Marten V7.35 Drops for a Little Post Christmas Cheer

And of course, JasperFx Software is available for any kind of consulting engagement around the Critter Stack tools, event sourcing, event driven architecture, test automation, or just any kind of server side .NET architecture.

Absurdly enough, the Marten community made one major release (7.0 was a big change) and 35 different releases of new functionality. Some significant, some just including a new tactical convenience method or two. I think Marten ends the 2024 calendar year with the 7.35.0 release today.

The big highlight is some work for a JasperFx Software client who needs to run some multi-stream projections asynchronously (as one probably should), but needs their user interface client in some scenarios to be showing the very latest information. That’s now possible with the QueryForNonStaleData<T>()` API shown below:

var builder = Host.CreateApplicationBuilder();
builder.Services.AddMarten(opts =>
{
    opts.Connection(builder.Configuration.GetConnectionString("marten"));
    opts.Projections.Add<TripProjection>(ProjectionLifecycle.Async);
}).AddAsyncDaemon(DaemonMode.HotCold);

using var host = builder.Build();
await host.StartAsync();

// DocumentStore() is an extension method in Marten just
// as a convenience method for test automation
await using var session = host.DocumentStore().LightweightSession();

// This query operation will first "wait" for the asynchronous projection building the
// Trip aggregate document to catch up to at least the highest event sequence number assigned
// at the time this method is called
var latest = await session.QueryForNonStaleData<Trip>(5.Seconds())
    .OrderByDescending(x => x.Started)
    .Take(10)
    .ToListAsync();

Of course, there is a non-zero risk of that operation timing out, so it’s not a silver bullet and you’ll need to be aware of that in your usage, but hey, it’s a way around needing to adopt eventual consistency while also providing a good user experience in your client by not appearing to have lost data.

See the documentation on this feature for more information.

The highlight for me personally is that as of this second, the open issue count for Marten on GitHub is sitting at 37 (bugs, enhancement requests, 8.0 planning, documentation TODOs), which is the lowest that number has been for 7/8 years. Feels good.