tildelink is a distributed service discovery mechanism. The problem that lead to the creation of tildelink is: how do we allow people to discover services without creating hierarchy or single points of failure?
More concretely, tildelink is a distributed ZeroMQ-based key-value store that maps service names to ZeroMQ endpoints, a daemon that implements this store, and a collection of tools to establish connections from the command line.
TODO
tildelink can be installed via OPAM:
opam pin add -y tildelink .
All communication in tildelink is done via ZeroMQ.
The central concept of tildelink is the notion of service.
A service is a collection of ZeroMQ endpoints and is identified
by a tilde:// URI. The URI contains the Curve25519
public key associated with the service; all communication is
encrypted.
The discovery service is just another tildelink service.
A tildelink URI is a RFC3986-conformant URI. The schema
component must be tilde. The userinfo, port and fragment components
must be empty. The query fragment must contain a Curve25519
public key, encoded using Base64 with URL- and filename-safe alphabet
(specified in RFC4648). Since any 32 bytes constitute a valid
Curve25519 public key, no validation besides length is required.
The host component contains a FQDN that identifies a node.
The path component contains an arbitrary string starting
with / that identifies a service logically associated with a node;
by convention:
- a path component equal to
/identifies a discovery service; - all other path components should start with a path segment of
the form
~user, where~useris the name of the user who is maintaining the service; the rest of path segments are arbitrary.
The discovery service is a tildelink service that performs two jobs:
- it accepts registration and discovery requests from the clients wishing to use the network;
- it disseminates the updated service mappings among the network.
The discovery service uses the request-reply pattern and JSON for serialization.
The requests are of the form {"version": "<ver>", "command": "<cmd>", ..},
where <cmd> is the command name and .. is command-specific fields.
The responses are either of the form {"ok": ..}, where ..
is a command-specific value, or {"error": {"code": "<code>", "message": "<msg>"}},
where <code> is a command-specific error code, and <msg> is
a human-readable error message.
Currently, <ver> is 1. If the service is unable to recognize
the version, an error with code unknown-version is returned.
If the service is unable to parse JSON or required fields are missing,
an error with code protocol-error is returned.
{"version": 1, "command": "node-info"}
{"ok": {"domain": "<domain>"}}
The node information command allows to request metadata from the current node. Currently, only node domain is returned.
{"version": 1, "command": "service-list"}
{"ok": {"<uri>": [{"host": "<host>", "port": <port>}, ..], ..}
The service list command returns all registered services.
{"version": 1, "command": "discover", "uri": "<uri>"}
{"ok": [{"host": "<host>", "port": <port>}, ..]}
{"error": {"code": "not-found", ..}}
The service discovery command returns the list of endpoints (host:port pairs) associated with the given service.
The documentation for the OCaml API is available online.
tildelink is distributed under the terms of MIT license.