# Subsystems

This documentation refers to individual [protocol](../Network/Protocol.md) features,
it links to the implementation and technical documentation for each subsystem.

Most modules are optional, see [security considerations](../Usage/Security.md).

## Concepts

* Client Module: feature implementation loaded by the client, it interfaces with the corresponding "Client Connection Module" on the server side
* Client Connection Module: for each connection to a client, the server will instantiate a handler
* Server Module: feature implemented by the server, it may interact with multiple "Client Connection Modules"


| Subsystem                         | [Client Module](https://github.com/Xpra-org/xpra/blob/master/xpra/client/mixins/)                | [Server Module](https://github.com/Xpra-org/xpra/blob/master/xpra/server/mixins)           | [Client Connection Module](https://github.com/Xpra-org/xpra/blob/master/xpra/server/source/)    | User Documentation                                    |
|-----------------------------------|--------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------|-------------------------------------------------------|
| [Audio](Audio.md)                 | [audio](https://github.com/Xpra-org/xpra/blob/master/xpra/client/mixins/audio.py)                | [audio](https://github.com/Xpra-org/xpra/blob/master/xpra/server/mixins/audio.py)          | [audio](https://github.com/Xpra-org/xpra/blob/master/xpra/server/source/audio.py)               | [audio feature](../Features/Audio.md)                 |
| [Clipboard](Clipboard.md)         | [clipboard](https://github.com/Xpra-org/xpra/blob/master/xpra/client/mixins/clipboard.py)        | [clipboard](https://github.com/Xpra-org/xpra/blob/master/xpra/server/mixins/clipboard.py)  | [clipboard](https://github.com/Xpra-org/xpra/blob/master/xpra/server/source/clipboard.py)       | [clipboard feature](../Features/Clipboard.md)         |
| [MMAP](MMAP.md)                   | [mmap](https://github.com/Xpra-org/xpra/blob/master/xpra/client/mixins/mmap.py)                  | [mmap](https://github.com/Xpra-org/xpra/blob/master/xpra/server/mixins/mmap.py)            | [mmap](https://github.com/Xpra-org/xpra/blob/master/xpra/server/source/mmap.py)                 | enabled automatically                                 |
| [Logging](Logging.md)             | [remote-logging](https://github.com/Xpra-org/xpra/blob/master/xpra/client/mixins/logging.py)     | [logging](https://github.com/Xpra-org/xpra/blob/master/xpra/server/mixins/logging.py)      | none                                                                                            | [logging usage](../Usage/Logging.md)                  |
| [Notifications](Notifications.md) | [notifications](https://github.com/Xpra-org/xpra/blob/master/xpra/client/mixins/notification.py) | [logging](https://github.com/Xpra-org/xpra/blob/master/xpra/server/mixins/notification.py) | [notification](https://github.com/Xpra-org/xpra/blob/master/xpra/server/source/notification.py) | [notifications feature](../Features/Notifications.md) |
