PollingConsumer (Camel :: API 3.16.0 API)

All Superinterfaces:

AutoCloseable, Consumer, EndpointAware, Service
```
public interface PollingConsumer
extends Consumer
```
Represents a Polling Consumer where the caller polls for messages when it is ready.
When you are done with the returned Exchange you must ensure to invoke UnitOfWork.done(Exchange) to signal to Camel that the Exchange is done.
This is needed to ensure any Synchronization works is being executed. For example if you consumed from a file endpoint, then the consumed file is only moved/delete when you done the Exchange.
Important: Do not do any initialization in the constructor. Instead use BaseService.doInit() or BaseService.doStart().

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Exchange`	`receive()`	Waits until a message is available and then returns it.
`Exchange`	`receive(long timeout)`	Attempts to receive a message exchange, waiting up to the given timeout to expire if a message is not yet available.
`Exchange`	`receiveNoWait()`	Attempts to receive a message exchange immediately without waiting and returning `null` if a message exchange is not available yet.

Methods inherited from interface org.apache.camel.Consumer
createExchange, defaultConsumerCallback, getProcessor, releaseExchange

Methods inherited from interface org.apache.camel.EndpointAware
getEndpoint

Methods inherited from interface org.apache.camel.Service
build, close, init, start, stop

- Method Detail
  - receive
```
Exchange receive()
```
    Waits until a message is available and then returns it. Warning that this method could block indefinitely if no messages are available.
    Will return null if the consumer is not started
    Important: See the class javadoc about the need for done the UnitOfWork on the returned Exchange
    
    Returns:
    
    the message exchange received.
  - receiveNoWait
```
Exchange receiveNoWait()
```
    Attempts to receive a message exchange immediately without waiting and returning null if a message exchange is not available yet.
    Important: See the class javadoc about the need for done the UnitOfWork on the returned Exchange
    
    Returns:
    
    the message exchange if one is immediately available otherwise null
  - receive
```
Exchange receive(long timeout)
```
    Attempts to receive a message exchange, waiting up to the given timeout to expire if a message is not yet available.
    Important: See the class javadoc about the need for done the UnitOfWork on the returned Exchange
    
    Parameters:
    
    timeout - the amount of time in milliseconds to wait for a message before timing out and returning null
    
    Returns:
    
    the message exchange if one was available within the timeout period, or null if the timeout expired