---
id: udp-sockets
title: UDP Sockets
sidebar_label: UDP sockets
---
## Consuming the module
### Communication Protocol
The client sends to the server a JSON file with the value of parameter `p` in the following format:
```json
{
"parameter" : [1.0, 2.3]
}
```
The server solves the optimization problem and returns a JSON file in the following format:
```json
{
"p" : [1.0, 2.3],
"u" : [1.1479546337, 1.2921200844, 1.6371973229, 2.6535245176],
"n" : 6,
"f" : -7.032997779803717,
"dt" : "422.958µs"
}
```
Here `p` is the parameter sent by the client, `u` is the solution, `n` is the number of iterations, `f` is the logarithm (base 10) of the fixed-point residual and `dt` is the elapsed time.
**NOTE:** Every time the solver is called, it is warm started with the previous solution.
### Errors
If the server receives a request it cannot process, it will return an error message. For example:
```json
{
"parameter": [1.0, 22.0, 33.0]
}
```
Will return:
```json
{
"error":"wrong param size (np=2, len(p)=3)"
}
```
### Killing the solver
To **kill** the process gracefully send the message `x`. The server will return to you the message:
```json
{
"msg":"Received quit command"
}
```
and will exit immediately.
### Linux command line
```bash
netcat -u 127.0.0.1 3248
```