AWS SDK for JavaScript
Developer Guide for SDK v2.138.0

Working with Services in the SDK for JavaScript

The AWS SDK for JavaScript provides access to services that it supports through a collection of client classes. From these client classes, you create service interface objects, commonly called service objects. Each supported AWS service has one or more client classes that offer low-level APIs for using service features and resources. For example, Amazon DynamoDB APIs are available through the AWS.DynamoDB class.

The services exposed through the SDK for JavaScript follow the request-response pattern to exchange messages with calling applications. In this pattern, the code invoking a service submits an HTTP/HTTPS request to an endpoint for the service. The request contains parameters needed to successfully invoke the specific feature being called. The service that is invoked generates a response that is sent back to the requestor. The response contains data if the operation was successful or error information if the operation was unsuccessful.

                The AWS request response service pattern.

Invoking an AWS service includes the full request and response lifecycle of an operation on a service object, including any retries that are attempted. A request is encapsulated in the SDK by the AWS.Request object. The response is encapsulated in the SDK by the AWS.Response object, which is provided to the requestor through one of several techniques, such as a callback function or a JavaScript promise.