A property schema enables you to define promoted properties in a common location and have them referenced by other schemas.
A property schema can have a namespace but not records or attributes.
Elements defined in the property schema have a name and type.
The property schema must get deployed to BizTalk Server like all other schemas because the property schema may need to be referenced by more than one schema, and because the information in the property schema must be available to components at runtime.
After a property schema has been created, elements and attributes with the same type can be promoted as one of the named properties in the property schema.
Schema is the meta-data used to describe the content and structure of a Business Document. Implemented by parsers that validate a Business Document’s conformance to the Schema at runtime.
Schemas for business documents do not contain any BizTags but contains only those tags required to support the business transaction, as designed by the publishing organization.
A document schema is used to define a message. It is a definition on an Xml message with optional extensions for flat files, EDI file, etc that enable the parsers to convert the native format into Xml.
A property schema is used to define message context properties. These can be of type MessageDataPropertyBase (the property value is promoted or demoted from/to the message itself) or MessageContextPropertyBase(property value only exists within the message context and can be set by adapters, pipelines or within orchestrations).
If you wish to promote a field from a message into the message context the you need to define a document schema and property schema. In the document schema you promote the required field using the property schema to define the property type that will be used in the message context.
Message context properties are used for content based routing, correlation, modifying message content within orchestrations, etc.