designing a url shortening service like tinyurl

Then we check that string in DB to see if it has been already taken or not. We first do an MD5 of a given long URL then we take the first 42 bits to create the 7 bases 64 characters string. Two long URLs can result in an MD5 that has the same first 42 bits. H ow to prevent collisionĪs you can see that the biggest issue with the MD5 approach is a collision. We can also take the first 48 bits to represent it as 8 base64 characters. Each character in base64 takes 6 bits that is why 6*7=42 bits overall.

We can take the first 42 bits to represent it as 7 base64 characters. The MD5 string is of 128-bit fixed length. We will have an MD5 function that will return a unique string for a given long URL. There are three solutions to design a unique short character for a given long URL Before looking at the solution let’s look at some of the encoding schemes that can be used to produce a short URL string Encoding Schemes One of the most important parts of implementing a short URL service is to generate a short URL string. This is the standard way of redirection as specified by the HTTP protocol The browser will then redirect to the long URL. The Location response header will contain the long or original URL.

If present then it will issue an HTTP 302 redirect to the browser.

If not present it will respond with 404 Resource Not Found back to the browser.

How Short URL will redirect to the Long URLĪs soon as our service will receive the short URL it will fetch the corresponding long or original URL for that short URL.

List Short URL – See all Short URLs for a particular user.

GET URL – This API will redirect to the long URL given a short URL.

Delete Short URL – This API will be used to delete a short URL that was created earlier.

Create short URL – This API will create a short URL given a long URL.

API Detailsīelow will be the API that will be needed in the system Here is one example of a short URL that has 7 characters as part of the short string.

It should only have characters that are URL safe.

What a short URL should look like? Before we look at the requirements, let’s look at a sample example URL.

There should be no single point of failure.

What it means is that once a short URL is generated for a given long URL then the system should be able to return that long URL given the short URL in the next immediate call.

The system should be strongly consistent.

Here are some of the non-functional requirements

We are also going to consider the case where a short URL never expires later in this tutorial.

After that, the shortened URL will expire

There should be an expiration time with each of the URLs.

Once the shortened URL is clicked it should be able to redirect the user to the actual URL.

You should be able to generate the short URL of fixed length irrespective of the length of the input URL.

Let’s note down the functional requirement of the system

It will always be of fixed length irrespective of the length of the input URL. Notice the second part of the URL in bit.ly. The short URL will not be dependent upon the length of the actual URL. The URL shortening service is used to shorten a long URL. Is not KGS service a single point of failure?.What happens if the key ranges are getting exhausted.How Short URL will redirect to the Long URL.

Designing a url shortening service like tinyurl