document nodes. 
XML documents are treated as trees of nodes. The topmost element of the tree is called the root element. 

x-path queries

Lets see about relationship between nodes and read element value using xpath with the below xml document, 

<OrderCollection> 
<AddressBookEntryIdentifier>1212121212</AddressBookEntryIdentifier>
  <ConsumerOrderNumber>100-200</ConsumerOrderNumber>
  <Orders>
    <Order>
      <MetadataCollection>
        <Metadata>
          <Name>LoanNumber</Name>
          <Value>100</Value>
        </Metadata>
        <Metadata>
          <Name>TID</Name>
          <Value>10</Value>
        </Metadata>
        <Metadata>
          <Name>ID</Name>
          <Value>11</Value>
        </Metadata>
        <Metadata>
          <Name>ProviderID</Name>
          <Value>1000</Value>
        </Metadata>
      </MetadataCollection>
      <OrderNumber>10000</OrderNumber>
      <ReferenceNumbers>
        <OrderReference>
          <ReferenceNumber>10101010</ReferenceNumber>
          <ReferenceType>FileId</ReferenceType>
        </OrderReference>
      </ReferenceNumbers>
    </Order>
    <Order>
      <MetadataCollection>
        <Metadata>
          <Name>LoanNumber</Name>
          <Value>200</Value>
        </Metadata>
        <Metadata>
          <Name>TID</Name>
          <Value>20</Value>
        </Metadata>
        <Metadata>
          <Name>EID</Name>
          <Value>21</Value>
        </Metadata>
        <Metadata>
          <Name>ProviderID</Name>
          <Value>2000</Value>
        </Metadata>
      </MetadataCollection>
      <OrderNumber>20000</OrderNumber>
      <ReferenceNumbers>
        <OrderReference>
          <ReferenceNumber>202020</ReferenceNumber>
          <ReferenceType>FileId</ReferenceType>
        </OrderReference>
      </ReferenceNumbers>
    </Order>
  </Orders>
</OrderCollection> 

Relationship of Nodes 

Parent 

• Each element and attribute has one parent. 
• In the sample shown; the Order element is the parent of the MetadataCollection, OrderNumber and ReferenceNumbers 

Child 

• Element nodes may have zero, one or more children. 
• In the example; the ReferenceNumber and ReferenceType elements are all children of the OrderReference element 

Siblings 

• Nodes that have the same parent. 
• In the sample shown example; the Name and Value elements are all siblings 

Ancestors 

• A node's parent, parent's parent, etc. 
• In the sample shown; the ancestors of the Order element are the Orders and OrderCollection elements 

Xpath Queries:

Select all the occurrence of an element irrespective of its parent, 

• /*[local-name()='OrderCollection' and namespace-uri()='']/*[local-name()='Orders' and namespace-uri()='']/*[local-name()='Order' and namespace-uri()='']/*[local-name()='MetadataCollection' and namespace-uri()='']/*[local-name()='Metadata' and namespace-uri()=''] 

• /*[local-name()='OrderCollection' and namespace-uri()='']/*[local-name()='Orders' and namespace-uri()='']/*[local-name()='Order' and namespace-uri()='']/*[local-name()='MetadataCollection' and namespace-uri()='']/*[local-name()='Metadata' and namespace-uri()='' and *[local-name()='Name' and namespace-uri()='' and .='ProviderID']]/*[local-name()='Value' and namespace-uri()=''] 

• /*[local-name()='OrderCollection' and namespace-uri()='']/*[local-name()='Orders' and namespace-uri()='']/*[local-name()='Order' and namespace-uri()='']/*[local-name()='ReferenceNumbers' and namespace-uri()='']/*[local-name()='OrderReference' and namespace-uri()='' and *[local-name()='ReferenceType' and namespace-uri()='' and .='FileId']]/*[local-name()='ReferenceNumber' and namespace-uri()='']

Select an element within a specific parent 

• /*[local-name()='OrderCollection' and namespace-uri()='']/*[local-name()='Orders' and namespace-uri()='']/*[local-name()='Order' and namespace-uri()='' and *[local-name()='OrderNumber' and namespace-uri()='' and .='10000']]/*[local-name()='MetadataCollection' and namespace-uri()='']/*[local-name()='Metadata' and namespace-uri()='' and *[local-name()='Name' and namespace-uri()='' and .='ProviderID']]/*[local-name()='Value' and namespace-uri()=''] 

Select parent with its child element 

• //*[local-name()='Metadata' and namespace-uri()='' and *[local-name()='Name' and namespace-uri()=''and .='ProviderID']]

Select an element with its sibling 

• //*[local-name()='Metadata' and namespace-uri()='' and *[local-name()='Name' and namespace-uri()='' and .='ProviderID']]/*[local-name()='Value' and namespace-uri()=''] 

Select an element with case insensitive evaluation using translate function 

• /*[local-name()='OrderCollection' and namespace-uri()='']/*[local-name()='Orders' and namespace-uri()='']/*[local-name()='Order' and namespace-uri()='']/*[local-name()='MetadataCollection' and namespace-uri()='']/*[local-name()='Metadata' and namespace-uri()='' and *[local-name()='Name' and namespace-uri()='' and translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz') ='id']] 

Select Ancestor/Parent with its child 

• /*[local-name()='OrderCollection' and namespace-uri()='']/*[local-name()='Orders' and namespace-uri()='']/*[local-name()='Order' and namespace-uri()='' and *[local-name()='OrderNumber' and namespace-uri()='' and .='10000']] 

• /*[local-name()='OrderCollection' and namespace-uri()='']/*[local-name()='Orders' and namespace-uri()='']/*[local-name()='Order' and namespace-uri()='' and *[local-name()='ReferenceNumbers' and namespace-uri()='' and *[local-name()='OrderReference' and namespace-uri()='' and *[local-name()='ReferenceNumber' and namespace-uri()='' and .='10101010']]]]

Conclusion: 
This article would help you understand writing xpath queries on xml and as BizTalk Server is a message-based system and all the messages that enter the BizTalk are converted to XML format, it would help you read elements inside maps/orchestration and pipeline components using xpaths