Websocket link for Blockfrost API

Build a Websocket link for Blockfrost API standard to enable developers to better optimize their applications.

We are the creators of Blockfrost.io, creating services and tools lowering barriers to entry for developers.

## What is Blockfrost.io?
Blockfrost.io is an instant, public and freely accessible API that removes the obstacles for developers so that everyone can start building (d)apps on Cardano.

At the moment, we have more than 600 developers onboarded in Blockfrost!

## What are WebSockets?
Typically, HTTP requests are short-lived. Usually, when your application requires a remote API, a socket connection opened from your application sends an HTTP request to the API endpoint you want to reach. The API sends a response, and the socket connection is closed.

WebSockets allow you to keep your socket connection open. On the WebSocket, the API can send new information to the application as well as the other way around (full-duplex).

The support for WebSockets is missing in most of the Cardano ecosystem APIs. We only know of the Ogmios project that does provide this support, but it is communicating with Cardano-node protocols. However, WebSocket are crucial for the unhindered scaling of classic web applications that use Cardano as a backend.

## Roadmap, deliverables and performance
The bridge itself will connect to the Blockfrost API on the backend and provide a new API endpoint with WebSockets support.
We plan to deliver the first stable version of the bridge no later than 3 months since the funding. We define success as having at least one major (100+ users) implementation of this bridge by half a year after the funding. Long term success is if the project is maintained and used after 12 months after the funding.

The first version will mainly target lightweight wallet-like application that requires constant monitoring of the Cardano network, for example for incoming transactions or fees changes to a staking pool. Application using Cardano as a backend will be able subscribe to several classes of hooks, that will provide at least the following:

• Subscription to the block and its associated addresses, making it possible for the application to trigger an account refresh if a new tx affecting the wallet comes in
• Subscription to the specific address
• Subscription to the specific account
• Subscription to a specific UTXO
• Lightweight fees estimates

We will also provide a handy UI as a demo application.

## Relevant experience

Five Binaries is an infrastructure development company. We're Cardano pioneers - with the first Cardano block minted on an aeroplane, first stake pool on the ITN and the first Shelley transaction on the mainnet.

We are the creators of Blockfrost.io. We have also experience with deploying Yoroi backend and contributed several changes to the backend itself too.

We are also the winner of several proposals in Fund 3, such as Go serialization library for Cardano or Cardano Metadata Oracles.

We are trusted by customers such as Emurgo, Trezor or Cardano Foundation. To get in touch or find more information about us, please visit https://fivebinaries.com/.

## Budget
We estimate it will take us 150 engineering-hours to complete the deliverables and maintain this project for the duration of this year.

Our standard rate, which comprises of our engineers' salaries, infrastructure costs, office rent, accounting and taxes is 100 EUR per hour.

We pay our people well because they are both skilled and exceptionally experienced in the industry. And last but not least, because we respect them and want them to feel good and appreciated while working on Cardano.

## License
The entire outcome of this project will be open sourced under Apache License 2.0.