AWS JavaScript SDK V3

October 26, 2020 2 min read aws, sdk, javascript

Written in 2020. Tools, APIs and prices may have changed since.

Lab note What I wrote down while learning this by building with it. Short by design; the code is in pfeilbr/aws-javascript-sdk-v3-playground.

learn AWS JavaScript SDK v3

New Features

v3 Commands

commands for each AWS Service package to enable you to perform operations for that AWS Service. After you install an AWS Service, you can browse the available commands in your project’s node-modules/@aws-sdk/client-PACKAGE_NAME/commands folder

middleware stack

can use a new middleware stack to control the lifecycle of an operation call

Each middleware stage in the stack calls the next middleware stage after making any changes to the request object. This also makes debugging issues in the stack much easier, because you can see exactly which middleware stages were called leading up to the error.

Use Cases

debugging
logging
request updates
instrumentation

Example middleware args

DynamoDB ListTablesCommand

{
      middlewareStack: {
        add: [Function: add],
        addRelativeTo: [Function: addRelativeTo],
        clone: [Function: clone],
        use: [Function: use],
        remove: [Function: remove],
        removeByTag: [Function: removeByTag],
        concat: [Function: concat],
        applyToStack: [Function: cloneTo],
        resolve: [Function: resolve]
      },
      input: {},
      request: HttpRequest {
        method: 'POST',
        hostname: 'dynamodb.us-east-1.amazonaws.com',
        port: undefined,
        query: {},
        headers: {
          'Content-Type': 'application/x-amz-json-1.0',
          'X-Amz-Target': 'DynamoDB_20120810.ListTables',
          'user-agent': 'aws-sdk-nodejs-v3-@aws-sdk/client-dynamodb/1.0.0-rc.2 darwin/v12.16.1',
          'content-length': '2'
        },
        body: '{}',
        protocol: 'https:',
        path: '/'
      }
    }

Running

# run tests that exercise new features
npm run test -- --watch

Resources

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