Channel hierarchy

IngestChannel<T> is the top of a layered class hierarchy. Each layer adds a specific capability.

classDiagram
    class BufferedChannelBase~TOptions,TEvent,TResponse~ {
        +TryWrite(TEvent) bool
        +WaitToWriteAsync(TEvent, CancellationToken) Task~bool~
        +TryWriteMany(IEnumerable~TEvent~) bool
        +WaitForDrainAsync(TimeSpan?, CancellationToken) Task
        #ExportAsync(ArraySegment~TEvent~, CancellationToken) Task~TResponse~
        #RetryBuffer(TResponse, list, buffer) list
    }

    class ResponseItemsBufferedChannelBase~...,TBulkResponseItem~ {
        #Retry(TResponse) bool
        #RetryAllItems(TResponse) bool
        #RetryEvent(TEvent, TBulkResponseItem) bool
        #RejectEvent(TEvent, TBulkResponseItem) bool
        #Zip(TResponse, list) IEnumerable
    }

    class TransportChannelBase~...,TBulkResponseItem~ {
        #ExportAsync(ITransport, ArraySegment~TEvent~, CancellationToken) Task~TResponse~
    }

    class IngestChannelBase~TDocument,TOptions~ {
        #ExportAsync(ITransport, ArraySegment, CancellationToken) Task~BulkResponse~
        #Retry(BulkResponse) bool
        #RetryAllItems(BulkResponse) bool
        #RetryEvent(TDocument, BulkResponseItem) bool
        #RejectEvent(TDocument, BulkResponseItem) bool
    }

    class IngestChannel~TEvent~ {
        +BootstrapElasticsearchAsync() Task~bool~
        +ApplyAliasesAsync(string, CancellationToken) Task~bool~
        +RolloverAsync(string?, string?, long?, CancellationToken) Task~bool~
        +TemplateName string
        +TemplateWildcard string
        +ProvisioningStrategy IIndexProvisioningStrategy
    }

    BufferedChannelBase <|-- ResponseItemsBufferedChannelBase
    ResponseItemsBufferedChannelBase <|-- TransportChannelBase
    TransportChannelBase <|-- IngestChannelBase
    IngestChannelBase <|-- IngestChannel

The foundation layer in Elastic.Channels. Provides:

• Two-stage inbound/outbound buffer (see push model)
• Concurrent export with throttling
• Backpressure and drain
• Retry with configurable backoff

All buffer configuration, threading, and lifecycle management lives here.

Adds per-item response analysis. Where the base class treats a response as pass/fail for the whole batch, this layer can:

• Zip sent items with individual response items
• Decide per-item whether to retry, reject, or accept
• Retry the entire batch for certain response codes (for example, HTTP 429)

In Elastic.Ingest.Transport. Integrates ITransport from Elastic.Transport:

• Passes the transport instance to ExportAsync
• Subclasses implement ExportAsync(ITransport, ArraySegment<TEvent>, CancellationToken) to make HTTP calls

In Elastic.Ingest.Elasticsearch. Implements the Elasticsearch _bulk API:

• Serializes documents into NDJSON bulk format
• Parses BulkResponse and maps items
• Defines retry status codes (429, 500-599)
• Defines rejection criteria (non-2xx that aren't retryable)

The composable channel that users interact with. Adds:

• Strategy pattern for bootstrap, ingest, provisioning, alias, and rollover
• Auto-configuration from ElasticsearchTypeContext
• Public API for bootstrap, alias management, and rollover

Before IngestChannel<T>, specialized channel subclasses existed for each use case. These are now obsolete. See legacy channels for migration guidance.