SSRS SharePoint Integration on 2 Computer Deployment

Question

I understand that on the computer running SSRS in SharePoint Integrated mode I must also have a minimal installation of SharePoint. The following from MSDN illustrates this:

My setup consists of a SharePoint web front end and a SQL server so the only way for SSRS Integrated Mode to work is if do one of the following:

1. Install SSRS using SharePoing Integrated mode on the SharePoint front end server.
2. Or I put a minimal SharePoint 2010 installation on the SQL Server.

Since installing SharePoint on a SQL Server is a no-no, I must do the former. Now my question to you experts is why. Why do I need to have SharePoint installed on the same computer as SSRS Integrated Mode when I do not need this in native mode.

Based on an error I get, pasted below, I can assume that it is because it needs access to the object model. Again I ask why. Why does it need the object model in this case but not when running in native mode. Does it not also have access to the object model when in native mode?

The configuration parameter SharePointIntegrated is set to True but 
SharePoint Object Model cannot be loaded. The error was: 
System.IO.FileNotFoundException: Could not load file or assembly 
'Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, 
PublicKeyToken=71e9bce111e9429c' or one of its dependencies.

Answer 1

You're correct in that it needs access to the object model when running in Integrated Mode. In Native Mode the reports run in SSRS/SQL and not SharePoint directly. The report viewer for a native mode report is just an iframe, essentially.

In integrated mode the reports are stored within SharePoint, so SSRS needs to be able to communicate with SharePoint to get to the reports, data sources, etc. Hence the object model..

if this is a dev environment, I've heard some people being able to get around this requirement by manually installing the SharePoint assemblies, but I've never tried it personally.

Hope that helps.