ObservationCollector (RabbitMQ Stream Java Client 0.21.0 API)

```
public interface ObservationCollector<T>
```
API to instrument operations in the stream client. The supported operations are publishing, and asynchronous delivery.
Implementations can gather information and send it to tracing backends. This allows e.g. following the processing steps of a given message through different systems.
This is considered an SPI and is susceptible to change at any time.

Since:

0.12.0

See Also:

EnvironmentBuilder.observationCollector(ObservationCollector), MicrometerObservationCollectorBuilder

Field Summary

Fields
Modifier and Type Field Description

static ObservationCollector<Void> NO_OP

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`default boolean`	`isNoop()`	Says whether the implementation does nothing or not.
`T`	`prePublish(String stream, Message message)`	Start observation.
`void`	`published(T context, Message message)`	Callback when the message is about to be published.
`MessageHandler`	`subscribe(MessageHandler handler)`	Decorate consumer registration.

- Field Detail
  - NO_OP
```
static final ObservationCollector<Void> NO_OP
```
- Method Detail
  - prePublish
```
T prePublish(String stream,
             Message message)
```
    Start observation.
    Implementations are expecting to return an observation context that will be passed in to the published(Object, Message) callback.
    
    Parameters:
    
    stream - the stream to publish to
    
    message - the message to publish
    
    Returns:
    
    observation context
  - published
```
void published(T context,
               Message message)
```
    Callback when the message is about to be published.
    
    Parameters:
    
    context - the observation context
    
    message - the message to publish
  - subscribe
```
MessageHandler subscribe(MessageHandler handler)
```
    Decorate consumer registration.
    
    Parameters:
    
    handler - the original handler
    
    Returns:
    
    a decorated handler
  - isNoop
```
default boolean isNoop()
```
    Says whether the implementation does nothing or not.
    
    Returns:
    
    true if the implementation is a no-op