# Overview

To have a better understanding of Libervia, this page gives a global view of what it is and what are the important concepts linked to it. You don’t need to read this to use it, but you can if you wish to understand “who is doing what”.

Libervia is a XMPP client. XMPP is an open standard used for communication (notably instant messaging but not only). XMPP is a solid standard, which is decentralised and federated.

Libervia is not only focusing on instant messaging, and aims to be a universal communication tools. In other words, you can use Libervia to chat, but also to blog publicly or privately, to share file, photo albums, to create events, to have discussion forum, etc.

Libervia is actually a whole ecosystem, and is made in a way that you can use it with many different interfaces (or “frontends”). There is a common central part which is called the “backend”, it handles most of the work, while frontends are mostly about the interactions with user(s).

To work, as Libervia is a XMPP client, a XMPP server is needed. You can either run your own, or use an existing one (either public, or run by an organisation you belong to, like family server, run by a friend, your company, university, association, etc.). If you want to run your own server, there are already plenty of them and happily most of which are libre, you can check an up-to-date list on the XSF website (the XSF or XMPP Standards Foundation being the non-profit organisation taking care of the XMPP standard).

So to summarise, Libervia is a communication ecosystem. Technically, it is a XMPP client which connect to an XMPP server. Libervia itself works with a backend and one or many frontends.

## Backend

The backend is a daemon, that means that it’s a service running in the background. It takes its main configuration from a file named `libervia.conf` and can be in different locations (see below). It uses data in a directory called `local_dir`, and which default, on suitable platforms, to the corresponding XDG directory, which is most of time `~/.local/share/libervia`. In this directory, you’ll find the main database in the `libervia.db` file, which is a SQLite database.

The backend is run and stopped with the `libervia-backend` executable. Running it without argument launch the backend in the background, with `libervia-backend fg` you run it in the foreground (you’ll see log directly and can stop the backend with `Ctrl + c`). The `libervia-backend status` commands help you discover if the backend is running or stopped.

## Frontends

Frontends are used to make the interface between user and the backend. Frontends are adapted to different use cases, and must be started after the backend (if the backend is not started, you’ll see a message telling you so). In most installations, the backend should be started automatically when you want to use a frontend.

Bellow you’ll see a list of the official frontends currently maintained:

### Libervia Deskop/Mobile (Cagou)

Libervia Desktop (alias `Libervia Mobile` or `Cagou`) is the desktop/mobile frontend. It’s probably the main interface for most users. It is based on the Kivy framework and should run on most platforms (for now it is officially tested only on GNU/Linux and Android phones and tablets).

### Libervia Web

The Web frontend is the second main interface for most users. This frontend has the particularity to be in 2 parts: a server which serves HTTP content, and a client which runs in the browser. So you have Libervia Web server which connect to Libervia backend which itself connect to the XMPP server, and your browser will connect to Libervia Web server.

The Libervia Web Pages are web pages managing a single feature. They can work without JavaScript when it’s possible (it’s not the case for instant messaging or similar highly dynamic contents). They aims to be simple and straightforward to use. That what you’re accessing when you’re using Libervia Web.

Libervia Web is also the central part of the Web Framework. Indeed, in addition of being a frontend to Libervia features (which is built with this framework), you can create totally different websites which are integrated in Libervia (and so XMPP) ecosystem. This framework uses Libervia template engine (based on Jinja2) and makes the creation of decentralised and federated websites simple. Thanks to this framework, it’s easy to experiment new ideas/features, or to change completely the look and feel of the Libervia frontend.

The official Libervia website is made with Libervia web framework.

### Libervia TUI (Primitivus)

Libervia TUI (alias `Primitivus`) is the Terminal User Interface. In other words, it works in console and is intended for people at ease with it. Its text only interface has several advantages: you get rid of many distracting things (like images), it works without graphical environment installed (which is often the case on servers) and it works on distant shell (like ssh) while staying gentle with your bandwidth.

Primitivus is shipped with the backend, so it should be always available once Libervia is installed (but some distributions may provide it separately).

You can check Libervia TUI documentation for more details.

### Libervia CLI (jp)

Libervia CLI (alias `li` or `jp`) is the Command Line Interface. It’s a powerful tool which allows to do nearly everything you can do with other frontends. Particularly useful if you want to check something quickly, or if you want to do some automation.

You can check Libervia CLI documentation documentation for more details.

## Glossary

While using Libervia you may see some terms or concept. This section explain the most important ones.

### profile

A profile is the name linked to an account data. Usually a profile correspond to an XMPP account, but you can have several profiles using the same XMPP account (with different parameters) even if this is not usual.

On a Libervia installation used by a single user, the profiles are usually used for multiple accounts. On a multi-users installations, there is usually one profile per user.

When you connect to a Libervia frontend, you need to specify a profile and the associated password. The profile password is not the same as the password of the XMPP account. While this may sounds confusing, there are several reason why we use this notion of profile instead of directly the XMPP account/password:

- Libervia needs to know the plain XMPP password to connect, and it is encrypted in database. The profile password is used to encrypt/decrypt it, this way only a password hash is stored and the XMPP password is encrypted at rest.

- As a further benefit, several passwords could be associated to the same profile (this feature is currently not used in Libervia).

- profile password can be empty, in which case no password is requested when a profile is used

Note

if you use an empty profile password, the XMPP password won’t be encrypted in database (or more precisely, will be trivial to decrypt).

- a profile is a simple name associated with an account, it’s easier to remember than a whole XMPP identifier (also named “JID” for Jabber ID)

You always have a default profile which is the profile used when you don’t select any (notably used in jp). This is the first profile that you have created except if you have changed it using a frontend (you can change it with jp).

### profile key

A profile key is a special name used as a way to select automatically one profile. The most important one is `@DEFAULT@` which, as you can guess, means the default profile.

### bridge

The “bridge” is the name used to design Libervia’s IPC, or in other words the way the backend communicate with frontends. Several bridges can be used, the default one being D-Bus.

The other available bridges are:

pb

  Perspective Broker is a part of Twisted (the framework used by the backend and some frontends)

embedded

  this embeds the backend into the frontend. The frontend is then using the backend as a library.

### Libervia Media

Most of the frontends use images or other media. To avoid duplication and to make the code repositories lighter, those media are grouped in a separate repository. The Libervia media repository is available at https://repos.goffi.org/sat_media. You can also download media at https://ftp.goffi.org/sat_media/sat_media.tar.bz2. The path where Libervia media are installed must be specified in `libervia.conf` in `media_dir` option of the `[DEFAULT` section.

### Libervia Templates

Libervia embeds a Jinja2 template engine (see Libervia Web above). “Libervia templates” refers to the default templates (i.e. the official templates, the ones used in default Libervia pages). Those template may also be used by other frontends than Libervia (jp can use them with the output arguments).

Libervia templates repository is available at https://repos.goffi.org/sat_templates, they can also be downloaded at PyPI and will be installed automatically if you install Libervia.

## Related projects

Some project are closely related to Libervia, here is a list of official related project.

### Libervia PubSub

Numerous features of Libervia are taking profit of PubSub functionalities of XMPP. Because PubSub implementations in the wild are not all on the same level, and some experimental features are sometimes explored, a PubSub service as been written specifically for the needs of Libervia (but it’s not depending on Libervia and any XMPP software can use it).

Libervia PubSub aims to be a feature complete, server-independent PubSub implementation, and try to be up-to-date with latest XMPP PubSub extensions. It is the privileged service to use with Libervia because it supports everything needed (but Libervia can work with any XMPP PubSub service, it will adapt itself to available features).

Libervia PubSub can also be used as a PEP service, if some XMPP extensions are supported by your server (see below).

### XMPP Extension Protocols

For the needs of Libervia or Libervia PubSub, some XMPP Extension Protocols (or XEP) have been proposed and got an official number. The current list of extensions is:

XEP-0355: Namespace Delegation

  This has been proposed for the needs of Libervia PubSub, and allows the XMPP server to “delegate” some features management to a third party service. It is needed to use Libervia Pubsub as a PEP service.

XEP-0356: Privileged Entity

  In the same spirit as previous one, this has been done so Libervia PubSub could be used as a PEP service. This extensions allows a “component” (which is more or less a server generic plugin) to gain some privileged access to data such as presence information, roster or to send a message like if it was sent by the server.

XEP-0413: Order-By

  This extension is used to specify the sorting order in which a client wishes to retrieve some results. It is notably used by Libervia and Libervia PubSub to retrieve items like blog posts or tickets in creation order or order of last modification.

### Prosody’s mod_delegation and mod_privilege

Prosody modules have been created to implement the Namespace Delegation and Privileged Entity extensions mentioned above. If you use Prosody, you’ll have to activate those 2 modules to use Libervia PubSub as a PEP service.

### Libervia official website

The official website is made with Libervia web framework. You’ll find it at https://repos.goffi.org/sat_web_site

### Salut

Probably the smaller side project used by Libervia, it is a simple users directory (registration must be done explicitly by users) using XEP-0055 (Jabber Search).

You’ll find it at https://repos.goffi.org/salut/