# Anatomy of a CDK connector

This article breaks down the anatomy of a CDK connector, explaining each component in detail.

## Project Structure

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![connector-directory](https://tray.ai/documentation/images/developer/connector-development-kit/overview/key-concepts/connector-directory.png)

A CDK project is essentially a Node.js and TypeScript project preconfigured with necessary dependencies, linter rules, and compiler options. A connector folder contains the following key files / folders:

* **connector.json**: Contains metadata about the connector, such as name, version, title, and more.
* **src directory**: Houses the core logic of the connector, including authentication files, operation folders, and test context files.

## Context and Authentication

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* **Context (ctx)**: Passed along with inputs in handlers, containing common values for all operations, primarily the auth property which typically includes tokens for third-party service authentication.
* **Authentication**: Defined in `auth.ts` file within the src directory, specifying the type of authentication used (e.g., OAuth, API Key).

## Operations

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Each operation of a connector resides in its own folder under the src directory, containing:

* **operation.json**: Operation metadata like name and title.
* **input.ts and output.ts**: Define the input and output types for the operation.
* **handler.ts**: Contains the logic of the operation.
* **handler.test.ts**: Includes test cases for the operation.

## Input & Output

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* **Input (input.ts)**: Specifies the data structure expected by an operation.
* **Output (output.ts)**: Defines the data structure returned by an operation.

## Handler

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The handler is where the operation's functionality is implemented. It can be configured to perform HTTP requests to third-party services or composite operations that combine multiple steps.

### HTTP Implementation

* Configures HTTP requests, including method, headers, body, and response handling.
* Utilizes the handleRequest and handleResponse methods to customize request preparation and response parsing.

### Composite Implementation

* Defines operations that combine multiple steps or invoke other operations.
* Uses the invoke function to call other operations within the handler.

## Testing

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* **handler.test.ts**: Contains test cases to verify the operation's behavior.
* Utilizes the CDK's testing framework to simulate operation execution and validate outcomes.

## Deployment

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Once developed and tested, the connector can be deployed to the Tray platform, making it available for use in workflows.

## Next Steps

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If you have followed the [introduction](https://tray.ai/documentation/developer/connector-development-kit/overview/introduction) to install CDK CLI and initialize a connector project, you can follow the [quickstart](https://tray.ai/documentation/developer/connector-development-kit/overview/quickstarts/token-raw-http) to build / deploy a connector.