diff --git a/src/EventStore.Plugins/Subsystems/ISubsystem.cs b/src/EventStore.Plugins/Subsystems/ISubsystem.cs
new file mode 100644
index 0000000..d591283
--- /dev/null
+++ b/src/EventStore.Plugins/Subsystems/ISubsystem.cs
@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace EventStore.Plugins.Subsystems;
+
+public interface ISubsystem {
+	IApplicationBuilder Configure(IApplicationBuilder builder);
+	IServiceCollection ConfigureServices(IServiceCollection services);
+	IEnumerable<Task> Start();
+	void Stop();
+}
diff --git a/src/EventStore.Plugins/Subsystems/ISubsystemFactory.cs b/src/EventStore.Plugins/Subsystems/ISubsystemFactory.cs
new file mode 100644
index 0000000..fcd39ec
--- /dev/null
+++ b/src/EventStore.Plugins/Subsystems/ISubsystemFactory.cs
@@ -0,0 +1,5 @@
+namespace EventStore.Plugins.Subsystems;
+
+public interface ISubsystemFactory<TArg> {
+	ISubsystem Create(TArg arg);
+}
diff --git a/src/EventStore.Plugins/Subsystems/ISubsystemsPlugin.cs b/src/EventStore.Plugins/Subsystems/ISubsystemsPlugin.cs
new file mode 100644
index 0000000..62f6a0c
--- /dev/null
+++ b/src/EventStore.Plugins/Subsystems/ISubsystemsPlugin.cs
@@ -0,0 +1,12 @@
+using System.Collections.Generic;
+
+namespace EventStore.Plugins.Subsystems;
+
+// A plugin that can create multiple subsystems.
+// A TArg is required to produce each subsystem from its respective factory.
+public interface ISubsystemsPlugin<TArg> {
+	string Name { get; }
+	string Version { get; }
+	string CommandLineName { get; }
+	IEnumerable<ISubsystemFactory<TArg>> GetSubsystemFactories(string configPath);
+}