Frequently asked questions about the Saros project

This page lists common questions about Saros. If your question is not answered here you should look aroud the Support area. There you will find more information that may help you.

1. General

Why is the software called Saros?

A Saros cycle is an eclipse cycle, i.e. after one Saros cycle the Sun, Earth, and Moon return to approximately the same relative geometry. When creating the plug-in, Riad Djemili thought this would make a nice name for an Eclipse plug-in about Pair Programming, where driver and observer cycle their roles while revolving around code of interest.

How does Saros compare to screen sharing (e.g. VNC)?


  • Saros requires much less bandwidth (as it transfers only editing commands, not screen contents)
  • Each Saros participant can use a different screen resolution, different IDE-settings, keyboard layout -- and soon, even different IDEs.
  • Saros does not slavishly chain users together. For instance, Saros allows multiple participants to write to the same file in different spots at the same time. It also allows one participant to look something up (in the same or a different file) while another user is writing.
  • Saros scales to more than two participants naturally.


  • Saros does not support sharing information which occur outside of the IDE (so even all participants can run the application under development independently, they cannot see the others doing so).
  • Saros requires each participant to have an Eclipse installation setup.

How many users does Saros support?

Saros supports up to 5 users. However, this is not a hard limit. But the sixth and seventh and n-th user will get the same gray-ish color.

On which operating systems does Saros work?

In theory, the same version of Saros will run on any platform for which there is a version of Eclipse. We generally perform our testing on multiple flavours of Windows, Linux and Mac OS X.

I'm working with a version control system, can I use Saros?

SVN: Yes, you can. In theroy, there should be no problems since so called derived files are not shared by Saros. Usually, the corresponding Eclipse plugins (such as Subclipse) take care of setting the "derived" attribute for ".svn" directories (as well as Java ".class" files, which are also not synced).
If in doubt or if you don't use such plugins, you can always set this attribute on your own: Just right-click on the respective directory, select "Properties", and check the attribute "Derived".

Git: To make completely sure that Saros won't mess with your precious versioning data, you might consider a folder layout where your Eclipse project(s) reside on a level below the .git folder (see below). That's the way we organize our own source code (even though we do so for other reasons).
We're working on Saros's Git-friendliness so it also supports repositories adhering to the one-project-per-repository policy.

Risky Layout ("one project per repository") Safe layout ("multiple projects per repository")
my-project/    <-- you shouldn't share this one
  module-a/  <-- totally safe to share
  module-b/  <-- so is this one

2. Network Issues

How much bandwidth do you need to run Saros?

The real bandwidth problem is usually not during a Saros session, but rather with the project synchronization needed for starting one, which may take quite long (many minutes) for larger projects over a low-bandwidth connection. Make sure all participants have local copies of the project that are not too different before the session starts.

Does Saros work between two home users? Or through two firewalls?

Home users (using DSL) and most corporate networks employ NAT. Computers behind a NAT can open TCP connections to other computers, but other computers cannot open TCP connections to them.

So how can two Saros users that both sit behind a NAT create a joint Saros session?

  • Saros uses an XMPP server to get in contact with the other participant(s). Companies can run their own XMPP server for maximum privacy; home users can use almost any public XMPP server.
  • Thoughout the session (if possible) Saros uses Socks5 connections (direct or mediated) between the participants. Saros supports optional UPnP port forwarding to improve chances of direct connections. (see Saros network preferences)

How to use a Google account / Google Talk service with Saros?

We don't recommend to use you Google account for XMPP anymore, since Google has droped Google Talk XMPP support with the introduction of Google Hangouts.

3. Special use cases

Is Saros language dependent or which languages does Saros support?

No, Saros is not language-dependent as it works on a character-level. For a list of programming language plugins explicitly tested see: compatible plugins. If your favorite plugin is not supported, please let us know.

In case of problems see troubleshooting.