The Media Center Sandbox

Hi all,

Is there a way to go to previous page in MCML?

It's exactly the same with invoking  "HistoryOrientatedPageSession.BackPage() " from MCML.

I couldn't find the way to get a reference to HistoryOrientedPageSession instance.

I'm writing Web Application. So using C# is out of choice.

A Client wants to locate "Back" button on the screen.

If the button is clicked, the page should go to previous one.

I don't want to use "Navigate" element because it put the current page on top of the stack.

I hope I could make myself clear.

Any help is really appreciated.

Kenichiro,

You may be able to add the HistoryOrientedPageSession as an object in your properties section of your MCML, as follows:

You can then access it in your MCML - and pass it down through UIs in the properties section.

Cheers,
Andrew

AndyC, Thank you very much for your response.

I tried the code below. But it didn't work.
When I execute FirstPage.mcml from MCMLPad through MediaCenter,
I received UnhandledAddInException.

Attempt to build an object of type 'HistoryOrientedPageSession' failed.
StackTrace:
Microsoft.MediaCenter.Hosting.PageSession..ctor()
Microsoft.MediaCenter.Hosting.HistoryOrientedPageSession..ctor()
...

If I execute the page below from MCMLPreviewToolLaucher, I received Fatal Runtime error after I clicked "NextPage".

Exception: AddInHost cannot be null (InvalidOperationException)
Stack:
  Microsoft.MediaCenter.Hosting.Infrastructure.McpfState.get_AddInUiHost()
  Microsoft.MediaCenter.Hosting.PageSession.EnsureFullscreenSession()

Situation is almost the same even if I locate the files on the web server.
Do I misunderstand something? I'm using Vista(TM) RC1 Build 5600.
I'm so close to goal. This would be the last problem. But not so much time left. Any help is really appreciated.

Kenichiro,

PS:

I thought that PageSession is kind of runtime environment. And MCML was executed on top of it.

So I felt uncomfortable to instantiate PageSession object from MCML.

I might be wrong though.

--FirstPage.mcml--

<Mcml xmlns="http://schemas.microsoft.com/2006/mcml"
     xmlns:host="assembly://Microsoft.MediaCenter/Microsoft.MediaCenter.Hosting"
   xmlns:me="Me">
 <UI Name="NavigateTest">
  <Properties>
   <host:HistoryOrientedPageSession Name="Session"/>
  </Properties>
  <Locals>
   <ClickHandler Name="Clicker"/>
   <NavigateCommand Name="NavCommand" Source="file://NextPage.mcml" Session="[Session]"/>
  </Locals>
  <Rules>
   <Default Target="[Input.KeyInteractive]" Value="true"/>
   <Default Target="[Clicker.Command]" Value="[NavCommand]"/>
  </Rules>
  <Content>
   <Text Content="NextPage" Color="White"/>
  </Content>
 </UI>
</Mcml>

--NextPage.mcml--

<Mcml xmlns="http://schemas.microsoft.com/2006/mcml"
     xmlns:host="assembly://Microsoft.MediaCenter/Microsoft.MediaCenter.Hosting">

 <UI Name="BackPageTest">
  <Locals>
   <ClickHandler Name="Clicker"/>
  </Locals>
  <Properties>
   <host:HistoryOrientedPageSession Name="Session"/>
  </Properties>
  <Rules>
   <Changed Source="[Clicker.Invoked]">
    <Actions>
     <DebugTrace Message="Go to Prev Page (Session.BackPage) Invoke"/>
     <Invoke Target="[Session.BackPage]"/>
    </Actions>
   </Changed>
  </Rules>
  <Content>
   <Text Content="Go to prev page" Color="White"/>
  </Content>
 </UI>
</Mcml>

• You are running on RC2 or later.
• You are trying your sample outside of Media Center Preview Tool (MCMLPad.exe), as this application does not implement the page stack session yet. You will need to register an entry point for your application in order to do this (see this post for more info).

• Declare the following XML namespace:
• xmlns:host="assembly://Microsoft.MediaCenter/Microsoft.MediaCenter.Hosting"
• Declare the following entry on your properties/locals section  (the name does matter):
  
• <host:PageSession Name="Session" PageSession="$Required"/>
  
• Invoke the following method where you want the back operation to happen:
• <Invoke Target="[Session!host:HistoryOrientedPageSession.BackPage]"/>

Hi mvarela-san, Arigato(="Thank you" in Japanese).

Your advise gave me sight.
If you move a page from A to B using Navigate, then you can come back to page A just clicking back button in page B.
So I thought that MCMLPad keeps some kind of session and it should be available from mcml.

Anyway, I tried according to your suggestion, but it didn't work.

I located two pages.
http://www.digicas.com/mcml/trial/FirstPage.mcml
http://www.digicas.com/mcml/trial/NextPage.mcml

Here's the xml to register.
<?xml version="1.0" encoding="utf-8"?>
<application title="WMCPL Web Application Example" id="{f2cd7fc9-a5c9-11db-96d5-005056c00008}">
  <entrypoint id="{01573692-a5ca-11db-96d5-005056c00008}"
                  addin="Microsoft.MediaCenter.Hosting.WebAddIn,Microsoft.MediaCenter"
                  title="PageSession Test"
                  description="HistoryOrientedPageSession Trial"
                  context="http://www.digicas.com/mcml/trial/FirstPage.mcml">
    <category category="More Programs"/>
  </entrypoint>
</application>

I received an exception like below:
  System.InvalidOperationException: Error evaluating path 'Session!host:History..."
  The 'Session' member on ... returned 'null' and evaluation could not continue.

Unfortunatelly, I failed to get RC2, though SDK is the latest one.
It might be the reason. It'll be very appreciated if you try on latest environment.

Thank you.
Kenichiro,

Just tried it on a brand-new install of Vista Ultimate RTM - works perfectly.  Shows text at the top of the page, click it it moves to the next page, click the text on that page and it returns you to the previous page.

My understanding is that you need to run the version of the SDK for the version of the OS you are using - so for RC1, you need the RC1 SDK.

Do you have access to the RTM version of Vista?  Via MSDN for example?

Cheers,
Andrew

Thank you, AndyC.
I've spent a whole day on it yesterday. And I'd gave up this afternoon and started to seek another approach.
I merged two pages into one (putting one UI that covers whole screen onto another, and control visibility).
After I've finished it, I found your response...

Anyway, It's pretty good to know that it worked. AndyC, Thank you very much. Very appreciated.

Kenichiro,

KenichiroTanaka's URL doesn't work on my Vista X64 with SP1. I got the same error message: "System.InvalidOperationException: Error evaluatin path 'Session!host:HistoryOrientedPageSession.BackPage'. The 'Session' member on 'Microsoft.MediaCenter.UI.View' returned 'null' and evaluation could not continue."

Since PageSession is "$Required" in NextPage.mcml, you should pass a host:PageSession object to PageSession while navigating to NextPage.mcml, right? But I don't see this action in FirstPage.mcml. So, how could it work?

I believe the hosting environment for web-based MCML passes this value in.

Cheers,
Andrew

Again, just to confirm, this still works on x86 Vista Media Center (just tested).

Cheers,
Andrew

How are you accessing it?

Cheers,
Andrew

Just to check, you are running it from within Media Center not via standalone MCML Pad?  I get the exact error you describe if I run in MCML Pad.

Cheers,
Andrew

Register it using the XML file here (reposted from further up the thread):

<?xml version="1.0" encoding="utf-8"?>
<application title="WMCPL Web Application Example" id="{f2cd7fc9-a5c9-11db-96d5-005056c00008}">
  <entrypoint id="{01573692-a5ca-11db-96d5-005056c00008}"
                  addin="Microsoft.MediaCenter.Hosting.WebAddIn,Microsoft.MediaCenter"
                  title="PageSession Test"
                  description="HistoryOrientedPageSession Trial"
                  context="http://www.digicas.com/mcml/trial/FirstPage.mcml">
    <category category="More Programs"/>
  </entrypoint>
</application>

and it should work.  Access through it's own icon rather than McmlPad - it doesn't work in McmlPad either standalone or within Media Center.

Cheers,
Andrew