Feb 272014

What does Side by Side Mean?

Side by Side implementation allows binaries co-exist side by side even with identical names. Well internally the binaries are placed into different folders based on type, name, version, processorArchitecture and publickeytoken. All these elements make up a unique folder/file name. For developers all they need is to embed a manifest into their application which I guess most of you would know. Mostly side by side dependencies are specified via #pragma comment statements or Visual Studio creates a manifest file which is then embedded into the binary using mt.exe. Visual Studio creates a manifest file in the intermediate output folder which follows the following naming convention.


How is a manifest embedded into an application?

If you build your application then you should see following line in the build output window…

1>Copyright (C) Microsoft Corporation. All rights reserved.
1>Embedding manifest...

This file will be embedded into the binary as a resource of type RT_MANIFEST which is just an XML file. The OS application loader will pick up this file from the application’s resource section and will figure out application dependencies from the manifest entries.

Viewing Manifest file embedded into an executable file

Viewing Manifest file embedded into an executable file

What does Side by Side Solve?

The intention was to solve dll hell but this itself went on to become a bigger hell making bloggers like me to blog on this issue. Side by Side errors are hard to figure out hence there is a dedicated tool to help figure the errors out. Side by Side concept is cool but got screwed by the numerous ifs and buts that got into this technology.

How does a Side by Side error look like?

Side by side errors are troublesome to troubleshoot. You run an MFC/CRT application on customer machine and you run into error dialogs similar to the one shown below…


Don’t get overawed by the error. Its quite easy to troubleshoot, hmm well.

How to troubleshoot Side by Side errors using sxstrace?

As the error message suggests let use sxstrace.exe. The usage of sxstrace is pretty easy to understand…

WinSxs Tracing Utility.
Usage: SxsTrace [Options]
   Trace -logfile:FileName [-nostop]
       Enabling tracing for sxs.
       Tracing log is saved to FileName.
       If -nostop is specified, will not prompt to stop tracing.
   Parse -logfile:FileName -outfile:ParsedFile  [-filter:AppName]
       Translate the raw trace file into a human readable format and save the re
sult to ParsedFile.
       Use -filter option to filter the output.
       Stop the trace if it is not stopped before.
Example:  SxsTrace Trace -logfile:SxsTrace.etl
          SxsTrace Parse -logfile:SxsTrace.etl -outfile:SxsTrace.txt
Collecting sxstrace logs

The command usage message shows us two sample commands and that’s exactly what we’re going to try. Please make sure you’re running an elevated command prompt…

Run the following command…

C:\>SxsTrace Trace -logfile:SxsTrace.etl
Tracing started. Trace will be saved to file SxsTrace.etl.
Press Enter to stop tracing...

So now you’re in tracing mode. Go ahead and run your application which threw the side by side error. Press enter on the command prompt window once you’re done repro’ing the error, this will stop the side by side tracing that’s going on. Once you press enter the ETL trace file will be dumped into the current folder. The dumped trace file is not in human readable format…

Binary output from SxsTrace tool

Binary output from SxsTrace tool

Parsing sxstrace logs

To make it readable, we’ll need to parse this file using sxstrace tool. Run following command to do that…

C:\>SxsTrace Parse -logfile:SxsTrace.etl -outfile:SxsTrace.txt
Parsing log file SxsTrace.etl...
Parsing finished! Output saved to file SxsTrace.txt.

So now we have a text file as output. Lets open the file and find out what went wrong… Contents are as follows…

Parsed output from sxstrace

Parsed output from sxstrace

I’ve annotated the above screenshot for your convenience.

Sample location of a side by side assembly

So basically side by side works based on version of a dll. All side by side binaries go in the winsxs folder located in C:\Windows. For e.g. on my machine msvcr90d.dll is located in the following folder…

Viewing a side by side assembly

Viewing a side by side assembly

If you noticed, the folder name is made up of version number as well. So dll’s belonging to different versions are put in unique folders hence they exists “side by side” hence the name “side by side”.

So the above error means the application couldn’t find msvcr90d.dll in the above location. The way I would solve this is to create a setup project in VC9 and install the merge modules onto the target machine. Please note the dll’s are debug binaries else you could have just installed the redist’s.

Hope this will help you.