BizTalk Server : Deep dive in schema design | Logic app : Working with XML schema | XML schema example and XML Schema syntax

After seeing many questions asked based on schema design on the BizTalk forums, thought of writing article on it  and share as much as I know.

A Schema is a definition of a document which describes the structure of that particular document. 

In BizTalk, there are two common types of structures which mainly deal with XML-based and Flat Files. This article intends to explain bits and bytes of designing BizTalk Schema (XML Schema).

Same is applicable if working with XML in Logic app, any other technology for that matter.

The concept of XML schema, XML Syntax remains same.

An XML Schema describes the structure of an XML document.

XML Schema Example used in the article

<?xml version="1.0" encoding="utf-16"? >

-<xs:schema xmlns="http://testingschemas.incomingorder/ "xmlns:b="http://schemas.microsoft.com/BizTalk/2003"targetNamespace="http://testingschemas.incomingorder/"xmlns:xs="http://www.w3.org/2001/XMLSchema">

- <xs:simpleType name="eMailType">

- <xs:restriction base="xs:string">

  <xs:pattern value="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*" />

  </xs:restriction>

  </xs:simpleType>

- <xs:element name="Order">

- <xs:annotation>

- <xs:appinfo>

- <b:properties>

  <b:property distinguished="true" xpath="/*[local-name()='Order' and namespace-uri()='http://testingschemas.incomingorder/']/*[local-name()='Header' and namespace-uri()='']/*[local-name()='OrderId' and namespace-uri()='']" />

  <b:property distinguished="true" xpath="/*[local-name()='Order' and namespace-uri()='http://testingschemas.incomingorder/']/*[local-name()='Header' and namespace-uri()='']/*[local-name()='OrderDate' and namespace-uri()='']" />

  </b:properties>

  </xs:appinfo>

  </xs:annotation>

- <xs:complexType>

- <xs:sequence>

- <xs:element name="Header">

- <xs:complexType>

- <xs:sequence>

  <xs:element name="OrderId" type="xs:string" />

  <xs:element name="OrderDate" type="xs:string" />

  <xs:element name="Currency" type="xs:string" />

- <xs:element minOccurs="0" maxOccurs="1" name="ShipTo">

- <xs:complexType>

- <xs:sequence>

  <xs:element name="ID" type="xs:string" />

  <xs:element name="Name" type="xs:string" />

  <xs:element name="AddressLine1" type="xs:string" />

  <xs:element name="AddressLine2" type="xs:string" />

  <xs:element name="City" type="xs:string" />

  <xs:element name="State" type="xs:string" />

  <xs:element name="PostalCode" type="xs:string" />

  <xs:element name="Country" type="xs:string" />

  <xs:element name="TelephoneNumber" type="xs:string" />

  <xs:element name="EmailAddress" type="eMailType" />

  </xs:sequence>

  </xs:complexType>

  </xs:element>

- <xs:element minOccurs="0" maxOccurs="1" name="BillTo">

- <xs:complexType>

- <xs:sequence>

  <xs:element name="ID" type="xs:string" />

  <xs:element name="Name" type="xs:string" />

  <xs:element name="AddressLine1" type="xs:string" />

  <xs:element name="AddressLine2" type="xs:string" />

  <xs:element name="City" type="xs:string" />

  <xs:element name="State" type="xs:string" />

  <xs:element name="PostalCode" type="xs:string" />

  <xs:element name="Country" type="xs:string" />

  <xs:element name="TelephoneNumber" type="xs:string" />

  <xs:element name="EmailAddress" type="eMailType" />

  </xs:sequence>

  </xs:complexType>

  </xs:element>

  <xs:element name="HeaderComment" type="xs:string" />

  </xs:sequence>

  </xs:complexType>

  </xs:element>

- <xs:element name="Details">

- <xs:complexType>

- <xs:sequence>

- <xs:element minOccurs="1" maxOccurs="unbounded" name="Item">

- <xs:complexType>

- <xs:sequence>

  <xs:element name="ItemId" type="xs:string" />

  <xs:element name="ItemDescription" type="xs:string" />

  <xs:element name="Quantity" type="xs:string" />

  <xs:element name="UnitPrice" type="xs:string" />

  <xs:element name="LineNumber" type="xs:string" />

  <xs:element name="UOM" type="xs:string" />

  <xs:element name="RequestedDeliveryDate" type="xs:string" />

  <xs:element name="LineComment" type="xs:string" />

  </xs:sequence>

  </xs:complexType>

  </xs:element>

  </xs:sequence>

  </xs:complexType>

  </xs:element>

  </xs:sequence>

  </xs:complexType>

  </xs:element>

  </xs:schema>

Building blocks of BizTalk schema - xml schema syntax

The Schema is created with the help of following components:

1.     BizTalk Schema Editor.

2.     Version and Encoding.

3.     Namespace.

4.     Properties.

5.     Root Node and properties associated with it.

6.     Record Node and properties associated with it.

7.     Element and properties associated with it.

8.     Attributes and properties associated with it.

9.     Properties associated with Schema.

BizTalk Schema Editor

The BizTalk Editor shows the schema in two sections, the first section on the left shows  the tree view and the second section shows the XSD code.

Properties window can be found at the right bottom of the screen, which is used to set properties of the nodes. 

Note: XSD code can only be viewed and cannot be edited.

Version and Encoding

Both are used as a Processing Instruction.

xml version: It tells as to which XML output conforms to.

encoding: It tells as to which encoding standard is used for displaying the characters in XML.

Below are few encoding standards:

• "us-ascii"
• "windows-1252"
• "ISO-8859-1"
• "UTF-8"
• "UTF-16"

BizTalk always uses UTF-16 encoding for their schemas.

<?xml version="1.0" encoding="utf-16"? >

Namespace

By default, the BizTalk Editor will set the namespace of a schema to

• http://ProjectName.SchemaName.

Note: http://schemas.microsoft.com/BizTalk/2003 and http://www.w3.org/2001/XMLSchema are also added by BizTalk and are implicit. Basically, both are references to definitions, annotations defined by BizTalk and W3.org, it is the reason why we are able to build schema.

<xs:schema xmlns="http://testingschemas.incomingorder/ 

"xmlns:b="http://schemas.microsoft.com/BizTalk/2003"targetNamespace="http://testingschemas.incomingorder/"xmlns:xs="http://www.w3.org/2001/XMLSchema">

Common Properties across Root Node,Record Node,Element Field,Attribute Field

Properties	Description	Available For
Base Data Type	Determines the name of the type definition that the current node type is based upon.	Root Node, Record Node, Element Field,Attribute Field
Block	The Block property is used to prevent specific types of derivation to be used in place of this Node. The default value is ’None’.	Root Node, Record Node
Content Type	Content model of the complex type (either ofComplexContent, SimpleContent,None).The default is ‘None’.	Root Node, Record Node
Data Structure Type	Indicates the structure type of the record. Usually is a global complex type or named reference to a global element.	Root Node, Record Node
Group Max Occurs	Maximum Occurrences of the underlying group content of this Node. Its value should always be greater than or equal to Group Min Occurs. The default value is ‘1’.	Root Node, Record Node
Group Min Occurs	Minimum Occurrences of the underlying group content of this Node. Its value should always be less than or equal to Group Max Occurs. The default value is ‘1’.	Root Node, Record Node
Group Order Type	Determines the type of group ordering for children nodes under the current context. Available options are Sequence, Choice, All.	Root Node, Record Node
Mixed	Determines whether the sub-elements in the current context can be intermingled with text content. The default value is ‘False’.	Root Node, Record Node
Nillable	Determines whether this node can be null in the instance document. The default value is ‘False’.	Root Node, Record Node, Element Field
Node Name	Name of the Node.	Root Node, Record Node, Element Field, Attribute Field
Notes	This property is used to access a dialog for entry of what are effectively business level comments about the node with focus.	Root Node, Record Node, Element Field, Attribute Field
Max Occurs	Maximum Occurrences of this node. Its value should always be greater than or equal to minOccurs of this node. Use ‘unbounded’ or ‘*’ to indicate unlimited occurrences. The default value is ‘1’.	Record Node, Element Field
Min Occurs	Minimum occurrences of this node. Its value should always be less than or equal to MaxOccurs for this node. The default value is ‘1’.	Record Node, Element Field
Data Type	Data Type of the Node	Element Field, Attribute Field
Default Value	Default value of this node.This can be used in a scenario where you can get no value in the instance but it can't be left blank, thus, assign a value (so if no value then the default value is considered).	Element Field, Attribute Field
Derived By	Indicates how the underlying Simple Type of the Field is derived from its base data type. Options available are Restriction, List and Union.	Element Field, Attribute Field
Fixed	The fixed attribute is used to ensure that the field is set to particular fixed value. This can be used in a scenario where value has to be static.	Element Field, Attribute Field
Form	During instance validation, determines whether the items in the current context must be qualified with a namespace. Options are Qualified and Unqualified.	Element Field, Attribute Field

Root Node and properties associated with it

Root node is a special type of Record Node which has at least one child and no parent. Whenever you create a schema in BizTalk schema editor a Root node will be added automatically with the name as "Root".

It can be renamed, and its best practice to name it after the purpose, say "Order" if it is for order.

User have no control over certain properties:

There are few properties which are disabled (BizTalk has control) like Body XPath, Derived By, Form, Instance Path, Min Occurs, Max Occurs and Namespace.

Note : When the Envelope property of the Schema node is set to Yes its only then  Body XPath property can be set.Body XPath property is used to specify the XPath of the node which is root of the body which is wrapped using Envelope.

Record Node and properties associated with it

Whenever Record node is added, it's Content-Type is preset as complexType and whenever a child element field is added under it , the Group Order Type gets set as a sequence.

There are indicators as to how the elements should appear under Record.

• xs:Choice  
• xs:Sequence
• xs:All

When we use xs:choice group then only one of its child elements to appear, when xs:sequence is used then it is expected to have elements as in the schema as per the sequence and when xs:all is used, it  allow their child elements to appear zero (0) or one (1) time and in any order. 

- <xs:element name="Header">

- <xs:complexType>

- <xs:sequence>

  <xs:element name="OrderId" type="xs:string" />

  <xs:element name="OrderDate" type="xs:string" />

  <xs:element name="Currency" type="xs:string" />

Four properties which puzzles a lot:

The properties associated with occurrences are Group Max Occurs,Group Min Occurs,Max Occurs and Min Occurs.
Group Max Occurs and Group Min Occurs: This property tells about the number of times the group of elements (either of type sequence,group) which are under that particular Record can occur and by Default it is "1".

Max Occurs and Min Occurs: This property tells about the number of times that particular Record can occur and by Default it is "1".

Element and properties associated with it

Whenever an element is added its Data Type is set to xs:string, it can/should be changed as per requirement, and to do it click the Text field in front of Data Type property and select from the options which serves your purpose. If the requirement is to have some restrictions or pattern to be implemented then Base Data Type is to be used along with the Derived By property. 

- <xs:simpleType name="eMailType">

- <xs:restriction base="xs:string">

  <xs:pattern value="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*" />

  </xs:restriction>

  </xs:simpleType>

Form  is a special property as it is used only in the scenario where that particular element/attribute needs to qualify to the namespace. Default is unqualified.

There are situations where the elements need to have a default value, this can be done by Using Default Value property and setting value against it.

Note: Even if Max Occurs and Min Occurs appear blank in Properties  tab, it is implicitly considered as "1".

<  xs:element name="OrderId" type="xs:string" />

  <xs:element name="OrderDate" type="xs:string" />

  <xs:element name="Currency" type="xs:string" />

Attributes and properties associated with it

Whenever an attribute is added its Data type is set to xs:string, it can/should be changed as per requirement, and to do it click the Text field in front of Data Type property and select from the options which serves your purpose.

Note:  Max Occurs and Min Occurs property are not available .

<xs:attribute name="ForDemo" type="xs:string" />

Properties associated with Schema

The most important property is  Target Namespace. Target Namespace is to schema what a namespace is to .Net Object. 

It is used in the creation of MessageType and plays an important role to resolve schema references.

Note: Target Namespace can be empty.

Envelope is a BizTalk specific property which indicates whether the schema is an envelope schema (wrapper to some document schema). By default values is 'No'. It can/should be changed when creating Envelope schema and value should be 'Yes'.

CodeList Database : Specifies the database (*.mdb file) to be used to indicate code list property(enumeration values) on fields.

Attributes FormDefault: Describes how the attributes will appear in the instance. Default value is 'Unqualified'. If set to qualified then the instance will have all attribute field marked with namespaces.

Element FormDefault: Describes how the elements will appear in the instance. Default value is 'Unqualified'. If set to qualified then the instance will have all element  field marked with namespaces.

Property which raises questions:

Imports property which helps in using already existing schemas gives three options to choose from as per the requirement.

• XSD Import – Accessing  types and using them, deriving new types from them of another schema.
• XSD Include – Accessing types and using them of another schema within the same namespace (or blank), deriving new types from them.
• XSD Redefine – Accessing types and using them of another schema within the same namespace (or blank),deriving new  types from them and also type modifications are allowed, thus the name Redefine.

Will keep on posting as an when I find something to share!!!!!!!!!!!!

If you have questions or suggestions, feel free to do in comments section below !!!

Do share if you find this helpful .......

 

                          Knowledge Sharing is Caring !!!!!!

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