TypeDescriptor Class

Defines the data type of a parameter for a method.

Inheritance Hierarchy

System.Object
  Microsoft.Office.Server.ApplicationRegistry.MetadataModel.MetadataObject
    Microsoft.Office.Server.ApplicationRegistry.MetadataModel.TypeDescriptor

Namespace:  Microsoft.Office.Server.ApplicationRegistry.MetadataModel
Assembly:  Microsoft.SharePoint.Portal (in Microsoft.SharePoint.Portal.dll)

Syntax

'Declaration
<SharePointPermissionAttribute(SecurityAction.LinkDemand, ObjectModel := True)> _
<SharePointPermissionAttribute(SecurityAction.InheritanceDemand, ObjectModel := True)> _
Public Class TypeDescriptor _
    Inherits MetadataObject

'Usage
Dim instance As TypeDescriptor

[SharePointPermissionAttribute(SecurityAction.LinkDemand, ObjectModel = true)]
[SharePointPermissionAttribute(SecurityAction.InheritanceDemand, ObjectModel = true)]
public class TypeDescriptor : MetadataObject

Remarks

Every Parameter object has a TypeDescriptor object that defines the data type of the parameter. It is the most complex metadata object. It is a hierarchical object that recursively describes an abstract data structure built of primitives. In addition, each leaf node of the TypeDescriptor tree points to a set of possible default values specified by the MethodInstance object Therefore, given a MethodInstance and a parameter, the parameter's TypeDescriptor is a recipe to instantiate a default value for that parameter.

In addition, TypeDescriptors form the heart of the Business Data Catalog's ability to transform complex backend APIs into simple stereotypical operations like Find, FindSpecific, CheckAccess, ad so on. Once you define detailed type information via the TypeDescriptor metadata, you can tag TypeDescriptors as slots where Identifiers or Filter values can be plugged in by the Business Data Catalog. For example, a TypeDescriptor in a Parameter that is tagged to receive the Identifier for an Entity, results in a Method that can be used as a SpecificFinder.

Use the IsCollection property on a return TypeDescriptor object to indicate wherever there are collections within the return parameter. Consider a Web method that return collections of customers, each customer of which contains a collection of Addresses. In this example, the flag must be set twice—once at the root Customer[] level, and then again at the Customer[0].Address[] level. However, a collection TypeDescriptor object can have only a single child TypeDescriptor object under it that represents the structure in the collection.

Business Data Catalog clients such as the Business Data Web Parts do not handle complex structures. For example, consider the following structures:

class Customer { String Name; Address address; } 
class Address { Street street; String city; String zip; }
class Street { int Block; String street; }

To work around this limitation, Business Data Catalog supports the concept of "complex formatting." Because clients support flat structures of primitives, the Business Data Catalog will "render" complex structures as formatted strings via two mechanisms: a simple .NET Framework String formatter, or a more complex Renderer that one can write using any .NET language. This is accomplished by setting two String properties with the names "FormatString" (e.g. "{0}, {1} \n {2}, {3}") or "RendererDefinition" (MyMethodName!MyTypeName, MyAssemblyName), respectively. The Method object in the RendererDefinition must correspond to a public static .NET method on a public .NET Type that takes a single argument, which is an array of Objects. In either case, what gets passed to the Format string or to the .NET Renderer is basically an array of all the primitive child values of the complex structure, as modeled by the Business Data Catalog TypeDescriptor definition for that structure.

A controlling property called "ComplexFormatting" must appear on any structure that contains complex fields, to enable complex rendering.

Schema

Properties

Following are the properties that the TypeDescriptor object accepts for both database and Web service systems.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also

Reference

TypeDescriptor Members

Microsoft.Office.Server.ApplicationRegistry.MetadataModel Namespace