Walkthrough: Creating a Content Service Object
Last modified: September 30, 2009
Applies to: SharePoint Foundation 2010
This walkthrough explores how to define the logic for a custom service to manage site content in a SharePoint Foundation deployment. The example shows how to create classes that derive from classes in the Microsoft.SharePoint.Administration namespace to persist custom administrative settings in the database. The example includes class files that implement data structures that contain metadata about a list of locations. Each content location specifies a URL that must be preserved.
The example includes creating code files for the following classes:
ContentService Defines the top-level object, which derives from the SPService class and provides the logic for managing content locations in a deployment. This class includes constructors for initializing the ContentService object, as well as members for retrieving the content service and its collection of content locations.
ContentLocationCollection Defines a collection class that inherits from the SPPerisistedChildCollection class and provides an object to contain content locations. This class contains a constructor and an Add method.
ContentLocation Inherits from SPPersistedObject and defines a content location. This class includes constructors and members for custom property settings.
In addition to creating an assembly with the previous code files, the example shows how to use a custom action Feature to add a link on the Operations page so that administrators can access the service. The example also describes how to use custom .aspx pages to provide the user interface that is required for managing the content service and its content location items. For information about creating a SharePoint Foundation project in Microsoft Visual Studio 2005, see Getting Started with Programmatically Customizing a SharePoint Web Site in Visual Studio.
The following code example defines a FormatType enumeration, and the top-level ContentService class, which includes constructors and the following members:
Local A static property to retrieve the current content location service.
Locations A static property to access the content location collection.
GetAllContentLocations A method to return all content locations provided through the service.
Format A property to get or set the type of format for the content service.
At the top of each code file that is subsequently presented, add a directive to import the Microsoft.SharePoint.Administration namespace, as in the following example. Use the Persisted attribute to make property settings persist in the database. The custom namespace that contains objects in the example is named MS.Samples.SharePoint.ContentManager.
Imports System Imports System.Collections.Generic Imports System.Text Imports Microsoft.SharePoint.Administration Namespace MS.Samples.SharePoint.ContentManager Public Enum FormatType HTML XML End Enum 'ContentLocationType <System.Runtime.InteropServices.Guid("BB69A6EB-3230-43ca-B4F5-752EAC39C74A")> _ Public Class ContentService Inherits SPService <Persisted()> _ Private formatType As FormatType Private Shared locations As ContentLocationCollection Private Shared local As ContentService = Nothing ' A static property that retrieves the content service. Public Shared ReadOnly Property Local() As ContentService Get If ContentService.local Is Nothing Then ContentService.local = _ SPFarm.Local.Services.GetValue < ContentService > "ContentService" End If Return ContentService.local End Get End Property ' A static property for accessing the location collection. Public Shared ReadOnly Property Locations() As ContentLocationCollection Get If Me.locations Is Nothing Then Me.locations = New ContentLocationCollection(Me) End If Return Me.locations End Get End Property ' An empty public constructor required for serialization. Public Sub New() End Sub 'New Public Sub New(farm As SPFarm) MyBase.New("ContentService", farm) ' Add code to initialize as needed. End Sub 'New ' A method to retrieve the content location collection. Public Function GetAllContentLocations() As ContentLocationCollection Dim service As ContentService = ContentService.Local If service Is Nothing Then Return Nothing End If Return service.Locations End Function 'GetAllContentLocations Public Property Format () As FormatType Get Return Me.formatType End Get Set Me.formatType = value End Set End Property End Class 'ContentService End Namespace 'MS.Samples.SharePoint.ContentManager
Define a custom Provision method to add the ContentService object to the database, such as in the following example. This method can be contained in the previous ContentService class, or it can be separately contained to be more modular and callable from different contexts, such as from a Feature installer that you can create to install the service, or from a command-line operation. The Provision method adds the ContentService object to the database without requiring that you specify the assembly and class.
The following example defines the ContentLocationCollection class, which includes constructors and an Add method for adding new content locations to the collection.
The following example defines an enumeration, ContentLocationType, that specifies the type of content location, and a class, ContentLocation, that defines the properties for a content location, including its display name, type, URL, and output path. Specifying the Persisted attribute makes a property setting persist in the database.
The ContentLocation class includes the following members:
DisplayName Property to get the display name of the location.
Url Property to get or set the URL for a content location.
LocationType Property to get or set the location type.
ContentOutputPath Property to get or set an output path.
Public Enum ContentLocationType Web List End Enum 'ContentLocationType Public Class ContentLocation Inherits SPPersistedObject <Persisted()> _ Private locationType As ContentLocationType <Persisted()> _ Private contentOutputPath As String <Persisted()> _ Private url As String Public Sub New() End Sub 'New Public Sub New(name As String, parent As SPPersistedObject) MyBase.New(name, parent) End Sub 'New Public Overrides ReadOnly Property DisplayName() As String Get Return Me.url End Get End Property Public Property Url() As String Get Return Me.url End Get Set If Me.url = value Then Return End If Me.url = value ' The Name property must be unique among multiple children in a ' collection. Use the URL to ensure uniqueness. Me.Name = Me.url End Set End Property Public Property LocationType() As ContentLocationType Get Return Me.locationType End Get Set Me.locationType = value End Set End Property Public Property ContentOutputPath() As String Get Return Me.contentOutputPath End Get Set Me.contentOutputPath = value End Set End Property End Class 'ContentLocation
Add .aspx pages to the \Admin folder, and define their code behind in your assembly. For information on administrative .aspx pages, see Central Administration Pages. Use a Feature to add a custom action to a Central Administration page. For information on adding a custom action, see How to: Modify the User Interface Using Custom Actions.
The following Elements.xml file adds a Content export custom action to the Global Configuration section of the Operations page that links to a contentman.aspx page for managing content locations.
<?xml version="1.0" encoding="utf-8" ?> <Elements xmlns="http://schemas.microsoft.com/sharepoint/"> <CustomAction Id="ContentManagement" GroupId="GlobalConfiguration" Location="Microsoft.SharePoint.Administration.Operations" Sequence="31" Title="Content export"> <UrlAction Url="/_admin/contentman.aspx" /> </CustomAction> </Elements>
The contentman.aspx file to which the custom action points can include links to form pages for creating, displaying, or editing content location items. Code behind for the New item page, for example, can include logic like the following, which adds location items for URLs that are typed in a urlImportExport box on the page, and which redirects to the contentman.aspx page:
Imports System Imports System.Collections.Generic Imports System.Text Imports Microsoft.SharePoint.WebControls Imports System.Web.UI Imports System.Web.UI.WebControls Namespace MS.Samples.SharePoint.ContentManager Public Class NewContentImportExportPage Inherits Page Protected urlImportExport As InputFormTextBox Protected Sub SaveNewImportExport(sender As Object, eventArgs As EventArgs) Dim service As ContentService = ContentService.Local service.Locations.Add(Me.urlImportExport.Text) Response.Redirect("/_admin/contentman.aspx", True) End Sub 'SaveNewImportExport End Class 'NewContentImportExportPage End Namespace 'MS.Samples.SharePoint.ContentManager
After you implement your custom service, you can access its data by instantiating the service and calling its members. You can also create other custom objects that inherit from other persisted objects in the Microsoft.SharePoint.Administration namespace. You can create a class, for example, that derives from the SPJobDefinition class to implement a timer job and perform timed operations through your custom service. Or you can inherit from the SPFeatureReceiver class to define event handling to register the service when it is installed or activated as a Feature.
Through persisted objects, you can add custom administration objects to the configuration database to persist the logic and data for a Web application that is built on the SharePoint Foundation platform.