# Servers without System One

ThinkThen speaks one wire shape, System One. A server with another shape needs a small server in front of it that speaks System One.

## What the server must do

- Accept `POST BASE/systemone` with a JSON body.
- Read the body below: the text in `state`, the model in `model`, and named questions in `questions`.
- Answer every question by its name, with a probability for yes, or one probability for each option or level it was sent.
- Name the model that answered.
- Report the tokens it used under `usage`. Without them, `check` warns and the usage totals leave them out.
- Serve `https`, or plain `http` on this machine only.
- Take a bearer key, or no key on this machine.

*The plan prints the exact body a server receives at BASE/systemone.*

```
question="Does the customer ask for a refund?"

printf '%s\n' "I want to send this back." |
thinkthen decide "$question" \
  --url http://localhost:8080/v1 \
  --plan |
head -1 |
jq .request
```

*Output*

```
{
  "state": "Each question quotes the text it asks about.",
  "model": "jev-1.13.0",
  "questions": {
    "q1": {
      "type": "noul",
      "instructions": "The text is \"I want to send this back.\\n\". Does the customer ask for a refund?"
    }
  }
}
```

*exit 0*

The [backends specification](https://github.com/botassembly/thinkthen/blob/main/specification/backends.md) gives every field of the request and the reply.

## Test that server

Point `thinkthen check` at that server. When no row is critical, every ThinkThen command works through it. The [System One page](/install/backends/system-one/) shows the check.

[All backends](/install/backends/) · [Any System One server](/install/backends/system-one/)

On GitHub: [github.com/botassembly/thinkthen](https://github.com/botassembly/thinkthen)