Resources and methods in AWS - Step-by-Step Execution

Process Flow - Resources and methods

Define Resource

↓

Attach Methods

↓

Configure Method Settings

↓

Deploy API

↓

Client Calls Method

↓

API Executes Resource Logic

↓

Return Response to Client

This flow shows how an API resource is defined, methods are attached and configured, then deployed and called by clients.

Execution Sample

AWS

Resource: /books
Method: GET
Integration: Lambda function
Deploy API
Client calls GET /books

Defines a /books resource with a GET method integrated to a Lambda function, then deploys and calls it.

Process Table

Step	Action	Resource State	Method State	Result
1	Define resource /books	Resource /books created	No methods yet	Resource ready
2	Attach GET method to /books	Resource /books exists	GET method attached	Method ready
3	Configure GET method integration	Resource /books exists	GET method integrated with Lambda	Integration set
4	Deploy API	Resource and methods deployed	Methods active	API live
5	Client calls GET /books	Resource /books exists	GET method invoked	Lambda function executed
6	Lambda returns data	Resource /books exists	GET method completed	Response sent to client
7	End	Resource /books exists	GET method ready	Execution complete

💡 Execution stops after response is sent to client and method completes.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	Final
Resource	None	/books created	/books exists	/books exists	/books deployed	/books exists	/books exists	/books exists
Method GET	None	None	Attached	Integrated with Lambda	Active	Invoked	Completed	Ready
API Deployment	Not deployed	Not deployed	Not deployed	Not deployed	Deployed	Deployed	Deployed	Deployed
Client Call	No call	No call	No call	No call	No call	Call made	Response sent	No call

Key Moments - 3 Insights

Why do we need to attach a method to a resource before deployment?

Because methods define how clients interact with the resource. Without methods, the resource cannot respond to requests. See execution_table step 2 where method is attached before deployment at step 4.

What happens if the method integration is not configured?

The method exists but has no backend logic to execute, so calls will fail or return errors. See execution_table step 3 where integration is set before deployment.

Why does the client call happen only after deployment?

Because the API must be deployed to make resources and methods live and accessible. See execution_table step 4 deploys API, then step 5 client calls method.

Visual Quiz - 3 Questions

Look at the execution_table, what is the state of the GET method after step 3?

A Method integrated with Lambda function

B Method attached but not integrated

C Method invoked by client

D Method completed execution

💡 Hint

Check the 'Method State' column at step 3 in execution_table.

At which step does the API become live and ready to accept client calls?

A Step 2

B Step 4

C Step 3

D Step 5

💡 Hint

Look for 'API live' in the 'Result' column of execution_table.

If the resource /books was not created at step 1, what would happen at step 5 when client calls GET /books?

A Method would execute normally

B API would deploy successfully

C Client call would fail because resource does not exist

D Lambda function would run without resource

💡 Hint

Refer to variable_tracker for Resource variable state at step 1 and step 5.

Concept Snapshot

Resources are API paths like /books.
Methods (GET, POST) attach to resources to handle requests.
Methods must be integrated with backend logic (e.g., Lambda).
API must be deployed to make resources and methods live.
Clients call methods on resources to get responses.

Full Transcript

This visual execution shows how an API resource is created, methods are attached and integrated with backend logic, then deployed. The client calls the method after deployment, triggering backend execution and response. Variables track resource and method states step-by-step. Key moments clarify why method attachment and integration are needed before deployment, and why deployment is required before client calls. The quiz tests understanding of method state, deployment timing, and resource existence impact.

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