Couchbase Server communicates with a web application in the following ways:

• Through APIs in your chosen SDK that are supported by Couchbase Server
• Through a RESTful interface that you can use to manage an entire cluster

Couchbase SDKs enable you to perform read/write operations to Couchbase Server and will be responsible for getting updates on cluster topology from Couchbase Server. The SDKs provide an abstraction level so that you do not need to be concerned about handling the logic of cluster rebalance and failover in your application. All SDKs are able to automatically get updated server and cluster information so that your web application continues to function during a Couchbase Server rebalance or failover.

Couchbase SDKs are written in several programming languages so that you can interact with Couchbase Server using the same language you use for your web application. The SDKs available from Couchbase are at: Couchbase SDK Downloads

You use a Couchbase SDK for storage, retrieval, update, and removal of application data from the database. As of Couchbase 2.0 you can also use the SDKs to index and query information and also determine if entries are available to index/query. Couchbase SDK read/write methods are all built upon the binary version of the memcached protocol. When you perform an operation an SDK converts it into a binary memcached command which is then sent to Couchbase Server. For more information about memcached protocol, see memcached protocol.

Couchbase REST API can be used to get information about a cluster or make changes to a entire cluster. At an underlying level, Couchbase SDKs use the REST API to perform indexing and querying; for developers who want to write their own SDK, the REST API can also be used to provide cluster updates to a SDK. There are also some helpful bucket-level operations that you will use as an application developer, such as creating a new data bucket, and setting authentication for the bucket. With the REST API, you can also gather statistics from a cluster, define and make changes to buckets, and add or remove new nodes to the cluster. For more information about helpful bucket-level operations you can use as you develop an application, refer to the Couchbase REST API reference.