what happens when you type "https://www.google.com" in your browser and press Enter.
Yea. Interesting right? Let me guess, some of you might say "google website page, duh". Yeah, you are right. Well Everybody know what kind of result it gives, but few know how it works under the hood! Hello, My name is Ebenezer and in this article, I will take you on a journey from www.google.com all the way to Google website page. Does this feels like an adventure? Let's get started!
INTRODUCTION TO HOW THE WEB STACK WORKS
We use internet all the time for all sorts of purposes, and it has become like a second nature to browse all day. So much so that we’re most of the time content with just knowing that our browser works and does what it’s asked. But it’s not magic (or is it?), and the web pages we see in that rectangle machine must come from somewhere. So how is it all happening? What is happening under the hood between the moment we enter a URL (Uniform Resource Locator) in the search bar and the moment we receive the content of the desired page?
Before we dive deep into details, it is important to know what a client-server model is. In-order for us to communicate with "Google", we need our computer with a browser from our side, and Google server to respond to our request. Like dialing a phone need a receiver or someone to pick the phone up, we also need some kind of responder from the google side in-order a that webpage, and we call it server. Server is nothing more than a computer. So, in this case, our computer is a client, and the google 'computer' is a server. But this is not merely what happens when you type 'www.google.com'. There are many other layers between the client and the server in a client-server model, let’s break is down.
When we type the URL?www.google.com?into our browser (could be Google, Firefox, Safari, et cetera) and press ‘Enter’, the first thing that the browser is going to do is break down the URL in pieces. The browser is going to consider the?google.com?part first, which is a?domain name. To understand what 'domain name' is, first we need to know what an 'IP address' is. IP - Internet Protocol.
Say you want to make a phone call to one of your friend. Obviously you need the phone number of your friend you want to call. Well like wise, computers use an IP address to communicate with each other through the internet. Like a person has unique phone number, so do computer. They have unique IP address. In my country Ethiopia, we have a defined type of format for a phone number. A phone number digit must be exactly 10 digits, like the new Safaricom's phone be like, 0756748323. Other wise it won't work. Same thing to IP addresses. they have a specific format. There should be four numbers, from 0 to 255 separated by dots, like this, 231.95.4.23. This is called IPv4. More on IPv4 and IPv6 on another topics. But the concept is the same, unique numbers that identifies computers uniquely. And Google server has one too, 8.8.4.4. YouTube has one too, which is 208.65.153.238. Also LinkedIn, Instagram, Snapchat, Telegram, et cetera. As you can see it, it is getting already really difficult to memorize the IP addresses. Imagine we have to search websites with IP address. That is when domain name comes to the recue. Like you save you friend's phone number in your contact with a name you want to, domain names are alphabetic representation for IP address. The reason we have domain names in the first place is because humans remember words better than numbers. Thankfully, the DNS is here for us to remember the IP of each domain. If the browser doesn’t know that domain name (it’s not stored in its cache), it is going to ask the?Domain Name System?for the IP address corresponding to this particular domain name.
The DNS request first goes through the?resolver. The resolver is usually our Internet Service Provider, and if it doesn’t find the IP in its cache, it’s going to request the?root?server. The root server knows where the?TLD?(Top-Level Domain) server is. In our case, the top-level domain is?.com. Other types of TLD are?.net,?.fr, etc. If the TLD server doesn’t know the IP, it points the resolver to the?Authoritative Name Servers?for the domain name. Usually, there is more than one name server attached to one domain name. But any of those name servers can give the IP for the domain name they are attached to. Now the resolver has the IP address(for example, 54.172.4.191), and can send it back to the browser which will perform its request to the corresponding server.
2. Protocols: TCP/IP
We mentioned how domain names actually represent IP addresses, but IP is not the only type of protocol use by the Internet. The?Internet Protocol Suite?is often referred to as TCP/IP (TCP stand for Transmission Control Protocol), and it also contains other types of protocols. It’s a set of rules that define how servers and clients interact over the network, and how data should be transferred, broken into packets, received, etc.
3. Firewall
To protect themselves from hackers and attacks, servers are often equipped with a firewall. A firewall is a software that sets rules about what can enter or leave a part of a network. In the case of our example, when the browser asks for the website at the address 54.172.4.191, that request has be processed by a firewall which will decide if it’s safe, or if it’s a threat to the server’s security. The browser itself can also be equipped with a firewall to detect if the IP given by the DNS request is a potential malicious agent.
4. HTTPS/SLL (Security & Encryption)
Now that the browser has the IP address, it is going to take care of the other part of the URL, the?https://?part. HTTPS stands for HyperText Transfer Protocol Secure, and is a secure version of the regular HTTP. This transfer protocol defines different types of?requests?and?responses?served to clients and servers over a network. In other terms, it’s the main way to transfer data between a browser and a website. HTTP and HTTPS requests include GET, POST, PUT, and others. The HTTPS requests and responses are encrypted, which ensure the users that their data can’t be stolen or used by third-parties. For example, if we put our credit card information in a website that uses HTTPS, we are guaranteed that this info is not going to be stored in plain text somewhere accessible to anybody.
Another key component in securing websites is the SSL certificate. SSL stands for Secure Sockets Layer (also known as TSL, Transport Layer Security). The certificate needs be issued from a trusted Certificate Authority, like the famous?Let’s Encrypt?for example, which gives free SSL certificates. When a website has this certificate, we’re able to see a little lock icon next to the website name in the search bar. On some browsers and with certain types of SSL certificates, the bar turns green.
5. Load Balancer
As we mentioned earlier, websites live on servers. For most website where the traffic is consequent, it would be impossible to be hosted on a single server. Plus, it would create a?Single Point of Failure?(SPOF), because it would only need one attack on said server to take the whole site down.
As needs for higher availability and security rises, websites started augmenting the number of servers they have, organizing them in?clusters, and using?load-balancers. A load-balancer is a software program that distribute network requests between several servers, following a load-balancing algorithm. HAProxy is a very famous load-balancer, and example of algorithms that we can use are the?round-robin, which distributes the requests alternating between all the servers evenly and consequentially, or the?least-connection, which distributes requests depending on the current server loads.
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6. Web Server
Once the requests have been evenly distributed to the servers, they will be processed by one or more?web servers. A web server is a software program that serves static content, like simple HTML pages, images or plain text files. The web server is responsible for finding where the static content corresponding to the address asked for is living, and for serving it as an HTTP, or HTTPS response. Examples of web servers are Nginx or Apache. Nginx is a web server, but it can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache. It is free and opensource.
7. Application Server
Having a web server is the basis of any web page. But most sites don’t just want a static page where no interaction is happening, and most websites are?dynamic. That means that it’s possible to interact with the site, save information into it, log in with a user name and a password, etc.
This is made possible by the use of one or more?application servers. These are software programs responsible for operating applications, communicate with databases and manage user information, among other things. they work behind web servers and will be able to serve a dynamic application using the static content from the web server. Gunicorn is an application server. It translates HTTP requests into something Python can understand. It is python application server. Gunicorn implements the Web Server Gateway Interface (WSGI), which is a standard interface between web server software and web applications. The Gunicorn server is broadly compatible with various web frameworks, simply implemented, light on server resources, and fairly speedy.
8. Data Base
The last step in our web infrastructure is the?Data Base Management System (DBMS). A?database?is a collection of data, and the DBMS is the program that is going to interact with the database and retrieve, add, modify data in it.
There are several types of database models. The two main ones are?relational?databases, and?non-relational?databases. A relational database can be seen as a collection of tables representing objects, where each column is an attribute and each row is an instance of that object. We can perform SQL (Structured Query Language) queries on those databases. MySQL and PostgreSQL are two popular relational databases. A non-relational database can have many forms, as the data inserted in it doesn’t have to follow a particular schema. They are also called?NoSQL?databases.
A web stack has many layers, and we touched just the surface of it. When we type a URL in a browser, it takes only microseconds for all the agents we talked about to form a response and serve it to the client. Even knowing what is happening behind the curtain, it is still pretty magical to see it happening before our eyes.
There is much to say, but the time limit us. Let me conclude my article by showing you a diagram of what we talked about.
I hope you learned something. If you want to go more deep in this topics, links are provided as follows. Have a great day. Adios.