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High Level Design

1. Create Tiny-Url Service​

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URL Generation Service (Handling Collisions)​

  1. One approach to generating short URLs is to create random strings and check for collisions. If a collision occurs, the system regenerates a new string. The drawback of this approach is that, in the worst case, the system may repeatedly encounter collisions, which can increase latency and make the system less efficient.

  2. Another method is to generate a unique string from the input using a hashing algorithm such as MD5. While this approach ensures uniqueness, the generated strings are typically long, whereas the goal of a URL shortener is to produce short URLs.

  3. A more reliable approach is to use incrementing counters. For example, the first request could receive tinyurl/0, the second tinyurl/1, and so on. This guarantees uniqueness. However, in a distributed system with multiple servers, the counters must remain synchronized across all servers.

    To solve this issue, a coordination service such as Zookeeper can be used.

    • Each server requests a range of counters from Zookeeper.
    • Zookeeper ensures that each server receives a non-overlapping counter range.
    • Example:
      • Server-1: [0, 1000] 
      • Server-2: [1001, 2000] 
      • Server-3: [2001, 3000]
    • This allows each server to generate unique short URLs independently within its assigned range.

    Another optimization involves improving the encoding scheme. Currently, if we use only digits [0–9], each position can represent 10 possibilities (Base10 encoding). Instead, we can use Base62 encoding, which includes [0–9 + A–Z + a–z].

    For a fixed code length of 2, Information Storing Capacity for :
    Base10 = 10 * 10 = 100 ways
    Base62 = 62 * 62 = 3844 ways

    Therefore, Base62 will store way more information than Base10

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2. Ascess Tiny-Url Service​

The resposne can be returned with either response-code: 301 or responsec-code: 302 signalling to re-direct to the url specified within the location header.

Status-CodeNameDescription
301Permanently Moved RedirectThe Browser cahces the response, and further calls will not go back to the tinyUrl server
302Temporarily Moved RedirectSubsequent calls will go to the tinyUrl server each time to retrieve longUrl

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For excalidraw file, click here to download