How the platform is built

Applies to: SimpleTwo 0.9.x · Checked: 08.10.2026

The platform is installed entirely inside your own perimeter. Below is what it is made of and what talks to what; the role-by-role installation is in the deployment manual. Which roles belong to the base and to which product is in Products.

The planes, and why the split is load-bearing

The split is not organisational, it is about availability requirements: communications, the directory, the intranet and management have different ones, and mixing them means holding everything to the strictest.

Plane	Services	How it is reached	Availability requirement
Communications	messaging, sfu, turn, recorder, mcu, pstn, mail, mx, drive	directly over TLS; the tunnel is not required	the highest — it has to work while the tunnel is down, or "the VPN is down and there is no way to say so"
Directory and sign-in	directory	directly over TLS on 443, with its own certificate	high for new sign-ins: without it nobody signs in afresh, while whoever is signed in keeps working — sessions are issued and renewed by coordinator
Intranet	gateways, internal systems, the DMZ	through the tunnel only	follows the tunnel; a gateway failure is a routing incident, not a communications one
Management	coordinator, the console, the node API, agent, monitoring	tunnel or SSH	the lowest, with the highest privileges: the platform is designed so that conversations outlive its own unavailability

Services

Service	Responsible for	Note
coordinator	sessions and permissions, policy, the node registry, meetings, the admin console, the product options; who runs the browser sign-in — it or directory — and whose token the services accept are switches in the console, see Sign-in: the coordinator and identity	one instance by design; what scales is not it, but the ability to work without it
directory	the directory with the calendar: accounts, groups and the organisation's contacts, SCIM; calendars, invitations, ICS and CalDAV, personal and team address books (CardDAV) — the calendar answers under /cal on the same name; sign-in of local accounts and guests with a second factor and sign-in approval on the phone, the broker to the organisation's identity provider	part of the core: the organisation's groups and contacts live only here. More in sign-in and participants
messaging	conversations and messages, call signalling, presence, bots, attachments	scales horizontally behind an event bus
sfu	conference media	a pool of nodes behind a TLS edge; adding a node is adding capacity
turn	relaying media where the direct path is closed	needed on networks with strict NAT
recorder	meeting recording	files go to your storage, never outside it
mcu	the media server for your meeting-room SIP terminals (Poly, Cisco) in meetings, with voice, video and presentation. Not the PSTN gateway: it has no trunks and no telephone numbers	Messaging Plus; one node, or several behind DNS SRV
pstn	the PSTN gateway: a carrier's SIP trunks, dialling into a meeting and calling telephone numbers	Messaging Plus; a host of its own, never shared with mcu. More in telephony
mail	mailboxes and search, JMAP and push for the clients, Sieve rules and the vacation response, shared mailboxes	its own database and its own storage; mail from the internet is received by mx, not by it
mx	the mail edge in the DMZ: receiving from the internet and sending out with a DKIM signature, SPF, DKIM and DMARC checks, content filters; submission for devices and integrations	no database and no mailboxes — only a queue on its own disk; two nodes by design. More in mail
postgres	the database: every role has its own database on one instance	the base's infrastructure; your own Postgres cluster can stand in for the role
redis	the event bus: coordination of the sfu and mcu nodes, recording jobs	needed from the second sfu or mcu node and for recording; an external one can be used
s3	object storage: attachments, avatars, recordings, mail, files	infrastructure; an object is an ordinary file, so backup and migration are filesystem work. Instead of the role you can point the platform at storage you already run
gateway	a VPN node	a "dumb" tunnel: it holds no rules of its own
agent	installs and updates roles on hosts	certificates and configuration arrive the same way
monitoring	metrics, logs and traces from every host; its interface opens from the console	an option for any installation, one per installation; holds no product data — without it only the history is lost
support	the support bot: requests, the knowledge base, AI-assisted answers	Messaging Plus
drive	the files a person keeps: a personal space for everyone who has signed in and a space per group in their token; its catalogue in its own database, the files in object storage; iOS, macOS and Android clients	the Drive product; obtains its own certificate for its public name, which is announced to clients as drive_url once it answers (files)

Data

Postgres is the source of truth for conversations, calendars, the directory and mail, each service in its own database; the event bus (redis) carries events between messaging instances; files and recordings live in object storage inside your perimeter. None of the three faces the internet.

Storage comes one of two ways, like the database: the s3 role inside the platform, or external S3-compatible storage you already run (MinIO, AWS S3, Ceph, anything speaking the same protocol). The console shows which one is in effect. File bytes always travel through messaging, which checks the right to every file; the platform never hands out links straight into the store. The role keeps an object as an ordinary file, so on ZFS a filesystem snapshot is a consistent backup of the attachments and zfs send is a copy at a second site. The disk for objects is requested when the host is added: the platform builds the pool and the dataset with the properties it needs and refuses a disk with anything already on it.

Boundaries with external systems

System	Direction	What crosses the boundary
AD / ADFS	read-only: people into coordinator, groups into directory	who exists, groups, attributes; the platform never writes back. ADFS is also a sign-in provider for directory
SimpleOne	both ways, through messaging	a conversation linked to a ticket, presence, and a call from inside the ticket form
Another SimpleTwo installation	both ways, through messaging	messages addressed user@domain — federation, off by default
Meeting-room SIP terminals	inbound, through mcu	joining a meeting by the room's number
Telephone network (PSTN)	through pstn, the PSTN gateway	dialling into a meeting and calling telephone numbers
Mail from the internet	through mx	the outer ring of the same federation: receiving and sending, DKIM, SPF, DMARC and MTA-STS. Mail from the internet comes in once you publish an MX record pointing at an mx node

What the diagram claims, and what it does not

It shows roles and boundaries, not sizes. How many sfu nodes and how large is a sizing question, and it is answered by the number of simultaneous conferences rather than by headcount.