Resources and methods in AWS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a resource in AWS API Gateway?

A resource is a part of the API that represents an object or a path, like a folder or file in a website URL. It organizes the API structure and holds methods to handle requests.

beginner

What is a method in AWS API Gateway?

A method is an action you can perform on a resource, such as GET, POST, PUT, or DELETE. It defines how the API responds to different types of requests.

intermediate

How do resources and methods work together in AWS API Gateway?

Resources define the URL paths, and methods define the actions on those paths. Together, they create the API's structure and behavior for handling client requests.

intermediate

Why is it important to configure methods with integration types in API Gateway?

Integration types connect methods to backend services like Lambda functions or HTTP endpoints, enabling the API to process requests and return responses properly.

beginner

What is the role of HTTP status codes in methods of API Gateway?

HTTP status codes tell the client if the request was successful or if there was an error. Methods use these codes to communicate the result of the request clearly.

In AWS API Gateway, what does a resource represent?

A A URL path or object in the API

B A backend database

C A user account

D A security policy

Resources represent URL paths or objects that organize the API structure.

Which HTTP method is NOT commonly used in API Gateway methods?

A CONNECT

B POST

C DELETE

D GET

CONNECT is rarely used in API Gateway; common methods are GET, POST, PUT, DELETE.

What connects a method in API Gateway to a backend service?

A API key

B Resource policy

C Integration type

D CloudWatch logs

Integration type defines how the method connects to backend services like Lambda or HTTP endpoints.

Which HTTP status code indicates a successful GET request?

A 404

B 301

C 500

D 200

200 means the request was successful and the server returned the requested data.

What is the purpose of defining methods under resources in API Gateway?

A To store user credentials

B To specify actions clients can perform on API paths

C To create database tables

D To monitor server health

Methods define what actions (like GET or POST) clients can perform on the API's resources (paths).

Explain how resources and methods work together in AWS API Gateway to handle client requests.

Think about how a website URL and clicking buttons relate to resources and methods.

Describe why integration types are important when configuring methods in API Gateway.

Consider how a phone call connects you to a person who can help.

Practice

1. What does a resource represent in AWS API Gateway?

easy

A. A URL path that clients can access

B. A backend database connection

C. A security policy for API access

D. A method to deploy the API

Solution

1. Step 1: Understand the role of resources in API Gateway

   Resources define the URL paths that clients use to reach your API endpoints.

2. Step 2: Differentiate resources from other components

   Resources are not backend connections, security policies, or deployment methods; they are URL paths.

3. Final Answer:

   A URL path that clients can access -> Option A

4. Quick Check:

   Resource = URL path [OK]

Hint: Resources are the API's URL paths clients call [OK]

Common Mistakes:

• Confusing resources with backend services
• Thinking resources are security settings
• Mixing resources with deployment steps

2. Which HTTP method is correctly defined in AWS API Gateway to retrieve data?

easy

A. GET

B. POST

C. DELETE

D. PUT

Solution

1. Step 1: Identify the HTTP method for data retrieval

   GET is the standard HTTP method used to retrieve or read data from a resource.

2. Step 2: Confirm other methods' purposes

   POST creates data, DELETE removes data, and PUT updates data, so they are not for retrieval.

3. Final Answer:

   GET -> Option A

4. Quick Check:

   GET = retrieve data [OK]

Hint: GET method is for reading data from resources [OK]

Common Mistakes:

• Using POST instead of GET to fetch data
• Confusing DELETE with data retrieval
• Mixing PUT with GET for reading data

3. Given this API Gateway setup: a resource /items with a POST method integrated to a Lambda function. What happens when a client sends a POST request to /items?

medium

A. The API Gateway returns a static mock response

B. The API Gateway returns a 404 Not Found error

C. The Lambda function is triggered to process the request

D. The request is ignored because POST is not allowed

Solution

1. Step 1: Understand the integration of POST method with Lambda

   The POST method on the /items resource is connected to a Lambda function, so requests trigger that function.

2. Step 2: Analyze the client request effect

   When a client sends a POST request to /items, API Gateway forwards it to Lambda for processing.

3. Final Answer:

   The Lambda function is triggered to process the request -> Option C

4. Quick Check:

   POST + Lambda integration = Lambda triggered [OK]

Hint: POST method triggers Lambda if integrated [OK]

Common Mistakes:

• Assuming POST is not allowed without checking method setup
• Thinking API Gateway returns 404 if resource exists
• Confusing mock responses with Lambda integration

4. You created a resource /users and added a GET method, but clients get a 403 Forbidden error when calling it. What is the most likely cause?

medium

A. The client is using POST instead of GET

B. The resource path is misspelled

C. The API Gateway is not deployed

D. The method does not have an integration configured

Solution

1. Step 1: Check method integration setup

   A 403 Forbidden often means the method exists but lacks proper integration or permissions.

2. Step 2: Rule out other causes

   If the resource path was misspelled, the error would be 404. If API Gateway was not deployed, the error would differ. Using POST instead of GET would cause a 405 Method Not Allowed.

3. Final Answer:

   The method does not have an integration configured -> Option D

4. Quick Check:

   403 Forbidden = missing integration or permissions [OK]

Hint: 403 often means method lacks integration or permissions [OK]

Common Mistakes:

• Confusing 403 with 404 or 405 errors
• Ignoring deployment status
• Assuming client method is always correct

5. You want to create an API with a resource /orders that supports both GET and POST methods. The GET method returns a mock response, and the POST method triggers a Lambda function. Which configuration correctly sets this up?

hard

A. Create /orders resource; add GET and POST methods both with MOCK integration

B. Create /orders resource; add GET method with MOCK integration; add POST method with Lambda integration

C. Create /orders resource; add GET method with Lambda integration; add POST method with MOCK integration

D. Create /orders resource; add GET and POST methods both with Lambda integration

Solution

1. Step 1: Match method to integration type

   The GET method should use MOCK integration to return a static response without backend calls.

2. Step 2: Configure POST method to trigger Lambda

   The POST method must be integrated with Lambda to process incoming data.

3. Step 3: Verify the correct combination

   Create /orders resource; add GET method with MOCK integration; add POST method with Lambda integration correctly assigns MOCK to GET and Lambda to POST on the /orders resource.

4. Final Answer:

   Create /orders resource; add GET method with MOCK integration; add POST method with Lambda integration -> Option B

5. Quick Check:

   GET=MOCK, POST=Lambda [OK]

Hint: GET with MOCK, POST with Lambda for mixed behavior [OK]

Common Mistakes:

• Swapping MOCK and Lambda integrations between methods
• Using same integration for both methods incorrectly
• Forgetting to create the resource before methods