All Implemented Interfaces:

dev.langchain4j.rag.RetrievalAugmentor
```
public class DefaultRetrievalAugmentor
 implements RetrievalAugmentor
                    
```
The default implementation of RetrievalAugmentor intended to be suitable for the majority of use cases. It's important to note that while efforts will be made to avoid breaking changes, the default behavior of this class may be updated in the future if it's found that the current behavior does not adequately serve the majority of use cases. Such changes would be made to benefit both current and future users. This implementation is inspired by this article and this paper. It is recommended to review these resources for a better understanding of the concept. This implementation orchestrates the flow between the following base components:
```
- QueryTransformer
- QueryRouter
- ContentRetriever
- ContentAggregator
- ContentInjector
```
Visual representation of this flow can be found here. For each base component listed above, we offer several ready-to-use implementations, each based on a recognized approach. We intend to introduce more such implementations over time and welcome your contributions. The flow is as follows: 1. A Query (derived from an original UserMessage) is transformed using a QueryTransformer into one or multiple Querys. 2. Each Query is routed to the appropriate ContentRetriever using a QueryRouter. Each ContentRetriever retrieves one or multiple Contents using a Query. 3. All Contents retrieved by all ContentRetrievers using all Querys are aggregated (fused/re-ranked/filtered/etc.) into a final list of Contents using a ContentAggregator. 4. Lastly, a final list of Contents is injected into the original UserMessage using a ContentInjector. By default, each base component (except for ContentRetriever, which needs to be provided by you) is initialized with a sensible default implementation:
```
- DefaultQueryTransformer
- DefaultQueryRouter
- DefaultContentAggregator
- DefaultContentInjector
```
Nonetheless, you are encouraged to use one of the advanced ready-to-use implementations or create a custom one. When there is only a single Query and a single ContentRetriever, query routing and content retrieval are performed in the same thread. Otherwise, an Executor is used to parallelize the processing. By default, a modified (keepAliveTime is 1 second instead of 60 seconds) newCachedThreadPool is used, but you can provide a custom Executor instance.

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`public class`	`DefaultRetrievalAugmentor.DefaultRetrievalAugmentorBuilder`

Field Summary

Fields
Modifier and Type	Field	Description

Constructor Summary

Constructors
Constructor	Description
`DefaultRetrievalAugmentor(QueryTransformer queryTransformer, QueryRouter queryRouter, ContentAggregator contentAggregator, ContentInjector contentInjector, Executor executor)`

Enum Constant Summary

Enum Constants
Enum Constant	Description

Method Summary

Modifier and Type	Method	Description
`UserMessage`	`augment(UserMessage userMessage, Metadata metadata)`
`AugmentationResult`	`augment(AugmentationRequest augmentationRequest)`	Augments the ChatMessage provided in the AugmentationRequest with retrieved Contents.
`static DefaultRetrievalAugmentor.DefaultRetrievalAugmentorBuilder`	`builder()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - DefaultRetrievalAugmentor
```
DefaultRetrievalAugmentor(QueryTransformer queryTransformer, QueryRouter queryRouter, ContentAggregator contentAggregator, ContentInjector contentInjector, Executor executor)
```
- Method Detail
  - augment
```
@Deprecated() UserMessage augment(UserMessage userMessage, Metadata metadata)
```
  - augment
```
 AugmentationResult augment(AugmentationRequest augmentationRequest)
```
    Augments the ChatMessage provided in the AugmentationRequest with retrieved Contents. This method has a default implementation in order to temporarily support current custom implementations of RetrievalAugmentor. The default implementation will be removed soon.
    
    Parameters:
    
    augmentationRequest - The AugmentationRequest containing the ChatMessage to augment.
    
    Returns:
    
    The AugmentationResult containing the augmented ChatMessage.
  - builder
```
 static DefaultRetrievalAugmentor.DefaultRetrievalAugmentorBuilder builder()
```

Class DefaultRetrievalAugmentor

Nested Class Summary

Field Summary

Constructor Summary

Enum Constant Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

DefaultRetrievalAugmentor

Method Detail

augment

augment

builder