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Python DSLAPI: Streams
Python API reference pipeline.input() | pipeline.sink()

Input and Sink — Python Architecture DSL

Bind a stream graph to connector endpoints for inbound and outbound transport.

When to use

Use Input to admit endpoint messages and Sink to submit graph messages through an endpoint.

Behavior

  • Input may define a primary source or sources for endpoint patterns that participate in a cycle.
  • Sink may reference an error stream for failures returned by the transport adapter.
  • Endpoint and value type compatibility is validated across all uses of an endpoint. Multiple independent Sink streams may share it, including within one service. Each Sink keeps its own consumer and result/error path; compatible request and response contracts are required across all callers.
  • An endpoint may have at most one Input per service. Configure dedicated failure paths after construction with stream.on_error(error_stream) or stream | error_stream, not an error_stream= factory argument.

Pipeline.input() properties

Inbound boundary.

PropertyTypeDescription
namestr

Human-readable stream name; the symbolic key is derived automatically.

Required
sourceStream | None

Optional primary upstream stream.

Default: None
appearanceAppearance | None

Optional Designer coordinates and color supported by this entity.

Default: None
endpointEndpoint

Endpoint consumed by the stream.

Required
value_typeTypeDefinition | DataType | str | None

Output or boundary payload contract.

Default: None
sourcesSequence[Stream]

Additional sources.

Default: ()

Pipeline.sink() properties

Outbound boundary.

PropertyTypeDescription
namestr

Human-readable stream name; the symbolic key is derived automatically.

Required
sourceStream | None

Optional primary upstream stream.

Default: None
appearanceAppearance | None

Optional Designer coordinates and color supported by this entity.

Default: None
endpointEndpoint

Endpoint called or published to.

Required
value_typeTypeDefinition | DataType | str | None

Output or boundary payload contract.

Default: None

Python example

consume = orders.input(
    "Consume Orders", endpoint=order_topic, value_type=order
)
publish = orders.sink(
    "Publish Result", endpoint=result_topic, value_type=order_result
)
consume >> publish