Register your own services

When two nodes use the same device, put the device access in a C# class marked with [FlowService]. The Worker supplies it to node constructors.

Minimal example

using SereinFlow.Core.Api;

namespace MyFlowNodes;

public interface IDeviceReader
{
    string ReadStatus(string deviceId);
}

[FlowService<IDeviceReader>]
public sealed class DeviceReader : IDeviceReader
{
    public string ReadStatus(string deviceId) => $"{deviceId}: ready";
}

[FlowLibrary("Device tools")]
public sealed class DeviceNodes(IDeviceReader reader)
{
    [FlowNode(AnotherName = "Read device status")]
    public string Read([NodeParam(Name = "Device ID")] string deviceId)
        => reader.ReadStatus(deviceId);
}

[FlowService<IDeviceReader>] registers the implementation for interface injection. Use [FlowService] for concrete-type injection, or [FlowService(typeof(IDeviceReader))] as the non-generic form.

Lifetime

Lifetime	Behavior	Use
Run (default)	Shared by a library within one Worker run.	Per-run connections or state.
Invocation	Shared within one node invocation.	Invocation-specific work objects.
Transient	Created each time requested.	Lightweight stateless objects.

For example, [FlowService<IDeviceReader>(Lifetime = FlowServiceLifetime.Invocation)] creates a service per invocation. Resolving an interface or concrete type gives the same object under Run and Invocation. There is no singleton across runs.

Injectable dependencies

Node constructors can receive services registered with [FlowService] in the same uploaded assembly, plus Worker-provided IMessageService, IFlowWorkpiece, and IFlowNativeLibraryLoader. The implementation must be a concrete, non-open-generic class in that assembly.

Put IFlowContext on the node method. Host IServiceProvider, IServiceScopeFactory, configuration, API repositories, keys, and Worker internals are not node constructor services.

Separate from ASP.NET Core services

[FlowService] registers services only for an uploaded library in the Worker. To host SereinFlow in your ASP.NET Core app, see Host integration.