# Tinder

## Func req

1. Store profiles (with images)
2. Recommend matches
3. Note when you find match
4. Direct messaging

## NFR

5 images per profile 

active users (and 0.1% of them are matching)

## Trade offs

### How to store images

#### Blob in DB

BLOB (Binary Large OBject) is a <mark style="background-color:orange;">data type used to store large binary data, such as images, audio files, video files,</mark> documents (e.g., PDF, Word), and other types of binary data.

:thumbsup:Transaction guaranties (but we will not be doing changes to the image :x:)

:thumbsup:indexes (search) but we will not search by photo :x:

:thumbsup:action control (but file system will also provide it)

#### Store on file system

:thumbsup:cheaper

:thumbsup:faster

:thumbsup:we can use CDN on top of it

:thumbsup:we can store in DB following info (profile ID, image ID, File URL)

## Specific technologies

### XMPP protocol (7 layer)

* XMPP protocol for sending messages. Bsed on XML
* It supports various message types, including text, multimedia, and structured data.&#x20;
* Shares online/offline status of user.&#x20;
* Can support file transfer, group chat, voice and video calls, IoT communication via extensions.&#x20;
* Decentralized protocol.
* Supports TLS. Works on TCP (somehow WebSocket is onvolved)
* Users can subscribe to receive updates about the presence status of other users

<figure><img src="/files/wGxu2FymIKa6KwoPx4I2" alt=""><figcaption></figcaption></figure>


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