Implement long-polling message passing

plugin/rojo.json

@@ -22,6 +22,10 @@
       "path": "modules/testez/lib",
       "target": "ReplicatedStorage.TestEZ"
     },
+    "modules/promise": {
+      "path": "modules/promise/lib",
+      "target": "ReplicatedStorage.Rojo.modules.Promise"
+    },
     "tests": {
       "path": "tests",
       "target": "TestService"

plugin/src/ApiContext.lua

@@ -1,5 +1,6 @@
+local Promise = require(script.Parent.Parent.modules.Promise)
+
 local Config = require(script.Parent.Config)
-local Promise = require(script.Parent.Promise)
 local Version = require(script.Parent.Version)
 local Http = require(script.Parent.Http)
 
@@ -24,7 +25,8 @@ function ApiContext.new(url, onMessage)
 		url = url,
 		onMessage = onMessage,
 		serverId = nil,
-		currentTime = 0,
+		connected = false,
+		eventCursor = -1,
 	}
 
 	setmetatable(context, ApiContext)
@@ -35,9 +37,9 @@ end
 function ApiContext:connect()
 	return Http.get(self.url)
 		:andThen(function(response)
-			response = response:json()
+			local body = response:json()
 
-			if response.protocolVersion ~= Config.protocolVersion then
+			if body.protocolVersion ~= Config.protocolVersion then
 				local message = (
 					"Found a Rojo dev server, but it's using a different protocol version, and is incompatible." ..
 					"\nMake sure you have matching versions of both the Rojo plugin and server!" ..
@@ -47,14 +49,43 @@ function ApiContext:connect()
 				):format(
 					Version.display(Config.version), Config.protocolVersion,
 					Config.expectedApiContextVersionString,
-					response.serverVersion, response.protocolVersion
+					body.serverVersion, body.protocolVersion
 				)
 
 				return Promise.reject(message)
 			end
 
-			self.serverId = response.serverId
-			self.currentTime = response.currentTime
+			self.serverId = body.serverId
+			self.connected = true
+
+			return self:_retrieveMessages()
+		end)
+end
+
+function ApiContext:_retrieveMessages()
+	if not self.connected then
+		return Promise.resolve()
+	end
+
+	return Http.get(self.url .. "/subscribe/" .. self.eventCursor)
+		:andThen(function(response)
+			local body = response:json()
+
+			if body.serverId ~= self.serverId then
+				return Promise.reject("server changed ID")
+			end
+
+			for _, event in ipairs(body.events) do
+				self.onMessage(event)
+			end
+
+			self.eventCursor = body.eventCursor
+
+			return self:_retrieveMessages()
+		end, function(err)
+			self.connected = false
+
+			return Promise.reject(err)
 		end)
 end
 

plugin/src/Http.lua

@@ -2,7 +2,8 @@ local HttpService = game:GetService("HttpService")
 
 local HTTP_DEBUG = false
 
-local Promise = require(script.Parent.Promise)
+local Promise = require(script.Parent.Parent.modules.Promise)
+
 local HttpError = require(script.Parent.HttpError)
 local HttpResponse = require(script.Parent.HttpResponse)
 

plugin/src/Main.server.lua

@@ -43,12 +43,19 @@ local function main()
 
 	local toolbar = plugin:CreateToolbar("Rojo " .. displayedVersion)
 
+	local currentSession
+
 	toolbar:CreateButton("Connect", "Connect to Rojo Session", "")
 		.Click:Connect(function()
 			checkUpgrade()
-			Session.new()
 
-			error("NYI")
+			if currentSession ~= nil then
+				warn("Rojo: A session is already running!")
+				return
+			end
+
+			print("Rojo: Started session.")
+			currentSession = Session.new()
 		end)
 end
 

plugin/src/Session.lua

@@ -1,7 +1,8 @@
+local Promise = require(script.Parent.Parent.modules.Promise)
+
 local Config = require(script.Parent.Config)
 local Http = require(script.Parent.Http)
 local ApiContext = require(script.Parent.ApiContext)
-local Promise = require(script.Parent.Promise)
 
 local REMOTE_URL = ("http://localhost:%d"):format(Config.port)
 
@@ -13,7 +14,9 @@ function Session.new()
 
 	setmetatable(self, Session)
 
-	local api = ApiContext.new(REMOTE_URL)
+	local api = ApiContext.new(REMOTE_URL, function(message)
+		print("Got message:", message)
+	end)
 	api:connect()
 
 	return self