With Elsa Workflow 2.0 how to create an activity based on HttpEndpoint - elsa-workflows

Question

We're trying to use Elsa for a project, but we're facing some difficulties now, so need suggestions badly. One thing we're trying to do is to create an Activity based on existing HttpEndpoint. However, with the source code got from https://github.com/elsa-workflows/elsa-core, after googled some docs and samples, we haven't been able to figure it out.
Here is what exactly we're attempting to do.
create a new Activity based on HttpEndpoint
make the Path include WorkflowInstanceId by default
a little bit more customizations needed in our scenario
Looking forward to suggestions and guidance. Thanks!

Answer 1

You could do something like what the Webhooks module is doing. Instead of
inheriting from HttpEndpoint, it uses an IActivityTypeProvider implementation that dynamically yields new activity types that reuse HttpEndpoint.
In your case, your activity type provider would only have to yield a single activity type (e.g. MyEndpoint) that pre-configures any and all aspects that you want, including the default Path property value.
Deriving a new activity type from HttpEndpoint directly works too. You will have to implement your own bookmark provider that provides HttpEndpointBookmark objects - the HTTP middleware for the HttpEndpoint activity relies on that.
Example:
public class MyEndpointBookmarkProvider : BookmarkProvider<HttpEndpointBookmark>
{
public override bool SupportsActivity(BookmarkProviderContext context) => context.ActivityType.TypeName == nameof(MyEndpoint);
public override async ValueTask<IEnumerable<BookmarkResult>> GetBookmarksAsync(BookmarkProviderContext context, CancellationToken cancellationToken)
{
var path = await context.ReadActivityPropertyAsync<MyEndpoint, PathString>(x => x.Path, cancellationToken);
var methods = (await context.ReadActivityPropertyAsync<MyEndpoint, HashSet<string>>(x => x.Methods, cancellationToken))?.Select(ToLower) ?? Enumerable.Empty<string>();
BookmarkResult CreateBookmark(string method) => Result(new(path, method), nameof(HttpEndpoint));
return methods.Select(CreateBookmark);
}
private static string ToLower(string s) => s.ToLowerInvariant();
}
The above bookmark provider provides bookmarks for your custom activity when the activity being indexed is of type "MyEndpoint".
Alternatively, you might go a different route altogether and simply implement an API endpoint (an ASP.NET Core controller, middleware or route endpoint) that triggers workflows based on your custom activity. I've written some documentation about that process here: https://elsa-workflows.github.io/elsa-core/docs/next/guides/guides-blocking-activities