Office Web Apps SharePoint 2010 - IFrame

Issue:

1. In a project I'm working on we use Office Web Apps in SP2010 to preview selected documents in the browser.

2. We've created a very simple web part that renders an I-Frame with the URL set to one of the Office Web Apps urls depending on the document extension. Now the are not renderring in IFrame.

Reason:

Unfortunately the X-Frame header, that is added by the Office Web Apps service, prevents Internet Explorer to render the documents in an I-Frame!

Solution:

To solve this we've created a very simple HttpModule that checks for the header and changes the value from "DENY" to "SAMEORIGIN". This post simply shows the code for such a module that enables previewing of documents with Office Web Apps inside an I-Frame.

Implement the Module

http://support.microsoft.com/kb/307996

1. Create a new Visual Studio .NET C# Class Library project named MyModule.
2. Set a reference to the System.Web.dll assembly.
3. Add the following directive to the class:

   using System.Web;     

4. Rename the class SyncModule.cs, and then change the class definition to reflect this.
5. Implement the IHttpModule interface. Your class definition should appear as follows:

   public class OfficeWebAppIntModule : IHttpModule

6. Write the following code in the interface which changes the value of header(
   
   "X-FRAME-OPTIONS") from "DENY" to "SAMEORIGIN" in the Init event.
   

public class OfficeWebAppIntModule : IHttpModule

    {

        private const string XFrameOptionsHeaderName = "X-FRAME-OPTIONS";

        LogMessage errorLogger = new LogMessage();

    /// <summary>

    /// Initializes a new instance of the <see cref="XFrameOptionsModule"/> class.

    /// </summary>

        public OfficeWebAppIntModule()

        {

        }

        /// <summary>

        /// Disposes of the resources (other than memory) used by the module that implements <see cref="T:System.Web.IHttpModule"/>.

        /// </summary>

        public void Dispose()

        {

        }

        /// <summary>

        /// Initializes a module and prepares it to handle requests.

        /// </summary>

        /// <param name="context">An <see cref="T:System.Web.HttpApplication"/> that provides access to the methods, properties, and events common to all application objects within an ASP.NET application</param>

        public void Init(HttpApplication context)

        {            

            context.PreSendRequestHeaders += new EventHandler(ChangeXFrameOptionsHeaderToSameOrigin);

            //context.PreSendRequestHeaders += ChangeXFrameOptionsHeaderToSameOrigin;

        }

        /// <summary>

        /// Changes the X-Frame-Options "DENY" header to "SAMEORIGIN".

        /// </summary>

        /// <param name="sender">The HttpApplication that triggers the event.</param>

        /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>

        private void ChangeXFrameOptionsHeaderToSameOrigin(object sender, EventArgs e)

        {

                //throw new ApplicationException("Testing HTTP Module");

                HttpApplication application = (HttpApplication)sender;

                HttpResponse response = application.Response;

                string headerValue = response.Headers[XFrameOptionsHeaderName];

                if (headerValue != null && headerValue.Equals("DENY", StringComparison.OrdinalIgnoreCase))

                {

                    response.Headers[XFrameOptionsHeaderName] = "SAMEORIGIN";

                }            

        }

    }

 7. Compile the Project.

Deploy the Module

Register the dll into GAC

Configure the System

In the C:\Inetpub\Wwwroot\Module\ directory, create a new file named Web.config.

Paste the following text in Web.config:

<system.webServer>

    <modules runAllManagedModulesForAllRequests="true">

     

      <add name="OfficeWebAppIntegration"type="OfficeWebAppIntegration.OfficeWebAppIntModule, OfficeWebAppIntegration, Version=1.0.0.0, Culture=neutral, PublicKeyToken=0bb6b20dfb6d61a1" preCondition="managedHandler" />

    </modules>

</system.webServer>