Okay, let's discuss 2.b Servers.

  • Definition: A server is a computer or a software application that provides services or resources to clients. It's the "responder" in a client-server architecture. Servers listen for incoming requests from clients, process those requests, and send back responses.
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  • Types of Servers:
    • Web Servers: Handle requests for web pages and other web content (e.g., Apache, Nginx, IIS). They receive HTTP/HTTPS requests from web browsers and return HTML, CSS, JavaScript, images, and other files.
    • Application Servers: Host and execute the business logic of an application. They often sit between web servers and databases, processing data and performing complex operations. (e.g., Tomcat, JBoss, Node.js)
    • Database Servers: Store and manage data (e.g., MySQL, PostgreSQL, MongoDB, Cassandra). They receive queries from application servers or other clients and return data.
    • Mail Servers: Handle sending and receiving emails (e.g., Sendmail, Postfix, Microsoft Exchange).
    • File Servers: Store and manage files that can be accessed by clients over a network (e.g., NFS, SMB/CIFS).
    • Proxy Servers: (As discussed before) Act as intermediaries between clients and other servers.
    • Game Servers: Host multiplayer online games.
    • DNS Servers: Translate domain names to IP addresses.
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  • Key Considerations:

    • Server-Side Logic: Servers are responsible for executing the core logic of an application, processing data, and interacting with databases and other services.
    • Concurrency: Servers must be able to handle multiple requests concurrently, often using multi-threading or asynchronous programming techniques.
    • Scalability: Servers need to be designed to handle increasing load, either through vertical scaling (adding more resources to a single server) or horizontal scaling (adding more servers).
    • Security: Servers must be secured to protect against unauthorized access and attacks.
    • Operating System: Servers typically run on server-oriented operating systems (e.g., Linux, Windows Server).

  • Example: When your web browser requests a webpage from Google, the request goes to a web server. The web server might then communicate with an application server to process the request and retrieve data from a database server. The web server then sends the results back to your browser.

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