# Basic Concept

The **InteractionFree** protocol involves two main roles, the *Broker* and the *Workers*.
A network consists of one and only one *Broker*, and several *Workers*.
The *Broker* stands for a central coordinator that connects all the *Workers*, constructing a star-type network.
A *Worker* can have a unique name that can be addressed by other *Workers* (also called *Service*), or anonymous (also called *Client*).

Just like a normal server-client mode, the *Service* provides certain service, and the *Client* consumes the service.
The only difference is that the *Client* does not need to know the address of the *Service*, or access the *Service* directly.
They just need to know the *Broker* address and the unique name of the *Service*, and the *Broker* will take care of the rest.
A typical topological diagram is shown in the figure below.

```{image} _static/topological.svg
:width: 70%
:align: center
```

Here, the yellow circle presents the named *Worker* (*Service*), and the green circles present the anonymous *Workers* (*Clients*).

The major method of using this protocol is constructing an instance of `IFWorker`, connecting to the *Broker*, and then making designed function calls on the `IFWorker` object.

```{code-block} python
:lineno-start: 1

worker.ServiceName.functionName(args)
```

`worker` is the instance of `IFWorker`.
`ServiceName` is just like a member of `worker`, and `functionName` is just like a method of `worker.ServiceName`. 

For example, if a *Service* named `DragonCipher` provides a function `encrypt_to_dragon_speech`, the call would be like this:

```{code-block} python
:lineno-start: 1

worker.DragonCipher.encrypt_to_dragon_speech(humam_speech)
```

When any *Worker* makes the above invocation, it is actually the function in the *Service* `DragonCipher` that is executed.

There are also several functions provided by the `IFBroker` (actually by the `Manager` of the *Broker*).
Calling these functions is similar to calling the functions of a *Worker*, except that the `ServiceName` is emitted, as follows,

```{code-block} python
:lineno-start: 1

worker.functionName(args)
```

The functions available in the *Broker* are listed in the API documentation {py:class}`Manager <interactionfreepy.broker.Manager>`.
Please note that, when invoking the function of `Manager` through the protocol, the parameter `sourcePoint` will be automatically passed, you do not need to pass it manually.
The `Manager` can also be customized by the user.
See more detailed information in [Customizing the Manager](costomize-manager).