Deploying SharePoint Event Receiver Assembly to Web Application BIN

Question

Is it possible to successfully deploy an assembly containing event handlers for a custom SharePoint list feature (thus, classes that depend on the Microsoft.SharePoint assembly) to a web application's bin instead of the GAC?

The option to do so certainly appears to be present in the XML markup in my feature's manifest.xml file. However, I've seen several references that deploying CAS policies for the assembly are a must with little instruction on how to successfully achieve this for an assembly that requires privileges like access to the SharePoint object model. I've also seen discussion suggesting that the GAC is nearly a requirement because of difficulties/issues with CAS.

I have been able to actually deploy the assembly to the folder. The security issues however, have been a big impediment. The only way I've been able to get my assembly to run (instead of simply erroring out with exceptions) is by elevating the web.config's trust level to <trust level="Full" originUrl=""> which won't fly in my environment. I'm hoping to verify that what I'm trying to do is possible before I continue to further wrestle with CAS.

If this is possible, if anyone has guidance or resources that would assist me in modifying my feature to deploy my event handlers in this fashion, I'd appreciate it.

Answer 1

Don't elevate the web.config's trust level - pretty large hammer for a tiny problem. You must package up a custom CAS policy in your WSP to grant your assembly higher privileges that the web.config bestows on it.

-Oisin

Answer 2

One way to approach this is to crank up the logging, record the various exceptions that are thrown and then write a CAS policy manually. This is a very probabalistic approach and rather painful.

It seems likely that all of the permission demands for any given method or class are known up front. If so, it should be possible to write a tool to statically analyse your code and dependant assemblies and compose the required CAS file. Unfortunately, I'm not aware of any tool that does this.

For what it's worth, GAC'ing your assembly seems much "lighter" than upping the trust level.

Answer 3

If I got your question right, you want to deploy a list event receiver to the web application's BIN directory.

This is not possible within SharePoint 2010, but I don't know if it was supported on MOSS 2007 (i guess it wasn't supported either).

This behavior is by design, because SharePoint internally uses the System.Reflection.Assembly.Load() Method to load the event receiver assembly. The Load() method does only work with fully qualified assembly names, thus requiring the assembly to reside in the global assembly cache.