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FAQ
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General
What is Matrix?
Matrix is an ambitious new open standard for open, distributed, real-time communication over IP. It defines interoperable Instant Messaging and VoIP, providing pragmatic HTTP APIs and open source reference implementations for creating and running your own real-time communication infrastructure.
What is Matrix's Mission?
Matrix.org's initial inspiration and goal has been to fix the problem of fragmented IP communications. But Matrix's real potential and ultimate mission is to be a generic messaging and data synchronisation system for the web - allowing people, services and devices to easily communicate with each other with full history.
What does Matrix provide?
Today Matrix provides a new open standard, APIs to integrate a service to the Matrix ecosystem and reference open source implementations of the standard.
What does this mean for users?
The aim is to provide an analogous ecosystem to email - one where you can communicate with pretty much anyone, without caring what app or server they are using, using whichever app & server you chose to use, and a nice neutral identity system like an e-mail address or phone number to discover people to talk to.
What kind of company is Matrix.org?
Matrix is an open initiative which acts as a neutral custodian of the Matrix standard. It's not actually incorporated anywhere at the moment but we are looking at the best legal structure for the future. We are committed to keeping the Matrix project open.
Who is funding Matrix.org?
We have been given permission by our employers, Amdocs, to work on Matrix as an independent non-profit initiative.
Who is building Matrix?
We're a team of ~10 people with decades of experience building custom VoIP and Messaging apps for mobile network operators. Most of us have day jobs at Amdocs or OpenMarket, but we are supported by a mix of freelancers and volunteers.
Why are you called Matrix?
We are called Matrix because we provide a structure in which all communication can be matrixed together.
Why have you released this as open source?
We believe that any open standard defining interoperable communication needs to be justified, demonstrated and validated with transparent open source implementations. For Matrix to achieve its mission of making all communications services interoperable we believe it needs to be truly open, giving people access to take all the code we produce and to use and build on top of it.
What do you mean by open?
Matrix is an open standard, meaning that we have freely published the details for how to interface with Matrix compliant servers and clients, and encourage anyone and everyone to interface with them. We also ensure the standard is not encumbered by any known patent licensing requirements.
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Matrix is also open source, meaning that we have released the source code of the reference servers and clients to the public domain under the Apache Licence v2, to encourage anyone and everyone to run their own servers and clients, and enhance them and contribute their enhancements as they see fit.
What does federated mean?
Federation allows separate deployments of a communication service to communicate with each other - for instance a mail server run by Google federates with a mail server run by Microsoft when you send email from @gmail.com to @outlook.com.
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Federation is different to interoperability, as interoperable clients may simply be running on the same deployment - whereas in federation the deployments themselves are exchanging data in a compatible manner.
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Matrix provides open federation - meaning that anyone on the internet can join into the Matrix ecosystem by deploying their own server.
How is this like e-mail?
When email was first set up in the early ‘80s, companies like Compuserve and AT&T and Sprint set up isolated email communities which only allowed you to exchange mail with users on the same system. If you got your email from one service and your friend from another, then you couldn't message each other. This is basically the situation we're in today with VoIP and IM.
Why has no-one done this before?
There have been several attempts before including SIP, XMPP and RCS. All of these have had some level of success, but technological/usability/economic factors have ended up limiting their success in providing true open federation.
What is the difference between Matrix and IRC?
We love IRC. In fact, as of today the core Matrix team still uses it as our primary communication tool. Between us we've written IRCds, IRC bots and admined dreamforge, UnrealIRCd, epona, ircservices and several others. That said, it has some limitations that Matrix seeks to improve on:
- Text only
- No history
- No multiple-device support
- No presence support
- Fragmented identity model
- No open federation
- No standard APIs, just an archaic TCP line protocol
- Non-standardised federation protocol
- No built-in end-to-end encryption
- Disruptive net-splits
- Non-extensible
What is the difference between Matrix and XMPP?
The Matrix team used XMPP (Openfire, ejabberd, spectrum, asmack, XMPPFramework) for IM before starting to experiment with open HTTP APIs as an alternative. The main issues with XMPP that drove us in this direction were:
- Not particularly web-friendly - you can't easily speak XMPP from a web browser. (N.B. Nowadays you have options like XMPP-FTW and Stanza.io that help loads with letting browsers talk XMPP).
- Single logical server per MUC is a single point of control and availability. (MUCs can be distributed over multiple physical servers, but they still sit behind a single logical JID and domain. FMUC improves this with a similar approach to Matrix, but at time of writing there are no open implementations.)
- History synchronisation is very much a second class citizen feature
- Stanzas aren't framed or reliably delivered without extensions. (See wiki.xmpp.org for an XMPP take on this)
- Multiple device support is limited. (Apparently Carbons and MAM help with this)
- Baseline feature set is so minimal that fragmentation of features between clients and servers is common
- No strong identity system (i.e. no standard E2E PKI, unless you count X.509 certs, which are questionable)
- Not particularly well designed for mobile use cases: push; bandwidth-efficient transports. (Since the time of writing a Push XEP has appeared, and wiki.xmpp.org claims that XMPP runs fine over a 9600bps + 30s latency link.)
The whole subject of XMPP vs Matrix seems to bring out the worst in people. We think of the standards as being quite different; at its core Matrix can be thought of as an eventually consistent global JSON db with an HTTP API and pubsub semantics - whilst XMPP can be thought of as a message passing protocol. You can use them both to build chat systems; you can use them both to build pubsub systems; each comes with different tradeoffs. Matrix has a 'kitchen sink' baseline of functionality; XMPP has a deliberately minimal baseline set of functionality. If XMPP does what you need it to do, then we're genuinely happy for you :) Meanwhile, rather than competing, an XMPP Bridge like Skaverat's xmpptrix beta has potential to let both environments coexist and make the most of each other's benefits.
What is the difference between Matrix and PSYC?
PSYC is a open federated messaging protocol loosely inspired by IRC. In version 1 it was a standalone protocol, and in version 2 it is being reutilised as the messaging layer on top of GNUnet. We honestly don't know that much about it, beyond trying to use psycd as an XMPP<->IRC bridge in 2010. Matrix differentiates primarily by providing simple HTTP APIs rather than the more exotic compact line protocol in PSYC v1 or the complicated GNUnet stack in v2. Meanwhile, Matrix doesn't provide of the metadata protection guarantees that GNUnet/PSYC aims for.
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See http://about.psyc.eu/Matrix for PSYC's views on Matrix.
What is the difference between Matrix and Tox?
Tox.im looks to be a very cool clone of Skype - a fully decentralised peer-to-peer network. Matrix is deliberately not peer-to-peer; instead each user has a well-defined homeserver which stores his data and that he can depend upon. Matrix provides HTTP APIs; Tox.im provides C APIs. We haven't actually played with Tox at all yet.
How does Matrix compare with something like Trillian or Pidgin?
Trillian and Pidgin and similar aggregating IM clients merge all your IM activity into a single user experience. However, your history and identity is still fragmented across the networks. People can't find you easily, and your history is fragmented (other than on the device where the client runs). And rather than being able to chose the right app for the job when communicating with people, you are pushed towards relying on a specific aggregation app.
What Matrix compliant apps are there?
None yet, other than our examples. It's early days :)
Why do you think existing apps will ever join this?
We firmly believe it is what is right for the consumer. As people begin to use interoperable communications tools service providers will see the benefit and compete on quality of service, security and features rather than relying on locking people into their walled garden. We believe as soon as users see the availability and benefits of interoperable services they will demand it.
Why aren't you doing this through the IETF? or W3C? or 3GPP?
We do recognise the advantages of working with existing standards bodies. We have been focused on writing code and getting it out. As Matrix matures it may well be appropriate to work with an official standard body.
Quick Start
How do I get an account and get started?
The quickest way is to just jump to the demo webclient at http://matrix.org/beta and sign up. Please note that you can point the webclient to access any homeserver - you don't have to use matrix.org, although as of day 1, matrix.org is the only communal homeserver available.
What can I actually do with this?
The demo webclient provides a simple chatroom interface to Matrix - letting the user interact with users and rooms anywhere within the Matrix federation. Text and image messages are supported, and basic voice-only VoIP calling via WebRTC is supported in one-to-one rooms.
How do I connect my homeserver to the public Matrix network?
See http://github.com/matrix-org/synapse for details
How do I Matrix-enable my existing app?
See the Client-Server API HOWTO for an example of how to use Matrix's client-server API to let your app communicate with users via Matrix. We're currently working out the best way to integrate your application's existing identity system with Matrix.
How can I write a client on Matrix?
See the Client-Server API HOWTO and the API docs and the Spec for all the details you need to write a client.
How can I help out with this?
Install synapse and tell us how you get on. Critique the spec. Write clients. Just come say hi on #matrix:matrix.org or the mailing lists!
Where can I get support?
#matrix:matrix.org, #matrix on irc.freenode.net or the mailing lists are your best bets.
How do I register custom matrix event types?
We're not yet managing a registry of custom matrix event types. If you have any particularly good ones you want to tell the world about, please use the mailing list for now.
How mature is this?
We started working on Matrix in July 2014, and have opened it to the public in September 2014. It's early days, and under no circumstances should you use Matrix or Synapse for anything other than experimentation and learning at this point. Obviously the spec and apps are maturing rapidly, but as of the time of writing APIs are not frozen and the apps are very much a work in progress.
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Sorry, the FAQ is still work in progress, the rest of it will up soon! In the mean time, don't hesitate to get in touch on #matrix:matrix.org or the mailing lists!
Standard
What is a home server?
Users in Matrix use one or more clients to communicate. This could be a web client, a command line client, a mobile client - or multiple of these being used simultaneously by the same user. The clients are registered to a single homeserver, which stores the communication history and account information, and shares data with the wider Matrix ecosystem by synchronising communication history with other homeservers.
What is an identity server?
Users in Matrix are identified via their matrix user ID (MXID). However, existing 3rd party ID namespaces can also be used in order to identify Matrix users. A Matrix "Identity" describes both the user ID and any other existing IDs from third party namespaces linked to their account.
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Matrix users can link third-party IDs (3PIDs) such as email addresses, social network accounts and phone numbers to their user ID. Linking 3PIDs creates a mapping from a 3PID to a user ID. This mapping can then be used by Matrix users in order to discover the MXIDs of their contacts.
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In order to ensure that the mapping from 3PID to user ID is genuine, a globally federated cluster of trusted "Identity Servers" (IS) are used to verify the 3PID and persist and replicate the mappings. Usage of an IS is not required in order for a client application to be part of the Matrix ecosystem. However, without one clients will not be able to look up user IDs using 3PIDs.
Where do my conversations get stored?
Each homeserver stores the communication history and account information for all of its clients, and shares data with the wider Matrix ecosystem by synchronising communication history with other homeservers and their clients. Clients typically communicate with each other by emitting events in the context of a virtual room. Room data is replicated across all of the homeservers whose users are participating in a given room.
What is a 3PID?
Third-party IDs (3PIDs) are IDs from other systems or contexts, such as email addresses, social network accounts and phone numbers.
How do you do VoIP calls on Matrix?
Voice (and video) over Matrix is built on the WebRTC 1.0 standard. Call events are sent to a room, like any other event. This means that clients must only send call events to rooms with exactly two participants as currently the WebRTC standard is based around two-party communication. Group calls are on the to-do list, though!
Can I log into other homeservers with my username and password?
Currently, no. We are looking at options for enabling multi-server access for users, and might add this feature at a later stage.
Why Apache Licence?
The Apache Licence is a permissive licence. We want the Matrix protocol itself to be free and open, but people are free to create both free and commercial apps and services that uses the protocol. In our opinion, any Matrix-service only enhances the Matrix ecosystem.
Can I write a Matrix homeserver?
Yes. Matrix is just a spec, so implementations of the spec are very welcome! It should be noted that at the moment, changes are still being made to the spec, so if you want to write a Matrix homeserver, it is strongly recommended that you chat to the Matrix.org devs in #matrix:matrix.org first! You can also read about the Federation API here.
How secure is this?
Server-server traffic is mandatorily TLS from the outset. Server-client traffic mandates transport layer encryption other than for tinkering. Clients that support PKI publish their public keys, and may encrypt and sign their messages for E2E security. "Well behaved" clients should participate in key escrow servers to allow private key submission for law enforcement. End-to-end encryption for group chat is supported through a per-room encryption key which is shared 1:1 between participating members.
Why aren't you using an ORM layer like SqlAlchemy?
APIs
How do I join the global Matrix federation?
You can download and run one of the available Matrix servers - please see this guide for details!
What ports do I have to open up to join the global Matrix federation?
That is up to you! Look at "Setting up Federation" in the Synapse readme file for details.
Reference Implementations
What is Matrix built on - and why?
How do I run my own homeserver?
Follow the instructions for the homeserver you want to run. If you want to run Synapse, the homeserver created by Matrix.org, follow these instructions.
Can I run my own identity server?
Yes - the reference implementation is sydent and you can run your own ID server cluster that tracks 3rd party to Matrix ID mappings. If you want your server to participate in the global replicated Matrix ID service then please get in touch with us. Meanwhile, we are looking at ways of decentralising the 'official' Matrix identity service so that identity servers are 100% decentralised and can openly federate with each other. N.B. that you can use Matrix without ever using the identity service - it exists only to map 3rd party IDs (e.g. email addresses) to matrix IDs to aid user discovery.
What is Synapse?
Synapse is a reference "homeserver" implementation of Matrix from the core development team at matrix.org, written in Python/Twisted for clarity and simplicity. It is intended to showcase the concept of Matrix and let folks see the spec in the context of a codebase and let you run your own homeserver and generally help bootstrap the ecosystem.
Why is Synapse in Python/Twisted?
What are Synapse's platform requirements?
What are the Synapse webclient's requirements?
Where is the mobile app?
The mobile apps can be downloaded from the Google Play store and Apple store.
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For the Android app, you can also install the latest development version built by Jenkins.
What decides the room member order on the webclient?
The members are ordered by their last active time.
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Any other questions? Please contact us in #matrix:matrix.org or the mailing lists!