Errors and logging

Lync sorts every failure into one of four kinds and handles each differently.

Kind	Examples	Handling
Your mistake	A send before start, the other side's send call, a second responder, an undeclared field, a value that doesn't fit	Throws at the call.
Dropped input	A value its codec or a :validate refused	Logged, not thrown.
A fault in your code	A listener or responder that throws	Logged with a stack trace. Other listeners still run.
Transport	A timeout, a player leaving, a shutdown	Returned as a request outcome.

Registering a listener for the other side, such as onServer on a client, logs a warning and attaches nothing. So one shared module can register both sides' listeners.

onLog

All log output goes through onLog. Branch on the fields of data, not on the message, which can change between versions.

Lync.onLog(function(kind, message, data)
    if data.code == "drop.validate" and data.player ~= nil then
        print("suspicious", data.player, data.reason)
    end
end)

Argument	Holds
kind	"warn" or "error". A drop on the server is a warning. A drop on a client, or a fault, is an error.
message	The text the default printer writes.
data.file, data.line	Where the definition was declared, or a place inside Lync when no definition is involved. Always present.
data.player	The sender, when there is one.
data.definition	The definition, when there is one.
data.code	For a drop, which kind. See below.

Codes

data.code	Means	Extra fields
drop.validate	A :validate refused the value.	reason, path
drop.tag, drop.count, drop.varint, drop.pad, drop.map-order, drop.sidecar	A value broke its codec's bounds.	path, expected, got
drop.bounds, drop.section, drop.defid	A frame was malformed.	said or expected, got
drop.hello	The handshake remote carried something that is not a handshake.
drop.unready	A client received more early frames than it holds while joining.
drop.mismatch	The two sides' schemas differ.	ours, theirs

When a client passes the drop limit, the extra drops of one code become a single record with data.suppressed, the number left unrecorded. It is logged when the 10-second window reopens or the player leaves.

The console

Lync.console is the built-in listener that prints to the output. Disconnect it to handle records yourself.

Lync.console:disconnect()

Connections

Every on* method except a query responder returns a connection.

local connection = Net.Notice:onClient(function(text)
    print(text)
end)

connection:disconnect()