ejabberd Frequently Asked Questions (FAQ)
Why is there a commercial version of ejabberd?
The needs from corporations and large scale deployments are very different from the needs of smaller deployments and community.
While we put a huge development effort to have a product that are on the edge of innovation with ejabberd community version, we are requested to provide a stable version with long term commitment and high level of quality, testing, audit, etc.
Maintaining such a version in parallel of the community version, along with extremely strong commitment in term of availability and 24/7 support has a cost. With ejabberd business edition we commit on a level of scalability and optimize thew software until it is performing to the level agreed with the customer.
Covering all those costs, along with all our Research and Development cost on ejabberd community in general is the real reason we need a business edition.
The business edition is also a way for our customers to share the code between our customers only, thus retaining a huge competitive edge for a limited time (See next section).
So, even if you are not using our business edition, this is a great benefit for you as a user of the community edition. This version is a healthy contributors to ejabberd community edition and is the reason you have seen so much improvements since 2002. Thanks to our business edition customers, ejabberd project itself is a major contributor to Erlang and Elixir community.
Does ProcessOne voluntarily hold some code in ejabberd community to push toward the business edition?
No. We never do that and have no plan doing so with the code we produce and we own.
However, when the code is paid by customer, they retain the ownership of the code. Part of our agreement is that the code produced for them will be limited to a restricted user base, ejabberd business edition until an agreed time expires, generally between 6 months and 1 year.
This is extremely important for both the users of the commercial edition and the users of the community edition:
For the customers of the business edition, it means this is a way to ask for new developments and keep their business advantage. This is fair as they paid for the development.
This is a great incentive for our customers as they also benefit of the development of other customers (I guess they agree for the reciprocal sharing of their own code with customers).
This is fair for the community as the community edition users know they will benefit from new extremely advanced features in a not to long future. For example, websocket module was contributed to ejabberd community as part of this process.
This is the model we have found to be fair to our all user base and keep on producing an amazing code base that benefit to all our user base.
This dual model is the core strength of our approach and our secret sauce to make sure everyone benefits.
Is ejabberd the most scalable version?
Yes. Definitely. Despite claims that there is small change you can make to make it more scalable, we already performed the changes during the past year, that make those claims unfunded:
ejabberd reduced memory consumption in 2013 by switching to binary representation of string instead of list. This can reduce given string by 8.
We have improved the C code performance a lot, using new Erlang NIF. This provide better performance, removes bottleneck
We have different clustering mechanism available to make sure we can scale to large clusters
This is a common misconception, but our feedback for production service on various customer sites shows that ejabberd is the most scalable version. Once it is properly configured, optimized and tuned, you can handle tens of millions of users on ejabberd systems.
... And we are still improving :)
As a reference, you should read blog post: ejabberd Massive Scalability: 1 Node — 2+ Million Concurrent Users
What are the tips to optimize performance?
Optimisation of XMPP servers performance, including ejabberd, is highly dependant on the use case. You really need to find your bottleneck by monitoring the process queues and finding out what is your limiting factor, and move to the next one.
The first step is to make sure you run the latest ejabberd. Each new release comes with a bunch of optimisations and a specific bottleneck you are facing may have gone away in the latest version.
To give you an idea ejabberd 15.07 is 2 to 3 times more efficient in memory, latency and CPU compared to ejabberd 2.1.
You should also make sure that you are also using the latest Erlang version. Each release of Erlang comes with more optimisation regarding locks, especially on SMP server, and using the latest Erlang version can also help tremendously.
Is ejabberd conform to the best Erlang practices?
Yes. Our build system is primarily based on rebar. However, as we are multiplatform and need to run in many various environments, we rely on a toolchain that can detect required library dependencies using autotools.
This gives developers and admins the best of both worlds. A very flexible and very versatile build chain, that is very adequate to make sure ejabberd can be used in most operating systems and even integrated in Linux distributions.