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RpcArgs and RpcInfo Structs

Daniel McGuinness edited this page Sep 30, 2018 · 1 revision

When you setup a Remote Procedure Call you will notice that the argument supplied to this is called RpcArgs. This is a struct that helps ease the pain of getting objects from the network byte array. This RpcArgs has a Info member variable which is a RpcInfo struct. This one argument to your RPC helps you get not only the data you sent on the network, but some other useful network meta-data as well.

Getting Data From RpcArgs

The RpcArgs is a wrapper around the network data with one important method that you actually care about. This method is the RpcArgs::GetNext method. This is an overloaded method with 2 overloads, the first being the parameter-less easy-use method and the other being the more advanced object selection by index method. If you look at the signature for the overload with the int index parameter, you may be thinking "what is index for?". This index is the index of the object you wish to pull from the network byte array. So lets say that you called an RPC with 3 arguments (an int, a string, and a float). If you wanted to get the float you could use GetNext<float>(2) where 2 is the index of arguments. the int being 0, the string being 1, and the float being 2. The power of the parameter-less GetNext<T>() method is that it auto moves to the next argument. So if you wanted to read the int, string and float from the preceding example you would do the following:

int num = args.GetNext<int>();
string name = args.GetNext<string>();
float val = args.GetNext<float>();


You must pull out the arguments IN ORDER, if you do not, you will run into an error. So the following WILL NOT work for the same example because of the order of the network data:

float val = args.GetNext<float>();
string name = args.GetNext<string>();
int num = args.GetNext<int>();

Using the Info

At the time of this writing, the Info member variable in the RpcArgs has 2 properties. A NetworkingPlayer named SendingPlayer and a ulong named TimeStep. The NetworkingPlayer is the sender of this RPC.

NOTE This is only useful on the server, clients will always see the server as the sending player since all network traffic first goes though the server. The ulong is used to know what timestamp that this message was sent at from the sender (this is time in milliseconds since the server started).

SendingPlayer.Networker.IsServer and SendingPlayer.IsHost

You may notice in client execution that the value of SendingPlayer.Networker.IsServer is False but the value of SendingPlayer.IsHost is True and this has caused some confusion for the community. The way that you should think of SendingPlayer.Networker is that it is the NetWorker that is used TO communicate with the server, it is not the server's NetWorker. So if it is the NetWorker used to talk to the server, then it is this client's NetWorker, which makes the IsServer getter False. This is actually why we created the IsHost boolean to help mitigate this confusion and it is less code to get to.


Getting Started
Network Contract Wizard (NCW)
Network Object
Remote Procedure Calls (RPCs)
Unity Integration
Basic Network Samples
Scene Navigation
Master Server
Web Server
Netcoding Design Patterns
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