Improve SQS README.md terminology (#1599)

Author: tomazfernandes

spring-cloud-aws-sqs/README.md

@@ -4,15 +4,15 @@
 
 **Why:** The SQS integration underwent a major redesign in Spring Cloud AWS 3.0 to address limitations in previous versions and build on AWS SDK v2’s async API, and it was [announced as GA in 2023](https://spring.io/blog/2023/05/02/announcing-spring-cloud-aws-3-0-0).
 
-**Who:** This document is meant for maintainers, contributors, and readers who want to understand the module’s internal structure and design. It describes the module in two phases: an assembly phase at startup, and a container execution phase where messages are polled, processed, and acknowledged. It focuses on the high-level structure and provides shared terminology for discussing the module’s flows and components.
+**Who:** This document is meant for maintainers, contributors, and readers who want to understand the module’s internal structure and design. It describes the module in two phases: an assembly phase at startup, and a runtime phase where messages are polled, processed, and acknowledged. It focuses on the high-level structure and provides shared terminology for discussing the module’s flows and components.
 
 ## Two-Phase Architecture
 
 The module is organized into two phases with different responsibilities:
 
 - **Assembly phase**: At startup, Spring detects [@SqsListener](src/main/java/io/awspring/cloud/sqs/annotation/SqsListener.java) annotations, creates listener endpoints, and wires [MessageListenerContainer](src/main/java/io/awspring/cloud/sqs/listener/MessageListenerContainer.java) instances through a factory and registry. This is similar to patterns used by Spring for Apache Kafka and other Spring messaging projects.
 
-- **Container execution phase**: When containers start, they run an asynchronous pipeline that polls SQS, invokes the listener, and acknowledges messages. This pipeline builds on AWS SDK v2’s async API ([SqsAsyncClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/sqs/SqsAsyncClient.html)) and uses a composable component model, including adaptive backpressure controls. While reusing familiar Spring abstractions such as [MessageListener](src/main/java/io/awspring/cloud/sqs/listener/MessageListener.java), the async processing pipeline is a module-specific design introduced in Spring Cloud AWS 3.0.
+- **Runtime phase**: When containers start, they run an asynchronous pipeline that polls SQS, invokes the listener, and acknowledges messages. This pipeline builds on AWS SDK v2’s async API ([SqsAsyncClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/sqs/SqsAsyncClient.html)) and uses a composable component model, including adaptive backpressure controls. While reusing familiar Spring abstractions such as [MessageListener](src/main/java/io/awspring/cloud/sqs/listener/MessageListener.java), the async processing pipeline is a module-specific design introduced in Spring Cloud AWS 3.0.
 
 This separation keeps startup wiring concerns independent from message processing concerns, and makes the runtime pipeline easier to reason about and evolve without changing the assembly flow.
 
@@ -33,10 +33,10 @@ flowchart LR
 	C --> D["SqsMessageListenerContainerFactory"]
 	D --> E["MessageListenerContainer"]
 	E --> F["MessageListenerContainerRegistry"]
-	F --> G["Container lifecycle start\n(transition to container execution)"]
+	F --> G["Container lifecycle start\n(transition to runtime)"]
 ```
 
-## Container Execution Phase
+## Runtime Phase
 
 When the [MessageListenerContainerRegistry](src/main/java/io/awspring/cloud/sqs/listener/MessageListenerContainerRegistry.java) starts its containers, each container assembles its processing pipeline and begins polling for messages. The [ContainerComponentFactory](src/main/java/io/awspring/cloud/sqs/listener/ContainerComponentFactory.java) creates the runtime components and wires them together.
 
@@ -48,16 +48,16 @@ The pipeline is built on [SqsAsyncClient](https://sdk.amazonaws.com/java/api/lat
 
 ### Composable Pipeline
 
-The runtime is structured as a composable pipeline. Within each [listener container](src/main/java/io/awspring/cloud/sqs/listener/AbstractPipelineMessageListenerContainer.java):
+The runtime is structured as a composable pipeline with four stages — **ingress**, **dispatch**, **processing**, and **acknowledgement** — each mapped to dedicated components within each [listener container](src/main/java/io/awspring/cloud/sqs/listener/AbstractPipelineMessageListenerContainer.java):
 
-- [**MessageSource**](src/main/java/io/awspring/cloud/sqs/listener/source/MessageSource.java): Polls SQS for messages and converts them to Spring [Message](https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/messaging/Message.html) objects. Uses a [BackPressureHandler](src/main/java/io/awspring/cloud/sqs/listener/backpressure/BackPressureHandler.java) to gate polling based on in-flight message capacity
-- [**MessageSink**](src/main/java/io/awspring/cloud/sqs/listener/sink/MessageSink.java): Dispatches messages to the processing pipeline. Composable component with implementations such as [FanOutMessageSink](src/main/java/io/awspring/cloud/sqs/listener/sink/FanOutMessageSink.java) (single-message), [BatchMessageSink](src/main/java/io/awspring/cloud/sqs/listener/sink/BatchMessageSink.java), [OrderedMessageSink](src/main/java/io/awspring/cloud/sqs/listener/sink/OrderedMessageSink.java), and [MessageGroupingSinkAdapter](src/main/java/io/awspring/cloud/sqs/listener/sink/adapter/MessageGroupingSinkAdapter.java) (FIFO)
-- [**MessageProcessingPipeline**](src/main/java/io/awspring/cloud/sqs/listener/pipeline/MessageProcessingPipeline.java): Chains together the stages that process each message:
+- **Ingress** — [**MessageSource**](src/main/java/io/awspring/cloud/sqs/listener/source/MessageSource.java): Polls SQS for messages and converts them to Spring [Message](https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/messaging/Message.html) objects. Uses a [BackPressureHandler](src/main/java/io/awspring/cloud/sqs/listener/backpressure/BackPressureHandler.java) to gate polling based on in-flight message capacity
+- **Dispatch** — [**MessageSink**](src/main/java/io/awspring/cloud/sqs/listener/sink/MessageSink.java): Dispatches messages to the processing pipeline. Composable component with implementations such as [FanOutMessageSink](src/main/java/io/awspring/cloud/sqs/listener/sink/FanOutMessageSink.java) (single-message), [BatchMessageSink](src/main/java/io/awspring/cloud/sqs/listener/sink/BatchMessageSink.java), [OrderedMessageSink](src/main/java/io/awspring/cloud/sqs/listener/sink/OrderedMessageSink.java), and [MessageGroupingSinkAdapter](src/main/java/io/awspring/cloud/sqs/listener/sink/adapter/MessageGroupingSinkAdapter.java) (FIFO)
+- **Processing** — [**MessageProcessingPipeline**](src/main/java/io/awspring/cloud/sqs/listener/pipeline/MessageProcessingPipeline.java): Chains together the stages that process each message:
   - [MessageInterceptor](src/main/java/io/awspring/cloud/sqs/listener/interceptor/MessageInterceptor.java) - before/after processing hooks
   - [MessageListener](src/main/java/io/awspring/cloud/sqs/listener/MessageListener.java) - invokes the user's [@SqsListener](src/main/java/io/awspring/cloud/sqs/annotation/SqsListener.java) method
   - [ErrorHandler](src/main/java/io/awspring/cloud/sqs/listener/errorhandler/ErrorHandler.java) - handles processing failures
   - [AcknowledgementHandler](src/main/java/io/awspring/cloud/sqs/listener/acknowledgement/handler/AcknowledgementHandler.java) - triggers acknowledgement (deletion from SQS)
-- [**AcknowledgementProcessor**](src/main/java/io/awspring/cloud/sqs/listener/acknowledgement/AcknowledgementProcessor.java): Acknowledges processed messages by deleting them from SQS
+- **Acknowledgement** — [**AcknowledgementProcessor**](src/main/java/io/awspring/cloud/sqs/listener/acknowledgement/AcknowledgementProcessor.java): Acknowledges processed messages by deleting them from SQS
 - [**AcknowledgementResultCallback**](src/main/java/io/awspring/cloud/sqs/listener/acknowledgement/AcknowledgementResultCallback.java): Notified after acknowledgement succeeds or fails
 
 These components are assembled at container start and interact through interfaces, which makes it possible to swap or extend individual stages.