# Any System One server

ThinkThen posts every question to `BASE/systemone`. Any server that answers there in the System One shape can be a backend.

## By address

Set `THINKTHEN_BASE_URL` to the server's base, or pass `--url` on one command. The key comes from `THINKTHEN_API_KEY`. The model is the default unless you pass `--model`.

*THINKTHEN_BASE_URL names the server. The address came from the environment, and the key will come from THINKTHEN_API_KEY.*

```
export THINKTHEN_BASE_URL=http://localhost:8080/v1

thinkthen status --json |
jq '.backend | {url, url_source, key_variable}'
```

*Output*

```
{
  "url": "http://localhost:8080/v1/systemone",
  "url_source": "environment",
  "key_variable": "THINKTHEN_API_KEY"
}
```

*exit 0*

## By name

The configuration file can name a server under `backends`. An entry gives the server's `url`, the name of the variable that holds its key in `key_env`, and its `model`. The file never holds the key itself. Then `--backend NAME` or `THINKTHEN_BACKEND` picks the entry, and `backend` in the file makes it the default.

*config/thinkthen/config.json, the configuration file*

```
{
  "schema": "thinkthen.config/1",
  "backends": {
    "local-d1": {
      "url": "http://127.0.0.1:8080/v1",
      "key_env": "LOCAL_D1_KEY",
      "model": "d1:free",
      "requests_per_minute": 120
    }
  }
}
```

*The entry local-d1 brings its own address, model, and key variable.*

```
export XDG_CONFIG_HOME="$PWD/config"

thinkthen status --backend local-d1 --json |
jq '.backend | {name, url, model, key_variable}'
```

*Output*

```
{
  "name": "local-d1",
  "url": "http://127.0.0.1:8080/v1/systemone",
  "model": "d1:free",
  "key_variable": "LOCAL_D1_KEY"
}
```

*exit 0*

A name uses 1 to 32 lowercase letters, digits, and hyphens, and may not reuse a built-in name. The [Configuration page](/install/configuration/) says where the file lives.

## Pace the requests

ThinkThen sets no pace of its own. `requests_per_minute` on an entry caps how many requests one process starts each minute, retries included. It takes a whole number from 1 to 60,000. A built-in's name may appear under `backends` with a rate and nothing else. `THINKTHEN_REQUESTS_PER_MINUTE` outranks the file. The limit holds within one process. [Requests a minute](/install/settings/#requests-a-minute) gives the rule.

*bad/thinkthen/config.json, a rate out of range*

```
{
  "schema": "thinkthen.config/1",
  "backends": {
    "typesafe": {"requests_per_minute": 0}
  }
}
```

*A rate of 0 is out of range. The command names the field, exits 5, and sends nothing.*

```
export XDG_CONFIG_HOME="$PWD/bad"

thinkthen status
```

*Output*

```
thinkthen: configuration backend field requests_per_minute must be a whole number from 1 to 60000
```

*exit 5*

## Check the server

`thinkthen check --url BASE` sends four fixed questions that cover every question shape ThinkThen asks. It prints one row each for the connection, the key, the endpoint, the four questions, and the usage counts. A row reads `ok`, `warning` or `critical`. It exits 0 only when no row is critical. Every request is real, so a hosted server may charge for it. The [check reference](/reference/check/) explains every row.

*The check would post its four fixed questions to the server's systemone address.*

```
thinkthen check \
  --url http://localhost:8080/v1 \
  --plan |
head -n 4
```

*Output*

```
url http://localhost:8080/v1/systemone
provider systemone
model asked unspecified
model sent jev-1.13.0
```

*exit 0*

A threshold tuned on one model does not carry to another. Grade the new model on your own labeled records with [audit](/trust/) before you trust it.

## From your language

Each page shows how its language names a backend.

- [Bash](/install/shell/#backends)
- [Python](/install/python/#backends)
- [TypeScript](/install/typescript/#backends)
- [Ruby](/install/ruby/#backends)
- [R](/install/r/#backends)
- [Rust](/install/rust/#backends)
- [C](/install/c/#backends)
- [C++](/install/cpp/#backends)
- [Objective-C](/install/objective-c/#backends)
- [COBOL](/install/cobol/#backends)
- [Ada](/install/ada/#backends)
- [Java](/install/java/#backends)
- [Kotlin](/install/kotlin/#backends)
- [Scala](/install/scala/#backends)
- [C#](/install/csharp/#backends)
- [Go](/install/go/#backends)
- [Swift](/install/swift/#backends)
- [Zig](/install/zig/#backends)
- [PHP](/install/php/#backends)
- [Dart](/install/dart/#backends)

[All backends](/install/backends/) · [Servers without System One](/install/backends/other-servers/) · [Bring your own backend](/learn/beatles-bench/backends/)

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