Exposed-Server Functions

Overview

In many modern Roblox frameworks, such as AeroGameFramework (AGF) or Knit, we expose server-side functions to the client through a structured and dynamic API. This pattern allows client scripts to access and invoke specific server functions seamlessly, mimicking the way you'd call local functions. These exposed server functions simplify client-server communication, ensuring that server-side logic can be invoked safely and efficiently from the client without manual remote event handling.

What Are Exposed-Server Functions?

Exposed-server functions are server-side functions that are exposed to clients for remote invocation. These functions are wrapped around RemoteFunctions, allowing clients to call server-side logic just like they would call a local method.

Example Structure:

-- Client-Side Example
local points = self.Server.PointsService:GetLocalPoints()
print("Received points:", points)

In this example, PointsService is a server-side service, and GetLocalPoints is a remote function exposed to the client. The client can directly call this function, and the server handles the logic.

How Exposed-Server Functions Work

Exposed-server functions rely on a dynamic system that abstracts remote communication through a combination of metatables. This system allows developers to access server services and their exposed functions as if they were local.

Key Concepts:

• Service Name: Represents the name of the service that contains the server logic (e.g., PointsService).

• Event/Function Name: Represents the name of the server function that you want to call remotely (e.g., GetLocalPoints).

• Remote Function: A RemoteFunction object on the server that handles requests from the client and returns a result.

Client-Side Usage

On the client-side, you access these exposed functions via the self.Server object, which allows you to call server functions as if they were local.

Example:

-- Client-side
local points = self.Server.PointsService:GetLocalPoints() -- Calling the exposed server function
print("Received points:", points) -- Output the result

Server-Side Implementation

On the server, the functions that the client can call are registered and exposed through a dynamic API. These functions are typically defined within services and then registered as RemoteFunctions that the client can invoke.

Server-Side Example:

local PointsService = {}
PointsService.Client = {}

-- Define a server-side function exposed to the client

-- Do note, everything ran inside this function is on the Server runtime.
-- Also do not worry, important variables like passwords are not exposed 
-- as we use roblox's networking solutions
function PointsService.Client:GetLocalPoints(Player: Player)
    -- This function is invoked by the client
    -- You can implement your logic here, such as fetching data from a database
    local points = 100 -- Example points logic
    return points -- Return the result to the client
end

return PointsService

In the example above:

• PointsService is the service.

• GetLocalPoints is the function within the service that the client can call.

• The function handles server-side logic, such as retrieving the player's points, and returns the result to the client.

Why Use Exposed-Server Functions?

1. Simplified Client-Server Communication:

   • The client doesn't need to manually handle RemoteFunction objects. Instead, they can call server functions as if they were local, making the code easier to read and manage.

2. Dynamic and Flexible:

   • Since service and function names are dynamically resolved using metatables, this system allows for easy scaling and customization. You can add new services and functions without changing much client-side code.

Common Use Cases

• Fetching Player Data:

  • Clients often need to request data stored on the server (e.g., player points, inventory, etc.).

  local points = self.Server.PointsService:GetLocalPoints()

• Server-side Calculations:

  • Sometimes the client may need to request complex calculations from the server.

  local result = self.Server.MathService:CalculateDistance(pointA, pointB)

• Interacting with Game State:

  • Clients can send requests to update the game state, such as interacting with NPCs or triggering server-side events.

  self.Server.NPCService:TriggerInteraction(npcId)