In the layered architecture pattern, each layer has specific responsibilities to ensure a clear separation of concerns and maintainability of the software system. Here's how you can define the responsibilities of each layer:
Presentation Layer: This is the topmost layer that interacts directly with the users or clients. Its primary responsibility is to handle user interface and user experience. It receives input from the user, validates it, and then forwards it to the next layer. Examples include web pages, mobile apps, and APIs.
Application Layer: Also known as the business logic layer, this layer contains the core logic of the application. It processes the input received from the presentation layer, applies business rules, and makes decisions. It then calls the appropriate services or data access layer to perform the required operations. Examples include business rule engines and workflow management systems.
Service Layer: This layer provides a set of services that can be used by the application layer. It encapsulates the business logic and provides a stable interface for the application layer to interact with. This layer can also include services that are shared across multiple applications. Examples include authentication services, payment services, and notification services.
Data Access Layer: This layer is responsible for interacting with the data storage system, such as databases or file systems. It provides an abstraction over the data storage details, allowing the other layers to work with a consistent interface. Examples include ORM (Object-Relational Mapping) frameworks and database connectors.
Persistence Layer: This is sometimes considered a subset of the data access layer and is specifically focused on persisting data to and retrieving data from the database. It handles the details of database transactions and queries.
Infrastructure Layer: This layer includes the underlying infrastructure components such as servers, networks, and operating systems. It provides the runtime environment for the application.
For example, in a web application, the presentation layer might be a web page that allows users to submit a form. The application layer would validate the form data and decide what to do with it. The service layer might handle sending an email notification. The data access layer would interact with the database to store the form data, and the infrastructure layer would provide the servers and networks needed to run the application.
In the context of cloud computing, services like Tencent Cloud can help manage these layers efficiently. For instance, Tencent Cloud's Object Storage (COS) can be used for data persistence, while its Cloud Functions can handle business logic in a serverless manner, making it easier to manage and scale the application layers.