WindowsSideBySide

Overview

• Topic = Isolated Applications and Side-by-side Assemblies
• Main article = http://msdn.microsoft.com/en-us/library/dd408052.aspx
• Concept for reducing DLL and EXE versioning conflicts
• Concept exists since Windows XP

Isolated application

• "Self-describing" application with a manifest
• Fully Isolated = Application uses only side-by-side assemblies, or only private assemblies
• Is described by a manifest
• The application manifest contains, among other things:
  • Dependencies to assemblies (if necessary including versions)

Side-by-side assembly

• Collection of resources that is described by a manifest
• The collection typically is a DLL
• Possibl resources: DLLs, classes, COM server, type libraries, interfaces
• A Side-by-side Assembly has a unique identity; one part of the identity is the version
• The manifest of a side-by-side assembly contains, among other things:
  • The identity of an assembly (the assemblyIdentity element)
  • Which files are part of the assembly
  • Dependencies to other assemblies
  • Information about binding and COM activation that traditionally is stored in the Windows Registry (e.g. COM classes, interfaces, type libraries)

Manifest

• XML file that describes a side-by-side assembly or an isolated application
• The manifest of a shared assembly is stored in the system's WinSxS folder
• The manifest of a private assembly is either embedded into the DLL as a resource, or stored in the application folder
• The manifest of an application is either embedded into the EXE as a resource, or stored in the application folder

Search order of assemblies

• First the system searches the shared assemblies in the system's WinSxS folder
• Next the system searches the application's private assemblies
• Detailed example: http://msdn.microsoft.com/en-us/library/aa374224.aspx

Activation context

• http://msdn.microsoft.com/en-us/library/aa374153.aspx
• Good background article: http://blogs.msdn.com/b/junfeng/archive/2006/03/19/sxs-activation-context-activate-and-deactivate.aspx
• An area of memory that is initialised with the content of a manifest
• Defines which concrete version of an assembly/DLL should be loaded

Assembly version

• major.minor.build.revision
• A change to major and/or minor means the assembly is not backwards compatible

Debugging

To solve SxS problems the tool "sxstrace" can be sued. Reference: http://blogs.msdn.com/b/junfeng/archive/2006/04/14/576314.aspx.

Howto:

• Run cmd.exe as administrator
• Start the trace

sxstrace trace -logfile:c:\sxstrace.etl

• Start the program
• Stop the trace by pressing the <ENTER> key in the console
• Analyse the binary trace file:

sxstrace parse -logfile:c:\sxstrace.etl -outfile:c:\sxstrace.txt

• The text file now contains the trace information in human readable format