Rest.li 2.0 response API

Pegasus 1.17.2 features a new set of response APIs for various batch operations. The motivation of this change is to simplify the old response APIs. This change focuses on two sets of operations: BatchGet and BatchUpdate/BatchPartialUpdate/BatchDelete.

BatchGet

The following table summarizes the Rest.li response types:

Response name	Returned by	Strong-typed key?	Value type	New in 1.17.2?
BatchResponse	BatchGetRequestBuilder.build()	No	T	No
BatchKVResponse	BatchGetRequestBuilder.buildKV()	Yes	T	No
BatchEntityResponse	BatchGetEntityRequestBuilder.build()	Yes	EntityResponse	Yes

EntityResponse is a new RecordTemplate class, which contains three fields:

• entity provides an entity record if the server resource finds a corresponding value for the key;
• status provides an optional status code;
• error provides the error detail from the server resource (generally entity and error are mutually exclusive as null, but it is ultimately up to the server resource).

Note that since EntityResponse contains error field, the Map<K, V> returned by BatchEntityResponse.getResults() contains both successful as well as failed entries. BatchEntityResponse.getErrors() will only return failed entries.

BatchUpdate/BatchPartialUpdate/BatchDelete

The response type of the BatchUpdate series methods are not changed. However, similar to EntityResponse, we added a new error field to UpdateStatus (the value type of the BatchUpdate series methods). Furthermore, BatchKVResponse<K, UpdateStatus>.getResults() will returns both successful as well as failed entries. getErrors() will only return failed entries.