Calling third party Api and exception handling

Topics to be covered:

• REST APIs
• REST API Best Practices
• Integrating FakeStore API
• Writing Models for our Product Service

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REST API

Introduction

• Definition:

REST API (Representational State Transfer Application Programming Interfaces) is a set of principles and conventions that allows different software systems to communicate over the internet. It is widely used to interact with web services.

• Core Concept:

When an API call is made, the state of an entity is being transferred. REST APIs have become a standard method for software systems to exchange data over the web.

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REST API Best Practices

Centralization Around Resources

• Resources as Central Concept:

In RESTful API design, resources (e.g., users, products, orders) represent entities in the system.

• Endpoint Structure:

API endpoints should be organized around these resources, with interactions performed using HTTP methods:

• GET - Retrieve a resource
• POST - Create a new resource
• PUT - Update an existing resource

• DELETE - Remove a resource

• Endpoint Naming:

Use nouns in endpoints rather than verbs. For example, use https://mysite.com/posts instead of https://mysite.com/getPosts.

Statelessness of REST APIs

• Concept:

Each API request should be independent and self-sufficient, containing all the necessary information to be processed by any server without relying on previous interactions.

Key Principles:

1. API Request Servicability:

   • Requests should be handled by any available server through a load balancer, ensuring uniformity and quick processing.
   • Architecture Overview:
     • The user's request is sent to a load balancer.
     • The load balancer forwards the request to any available server (e.g., server-1 or server-5).
   • Result: Servers should not store any session-specific data, which should instead be handled by a central database accessible by all servers.

1. Self-Sufficient API Requests:
   • Example: A user logs in via server-1, but subsequent requests might be routed to server-5. Server-5 won’t know if the user is logged in unless proper credentials (like tokens) are passed with the request.
   • Implementation: All APIs should include necessary credentials (e.g., tokens) to ensure they can be processed independently.

1. Avoiding Chatty APIs:

   • Misconception: API endpoints do not need to mirror database tables.
   • Best Practice: The API should expose only the necessary data and functionality, possibly involving data transformation within the API layer, without exposing the database structure.

2. Independence of Response Data Types:

   • Data Formats: RESTful APIs typically use JSON and XML, which are standard, easily parsed data formats ensuring interoperability between systems.
   • Documentation: Clearly specify the data formats used in your API documentation to avoid confusion.
   • Alternative Format: Proto (protocol buffers) is another format, more machine-friendly than human-readable, enabling faster responses.

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FakeStore API

Introduction & Usage

• Purpose: To simulate database interaction when you are not yet proficient in database handling via code.
• Tool: We will use FakeStore API as a proxy server.
• Application: The API will serve as a placeholder, enabling us to build our product service by calling this third-party API while also preparing to interact with an actual database in the future.

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Writing Models for Our Product Service

Defining Models

• Purpose:

Models define the structure and relationships of data within your application. For a product service, typical models include: - Product: - Categories - Name - Description - Additional attributes as needed - Category: - ID - Name

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