Processor Hosting

Processor Hosting

LiteBus ships inbox and outbox processors (one pass over pending work) and optional hosting modules that run those processors in the generic host. Inbox and outbox hosting are separate modules on purpose.

Module layout

Module	Package	Registers
Command inbox	LiteBus.Inbox	ICommandScheduler, ICommandInboxProcessor, processor options
Inbox hosting	LiteBus.Inbox.Extensions.Microsoft.Hosting	background service loop, host options, health-check state
Outbox	LiteBus.Outbox	IOutboxWriter, IOutboxProcessor, processor options
Outbox hosting	LiteBus.Outbox.Extensions.Microsoft.Hosting	background service loop, host options, health-check state

The only contract the hosting module needs from the core module is the processor interface (ICommandInboxProcessor / IOutboxProcessor).

Processor options (BatchSize, LeaseDuration, Retry) stay on CommandInboxProcessorOptions / OutboxProcessorOptions. Host options (PollInterval, StartupDelay, UseAdaptivePolling) stay on CommandInboxProcessorHostOptions / OutboxProcessorHostOptions in the hosting package.

Command inbox

Reference LiteBus.Inbox.Extensions.Microsoft.Hosting:

builder.Services.AddLiteBus(liteBus =>
{
    liteBus.AddCommandInboxModule(inbox =>
    {
        inbox.Contracts.Register<ProcessPaymentCommand>("payments.commands.process-payment", 1);

        inbox.UseProcessorOptions(new CommandInboxProcessorOptions
        {
            BatchSize = 50,
            LeaseDuration = TimeSpan.FromMinutes(2),
            LeaseOwner = Environment.MachineName
        });
    });

    liteBus.AddCommandInboxProcessorHosting(host =>
    {
        host.PollInterval = TimeSpan.FromSeconds(1);
        host.StartupDelay = TimeSpan.FromSeconds(5);
        host.UseAdaptivePolling = true;
    });
});

With Autofac, use the same hosting package inside containerBuilder.AddLiteBus (LiteBus registers IHostedService through the Autofac runtime adapter):

containerBuilder.AddLiteBus(liteBus =>
{
    liteBus.AddCommandInboxModule(/* same as above */);
    liteBus.AddCommandInboxProcessorHosting(host => host.PollInterval = TimeSpan.FromSeconds(1));
});

Manual processing

If you skip the hosting module, resolve ICommandInboxProcessor and invoke ProcessPendingAsync from your own worker, timer, or job scheduler:

var result = await inboxProcessor.ProcessPendingAsync(cancellationToken);
// result.LeasedCount helps your loop decide whether to sleep

Outbox

Reference LiteBus.Outbox.Extensions.Microsoft.Hosting:

liteBus.AddOutboxModule(outbox =>
{
    outbox.Contracts.Register<OrderPlacedEvent>("orders.events.order-placed", 1);
    outbox.UseProcessorOptions(new OutboxProcessorOptions { BatchSize = 100 });
});

liteBus.AddOutboxProcessorHosting(host => host.PollInterval = TimeSpan.FromSeconds(1));

Adaptive polling

When UseAdaptivePolling is true (default), the background service skips PollInterval after a pass that leased a full batch (LeasedCount >= BatchSize). When the pass leases fewer than a full batch, it waits PollInterval before the next pass.

Set PollInterval to TimeSpan.Zero to disable delays entirely (tight loop; use only when you understand CPU cost).

Health checks

Register optional health checks when using the Microsoft generic host:

builder.Services.AddHealthChecks()
    .AddLiteBusCommandInboxProcessor()
    .AddLiteBusOutboxProcessor();

Checks read the hosting module's internal pass state (last successful pass, consecutive failures). They report Unhealthy when the background service records repeated pass failures.

What LiteBus does not provide

• A combined inbox + outbox background worker (register two hosting modules or one application worker that calls both processors).
• Guaranteed exactly-once delivery (processors remain at-least-once; design idempotent handlers).
• Automatic schema migrations in production by default (schema bootstrap is opt-in; see PostgreSQL Schema Management).

PostgreSQL schema bootstrap

When using PostgreSQL stores, register schema hosting before processor hosting if you enable EnsureSchemaCreationOnStartup:

liteBus.AddPostgreSqlCommandInboxStore(postgres => postgres.EnsureSchemaCreationOnStartup());
liteBus.AddPostgreSqlCommandInboxSchemaHosting();
liteBus.AddCommandInboxProcessorHosting(/* ... */);

liteBus.AddPostgreSqlOutboxStore(postgres => postgres.EnsureSchemaCreationOnStartup());
liteBus.AddPostgreSqlOutboxSchemaHosting();
liteBus.AddOutboxProcessorHosting(/* ... */);

Reference LiteBus.Inbox.PostgreSql.Extensions.Microsoft.Hosting and LiteBus.Outbox.PostgreSql.Extensions.Microsoft.Hosting for those registrations.

v4 migration note

v4 included LiteBus.Commands.Extensions.Microsoft.Hosting with a single inbox BackgroundService. v5 keeps inbox and outbox hosting as separate optional modules. See Migration Guide v5.