具有 ASP.NET Web 服务的 SharePoint API 例外

我正在创建一个可以访问某些SharePoint API的Web服务，该服务将从某个WSS数据库中获取内容并创建要从中读取的CMP导出。 我已经成功地使用常规 Windows 窗体应用程序在 C# 中以编程方式执行此操作，只要该程序在 SharePoint 服务器上和服务器场管理员帐户下运行。 但是，当我尝试从我的 ASP.NET Web 服务运行相同的确切代码时，会出现此问题。 Web 服务下发生的错误是"对象引用未设置为对象的实例"，并带有 System.NullReferenceException。

请参阅下面的代码：

[WebMethod]
public bool SPRetreiveCMPTest()
{
    try
    {
        SqlConnectionStringBuilder scsb = new SqlConnectionStringBuilder("Data Source=sql1''sharepoint;Initial Catalog=WSS_Content_Sales_Test;Integrated Security=SSPI");
        SPContentDatabase spcd = SPContentDatabase.CreateUnattachedContentDatabase(scsb); // <-- ERROR OCCURS HERE!!
        SPExportObject speo = new SPExportObject();
        speo.Url = "http://sharepoint/sites/sales/productmgmt/Product Management";
        speo.IncludeDescendants = SPIncludeDescendants.All;
        speo.Type = SPDeploymentObjectType.List;
        SPExportSettings spes = new SPExportSettings();
        spes.UnattachedContentDatabase = spcd;
        spes.SiteUrl = "http://sharepoint1:8080/sites/sales";
        spes.FileLocation = "C:''users''sp_farm''test_restore";
        spes.LogFilePath = "C:''users''sp_farm''test_restore''test.log";
        spes.BaseFileName = "testout";
        spes.ExportObjects.Add(speo);
        spes.IncludeVersions = SPIncludeVersions.All;
        spes.LogExportObjectsTable = false;
        spes.IncludeSecurity = SPIncludeSecurity.All;
        using (SPExport spe = new SPExport(spes))
            spe.Run();
    }
    catch (Exception e) { return false; }
    return true;
}

我已确保运行 Web 服务的应用程序池使用的是服务器场管理员帐户。 关于为什么会发生此错误的任何想法？

编辑：

修好了！我开始关注下面的堆栈跟踪，我意识到这是一个由两部分组成的修复。

第一个堆栈跟踪：

at Microsoft.SharePoint.Utilities.SPUtility.ValidateFormDigest()
at Microsoft.SharePoint.Administration.SPPersistedObject.BaseUpdate()
at Microsoft.SharePoint.Administration.SPPersistedChildCollection`1.Add(T newObj, Boolean ensure)
at Microsoft.SharePoint.Administration.SPPersistedChildCollection`1.Ensure(T newObj)
at Microsoft.SharePoint.Administration.SPContentDatabase.CreateUnattachedContentDatabase(String databaseInstanceServer, String databaseName, String username, String password)
at PHSSPWebService.PHSSPWebServiceClass.SPRetreiveCMPTest() in D:''My Documents''Visual Studio 2008''Projects''PHS''PHSSPWebService''PHSSPWebService''PHSSPWebService.asmx.cs:line 100"

1.( 我必须在 IIS 中为我的 Web 服务网站启用表单身份验证，并出现了新的异常 (InvalidOperationException( 和堆栈跟踪。

第二个堆栈跟踪：

at Microsoft.SharePoint.WebControls.SPControl.SPWebEnsureSPControl(HttpContext context)
at Microsoft.SharePoint.Utilities.SPUtility.ValidateFormDigest()
at Microsoft.SharePoint.Administration.SPPersistedObject.BaseUpdate()
at Microsoft.SharePoint.Administration.SPPersistedChildCollection`1.Add(T newObj, Boolean ensure)
at Microsoft.SharePoint.Administration.SPPersistedChildCollection`1.Ensure(T newObj)
at Microsoft.SharePoint.Administration.SPContentDatabase.CreateUnattachedContentDatabase(String databaseInstanceServer, String databaseName, String username, String password)
at PHSSPWebService.PHSSPWebServiceClass.SPRetreiveCMPTest() in D:''My Documents''Visual Studio 2008''Projects''PHS''PHSSPWebService''PHSSPWebService''PHSSPWebService.asmx.cs:line 100"

2.( SPWebEnsureSPControl(HttpContext context)的修复方法是在我的代码开始时设置HttpContext.Current = null，瞧，它奏效了！

有关更多详细信息，请参阅此处：http://johnatjornata.wordpress.com/2012/01/23/runwithelevatedprivileges-operation-is-not-valid-due-to-the-current-state-of-the-object-error-explained/