Versioning SharePoint binary Workflow ASPX task forms

As noted by some developers, workflow versioning is somekind of headache in SharePoint.

I`m wondering is there a way I can version my aspx forms? For sure, i can version code behind assemblies, but if markup changes for any of m开发者_JAVA技巧y files in LAYOUTS folder? Is there versioning available for files or do i have to choose new filename for my form?

Sorry, i should have been more specific. Yes, i have files under version control (i can restore previous versions etc), but i`m not talking about this kind of version control. But by deploying new Workflow Version, i must not delete old one, because it is still running on many items in SharePoint, but rather , as noted in previous links, deploy new one so i don't break execution of workflows.

But workflows will still break if i don't preserve old aspx forms used by users to interact with workflows.

So i must ensure that

1. Assemblies with old version numbers used by old workflow exists (this one is ok, i just changed assembly version number and deployed to GAC)
2. I must ensure that old workflow still uses old aspx form used users to interact with workflow, but new workflow version should use new aspx form with more options (how to do this?).

If you were to host your WF task forms in _layouts like so:

/_layouts/myapp/task.aspx // <- unversioned
/_layouts/myapp/1.0.0.0/task.ascx // <- versioned
/_layouts/myapp/1.0.0.1/task.ascx
/_layouts/myapp/1.0.0.2/task.ascx

...and have the codebehind in task.aspx dynamically load the usercontrol (task.ascx) after first reading the AssemblyVersion attribute from the primary workflow assembly, you could version your task forms.