Remote Functions (Two-Way Communication) - Roblox Advanced Scripting #6 — Transcript

Full transcript

1. 0:00hey thanks for stopping by we're going to be  adding more security to our Roblox scripts
2. 0:04using a feature that further expands what we  learned upon in the last episode about remote
3. 0:09events this one is going to be about remote  functions which have its own use cases that
4. 0:14make it different from remote events and in this  episode I'm going to be showing you what these
5. 0:19are and how to use them and this example that  I have here uses remote functions so I have a
6. 0:24leader set with 50 coins and I have a prompt here  that says would you like to buy this button for
7. 0:2950 coins coins if I click on it then it then  the server should have deducted 50 coins from
8. 0:35my leader stats and that and that message should  have been sent back to the client to then update
9. 0:41this GUI to say purchase has been successful so  this had a two-way communication system that was
10. 0:48happening rather than one-way communication and  that is essentially the difference between the
11. 0:53two and that's what we're going to be discussing  about inside of this episode but before we start
12. 0:58implementing let me go back to our diagram that  I've showed you in previous episodes all right
13. 1:05let's think about this for a minute so we're  back on this diagram that shows us the server
14. 1:10and client model yet again I think you've seen  this before that's located in the Roblox developer
15. 1:14Hub link is in the description for that in the  last episode we covered remote events which act
16. 1:19as one-way communication between the server and  the client and like I mentioned remote events
17. 1:25act as one-way communication and there's three  ways of communicating with remote events so so
18. 1:30the first one is from one client to the server  the other way is from the server to one of the
19. 1:37clients and then there was the server to all  of the clients but what if we wanted to do a
20. 1:45communication that sends information to one party  and then with that it will send results back to
21. 1:53the the caller what I mean is what if we had this  player communicate to the server and then with
22. 2:00that communication to the server the server then  communicates back to the player with results to
23. 2:07give us more information or to let us know that  the call was successful this is essentially what
24. 2:13remote functions do that remote events can't do  the very important thing to know here is that what
25. 2:19we're going to be talking about in this episode  will act as two-way communication rather than
26. 2:24one-way communication so hopefully you were able  to understand this from my explanation now that we
27. 2:29understand let's Implement these remote functions  so I went ahead and created a leader stat script
28. 2:34inside of server script service with our player  added event and we're given 50 coins whenever we
29. 2:41join into the game so and then for the setup what  we're going to do is we're going to make a prompt
30. 2:47purchase with the coins that we have when we load  into the game so in starter GUI we're going to
31. 2:53create a screen GUI and then inside of the screen  GUI we're going to create a text label and we're
32. 2:59going going to rename this to prompt and let's  move this over here let's drag it a little bit
33. 3:06let's Center it let's go down here text scale it  and then let's change the text to would you like
34. 3:13to buy this button next what we'll do is we're  going to we're going to add a text button to the
35. 3:20screen gy so it's going to look like this and  then we're going to rename this to buy button
36. 3:27let's move this down here let's scale it up just  a little bit Center it go down here text scale it
37. 3:35and then change the text to buy button and then  in parenthesis we're going to say 50 coins to let
38. 3:43the player know that this is going to cost 50  coins let's just scale this a little bit here
39. 3:48so that it looks nicer and then Center it back  again okay and now what we'll do is we'll create
40. 3:53a local script inside of our screen GUI so let's  just create a local script here go back into our
41. 3:58game and now now that we have our setup let's  create our remote function and so because this
42. 4:04requires server and client communication we want  to be able to access this remote function from the
43. 4:09server and the client much like remote events  and one of the best places that the server and
44. 4:16client can access is replicated storage so we're  going to add this remote function inside of here
45. 4:22in replicated storage so we'll hit the plus  sign and let's add a remote function remember
46. 4:28it's remote function and let's rename this to BU  button that's what we're going to call this remote
47. 4:37function and now what we'll do is we're going to  open up our local script and let's delete this and
48. 4:44first make reference to our remote function so  we'll say local bu button and just to make this
49. 4:52easier we're going to call this by button remote  so that we know that this is a remote function
50. 4:58equals game . replicated storage. bu button and  and then what we'll do is make reference to our
51. 5:06GUI make reference to our prompt and also make  reference to our buy button so first we're going
52. 5:11to make reference to the GUI which is located in  the scripts parent and then we will locate The
53. 5:18Prompt which will be in the GUI itself so guy.  prompt and then finally the buy button so buy
54. 5:27button equals GUI bu button and now what we'll  do is we will make this button active when we
55. 5:34press it so that we can send the message to the  server using our remote function so in here let's
56. 5:40create a mouse click event so we'll say by button.  Mouse button oneclick colon connect function open
57. 5:52parentheses close parentheses enter so here's the  really interesting thing about remote functions
58. 5:57that makes them unique compared to remote events  so in order to fire the remote function much like
59. 6:03remote event all we need to do is use the function  provided to to call whatever side of the game we
60. 6:09want to fire to so in this case since we're in  the client we want to fire to the server so you
61. 6:15might say buy button remote colon fire server but  fire server is surprisingly not a function you can
62. 6:25use for remote functions because fire server is  very specifically a function for remote events
63. 6:34so in this case what we're going to say instead  of fire server is we're actually going to replace
64. 6:39fire with invoke so this is the function we need  to use in order to make call to make a call to the
65. 6:48server and in terms of parameters it's basically  the same thing with invoke server and in this
66. 6:54case the other one is invoke client where we don't  need to pass in a player if we're calling from the
67. 7:00client to the server but if we're going to pass  in arguments then we're going to need to do that
68. 7:06for here so it's basically structured the same  way as a remote event and the way we're going to
69. 7:12catch this function call is by doing it from the  server so let's copy this reference up here with
70. 7:18contrl c and then we're going to go to our leader  stats script let's drop two lines down here cop
71. 7:25paste that and then down here the same sytax here  is going to be a little weird like with invoke
72. 7:32server not being fire server there's a special  Syntax for catching this invoke server call and
73. 7:40it's not on server event but instead it's going to  be on server invoke so this is what it's going to
74. 7:47look like it's going to be by button remote.on  server invoke now you might be tempted to say
75. 7:58colon connect function open parentheses close  parentheses and enter this is actually incorrect
76. 8:04this is not the right way to write the Syntax for  on server invoke even though this pretty much is
77. 8:10what it is like for on server event so you might  ask why is it not like on server event why is the
78. 8:17syntax incorrect here it's important to understand  the difference between a call back and an event I
79. 8:22will explain what the difference is once we finish  writing our code as of right now what you need to
80. 8:28know is that this is not the right way to write  the on server invoke syntax because this is not an
81. 8:34event this is a callback and the way you structure  a call back is that it's basically a function
82. 8:40that is structured like this so after on server  invoke we say equals function because we create
83. 8:47a new function when we call this on server invoke  with the open parentheses closed parentheses and
84. 8:54the parameters are basically the same way as a  on server event event call so you know how over
85. 9:01here we have an on server event call for remote  events where the first parameter implicitly gives
86. 9:09you the player and then you have whatever other  arguments you have over here it basically works
87. 9:15the same way here where we are given the player  when we call on server invoke and then let's hit
88. 9:20enter now you might notice is that this end has  no end parentheses while on server vent does have
89. 9:29an end parentheses so this is something you have  to keep aware of is that there are tiny syntax uh
90. 9:35differences when it comes to using remote events  and remote functions and when you're calling on
91. 9:41server invoke you have to set this equal to a new  function that implicitly passes in the player much
92. 9:47like on server event and then it returns and  then it stops this block of code using an end
93. 9:53statement without the end parentheses so that's  something important to know about here so now
94. 9:58what we'll do is is we will make reference to the  player's coins and check if the player has enough
95. 10:03coins to be able to buy this uh button and then  we will subtract 50 currency from the players's
96. 10:10inventory so we're going to first make reference  to their leader stats by saying local leader stats
97. 10:15equals player. leer stats and then we will make  reference to the coins by saying leader stats.
98. 10:22coins and then we will check if coins. value  is greater than equal to 50 then we're going to
99. 10:32subtract the coins value by 50 we've now provided  one-way communication from the from the client to
100. 10:41the server to then tell the server whether the  player can buy this button and if they can then
101. 10:47we will subtract the currency so right now this is  functioning pretty much the same as a remote event
102. 10:54but now let's get to the interesting part that  makes this stand out from remote events and that
103. 11:00is the two-way communication part so I mentioned  that we're able to invoke the server by calling
104. 11:06invoke server and then telling the server to do  what it needs to do here but now let's actually
105. 11:11send information back to the client to let us know  that the purchase has been successful so that we
106. 11:16can let the client do something special when we  know that the player was able to buy the button
107. 11:22so let's go over here and let's make a Boolean by  dropping two lines at the very beginning so we'll
108. 11:28say local purchase successful equals false and  then let's drop a line down here after subtracting
109. 11:3750 coins by saying purchase successful equals true  so this basically lets us know that if the player
110. 11:47was able to successfully buy the button then we  set this purchase successful Boolean to true and
111. 11:54now what we'll do is we're going to go down  here and use the return key keyword to return
112. 12:00the purchase successful uh Boolean so not only  are we invoking the server to buy this button
113. 12:07and make computations to be able to get rid of 50  coins from the coins value we're also passing back
114. 12:13information to the client to let us know that  the purchase has been successful and the way
115. 12:19we will get the information back is by declaring  a Boolean and setting it equal to this function
116. 12:24call right here so behind our call let's create  a variable we will call this one local purchase
117. 12:32successful equals buy button remote invoke server  so what's going to happen is that this is going to
118. 12:39be essentially a Boolean that is set to whatever  this function call returns so when we call invoke
119. 12:47server to buy button remote it's going to go  to the server and it's going to first create
120. 12:53a Boolean called purchase successful and then  it'll check whether the player can buy the button
121. 12:57if they can then we're going to set purchase  successful equal to true and then we're going to
122. 13:02return whatever the value of purchase successful  is back to the client which is going to be set
123. 13:07here so now this will tell the client whether  we know that the purchase has been successful
124. 13:12and let's do that check down here by dropping  two lines and saying if purchase successful
125. 13:18then and when we just put in the Boolean variable  here this is implicitly saying if this is true or
126. 13:23not if this is true then what we will do is we're  going to change the prompt text label so this text
127. 13:31label right here we're going to change the prompts  text to purchase successful so that we can really
128. 13:41let the client know that the purchase has been  successful and let's even change the background
129. 13:45color of it too by saying prompt. background color  3 equals color 3. from RGB let's click this color
130. 13:55wheel and let's pick light green and so this will  let us know know whether the purchase has been
131. 14:00successful or not but we can also make a check  to see if it wasn't successful and we will do
132. 14:06this by dropping a line down here and saying else  and now down here let's just copy this code over
133. 14:12here and paste it down here so then we will say  purchase failed instead of success instead of it
134. 14:19being successful and let's also change this color  to Red so now we've successfully made a remote
135. 14:26function that basically allows the player to press  a button to buy that button by calling the server
136. 14:33and telling us whether the player can buy this  button or not and if they can then we will send
137. 14:38information back to the client to tell us that the  purchase was successful so that we can do whatever
138. 14:45we want to do after we get this information so  let's go into the game and see our results all
139. 14:52right so I've loaded into the game let's see if  we can buy this button so I have 50 coins up here
140. 14:57and this says would you like to by this button  let's click it and as you can see the server has
141. 15:03success has successfully decremented 50 coins from  my leader stats and the text label has updated to
142. 15:11say purchase has been successful now let's see  what happens if I press it again it'll then tell
143. 15:16the server to check whether the player can buy the  button or not which in this case we can't because
144. 15:22we have zero coins not 50 so then we told the  server that this is not possible and we sent the
145. 15:29information back to the client by saying it was  not possible to so then we could update this text
146. 15:34label to say the purchase has failed and so we  have successfully used a remote function to make
147. 15:42two-way communication with the server in client so  that we can pass information around and do what it
148. 15:48is we need to do with that two-way communication  from the server and client now there is another
149. 15:53method for this two-way communication because  what we did was go from the client to the server
150. 15:59and then back to the client the second method we  can do is from the server to the client and then
151. 16:05back to the server however what I can say to that  is I would actually advise not to do this method
152. 16:12from communicating from the server to the client  and then back to the server because the server
153. 16:17basically has access to all the information that a  client already has so there's no need for a server
154. 16:24to communicate to the client to get information uh  to be able to send it back to the server there's
155. 16:30just no need for that what you could do instead is  just use a remote event that communicates from the
156. 16:36server and then to the client so that the server  can tell the client what to do rather than having
157. 16:41to fetch information from the client because we  don't need information from the client because
158. 16:46the the server already knows everything that  a client knows so the only use case I can say
159. 16:51to remote functions is by communicating from the  client to the server and then back to the client
160. 16:56that's the only use case I can see with remote  functions at least in my opinion from my time
161. 17:02developing Roblox games that's the only use  I've seen with remote functions now you might
162. 17:07ask why does the Syntax for on server invoke look  like this where we need to create a new function
163. 17:14and not have an end parenthesis by the end here  rather than doing it like this with remote events
164. 17:20with the colon connect function and end it's  important to understand the difference between
165. 17:24events and callbacks so events are basically a  signal that gets fired when something happens
166. 17:32when we call the function of the remote event to  then catch that event using colon connect this is
167. 17:39specifically for events when they have to catch  the the event calls but in the way that a call
168. 17:43back is different for ons server invoke is that a  call back is basically a function that is passed
169. 17:50as an argument to another function and then it  is called to uh execute code after a task is
170. 17:56complete because the the whole point of a two-way  communication is that when we communicate from one
171. 18:05side which is the client to the server and we rely  on information from the server to be sent back to
172. 18:11the client the code does not continue until we get  the results from this call back to then continue
173. 18:18executing whatever else it is we need to execute  down here but in event call can happen multiple
174. 18:24times and execute without having to wait for  results to happen I hope that makes sense imagine
175. 18:30if you had two parts here that have a touched  event where if a player constantly stepped on
176. 18:37this part then it'll keep on firing events to then  to execute whatever it is that we need to execute
177. 18:43here but a call back relies on the information  to be received back to whatever party called that
178. 18:53function in this case we cannot have so many of  these invo calls at the same time as we do with
179. 19:01events I don't know if that made sense to you I  I really hope you kind of get the feel of what
180. 19:06I'm trying to say here but that is essentially  why the syntax difference matters between a call
181. 19:12back versus an event other than that everything  else is still pretty much the same it's just the
182. 19:17little syntax difference that you need to be able  to understand why it is the way it is so for this
183. 19:22last part of the video I'm actually going to  make this into a challenge and I'm not going
184. 19:26to lie to you this challenge is actually going to  be very fun at least I think so anyways because
185. 19:31essentially what we're going to do is we're going  to create a tools shop system using everything we
186. 19:37learned up until this point and there's three  requirements I have for you to do while you try
187. 19:42doing this Challenge on your own first and then  coming back to see what I do once we go through
188. 19:46this challenge together so the first requirement I  have for you is to use a remote function obviously
189. 19:53because that's the title of this episode the next  requirement is to make at least three buttons or
190. 19:58or tools for this shop system you can either go  to the toolbx to look at some tools for you to
191. 20:07use inside of your game or you can try creating  your own tools for your shop but either way works
192. 20:12for you the third requirement is I want you to use  the Clone function to take the bot tool and put it
193. 20:19inside of the player's backpack after the player  has bought whichever tool that they purchased in
194. 20:25the shop and if you don't remember how to do this  I highly encourage you to refer back to my tools
195. 20:31episode where I went through a bunch of properties  that will definitely help you with this challenge
196. 20:35so so just putting that out there before you start  this challenge so with that being said pause the
197. 20:40video try this challenge out on your own first and  then come back and we'll go through this together
198. 20:44all right so first thing we're going to do uh for  the sake of time we're just going to find three
199. 20:50random tools in the toolbox and just use that  and just use those as our tools so I think first
200. 20:56thing down here I can actually see that there's  the linked sword uploaded by Roblox so let's add
201. 21:02that in uh let's hit okay put tool in the starter  pack yes let's do that okay and let's look for two
202. 21:10more so I'm just going to search up tool and let's  look for two more things so there's a flashlight
203. 21:15tool let's just take this uh and it looks like  there's also a knife so we might as well take
204. 21:21that as well all right and they all should now be  inside of our starter pack let's also rename these
205. 21:27tools to make it more simple so we'll call Classic  sword sword you'll call flashlight flashlight and
206. 21:35then we'll keep knife as it is now we need a place  to store these tools so that we can fetch them by
207. 21:42the server uh and probably one of the most ideal  places is server storage so let's actually take
208. 21:49all of these tools and let's put them inside  of server storage now what we'll do is create
209. 21:55a shop so let's create another screen GUI here  let's rename this to shop let's just open up our
210. 22:03previous screen GUI and let's copy everything  that's into here by hitting control Z and then
211. 22:08just pasting it all into here so that we don't so  that we can just reuse what we currently have so
212. 22:13for our prompt let's change the text to Welcome  to my shop and let's just Center this a little
213. 22:21bit and let's also make this buy button one of  the tools so let's say sword for instance let's
214. 22:26rename this to sword and let's change this text  to buy sword and ideally we should make all these
215. 22:35tools different prices so let's make this sword  uh 10 coins let's just move this over here to the
216. 22:42left and then let's duplicate it and move this to  the center and let's call this one flashlight and
217. 22:51let's change the text to Flashlight and let's even  change the amount to let's say 15 all right and
218. 23:03let's duplicate that again put it over here this  one is going to be the knife and we will make this
219. 23:09knife 20 coins so let's BR to knife 20 coins so  this is now what our shop should look like on the
220. 23:17GUI side but now let's open up our script inside  of our shop and first thing we will do is instead
221. 23:24of make reference to one buy button we need to  make references to all three buttons so that
222. 23:29we can make all of them functional so what we're  going to do is rename by button to sword button
223. 23:37and change the reference to sword and let's copy  and paste this two more times so that we can get
224. 23:45reference so that we can get references to the  other buttons so this one will be flashlight so
225. 23:50this one's going to say flashlight and this one  is going to say knife and this one's going to
226. 23:57be a knife and so let's just change this variable  here from buy button to sword button and in order
227. 24:05to make all these buttons functional we need to  copy what we have with our code and just paste it
228. 24:10in like two different times so that we can make  all of them functional now this already does
229. 24:15look pretty messy I would not recommend doing  it like this what I would recommend is putting
230. 24:21all of these buttons inside of a table and looping  through that table so that you can just write this
231. 24:28code section only one time you don't need to write  it like three different times like I'm doing here
232. 24:33and so now we need to figure out how we can pass  in this information to the server to know which
233. 24:38button is being pressed what we can do inside of  the server is create additional parameters to let
234. 24:44us know which tool we're trying to look for when  we are uh making this purchase so let's actually
235. 24:51create two parameters here so the first one is  going to be the tool name and then the second
236. 24:59parameter is going to be the tool price when we  implicitly call player we want to pass in these
237. 25:06two parameters as well so that we know which tool  we're trying to look at so let's go back into our
238. 25:11local script and let's add in our additional  arguments now remember player is already
239. 25:19implicitly being thrown into here so we can skip  throwing in player what we do need to put in is
240. 25:24the tool name and the tool price so in quotations  we're going to say sword and then we'll space it
241. 25:33out with a comma and we will put in the price  which is going to be 10 coins and then we will
242. 25:38do the same thing down here with the flashlight  oh and uh I meant to change these to Flashlight
243. 25:45button and then down here to knife button so  that we're not doing this like three different
244. 25:51times uh and so now inside of our invoke function  inside of our invoke server function here let's
245. 25:57call this one flashlight and this one is going  to be 15 coins so now down here we're going to
246. 26:04say knife and this one's going to be 20 coins so  now we are effectively passing in uh arguments
247. 26:12into this into this callback so that we know which  tool we're talking about and so first thing we can
248. 26:20do is replace our coins value condition instead  of it being 50 all the time let's replace this
249. 26:28with the tool price and we will do the same thing  down here when we remove values from the coins so
250. 26:34now we have that done but now what we will do is  we're going to get the tool from server storage
251. 26:41use the tool colon clone function and then put  it inside of the player backpack the way we're
252. 26:47going to do that is by dropping two lines down  here or actually three lines um after we after
253. 26:53we know that the player has enough to be able to  buy this tool we're going going to first check in
254. 27:00server storage to see if we're able to find the  tool that we're looking for so what we're going
255. 27:04to say is local tool equals game. server storage  and we need to check if it's here so we're going
256. 27:12to say colon find First Child open parentheses  close parenthesis and inside of here we're going
257. 27:20to pass in our tool name Tool name because our  tool name could be sword or flashlight or knife
258. 27:27so we're trying to look for this inside of our  inside of our server storage and now let's check
259. 27:32to see if it actually does exist so we'll say if  tool then we're going to create a clone of that
260. 27:39tool and put it inside of the player's backpack  so we'll say local cloned tool equals tool colon
261. 27:47clone open parentheses close parenthesis and then  we're going to set the parent of this clone tool
262. 27:53so clone tool. parent equals the player players  backpack which is going to be player. backpack
263. 28:02so now we have successfully allowed the server to  check whether this tool exists inside of server
264. 28:08storage and if it does like let's say it's a  sword then we're going to clone this tool and
265. 28:14we're going to place this inside of the player  backpack while also decrementing the coins value
266. 28:20while also telling the client that this purchase  has been successful and we're going to send this
267. 28:25information back to the client so we're pretty  much done here this was basically our whole script
268. 28:31now again there are definitely better ways of  handling this code especially this right here when
269. 28:37we're duplicating a lot of stuff by using a table  and then looping through all those buttons inside
270. 28:41of a loop rather than creating three different  Mouse button oneclick events but other than that
271. 28:46I'd say our system we have is pretty good so  let's test it out inside of our game all right
272. 28:51so we've loaded into the game I have 50 coins and  let's see what happens if I try buying the sword
273. 28:57so as you can see first thing that happened was  that it checked if we had enough coins for 10 and
274. 29:03it did so we decremented 10 coins after buying  the sword the second thing that happened was
275. 29:10that the server checked server storage to see if  it had the sword we were looking for and it did
276. 29:15so the server created a clone of this tool and  put it inside of our backpack so if we open up
277. 29:21players our player and then go to backpack we can  see that our sword has successfully been placed
278. 29:27inside of our um backpack so that was successful  and the last thing that happened was that the
279. 29:34server sent the message back to the client to  tell us that the purchase has been successful
280. 29:40therefore we updated this text label to say the  purchase has been successful and we did all of
281. 29:45those things using remote functions now let's see  what happens if we try buying a flashlight we can
282. 29:50see that we now have the flashlight inside of our  backpack and we also decremented uh 15 coins from
283. 29:58buying this one now let's try buying the knife  and we have also successfully bought the knife
284. 30:03so it works as intended now let's try buying  something else we can't afford anything now so
285. 30:08let's try buying something and as you can see the  purchase has failed because now we only have five
286. 30:12coins and not at least 10 to buy any of these so  we're basically done here and what we got out of
287. 30:19this was a pretty nice shop system that allows  us to be able to buy these tools so I hope you
288. 30:24found this challenge to be very interesting uh  I definitely had fun explaining how this uh shop
289. 30:30system worked and I think we're starting to be  able to apply our skills to be able to create
290. 30:36actual systems inside of our games so I think  this was definitely a fun challenge to to do
291. 30:41so that's going to be it for this episode  on remote functions I hope you learned a
292. 30:45lot from this episode we were able to create  a shop system using everything we've learned
293. 30:49up until this point and I think we're starting  to make more and more progress into creating
294. 30:53bigger and better systems for Roblox games and I  hope you'll be sticking around for more episodes
295. 30:59to come in the future but other than that that's  pretty much it for this episode be sure to join
296. 31:03my Discord server the link is in the description  and I will see you in the next episode take care