REST vs SOAP vs GraphQL comparison in Rest API - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Key difference in data fetching between REST and GraphQL

Which statement best describes how REST and GraphQL differ in data fetching?

A REST allows clients to specify exactly what data they want, GraphQL fetches fixed data per endpoint.

B REST fetches fixed data per endpoint, GraphQL allows clients to specify exactly what data they want.

C Both REST and GraphQL always fetch all data from the server regardless of client request.

D REST and GraphQL both require multiple requests to fetch related data.

💡 Hint

Think about how flexible the client is in choosing data with each approach.

REST endpoints return fixed data structures, while GraphQL queries let clients specify exactly which fields they want.

❓ Predict Output

intermediate

Output of a SOAP fault response

What is the output when a SOAP service returns a fault response with this XML snippet?

Rest API

<?xml version="1.0"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <soap:Fault>
      <faultcode>soap:Client</faultcode>
      <faultstring>Invalid request</faultstring>
    </soap:Fault>
  </soap:Body>
</soap:Envelope>

A A timeout error from the server.

B A successful response with requested data.

C A syntax error in the SOAP message.

D An error indicating 'Invalid request' with fault code 'soap:Client'.

💡 Hint

Look at the element and its children.

The element signals an error. The faultcode and faultstring describe the error details.

❓ Predict Output

advanced

GraphQL query result for nested data

Given this GraphQL query, what is the expected JSON response?

Rest API

query {
  user(id: "1") {
    name
    posts {
      title
      comments {
        text
      }
    }
  }
}

A { "data": { "user": { "name": "Alice", "posts": [ { "title": "Hello", "comments": [ { "text": "Nice post!" } ] } ] } } }

B { "data": { "user": { "name": "Alice" } } }

C { "error": "Field 'posts' not found" }

D { "data": { "user": null } }

💡 Hint

GraphQL returns exactly the fields requested, including nested objects.

The query asks for user name, posts with titles, and comments with text, so the response includes all nested data.

🧠 Conceptual

advanced

SOAP vs REST protocol characteristics

Which of these is true about SOAP compared to REST?

A SOAP is stateless and uses JSON only, REST is stateful and uses XML only.

B SOAP is simpler and faster than REST for all use cases.

C SOAP uses XML and has built-in standards for security and transactions, REST is more flexible and uses multiple formats.

D SOAP does not support encryption, REST always requires encryption.

💡 Hint

Think about the protocol and message format differences.

SOAP is a protocol with strict standards and XML messages; REST is an architectural style supporting multiple formats and is more flexible.

🧠 Conceptual

expert

Choosing API style for complex client-driven data needs

A mobile app needs to fetch complex, nested data but wants to minimize the number of requests and data size. Which API style is best suited?

A GraphQL, because it allows clients to request exactly the nested data they need in one request.

B SOAP, because it uses XML which is smaller and faster than JSON.

C REST, because it requires multiple endpoints and requests for nested data.

D None, because all API styles require multiple requests for nested data.

💡 Hint

Consider how each API style handles nested data and request flexibility.

GraphQL lets clients specify nested data in one query, reducing requests and data size. REST often requires multiple calls, SOAP is verbose.

Practice

1. Which API style allows clients to request exactly the data they need in a single query?

easy

A. FTP

B. REST

C. SOAP

D. GraphQL

Solution

1. Step 1: Understand GraphQL's data fetching

   GraphQL lets clients specify exactly which fields they want in a query, reducing over-fetching.

2. Step 2: Compare with REST and SOAP

   REST uses fixed endpoints and HTTP methods, SOAP uses strict XML messages, neither allows flexible data selection like GraphQL.

3. Final Answer:

   GraphQL -> Option D

4. Quick Check:

   Exact data request = GraphQL [OK]

Hint: GraphQL = precise data queries in one request [OK]

Common Mistakes:

• Confusing REST with GraphQL's flexible queries
• Thinking SOAP supports flexible data selection
• Choosing unrelated protocols like FTP

2. Which of the following is the correct HTTP method typically used by REST APIs to update a resource?

easy

A. PUT

B. POST

C. GET

D. CONNECT

Solution

1. Step 1: Recall REST HTTP methods

   REST commonly uses PUT to update or replace a resource at a URL.

2. Step 2: Differentiate from other methods

   GET retrieves data, POST creates new resources, CONNECT is for network tunnels, so only PUT updates.

3. Final Answer:

   PUT -> Option A

4. Quick Check:

   Update resource = PUT [OK]

Hint: PUT method updates resources in REST [OK]

Common Mistakes:

• Using GET to update data
• Confusing POST with update instead of create
• Selecting non-REST HTTP methods like CONNECT

3. Given the following GraphQL query, what data will the client receive?

{ user(id: "123") { name email } }

medium

A. {"user": {"name": "Alice"}}

B. {"user": {"name": "Alice", "email": "[e-mail]"}}

C. {"user": {"id": "123", "name": "Alice"}}

D. {"user": {"email": "[e-mail]"}}

Solution

1. Step 1: Analyze the GraphQL query fields

   The query requests the user's name and email fields for user with id "123".

2. Step 2: Determine expected response

   The response includes both requested fields inside the user object, matching {"user": {"name": "Alice", "email": "[e-mail]"}}.

3. Final Answer:

   {"user": {"name": "Alice", "email": "[e-mail]"}} -> Option B

4. Quick Check:

   Requested fields = name and email [OK]

Hint: GraphQL returns only requested fields in response [OK]

Common Mistakes:

• Expecting all user fields returned
• Missing one of the requested fields
• Confusing id field presence

4. You have a SOAP API call that fails due to incorrect message format. What is the most likely cause?

medium

A. Using GraphQL query syntax in the request

B. Missing HTTP GET method in the request

C. Using JSON instead of XML in the request body

D. Not specifying the resource URL correctly

Solution

1. Step 1: Understand SOAP message format requirements

   SOAP requires XML formatted messages strictly following its schema.

2. Step 2: Identify common format errors

   Sending JSON instead of XML breaks the SOAP message format, causing failure.

3. Final Answer:

   Using JSON instead of XML in the request body -> Option C

4. Quick Check:

   SOAP needs XML, not JSON [OK]

Hint: SOAP messages must be XML formatted [OK]

Common Mistakes:

• Using JSON payloads with SOAP
• Confusing HTTP methods for SOAP
• Mixing GraphQL syntax with SOAP

5. You need to design an API for a mobile app that requires minimal data usage and flexible queries. Which API style is best and why?

hard

A. GraphQL, because it lets clients request exactly the data they need

B. REST, because it uses simple URLs and HTTP methods

C. SOAP, because it uses strict XML for secure communication

D. FTP, because it transfers files efficiently

Solution

1. Step 1: Identify requirements for minimal data and flexible queries

   The app needs to reduce data usage and allow clients to specify data fields.

2. Step 2: Match API styles to requirements

   GraphQL allows clients to request only needed data in one query, minimizing data transfer and providing flexibility.

3. Final Answer:

   GraphQL, because it lets clients request exactly the data they need -> Option A

4. Quick Check:

   Minimal data + flexible queries = GraphQL [OK]

Hint: Choose GraphQL for flexible, minimal data queries [OK]

Common Mistakes:

• Choosing REST without flexible data selection
• Selecting SOAP despite heavy XML overhead
• Confusing FTP with API styles