Tag Archives: Lamar

Environment Checks and Better Command Line Abilities for your .Net Core Application

Oakton.AspNetCore is a new package built on top of the Oakton 2.0+ command line parser that adds extra functionality to the command line execution of ASP.Net Core and .Net Core 3.0 codebases. At the bottom of this blog post is a small section showing you how to set up Oakton.AspNetCore to run commands in your .Net Core application.

First though, you need to understand that when you use the dotnet run command to build and execute your ASP.Net Core application, you can pass arguments and flags both to dotnet run itself and to your application through the string[] args argument of Program.Main(). These two types of arguments or flags are separated by a double dash, like this example: dotnet run --framework netcoreapp2.0 -- ?. In this case, “–framework netcoreapp2.0” is used by dotnet run itself, and the values to the right of the “–” are passed into your application as the args array.

With that out of the way, let’s see what Oakton.AspNetCore brings to the table.

Extended “Run” Options

In the default ASP.Net Core templates, your application can be started with all its defaults by using dotnet run.  Oakton.AspNetCore retains that usage, but adds some new abilities with its “Run” command. To check the syntax options, type dotnet run -- ? run:

 Usages for 'run' (Runs the configured AspNetCore application)
  run [-c, --check] [-e, --environment <environment>] [-v, --verbose] [-l, --log-level <logleve>] [----config:<prop> <value>]

  ---------------------------------------------------------------------------------------------------------------------------------------
    Flags
  ---------------------------------------------------------------------------------------------------------------------------------------
                        [-c, --check] -> Run the environment checks before starting the host
    [-e, --environment <environment>] -> Use to override the ASP.Net Environment name
                      [-v, --verbose] -> Write out much more information at startup and enables console logging
          [-l, --log-level <logleve>] -> Override the log level
          [----config:<prop> <value>] -> Overwrite individual configuration items
  ---------------------------------------------------------------------------------------------------------------------------------------

To run your application under a different hosting environment name value, use a flag like so:

dotnet run -- --environment Testing

or

dotnet run -- -e Testing

To overwrite configuration key/value pairs, you’ve also got this option:

dotnet run -- --config:key1 value1 --config:key2 value2

which will overwrite the configuration keys for “key1” and “key2” to “value1” and “value2” respectively.

Lastly, you can have any configured environment checks for your application immediately before starting your application by using this flag:

dotnet run -- --check

More on this function in the next section.

 

Environment Checks

I’m a huge fan of building environment tests directly into your application. Environment tests allow your application to self-diagnose issues with deployment, configuration, or environmental dependencies upfront that would impact its ability to run.

As a very real world example, let’s say your ASP.Net Core application needs to access another web service that’s managed independently by other teams and maybe, just maybe your testers have occasionally tried to test your application when:

  • Your application configuration has the wrong Url for the other web service
  • The other web service isn’t running at all
  • There’s some kind of authentication issue between your application and the other web service

In the real world project that spawned the example above, we added a formal environment check that would try to touch the health check endpoint of the external web service and throw an exception if we couldn’t connect to the external system. The next step was to execute our application as it was configured and deployed with this environment check as part of our Continuous Deployment pipeline. If the environment check failed, the deployment itself failed and triggered off the normal set of failure alerts letting us know to go fix the environment rather than letting our testers waste time on a bad deployment.

With all that said, let’s look at what Oakton.AspNetCore does here to help you add environment checks. Let’s say your application uses a single Sql Server database, and the connection string should be configured in the “connectionString” key of your application’s connection. You would probably want an environment check just to verify at a minimum that you can successfully connect to your database as it’s configured.

In your ASP.Net Core Startup class, you could add a new service registration for an environment check like this example:

// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
    // Other registrations we don't care about...
    
    // This extension method is in Oakton.AspNetCore
    services.CheckEnvironment<IConfiguration>("Can connect to the application database", config =>
    {
        var connectionString = config["connectionString"];
        using (var conn = new SqlConnection(connectionString))
        {
            // Just attempt to open the connection. If there's anything
            // wrong here, it's going to throw an exception
            conn.Open();
        }
    });
}

Now, during deployments or even just pulling down the code to run locally, we can run the environment checks on our application like so:

dotnet run -- check-env

Which in the case of our application above, blows up with output like this because I didn’t add configuration for the database in the first place:

Running Environment Checks
   1.) Failed: Can connect to the application database
System.InvalidOperationException: The ConnectionString property has not been initialized.
   at System.Data.SqlClient.SqlConnection.PermissionDemand()
   at System.Data.SqlClient.SqlConnectionFactory.Permissi
onDemand(DbConnection outerConnection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1
 retry, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, 
DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at MvcApp.Startup.<>c.<ConfigureServices>b_
_4_0(IConfiguration config) in /Users/jeremydmiller/code/oakton/src/MvcApp/Startup.cs:line 41
   at Oakton.AspNetCore.Environment.EnvironmentCheckExtensions.<>c__DisplayClass2_0`1.<CheckEnvironment>b__0(IServ
iceProvider s, CancellationToken c) in /Users/jeremydmiller/code/oakton/src/Oakton.AspNetCore/Environment/EnvironmentCheckExtensions.cs:line 53
   at Oakton.AspNetCore.Environment.LambdaCheck.Assert(IServiceP
rovider services, CancellationToken cancellation) in /Users/jeremydmiller/code/oakton/src/Oakton.AspNetCore/Environment/LambdaCheck.cs:line 19
   at Oakton.AspNetCore.Environment.EnvironmentChecker.ExecuteAll
EnvironmentChecks(IServiceProvider services, CancellationToken token) in /Users/jeremydmiller/code/oakton/src/Oakton.AspNetCore/Environment/EnvironmentChecker.cs:line 31

If you ran this command during continuous deployment scripts, the command should cause your build to fail when it detects environment problems.

In some of Calavista’s current projects , we’ve been adding environment tests to our applications for items like:

  • Can our application read certain configured directories?
  • Can our application as it’s configured connect to databases?
  • Can your application reach other web services?
  • Are required configuration items specified? That’s been an issue as we’ve had to build out Continuous Deployment pipelines to many, many different server environments

I don’t see the idea of “Environment Tests” mentioned very often, and it might have other names I’m not aware of. I learned about the idea back in the Extreme Programming days from a blog post from Nat Pryce that I can’t find any longer, but there’s this paper from those days too.

 

Add Other Commands

I’ve frequently worked in projects where we’ve built parallel console applications that reproduce a lot of the same IoC and configuration setup to perform administrative tasks or add other diagnostics. It could be things like adding users, rebuilding an event store projection, executing database migrations, or loading some kind of data into the application’s database. What if instead, you could just add these directly to your .Net Core application as additional dotnet run -- [command] options? Fortunately, Oakton.AspNetCore let’s you do exactly that, and even allows you to package up reusable commands in other assemblies that could be distributed by Nuget.

If you use Lamar as your IoC container in an ASP.Net Core application (or .Net Core 3.0 console app using the new unified HostBuilder), we now have an add on Nuget called Lamar.Diagnostics that will add new Oakton commands to your application that give you access to Lamar’s diagnostic tools from the command line. As an example, this library adds a command to write out the “WhatDoIHave()” report for the underlying Lamar IoC container of your application to the command line or a file like this:

dotnet run --lamar-services

Now, using the command above as an example, to build or add your own commands start by decorating the assembly containing the command classes with this attribute:

[assembly:OaktonCommandAssembly]

Having this assembly tells Oakton.AspNetCore to search the assembly for additional Oakton commands. There is no other setup necessary.

If your command needs to use the application’s services or configuration, have the Oakton input type inherit from NetCoreInput type from Oakton.AspNetCore like so:

public class LamarServicesInput : NetCoreInput
{
    // Lots of other flags
}

Next, the new command for “lamar-services” is just this:

[Description("List all the registered Lamar services", Name = "lamar-services")]
public class LamarServicesCommand : OaktonCommand<LamarServicesInput>
{
    public override bool Execute(LamarServicesInput input)
    {
        // BuildHost() will return an IHost for your application
        // if you're using .Net Core 3.0, or IWebHost for
        // ASP.Net Core 2.*
        using (var host = input.BuildHost())
        {
            // The actual execution using host.Services
            // to get at the underlying Lamar Container
        }

        return true;
    }


}

Getting Started

In both cases I’m assuming that you’ve bootstrapped your application with one of the standard project templates like dotnet new webapi or dotnet new mvc. In both cases, you’ll first add a reference to the Oakton.AspNetCore Nuget. Next, break into the Program.Main()entry point method in your project and modify it like the following samples.

If you’re absolutely cutting edge and using ASP.Net Core 3.0:

public class Program
{
    public static Task<int> Main(string[] args)
    {
        return CreateHostBuilder(args)
            
            // This extension method replaces the calls to
            // IWebHost.Build() and Start()
            .RunOaktonCommands(args);
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(x => x.UseStartup<Startup>());
    
}

For what I would guess is most folks, the ASP.Net Core 2.* setup (and this would work as well for ASP.Net Core 3.0 as well):

public class Program
{
    public static Task<int> Main(string[] args)
    {
        return CreateWebHostBuilder(args)
            
            // This extension method replaces the calls to
            // IWebHost.Build() and Start()
            .RunOaktonCommands(args);
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>();
    
}

The two changes from the template defaults is to:

  1. Change the return value to Task<int>
  2. Replace the calls to IHost.Build() and IHost.Start() to use the RunOaktonCommands(args) extension method that hangs off IWebHostBuilder and the new unified IHostBuilder if you’re targeting netcoreapp3.0.

And that’s it, you’re off to the races.

 

Lamar and Oakton join the .Net Core 3.0 Party

Like many other .Net OSS authors, I’ve been putting in some time this week making sure that various .Net tools support the brand spanking new .Net Core and ASP.Net Core 3.0 bits that were just released. First up is Oakton and Lamar, with the rest of the SW Missouri projects to follow soon.

Oakton

Oakton is yet another command line parser tool for .Net. The main Oakton 2.0.1 library adds support for the Netstandard2.1 target, but does not change in any other way. The Oakton.AspNetCore library got a full 2.0.0 release. If you’re using ASP.Net Core v2.0, your usage is unchanged. However, if you are targeting netcoreapp3.0, the extension methods now depend on the newly unified IHostBuilder rather than the older IWebHostBuilder and the bootstrapping looks like this now:

public class Program
{
    public static Task<int> Main(string[] args)
    {
        return CreateHostBuilder(args)
            
            // This extension method replaces the calls to
            // IWebHost.Build() and Start()
            .RunOaktonCommands(args);
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(x => x.UseStartup<Startup>());
    
}

 

Oakton.AspNetCore provides an improved and extensible command line experience for ASP.Net Core. I’ve been meaning to write a bigger blog post about it, but that’s gonna wait for another day.

Lamar

The 3.0 support in Lamar was unpleasant, because the targeting covers the spread from .Net 4.6.1 to netstandard2.0 to netstandard2.1, and the test library covered several .Net runtimes. After this, I’d really like to not have to type “#if/#else/#endif” ever, ever again (and I do use ReSharper/Rider’s ALT-CTRL-J surround with feature religiously that helps, but you get my point).

The new bits and releases are:

  • Lamar v3.2.0 adds a netstandard2.1 target
  • LamarCompiler v2.1.0 adds a netstandard2.1 target (probably only used by Jasper, but who knows who’s picked it up, so I updated it)
  • LamarCodeGeneration v1.1.0 adds a netstandard2.1 target but is otherwise unchanged
  • Lamar.Microsoft.DependencyInjection v4.0.0 — this is the adapter library to replace the built in DI container in ASP.Net Core with Lamar. This is a full point release because some of the method signatures changed. I deleted the special Lamar handling for IOption<T> and ILogger<T> because they no longer added any value. If your application targets netcoreapp3.0, the UseLamar() method and its overloads hang off of IHostBuilder instead of IWebHostBuilder. If you are remaining on ASP.Net Core v2.*, UseLamar() still hangs off of IWebHostBuilder
  • Lamar.Diagnostics v1.1.0 — assuming that you use the Oakton.AspNetCore command line adapter for your ASP.Net Core application, adding a reference to this library adds new commands to expose the Lamar diagnostic capabilities from the command line of your application. This version targets both netstandard2.0 for ASP.Net Core v2.* and netstandard2.1 for ASP.Net Core 3.*.

 

The challenges

The biggest problem was that in both of these projects, I wanted to retain support for .Net 4.6+ and netstandard2.0 or netcoreapp2.* runtime targets. That’s unfortunately meant a helluva lot of conditional compilation and conditional Nuget references per target framework. In some cases, the move from the old ASP.Net Core <=2.* IWebHostBuilder to the newer, unified IHostBuilder took some doing in both the real code and in the unit tests. Adding to the fun is that there are real differences sometimes between the old, full .Net framework, netcoreapp2.0, netcoreapp2.1/2, and certainly the brand new netcoreapp3.0.

Another little hiccup was that the dotnet pack pathing support was fixed to what it was originally in the project.json early days, but that broke all our build scripts and that had to be adjusted (the artifacts path is relative to the current directory now rather than to the binary target path like is was).

At least on AppVeyor, we had to force the existing image to install the latest .Net SDK as part of the build because the image we were using didn’t yet support the brand new .Net SDK. I’d assume that is very temporary and I can’t speak to other hosted CI providers. If you’re wondering how to do that, see this example from Lamar that I got from Jimmy Byrd.

 

Other Projects I’m Involved With

  • StructureMap — If someone feels like doing it, I’d take a pull request to StructureMap.Microsoft.DependencyInjection to put out a .Net Core 3.0 compatible version (really just means supporting the new IHostBuilder instead of or in addition to the old IWebHostBuilder).
  • Alba — Some other folks are working on that one, and I’m anticipating an Alba on ASP.Net Core 3.0 release in the next couple days. I’ll write a follow up blog post when that’s ready
  • Marten — I’m not anticipating much effort here, but we should at least have our testing libraries target netcoreapp3.0 and see what happens. We did have some issues with netcoreapp2.1, so we’ll see I guess
  • Jasper — I’ve admittedly had Jasper mostly on ice until .Net Core 3.0 was released. I’ll start work on Jasper next week, but in that is going to be a true conversion up to netcoreapp3.0 and some additional structural changes to finally get to a 1.0 release of that thing.
  • Storyteller — I’m not sure yet, but I’ve started doing a big overhaul of Storyteller that’s gotten derailed by the .Net Core 3.0 stuff

 

Lamar 3.1 – New Diagnostics and more

Lamar 3.1.0 was published today with a few fixes, new diagnostics, and a newly improved equivalent to StructureMap’s old “Forward” registration. The full details are here.

There’s one big bug fix on multi-threaded usage that was impacting folks using Lamar with MediatR (it’s worth a later blog post about debugging problems because this took several folks and at least two attempts from me to finally diagnose and solve).

“Inverse” Registration

For the not uncommon need to have one single object be the implementation for multiple role interfaces within the container, there’s the new “inverse” registration mechanism as shown below:

[Fact]
public void when_singleton_both_interfaces_give_same_instance()
{
    var container = new Container(services =>
    {
        services.Use<Implementation>()
            .Singleton()
            .For<IServiceA>()
            .For<IServiceB>();
    });

    var instanceA = container.GetInstance<IServiceA>();
    var instanceB = container.GetInstance<IServiceB>();

    instanceA.ShouldBeTheSameAs(instanceB);
}

What you see above is registering the concrete type Implementation as the shared, underlying service for both IServiceA and IServiceBregistrations.

HowDoIBuild

Lamar has been able to show you the “build plan” for registrations since the beginning, but now there’s a helper Container.HowDoIBuild() method that gives you easier access to this information that can be helpful for troubleshooting IoC configuration issues.

Lamar.Diagnostics

More on this one later, but there’s also a brand new package called Lamar.Diagnostics that, in conjunction with Oakton.AspNetCore, adds command line access to all the Lamar diagnostic capabilities directly to your ASP.Net Core application.

 

 

Lamar v3 is Released: Faster, smaller, quicker cold starts, internal type friendly

Lamar has had some churn lately with me almost giving up on it, changing my mind, and look at that, publishing a very significantly improved version up to Nuget just now.

I just published Lamar v3.0 with some bug fixes and big internal improvements. This release is mostly significant because it eliminates Lamar’s previous reliance on Roslyn for runtime code generation in favor of a more common model that builds Expression trees and compiles dynamic lambdas — inevitably with the excellent FastExpressionCompiler for maximum performance and faster cold starts.

All told, Lamar v3.0:

  • Has much faster “cold start” times compared to ❤
  • Is faster across the board, but especially when internal types are involved. The very early user feedback is “holy moses that’s much faster”
  • I think that we’re through with compatibility with internal types being registered into the container because the dynamic Lambdas don’t have to care about the type visibility
  • Will use way less memory without the Roslyn dependency tree in memory
  • Has far fewer dependencies now that some users complained about

There are no API changes to Lamar itself, but there’s now a different set of Nuget libraries:

  1. LamarCompiler — only has Lamar’s old helper for executing the Roslyn runtime compilation, but this is no longer referenced by Lamar itself
  2. LamarCodeGeneration — the Frame / Variable model that Lamar uses to generate code and now Expression trees in memory. This is used by Lamar itself, could be used as a stand alone library, and has no direct coupling to LamarCompiler
  3. Lamar itself

A touch of history…

I’ve been absolutely exhausted for years with maintaining StructureMap and dealing with user questions and oddball problems. I also knew it had some pretty ugly performance issues and it had been a massive pain in the ass force fitting StructureMap’s long standing functionality into ASP.Net Core’s new compliance requirements (that appear to have been made up by the ASP.Net team out of whole cloth with ZERO input from the major OSS IoC tool authors). I also knew from some experimentation that I wasn’t going to be able to fix StructureMap very easily, so…

Lamar was an attempt by me to throw together a new IoC tool that would mostly mimic StructureMap‘s public API (everybody has opinions, but there are actually quite a few people who like StructureMap’s usability and it’s had ~6 million downloads) and a large subset of its functionality. At the same time, I did change its lifecycle semantics and behavior to be ASP.Net Core-compliant from the very get go to head off more problems with that.

Lamar’s original model was based around using dynamic code generation and compilation with Roslyn. Woohoo, it was easy to use and I was able to get a large subset of StructureMap’s old functionality working over Christmas break a couple years ago. Unfortunately, that model doesn’t play well at all with internal types and my limited workarounds were pretty clumsy. It turns out that lots and lots of people and common frameworks like to put internal types into IoC containers (looking at you ASP.Net Core). So here we are. Lamar switched over to using Expressions compiled into Funcs like basically every other IoC container I’m aware of, but hopefully it starts fulfilling my real goal for Lamar:

Get folks complaining about StructureMap off of that and make my life easier overall by reducing user problems.

Jasper v0.9.9 is Released!

Jasper is an open source project I’ve been furiously working on for the past couple years as what I have to admit is mostly a chance to resurrect the best parts of the earlier FubuMVC framework while solving its technical and usability shortcomings. Along the way, Jasper has evolved a bit away from its FubuMVC roots to be more consistent and compatible with ASP.Net Core. At this point, Jasper is a fancy command execution pipeline that lives inside of the ASP.Net Core ecosystem. Jasper can be used as any mix of a lightweight messaging framework, an in-memory service bus, or handling HTTP requests as an alternative ASP.Net Core framework.

I was just able to push a new v0.9.9 release of Jasper that I want to effectively be the last alpha release. At this point, I think the public API surface is pretty well set and only a handful of features left before making the big ol’ 1.0 release. I think the most important thing for Jasper is to try to get folks to take it for a spin, or glance through tutorials, and generally try to get some feedback and visibility about the project.

Here’s some links to get you started:

There’ll hopefully be plenty of blog posts on Jasper in the next couple weeks, starting with how Jasper’s usability contrasts with MVC Core in the HTTP space or NServiceBus/MediatR/etc. for messaging and command execution.

The Road to 1.0

I’ve got to put Jasper down for awhile to focus on some Lamar and help out a lot more with Marten for probably a couple months before I do much more on Jasper, but I’d still love to get 1.0 out by at least the end of the summer.

I’m thinking out loud in this section, so everything is subject to change. Before I flip the switch to the big, giant 1.0, I think these things might need to happen:

  • There are some optimizations I want to make to the database backed message persistence I couldn’t quite get to for v0.9.9.
  • I’m very tempted just to wait until the netcoreapp3.0 wave of updates comes out. It’s a near guarantee that ASP.Net Core v3.0 will break some of Jasper’s internals, and it’d be very helpful to slim Jasper’s package dependency tree down if Jasper could depend on the new generic host model instead of IWebHostBuilder when 3.0 unifies that model somewhat.
  • Jasper heavily depends on the Task Parallel Library from Microsoft, but that seems to be somewhat deprecated now. I might look to rewire Jasper’s internals to use the newer System.Threading.Channels instead. I haven’t done any research into this one yet.
  • If the HTTP support is going to live on, it’ll need some kind of Swagger/Swashbuckle integration for the Jasper HTTP API support
  • I’d like to spend some time on supporting the Techempower Benchmarks for Jasper and some performance optimization. My goal here is to make Jasper the fastest HTTP application framework for .Net Core and be just barely slower than the raw ASP.Net Core benchmarks (not sure how feasible that is, but let me dream on).
  • Jasper is going to have to adjust to whatever becomes of Lamar. I don’t think this is going to change Jasper at development time, but might introduce a new production build step to optimize Jasper application’s “cold start” times for better hosting in Docker kind of worlds.

Lamar stays and how that enfolds

I wrote a blog post at the end of last week about Lamar when I just happened to be feeling discouraged about a couple things (it happens sometimes, and I swear that having to support IoC tools exposes me to more difficult people than every other project I work on combined). I got some rest this weekend, a bit of positive reinforcement from other folks, and actually thought through how to fix the issues. Long story short, I’m not giving up on anything and here’s what I think the very doable game plan is for Lamar (and the closely related Jasper project):

Lamar

  • Short term: Get a small bug fix release out soon that has some options to “force” all the compilation upfront in one dynamic assembly. That’s gonna hurt the cold start time, but should help the memory usage. We’ll also look to see if there’s any places where Lamar is holding on unnecessarily to the Roslyn compilation objects to ensure that they can be garbage collected
  • Medium term: Introduce an alternative compilation model based on Expressions compiled to Lambdas with FastExpressionCompiler. This model will kick in automatically whenever there’s one or more internal types in the “build plan”, and could be opted into globally through a container level switch. I didn’t want to do this originally because the model just isn’t very fun to work with.  After thinking it through quite a bit over the weekend, I think it won’t be bad at all to retrofit this alternative to Lamar’s existing Frame and Variable model. This will knock out the performance issues with internal types and address all the memory issues.
  • Long term: Probably split up LamarCompiler a little bit to remove the actual code compilation to significantly slim down Lamar’s dependency tree and move Lamar to a purely Expression based model. Introducing the Expression model will inevitably make the exception stacktrace messages coming out of Lamar explode, so there might have to be an effort to rewrite them to make them more user friendly (I had to do this in StructureMap 3 several years ago).

 

Jasper

I’m very close to pulling the trigger on a Jasper v1.0, with the understanding that it’s inevitable that there will be a Jasper v2.0 later in the year to incorporate .Net Core 3.0. I don’t think that Jasper will have any issues with memory usage related to Lamar because it uses Lamar very differently than MVC in any flavor. The changes to Lamar will impact Jasper though, so:

Short term: Jasper v1.0 with Lamar as it is.

Medium term: Jasper gets a model where you can happily use the runtime codegen and compilation during development time while things are churning, but for production usage you have the ability to just drop the code that would be generated to disk, have that compiled into your system in the first place, and let Jasper use those types. Ultra fast production time cold start times, no worries at all about Roslyn doing bad things from memory. I’ve already done successful proof of concept development on this one.

Long term: profit.

As an aside, I got quizzed quite a bit about why Jasper has to be specific to Lamar as its IoC container and can’t just support whatever tool folks want to use. The reason is that Jasper uses Lamar’s very specific code generation in its pipeline to avoid using an IoC container at runtime whatsoever and also to avoid forcing users to have to conform to all kinds of Jasper specific adapter interfaces. I could maybe force Jasper to still pull this off with the built in DI container or another IoC container with Jasper-centric adapters to expose all of its metadata in a way such that the codegen understands it, but just ick.

If you took Lamar’s runtime codegen away, I think Jasper inevitably looks like a near clone of NServiceBus or Brighter both in its usability and runtime pipeline and why does the world need that?

 

 

Lamar asks: Do I stay or do I go?

I happened to look into the Lamar issue list on GitHub late this afternoon at the end of a very long work day. What I saw was nothing to feel good about. A huge memory usage problem (probably related to Roslyn but I don’t know that for sure), a user who’s been very difficult in the past telling me he switched to another tool because it was easier to use and faster, bugs that unfortunately point to a huge flaw in Lamar’s basic premise, and folks really wanting a feature I’ve put off because it’s going to be a lot of work.

Lamar started its life as a subsystem of Jasper, the project that’s been my main side-project for the past couple years and my biggest ambition for several years before that. Jasper’s special sauce is the way that it uses Lamar to generate and compile code at runtime to glue together the runtime pipeline in the most efficient way possible. At the same time, it was killing me to support StructureMap and I wanted out of it, but didn’t want to leave a huge mess of folks with an abandoned project, so I turned Lamar into an IoC tool that was purposely meant to be a smooth transition for StructureMap users to an improved and more efficient IoC tool.

Right now, it’s becoming clear that the basic model of Lamar to use the runtime code generation isn’t working out. First because of what looks like some severe memory issues related to the runtime compilation, and second because it turns out that it’s very, very common for folks to use internal .Net types in IoC containers which pretty well defeats the entire code generation model. Lamar has workarounds for this to fall back to dynamic expressions for internal types, but it’s not optimized for that and Lamar’s performance degrades badly when folks use internal types.

As I see it, my choices with Lamar are to:

  • Retool it to use dynamic Expression compilation all the way down in the IoC engine usage like basically every other IoC tool including the older StructureMap library. That takes care of the performance issues most likely and knocks out the bugs due to internal types, but just sounds miserable.
  • Deal with the memory problems by trying to engage with the actual Roslyn team to figure out what’s going on and work around it. Which doesn’t solve the internal type issue.
  • Use pre-generated code build by Lamar during testing time baked into the real application for production deployments. There’s a bit more than a proof of concept already baked in, but this still doesn’t fix the internal problem

On the Jasper side I could:

  • Try to make it work with the built in IoC container but still try to do its “no IoC at runtime because it’s all codegen’d” model with a cutdown version of Lamar

Or, just call the whole thing off because while I would argue that Jasper shows a lot of promise technically and I still believe in its potential, it has zero adoption and I most likely won’t get to use it myself in any projects in the next year. If I give up on Jasper, I’m likely to do the same to Lamar. In that case, I’ll write off Lamar as a failed project concept, apologize profusely to all the folks that started to use it to replace StructureMap, and walk away.

Nobody needs to feel sorry for me here, so no need to try to cheer me up about any of this, but, I wouldn’t mind some feedback on whether it’s worth keeping Lamar around and what you think about the proposed improvements.