In this book, we've explored numerous patterns related to building cloud-native applications. Now, we'll apply these patterns to a real-world use case. This final chapter demonstrates how to leverage cloud-native patterns when building various aspects of such applications, including:
Connecting services
Managing decentralized data
Event processing
Stream processing
Exposing managed APIs
Connecting frontend applications
Performing dynamic application management
Building an Online Retail System
Our use case is a simplified online retail application for searching, purchasing, and shipping goods. While a real retail application is highly complex, this simplified version retains diverse business capabilities and requirements to effectively demonstrate the application of cloud-native patterns.
Key requirements and capabilities are categorized as follows:
Product catalog
Order management
Order tracking and prediction
Product recommendations
Customer and partner management
Let's examine each in more detail:
Product Catalog
The product catalog allows customers to search for products and obtain essential details for purchasing. Key functionalities include:
Searching for products
Obtaining product details for purchase decisions
Enabling product administrators and sellers to add, remove, and update products
Q- my notes : 

The features in this app are : 

—> Searching for products : 
You have a functionality to build  search bar where the user can type their preferred product and search for it  
—> Obtaining product details for purchase decisions
So you have a description of the particular product oky 
—> Enabling product administrators and sellers to add, remove, and update products
First we have deffirent using privileges one admin , one normal user 
We need to make the administrator tha ability to add , remove and update products 
Q- now let’s focus on the Product Catlog service give some ui’s as proff of concept how the front end may look like for these 3 different user story oky


https://v0.dev/chat/00PgDrn3koh?b=b_vT0jqTLPa5v
https://v0.dev/chat/00PgDrn3koh?b=b_0I2KHYguzAJ
https://v0.dev/chat/00PgDrn3koh?b=b_weopfH0xijQ 

Order Management
After selecting a product and quantity, the customer adds items to their shopping cart and places an order. Key functionalities of the order management subsystem include:
Placing an Order: Customers place orders for selected products and quantities.
Payment: Customers pay for their orders using their preferred payment method.
https://v0.dev/chat/00PgDrn3koh?b=b_K1gYiDbCW8M

Order Tracking and Prediction
After placing an order, customers can receive order and shipment updates and notifications. Key functionalities of this subsystem include:
Shipment Tracking: Customers can track the status of their shipment.
Notifications: Customers receive notifications about order status changes, delivery estimates, and other important updates.
Delivery Prediction: The system predicts delivery times based on past orders, real-time warehouse data, and shipping service information.
Product Recommendations
Customers receive product recommendations based on their search queries, past purchases, and current deals.
Customer and Partner Management
Customers can manage their accounts and profile information. They may access the system through various applications (e.g., mobile or web). Certain business capabilities may be exposed to multiple parties (customers and partners) via different frontend applications (customer mobile app, partner mobile app, etc.).
Non-functional Requirements:
The application must be highly available, scalable, secure, observable, and dynamically manageable across both on-premises data centers and a public cloud platform.
Based on these requirements and capabilities, we'll construct a cloud-native solution by applying patterns explored in previous chapters. Let's begin by outlining the high-level system architecture.



→ let’s focus on a set of business capabilities , it makes sens to start from it 
→ these business capabilities are essentially the apis that we would expose from out retail application 
→ we need to model our front-End application around these apis 
(we are following the top-down approach of the api 

We identify the key business capabilities that we want to expose: product catalog, order management, payments, recommendations, tracking, and delivery prediction (Figure 8-2). We then model these capabilities as managed APIs and expose them to the external parties, such as consumers and partners, via an API management plane. The microservices that back those APIs implement the required business logic by integrating with other microservices, external systems, databases, and other resour‐ ces. In this use case, we apply API management patterns such as API Gateway (dis‐ cussed in Chapter 7) to expose these services as managed APIs.

These APIs are accessible to external client applications, such as mobile and web applications, through a load-balancer layer. The frontend application development can leverage patterns such as Backend for Frontends to implement certain features. For example, the order API may have different BFF-style APIs for mobile and web applications. As we discussed in Chapter 7, most of the API traffic can be exposed as RESTful or GraphQL services through the API gateway. The cross-cutting capabilities such as security, throttling, caching, and policy enforcement are applied at the API gateway layer. The API runtimes that we implement at the gateway layer may use pat‐ terns such as API Microgateway to enable independent runtimes for each API.

The ownership of these APIs can be assigned to the team that owns the underlying microservice backing a given API. For example, if the Catalog service is owned by Team A, the same team can own the catalog API as well. The key idea here is to segre‐ gate the API management layer based on ownership so that we can change, scale, and manage APIs independently. Therefore, you may opt to use patterns such as API Microgateway to decentralize the gateway layer further.

Once we decide on the APIs that we need to expose at the API management plane, we can dive into the implementation of each of the microservices that are backing those APIs.


Q- using api first approach and given these software requirement  try to build a complete api documentation of this system 
Q- to get a good view of the application