> For the complete documentation index, see [llms.txt](https://docs.coherence.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coherence.io/0.8/simulators/client-vs-simulator-logic.md).

# Client vs. simulator logic

When scripting simulators, we need mechanisms to tell them apart.

### Am I a simulator ?

Ask `Coherence.SimulatorUtility.IsSimulator`.

```csharp
using Coherence;

if (SimulatorUtility.IsSimulator)
{
    // I'm a simulator!
}
```

There are two ways you can tell coherence if the game build should behave as a simulator:

* `COHERENCE_SIMULATOR` preprocessor define.
* `--coherence-simulation-server` command-line argument.

#### `Connect` and `ConnectionType`

The `Connect` method on `Coherence.Network` accepts a `ConnectionType` parameter.

```csharp
using Network = Coherence.Network;
using ConnectionType =Coherence.Connection.ConnectionType;

public class ConnectAsSimulator : MonoBehaviour
{
    void Start()
    {
        if (Network.Connect("127.0.0.1:32001", ConnectionType.Simulator))
        {
            // Connection successful
        }
        else 
        {
            // Connection failed
        }
    }
}
```

#### **COHERENCE\_SIMULATOR**

```csharp
#if COHERENCE_SIMULATOR

// simulator-specific code

#endif
```

Whenever the project compiles with the `COHERENCE_SIMULATOR` preprocessor define, coherence understands that the game will act as a simulator.

![The custom build pipeline lets us define preprocessor defines like COHERENCE\_SIMULATOR](https://3580906557-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FUrQ8GJkdHxImzMEWuxaz%2Fuploads%2Fgit-blob-20ac89cec8147ccb794bba5867df55b3da7d7d91%2Fimage.png?alt=media)

#### **Command-line argument**

Launching the game with `--coherence-simulation-server` will let coherence know that the loaded instance must act as a simulator.

{% hint style="info" %}
You can supply **additional parameters** to a simulator that define its area of responsibility, e.g. a sector/quadrant to simulate entities in and take authority over entities wandering into it.

You can also build a special simulator for AI, physics, etc.
{% endhint %}

### Server-side simulation

You can define who simulates the object in the **CoherenceSync** inspector.

![](https://3580906557-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FUrQ8GJkdHxImzMEWuxaz%2Fuploads%2Fgit-blob-3329b3dd8dac8269726a412ec504132aee23f74e%2Fsimtype.png?alt=media)

{% hint style="info" %}
Automatic simulator adoption of CoherenceSync objects is work in progress and will be available in one of the future releases of **coherence.**
{% endhint %}

### **Auto-reconnect**

The [sample UI](/0.8/api-reference/network-sdk/sample-ui.md) provided includes auto-reconnect behaviour out of the box for room and world based simulators. The root GameObject has AutoReconnect components attached to it.

![AutoReconnect in the sample UI](https://3580906557-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FUrQ8GJkdHxImzMEWuxaz%2Fuploads%2Fgit-blob-dc8cdb9a51598feaea277dda89541dcdb3fdc724%2Fautoreconnect.png?alt=media)

{% hint style="info" %}
Multi-room simulators have their own per-scene reconnect logic. The AutoReconnect components should not be enabled when working with multi-room simulators.
{% endhint %}

{% hint style="info" %}
If the simulator is invoked with the `--coherence-play-region` parameter, AutoReconnect will try to reconnect to the server located in that region.
{% endhint %}