Events between client and server

In MY Multiplayer (MYMP), client and server scripts communicate across the network by registering custom events and triggering them on the opposite side.

Creating and listening for an event

• addEvent(name, remote) registers an event name. Only an event created with remote set to true can arrive over the network from the other side; any other incoming remote event is dropped and logged.
• addEventHandler(name, element, callback) attaches a Lua handler function to the event on the element tree.

From the client to the server

triggerServerEvent(name, source, ...) sends an event from the client to the server.

• Server-known elements only: source and any elements passed as arguments must exist on the server. Passing a client-only element raises an error.
• Sender verification: on the server, the global variable client holds the player whose connection sent the packet. Always rely on client — never source or a handler argument — to identify who sent the event, because the client chooses both source and the arguments.

From the server to the client

triggerClientEvent([to,] name, source, ...) sends an event from the server to one or more clients:

• to: a single player, a table of players or any element in the tree (sending to every player below it). When omitted, the event goes to every connected player.
• For large payloads, triggerLatentServerEvent and triggerLatentClientEvent transfer data gradually within a bandwidth limit.

Complete example

Server:

addEvent("onShopBuy", true)

addEventHandler("onShopBuy", resourceRoot, function(itemId)
    if type(itemId) ~= "string" then return end
    triggerClientEvent(client, "onShopBought", resourceRoot, itemId)
end)

Client:

addEvent("onShopBought", true)

addEventHandler("onShopBought", resourceRoot, function(itemId)
    outputDebugString("You bought " .. itemId)
end)

triggerServerEvent("onShopBuy", resourceRoot, "burger")

Per-player rate limit

A player who triggers more than max_player_triggered_events_per_interval events (default: 100) within player_triggered_event_interval ms (default: 1000, both configured in server.cfg) causes the server to fire onPlayerTriggerEventThreshold. What happens next is up to the script — for example disconnecting the player with kickPlayer.