ALP Server

This is the server for the ALP (Automated Liquidity Pool) system.

What is an ALP?

Providing liquidity for the Nu network is integral to the security of the $1 peg of NuBits. Liquidity ensures that consumers can always buy and sell NuBits at $1 on the supported exchanges. Providing this liquidity means that the liquidity provider (LP) is a 'Market Maker' which can leave them susceptible to and adversely affected by sharp swings in the market. The liquidity that it most at risk from this market risk is the funds directly supporting the peg (at just a bit more than and just a bit less than $1). We call this rank 1 liquidity. The ALP model allows Nu to compensate LPs for the risk of rank 1 funds and makes Liquidity provision a more attractive proposition.

How does the system work?

LPs run NuBot which places orders on their behalf at one of the exchanges that allows NuBit trading. NuBot implements a 'parametric order book' design meaning that only a small percentage of the funds is used to directly support the $1 peg (rank 1). The rest of the funds are placed in orders away from the peg which give it visible support but keep the funds at less risk of market movements (rank 2).
If an ALP has been enabled in NuBot it sends some data to the ALP server every 60 seconds. This data allows the ALP server to query the exchange API using the LPs exchange account and get a list of the orders that have been placed. This is done is such a way that the API secret key is never exposed to the ALP server so it is unable to carry out any other operations with the LPs exchange account.
The ALP server looks at each placed order and decides whether they are rank 1 or rank 2 orders. Once every minute the ALP server calculates the total amount of liquidity in rank 1 and 2 that has been provided by all connected LPs. It then calculates the percentage of that total that each LP has provided. That percentage is used to reward the LP from a static pot of funds provided by the Nu network.
The total reward each minute is fixed. It is decided by the ALP operators and voted into existence by NuShare holders using the Custodial Grant mechanism of the Nu network. The fixed reward means that LPs who provide a larger percentage of rank 1 liquidity will receive a higher reward but will be exposed to greater risk.

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ALP server details

The ALP server is inspired by the proof of concept TLLP server developed by creon. It is written in Python 2.7 using the Bottle framework.
It exposes several end points which can accept data from NuBot or any other ALP client. These will be described below along with the details of the data they require. All POST endpoints require the Content-Type header to be set to application/json

POST /register  
{  
    "user": "Exchange API public Key",  
    "address": "A valid NBT payout address",  
    "exchange": "A supported exchange",  
    "unit": "A supported currency code"  
}  

Allows a client to register a new user for the exchnage/unit combination supplied. The exchange API public key serves as a user identifier.

POST /liquidity
{
   "user": "The exchange API public Key used to 'register'",
   "req": "A dictionary containing the parameters required by the exchange API",
   "sign": "The result of signing req with the exchange API private key",
   "exchange": "The target exchange",
   "unit": The target currency" 
}

Allows a client to submit a signed 'get_orders' request to the server. The server will use that to collect orders on behalf of the specified user and add them to the pool to be credited.

The ALP server also exposes some endpoints that can be used for statistics collection or logging. These are as follows:

GET /exchanges

Shows an object containing the exchanges supported by this ALP and the parameters of each of them.

GET /status  

Shows a large data object containing lots of data about the performance of the pool and the distribution of liquidity on it. For more information and a break down of the data shown, see the Stats section.

GET /<user>/orders

Shows the orders on record for the given user. This includes details of any credits associated with the order.

GET /<user>/stats

Shows the statistics for the given user. This includes a history of the users net worth to allow for easier tracking of profit/loss.

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###Stats

###Requirements libffi-dev