Microservices

Beamable Microservices are Beamable's Cloud Code solution. It is a wrapper around a HTTP Server that makes the development process much simpler.

What languages can I write my Microservice in?

At the moment, only C# Microservices are supported. But... that is likely to change in the future.

Getting Started with C# Microservices

To get started with Microservices in your project, you need a couple of things:

• Most Unreal .[vcs]ignore file templates will ignore all *.sln files. Instead of doing that, make sure to only ignore in the root directory with this /*.sln instead of *.sln.
  • You can also just ensure your Microservice .sln is not ignored explicitly.
• Ensure you have the Beamable CLI installed.

Creating your first microservice will automatically create your solution for you. Following the guide below will generate the following recommended folder structure:

/repo-root
|- ProjectName.uproject
|- ProjectName.sln
|- ProjectNameMS/
|-- ProjectNameMS.sln
|-- services/
|--- MicroserviceName/
|---- MicroserviceName.csproj

Open a terminal/shell at your project's root and run the following command to create a new project and add a new microservice.

beam project new service MicroserviceName --sln ProjectNameMS/ProjectNameMS.sln

Then, run the following command to link the newly created project to your UE project.

beam project add-unreal-project .

Linking a project informs the Microservice project that, whenever it recompiles the microservices, it should re-generate a ProjectNameMicroserviceClients UE plugin inside your Plugins/ directory.

Add this plugin as a dependency to any project/plugin you have from which you want to make calls to your microservices (don't forget to add it to Target.cs files as needed). Call ProjectNameMicroserviceClients.AddMicroserviceClients(this) on any of the Build.cs files you have.

Here are the constraints around these generated clients: - They follow the same pattern as our Auto-Generated UE APIs and are generated from the Microservice's OAPI docs. - They'll ONLY generate types that are found in [________Callable] methods of your Microservices. - The generated Plugin is NOT editable by the user (it gets destroyed/recreated with every new generation). - In general, the type-mapping seen in the Content section is what you can expect.

Customize the Generation?

We do have plans to enable you to declare the intent to generate a particular type via an attribute in the future. However, actually customizing the outputted code is unlikely as it is already simple enough to write wrapper around it should you want a different style interface.

Simple Example

Here's the sample code for a simple microservice that adds two integers together:

public class MSPlayground : Microservice  
{  
    [ClientCallable]  
    public int Add(int a, int b)  
    {
        return a + b;  
    }
}

Here's how you'd call that endpoint from inside Unreal.

// From inside any GameInstanceSubsystem, Actor or Component...

// Get the Generated API subsystem
const auto MsApi = GEngine->GetEngineSubsystem<UBeamMSPlaygroundApi>();  

// Create an instance of the generated Request object.
UMSPlaygroundAddRequest* Req = UMSPlaygroundAddRequest::Make(1, 2, GetTransientPackage(), {});  

// Declare the handler for the addition
const auto Handler = FOnMSPlaygroundAddFullResponse::CreateLambda([this](FMSPlaygroundAddFullResponse Resp)  
{  
    // If the request failed or we are retrying, we do nothing  
    if (Resp.State != RS_Success)  
       return;  

    // Otherwise, print the value 
    UE_LOG(LogTemp, Display, TEXT("Microservice Add: %d"), Resp.SuccessData->Value);
});  

// Make the request (the user slot will usually be the UBeamCoreSettings::GetOwnerPlayerSlot())
FBeamRequestContext Ctx;  
MsApi->CPP_Add(UserSlot, Req, Handler, Ctx, {}, this);

For more information on how to write microservice code itself, take a look at our SAMS C# Microservices docs.

Libraries and C# Microservices

One of the big advantages of Beamable C# Microservices is that they are regular .NET projects. This means you get access to Nuget packages should you need to integrate beamable with any particular Third-Party technology that we don't support out-of-the-box.

To do so, just use Nuget to add a package dependency to a project (this can be done easily through any IDE --- or through dotnet nuget command pallet).

In other cases, you might have a couple of services that share some logic. To write your own shared code inside this solution, all you need to do is create a dll project by running the following command and the adding a reference to it in any of your Microservice's .csproj files.

// Run the command to create the library
beam project new common-lib LibraryName --sln ProjectNameMS/ProjectNameMS.sln

// Add a reference to any Microservice's .csproj 
<ProjectReference Include="..\LibraryName\LibraryName.csproj"/>

Databases: MicroStorages

Beamable Microservices allow you to store data in Beamable's own managed services such as Stats(Per-Player key-value stores) and Inventory (Per-Player currency and item tracking). However, there are cases where you want to control your own data-model.

For those cases, Beamable offers a MicroStorage. This is a wrapper around a database that you can write to from your microservices. At the moment, we only support MongoDB but that is likely to change in the future as more and more use-cases arise.

To create a MicroStorage, run the command below.

beam project new storage StorageName --sln ProjectNameMS/ProjectNameMS.sln \
  --link-to MicroserviceName

The link-to option will make the given Microservice depend on the newly created storage.

Running Locally

MicroStorages require you to ALWAYS have docker running when running locally. Microservices that DO NOT DEPEND on storages can be run directly from the IDE without docker running at all. Microservices that DO DEPEND on storages can also be run from the IDE, but docker MUST be running too.

Development Workflow

Developing with microservices in Unreal is very straight forward:

1. Make changes to your microservice code and rebuild it.
   1. If we detect new or removed ______Callables, we'll automatically run the Generate Project Files utility for you so your UE project is updated.
2. If needed, make changes to your client code to make use of the new _____Callables, clean up removed ones or modify code to use the new API for your microservice.
3. Run the microservice locally through the IDE.
4. Run Unreal and verifies that it works locally.

You can just rinse-and-repeat the above until your logic is working locally.

Before pushing this to a realm so others can access this and/or pushing it to your VCS, its is good practice to test the service inside the docker container.

Why do I have to test things in docker?

For most cases, you don't. For cases, where you manually edited the .csproj file and/or the Dockerfile, we recommend you do.

To test your services locally but in Docker, run the following command with Docker running:

beam services run

After the images boot up, you can open Unreal and test it normally.

Minor Gotcha

Remember to turn off the microservice running from the IDE. If you have both the IDE and the Docker version running locally, they'll both be trying to service requests which means that you'd be seeing them every request hit one of them at random.

Deploying

Once you're satisfied with your service behavior and verified that its working, you can deploy it to a realm and test it.

Which realm?

How you wish to manage realms is a team-specific decision as there are cost implications per-microservice instance running in any realm to consider against how your team likes to work. At Beamable's UE team, we prefer the "team members are responsible not to break other team members environment"-approach so we recommend that you test things thoroughly and then push to your dev realm. Another strategy might be to have a designer-dev that lives between staging and dev that should be more stable and then you push to dev first and eventually promote it to designer-dev. Again, this is for your lead and team to discuss and decide how you wish to work.

To deploy services to a realm, run the following command with docker running.

beam services deploy

Beamable Microservices work through a declarative manifest. In less fancy terms, you give Beamable all services you have in your project and tell Beamable which of those services should be enabled or not. This information is defined in the .csproj files:

<BeamEnabled>false</BeamEnabled> to any of the services' `.csproj` <PropertyGroup></PropertyGroup> tags disables the service.

Not having the <BeamEnabled>false</BeamEnabled> implies that the service IS ENABLED.

The beam services deploy command will: - Figure out which services are enabled. - Figure out which services you deleted but were deployed at a certain point. - Build all images for which you have the source code and are enabled. - Upload these to Beamable's docker registry. - Build out the Manifest and ask Beamable to Make it so.

The Beamable backend will read that new manifest and adjust, without downtime, the resources in the cloud to match that new manifest.

Reverting changes

Sometimes, mistakes happen. When they do and you need to revert changes, you can re-deploy an older manifest by doing the following:

//Fetch an old manifest from the Portal (Operate -> Microservices -> Deployments)
beam project open-swagger MicroserviceName

//Run this command
beam services deploy --from-file "path/to/manifest.json"

How Many Microservices is too many?

The first impulse a lot of people have is to separate microservices semantically; one-per-feature. We do not recommend this. Here's why:

• Having a lot of microservices will increase your cost for potentially no benefit.
• Having a lot of microservices increases deployment times.
• Having a lot of microservices increases project complexity.
• Having a lot of microservices makes you add latency to things that otherwise wouldn't have it (cross microservice communication is possible, but rarely actually needed).

The key metric you should use to consider creating additional microservices is different load profiles at runtime. Basically, if you have a set of features with similar expected load profiles, you can keep them together as the auto-scaling will work uniformly to handle the increased load. If you have services with spikey load profiles, then consider putting each of them in their own service so that they can be scaled independently and faster (due to the smaller image size) than your other larger services.

Game Maker: "If I have 5 features in one microservices, how do I organize my ____Callable functions?" Beamable: "You can create add partial to your Microservice type and create other parts of it. You can declare utility static functions as well and make most ____Callable just forward the call along."

We've found these approaches gives you the proper runtime scalability for the lowest cost and provide a simple developer experience.

The Microservices Window

This window is a read-only view into the state of your local services. It serves two purposes:

• It shows you which services are currently running locally and which aren't.
  • In other words, a quick panoramic view of your local microservice state.
• It allows non-engineers to start up services from a UI window.
  • This is not a very common workflow as a lot of teams have designers/artists working in dedicated realms.