The IIS-side (SxS) collection allows an ASP application to specify which version of the system DLL or traditional COM component to use, such as MDAC, MFS, MSVCRT, MSXML, and so on. For example, if your ASP application relies on MSXML version 2.0, you can ensure that even the ServerAfter the Service Pack has been applied, your application still uses MSXML version 2.0. Any new version of MSXML is still installed on your computer, but it retains version 2.0 and is used by your application. Configuring the SxS assembly requires that you know the path to the DLL, and that the COM + manifest file exists in each virtual directory that needs to use the DLL. The COM + manifest is an XML file that contains information about the location of the DLL installation. IIS does not verify that the manifest exists. The manifest looks similar to the following file excerpt:
<?xml version= "1.0" encoding= "UTF-8" standalone= "yes"?
<assembly xmlns= "urn:schemas-microsoft-com:asm.v1" manifestversion= "1.0"
<assemblyidentity publickeytoken= "75e377300ab7b886" type= "Win32" Name= "Test4dir" version= "1.0.0.0" Processorarchitecture= "x86"/>
<file name= "DirComp.dll" hash= "35ca6f27b11ed948ac6e50b75566355f0991d5d9" hashalg= "SHA1"
<comclass clsid= "{6C6CC20E-0F85-49C0-A14D-D09102BD7CDC}" progid= "Dircomp.pathinfo" threadingmodel= "Apartment"/>
<typelib tlbid= ' {aa56d6b8-9adb-415d-9e10-16dd68447319} ' version= ' 1.0 ' helpdir= ' '/>
</file>
</assembly>
You can enable side-by-side collections either programmatically or by using IIS Manager on the IIS side.
Using IIS Manager on the IIS side to enable side-by-side collections
In IIS Manager, right-click the Web site or virtual directory, and then click Properties.
Click the Virtual Directory tab, and then click Configure.
If the configuration button is not available, the reason is that the application has not yet been created for the virtual directory. Click Create to create an application.
In the Application Configuration dialog box, click the Options tab.
Select the Enable collection by side together check box.
In the Manifest file name box, type a name for the COM + manifest file.
Click OK two times.
To programmatically enable side-by collection, set the ASPENABLESXS flag for AspAppServiceFlags metabase properties. Also, set the AspSxsName metabase property to the name of the COM + manifest. Set both metabase properties at the application level.
Important even if the feature is configurable at the application level, only one version of the system DLL can be used in any one of the application pools. For example, if an application App1 uses MDAC version 2.5 and the application APP2 uses MDAC version 2.4, APP1 and APP2 should not be in the same application pool. If they are in the same application pool, the application loaded first will load the corresponding version of MDAC, and other applications will only be forced to use that version until the applications are unloaded.
