Information and Communication Technology | Network Services and Implementation

Network Services and Implementation

Hey everyone! Welcome to your study notes for "Network Services and Implementation". Ever wondered how you can instantly watch a video on your phone, share files with a friend for a project, or even just connect to the Wi-Fi at home? This chapter pulls back the curtain on how it all works!

We'll explore how computers "talk" to each other (the client-server model) and then get practical by learning how to set up a simple network and share things like files and printers. It might sound technical, but we'll break it down with simple examples. Let's get started!

Part 1: How Computers Talk - Client-Server Communication

At the heart of the internet and most networks is a simple idea: one computer asks for something, and another computer gives it. This is the client-server model.

1.1 The Client and the Server: A Restaurant Analogy

Imagine you're at a restaurant. You are the customer, and you want to order food. The waiter and the kitchen are there to serve you.

- The Client: This is YOU! In the computer world, the client is your device (your computer, phone, tablet) that requests a service or information. For example, when you type a website address into your browser, your browser is acting as a client.

- The Server: This is the waiter and the kitchen. A server is a powerful computer that holds the information or provides the service that the client wants. It listens for requests, processes them, and responds by sending the data back. The website you want to visit lives on a server.

So, the roles are simple:
Client = Asks for things (makes requests)
Server = Provides things (sends responses)

1.2 The Language They Speak: Request and Response

The whole process is a conversation of requests and responses.

Step 1: Request
Your web browser (the client) sends a message to the web server asking for a specific webpage. This message is called an HTTP Request.

Step 2: Response
The web server receives the request, finds the webpage, and sends it back to your browser. This message is called an HTTP Response. Your browser then displays the webpage for you to see.

HTTP Requests: GET vs. POST

Don't worry, this is easier than it sounds! GET and POST are just two common types of requests.

- GET Request: This is used to retrieve data. It's like asking the waiter, "Can I get the menu?". When you type a website address like www.google.com and press Enter, your browser sends a GET request to get the Google homepage.

- POST Request: This is used to send data to the server to be processed. It's like filling out a form and handing it to the waiter to post to the kitchen. When you fill in a login form with your username and password and click "Submit", your browser sends a POST request.

Memory Aid: Think GET = "Go and get me something!" and POST = "Take this information I'm posting to you!".

TCP Port Numbers: Finding the Right Department

Imagine a server is a giant office building. The server's IP address is like the building's street address. But how do you find the right department inside? That's where port numbers come in!

A port number is attached to a request to tell the server exactly which service the client wants.

- Web browsing (HTTP) usually uses Port 80.
- Secure web browsing (HTTPS) uses Port 443.
- Sending email (SMTP) uses Port 25.

So, when you visit http://www.example.com, your computer is really sending a request to the server's IP address, directed at Port 80.

Did you know? There are 65,535 possible TCP port numbers! Most of the common services use ports under 1024, which are known as the "well-known ports".

1.3 The Super-Servers: Meet the Team!

A network has many different types of servers, each with a special job. Let's meet the main players:

- DHCP Server (Dynamic Host Configuration Protocol): The Address Giver. When you connect your phone to a Wi-Fi network, this server automatically assigns it a unique IP address. Without it, you'd have to manually type in an IP address every time!

- Domain Controller: The Security Guard. In a school or office network, this server manages all the user accounts, passwords, and security policies. It decides who is allowed to log in and what they can access.

- File Server: The Librarian. This is a central computer used for storing and sharing files. It's like a shared network drive where everyone in a group can save and open their project files.

- Proxy Server: The Middleman. It acts as a gateway between you and the internet. It can improve security by filtering content, and speed things up by storing copies (caching) of frequently visited websites.

- Web Server: The Shopkeeper. This server stores websites and delivers their pages to users' browsers when requested.

- Database Server: The Record Keeper. It stores and manages huge amounts of data in a structured way, like customer information, product inventories, or student records.

- Gateway: The Translator / Exit Door. A gateway connects two different networks that use different rules (protocols). Your home router acts as a gateway between your home network (LAN) and the internet (WAN).

Key Takeaway for Part 1: A client requests information (using GET or POST) from a server. Port numbers direct the request to the right service (like web or email). Different types of servers (DHCP, File, Web, etc.) perform specific jobs on the network.

Part 2: Building Your Own Network - Basic Implementation

Now that we know the theory, let's look at how to actually put a simple network together. Don't worry, you do this all the time at home!

2.1 Getting Connected: Ethernet vs. Wireless

There are two main ways to set up a simple network:

- Ethernet (Wired): This involves plugging a physical cable (an Ethernet cable) from your computer into a router or a network port. It's generally faster and more stable than wireless, making it great for gaming or desktop computers.

- Wireless (Wi-Fi): This connects devices using radio waves, no cables needed! It's super convenient for laptops, phones, and tablets.

Real-World Examples:
- A home network is a perfect example of a simple network. Your router connects all your devices (laptops, phones, smart TV) to each other and to the internet, using a mix of Ethernet and Wi-Fi.
- An ad hoc network is a temporary, direct connection between devices without a central router. You might use this at a special event or in a study group to quickly share files between two laptops.

2.2 Sharing is Caring: Resource Sharing

One of the biggest benefits of a network is sharing resources. This saves money and makes collaboration easy. You can share:

- Files: Instead of emailing a file back and forth, you can place it in a shared folder on a file server (or a shared folder on a classmate's computer) for everyone to access.

- Printers: An entire office or family can share one printer connected to the network, rather than everyone needing their own.

- Internet Connection: A single router takes one internet connection from your provider and shares it with all the devices in your home.

2.3 Who Can Do What? File and Folder Permissions

When you share files, you don't always want everyone to be able to do everything. Permissions are rules that control what users can do with a file or folder. The three basic permissions are:

- Read: The user can open and view the file, but cannot change or delete it. (Analogy: Reading a book in a library.)

- Write: The user can modify the file, save changes, and delete it. (Analogy: Editing a shared Google Doc.)

- Execute: The user can run the file if it's a program or a script. (Analogy: Double-clicking an application to start it.)

By setting these permissions, you can, for example, let your project group members read and write to the project folder, but let other classmates only read the final report.

Common Mistake to Avoid: Giving everyone "Write" access (often called "Full Control") when they only need "Read" access. This is a security risk, as someone could accidentally delete important files!

2.4 Powering Up: Setting Up Simple Network Services

Beyond sharing files, you can also set up simple services on your network. The syllabus wants you to know about two:

- Web Service: This means setting up a web server. You could actually run a simple web server on your own computer to host a personal website that only people on your local network can see. This is often used for testing websites before they go live on the internet.

- Database Service: This means setting up a database server. For a small project, you could run a database on one computer that holds information (like a list of movies or books), and other computers on the network could connect to it to search or add information.

Key Takeaway for Part 2: Simple networks can be wired (Ethernet) or wireless. They allow us to share resources like files, printers, and internet connections. To keep shared files safe, we use permissions (read, write, execute) to control who can do what. We can even set up basic web and database services on a local network.