Communication Between Tiers

Communication between tiers in a multitiered architecture is essential for the overall functionality and performance of the system. Here’s how communication typically occurs between the presentation, application, and data tiers:

1. Presentation Tier to Application Tier:

• User Requests: Users interact with the presentation tier by submitting requests through the user interface.
• HTTP Requests: In web-based applications, user requests are typically sent over HTTP (Hypertext Transfer Protocol) to the application tier.
• API Calls: The presentation tier may make API (Application Programming Interface) calls to the application tier to retrieve data, submit forms, or perform other actions.
• Data Transfer: Data is transferred between the presentation tier and the application tier in a format such as JSON (JavaScript Object Notation) or XML (eXtensible Markup Language).

2. Application Tier to Data Tier:

• Business Logic Execution: The application tier executes business logic and processes user requests.
• Data Access: When data is required, the application tier interacts with the data tier to retrieve or update information stored in the database.
• Database Queries: The application tier constructs and sends queries to the data tier to fetch or modify data.
• Data Manipulation: Upon receiving data from the data tier, the application tier may perform additional processing or transformation before sending it back to the presentation tier.

3. Data Tier to Application Tier:

• Query Processing: The data tier processes incoming queries from the application tier, such as SELECT, INSERT, UPDATE, or DELETE operations.
• Data Retrieval: If the query involves data retrieval, the data tier accesses the database, retrieves the requested data, and prepares it for transmission.
• Data Serialization: Data is serialized into a format suitable for transmission, such as JSON or XML, before being sent back to the application tier.
• Response Sending: The data tier sends the response containing the requested data or the result of the operation back to the application tier.

4. Application Tier to Presentation Tier:

• Data Processing: The application tier processes the data received from the data tier or user inputs.
• Response Generation: Based on the processed data and business logic, the application tier generates a response to be sent back to the presentation tier.
• Rendering: In web applications, the application tier may generate HTML (Hypertext Markup Language) or other markup language to be rendered by the browser.
• Response Sending: The application tier sends the response back to the presentation tier over the network.

Multitiered Architectures in Distributed Systems explains how complex computer systems are organized into different layers or tiers to improve performance and manageability. Each tier has a specific role, such as handling user interactions, processing data, or storing information.

• By dividing tasks among these tiers, systems can run more efficiently, be more secure, and handle more users at once.
• This architecture is widely used in modern applications like web services, where front-end interfaces, business logic, and databases are separated to enhance functionality and scalability.