isolated-task

Why

I ran into this annoyance when I would much have preferred to be getting actual work done. I had the constraint of needing to stay in Visual Studio 2008, and I needed custom build tasks. Trying to develop and debug these tasks when the build engine kept locking the DLLs was inefficient, as it required repeatedly closing and reloading Visual Studio.

The suggestion to derive custom tasks from AppDomainIsolatedTask did not completely solve the problem, but it pointed me in the right direction. Another suggestion to use <GenerateResourceNeverLockTypeAssemblies> similarly was not always workable. What I found was that MSBuild seemed to be parsing <UsingTask> directives by loading the DLL into the main application domain, even though it actually executes the task in a separate domain, provided that the task class derives from MarshalByRefObject (which AppDomainIsolatedTask does). It occurred to me, then, that a wrapper for custom tasks should be possible so that the actual custom task DLLs do not get locked, but a "sacrificial" wrapper DLL would get locked instead. This project is that wrapper.

Requirements

1. Visual Studio 2008 or 2013. 2010 and 2012 may also work with the 2013 version of the solution, but I have not tested those versions.
2. To build the solution, WiX Toolset 3.8 is required. Version 3.9 does not seem to integrate with Visual Studio 2008. If you are only using the VS2013 solution, version 3.9 of WiX will probably work.
3. To sign the IsolatedTask DLL, you will need your own signing key
4. Optional: To sign the MSI, you will need an installation of the Windows SDK in order to use Signtool.exe as well as your own Authenticode key

Use

1. Install the MSI

The installer for v1.1.0.0 is here.

2. Reference IsolatedTask.dll in your MSBuild file

For the current version (1.1.0.0) and the pre-built MSI, add:

<UsingTask AssemblyName="IsolatedTask, Version=1.1.0.0, Culture=neutral, PublicKeyToken=2b71fcced119aa9c, processorArchitecture=MSIL"
           TaskName="IsolatedTask" />

The current installer includes publisher policy assemblies that forward earlier versions of IsolatedTask to version 1.1.0.0, so older references should still work without modification. The current version targets both .NET 3.5 and .NET 4.0.

If you compile your own, you will of course need your own primary key token, version number, etc.

3. Replace your other <UsingTask> elements

Instead of <UsingTask> for your custom tasks, you will just reference your custom task assemblies in the <IsolatedTask> element within a target. See below.

4. Replace your custom task elements with <IsolatedTask> elements

You refer to the assembly with either the AssemblyName or AssemblyFile attribute, and refer to the task name with the TaskNameWithNamespace attribute. For example:

<Target Name="MyTarget">
  <IsolatedTask AssemblyFile="$(MyAssemblyPath)"
                TaskNameWithNamespace="MyNamespace.MyCustomTask"
                ParameterNames="OneParameter;AnotherParameter"
                ParameterValues="$(SomeProperty);false"
                TaskItems="" />
</Target>

XML Reference

Attribute	Type	Description	Required
AssemblyFile	string	The full path to the custom task DLL	Either AssemblyName or AssemblyFile must be specified
AssemblyName	string	The full name of a strong-named assembly	Either AssemblyName or AssemblyFile must be specified
InnerTaskOutput	string	The value of the output parameter in the custom task whose name was specified with OutputParameterName	Optional output parameter
OutputParameterName	string	The name of the output parameter from the custom task to copy to the InnerTaskOutput parameter	Optional
ParameterNames	string[]	The names of the custom task input parameters — use the same name multiple times to specify multiple values for an array	Optional
ParameterValues	string[]	The values of the custom task input parameters in the same order as specified in ParameterNames	Optional
TaskItems	ITaskItem[]	An item array that will be passed to any input parameter in the custom task of type ITaskItem[]	Optional
TaskNameWithNamespace	string	The full name, including the namespace, of the custom task class implementing ITask	Required

The number of items in ParameterNames and ParameterValues must match. To pass a literal array within XML, separate the items by semicolons.

Limits

1. For now, only one ITaskItem array is supported, and it will be passed to every input parameter of type ITaskItem[] in the custom task.
2. Only one output parameter (the one specified with OutputParameterName) will be available.
3. The task probably works in MSBuild 3.5 or later (from the command line or a continuous-integration server), though I have not yet tested this assertion. You will, of course, need to install the DLL on your build server.

Building IsolatedTask yourself

Currently, IsolatedTask.Setup.wixproj attempts to sign the MSI. I have a key that I use in the official MSI build. Authenticode keys are available from a number of vendors. However, if you want to turn off signing, set SignOutput to false in the IsolatedTask.Setup.wixproj MSBuild file.

Contributions

Pull requests are welcome. I do not anticipate having much time to maintain this project. Contributions must be dual-licenced under MIT and GPLv2, just as the current code is licensed.