Category Archives: GraphQL for Unity

GraphQL for Unity with WinCC Unified

In this post I will show how data from WinCC Unified V18 can be brought into Unity with the GraphQL for Unity Pro Asset.

First you need WinCC Unified V18 with the GraphQL Server. The GraphQL server comes out of the box with the new version and should be up and running automatically when you download and start your runtime. You should see a process “WCCILgraphQLServer.exe” in your task manager.

In Unity you have to create a project and download the GraphQL for Unity Pro Asset in the Package Manager.

  1. Prefab: Drag and drop the WinCC Unified Prefab from the Prefabs folder into your scene.
  2. Connection: In the properties you have to set your GraphQL Host, optionally the port, the path (typically /graphql), and if you want to have a secured TLS connection (HTTPS, WSS).
  3. Websocket: If you want to subscribe to tag value changes, then you have to open additionally a Websocket connection. Without the Websocket connection you can still read and write tag values, but a subscription to tag value changes is not possible.
  4. Authorization: Set the username and password to connect to WinCC Unified (at the time of writing, this user must have the role HMI Administrator).
  5. Logon: Check the “Logon” checkbox, if you want to start the connection at startup (you can also set this “on-demand” during runtime in your code.

Then you can already start the project in the editor to see if the connection can be established. If everything works fine, then the “Logged On” property turns to checked.

Now you can create your own C# script and read/write/subscribe tag values in an easy way in C# scripting. In that case I have simple added the script as additional component to the WinCC Unified GameObject (Prefab).

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using GraphQLWinccUnified;
using Newtonsoft.Json.Linq;

public class WinccUnified3 : MonoBehaviour
    private WinccUnified _connection;
    private bool _ready;

    // Start is called before the first frame update
    void Start()
        _connection = GetComponent<WinccUnified>();

    // Update is called once per frame
    async void Update()
        if (!_ready && _connection.IsWebsocketReady()) 
            _ready = true;

            // SubscribeTagValues
                new string[] { "HMI_String_1" }, 
                data => { Debug.Log(data.GetValue<string>()); });

            // WriteTagValues
            await _connection.WriteTagValues(
                new string[] { "HMI_String_1" },
                new JValue[] { new JValue("Hello World!") },
                new DateTime[] { DateTime.Now });

            // ReadTagValues
            var result = await _connection.ReadTagValues(
                new string[] { "HMI_String_1" });

If you deal with with a self-signed certificate, then you must uncheck “Validate Certificate” at the “Graph QL Http” Component. But the Websocket connection in Unity does not yet support self-signed certificates. So, it is better to use an insecure connection. Typically the GraphQL port is 4000, so be sure to set the Port to 4000. And don’t forget to open the firewall for that port on the host where the Unified runtime is running.

AWS AppSync query with Cognito User Pool

If you want to use the Cognito User Pool, then you first have to get somehow the JSON Web Token (jwt). Once you have this token, then you should pass the token in the header within the “Authorization” key.

graphQLHttp.Headers = new List<Header>()
      new Header() {Key = “Authorization”, Value = userSessionCache.getIdToken()}

Here you will find more information about jwt tokens.

AWS AppSync Real-Time Support for GraphQL for Unity…

The Asset GraphQL for Unity version 1.5.2 works now with AWS AppSync realtime Websocket connections. You can now subscribe to real-time value changes via a GraphQL Websocket connection with AWS AppSync. This was not possible before, because AWS has implemented it’s own specific protocol which is a little bit different to the Apollo Websocket protocol.

GraphQL Websocket AWS App Sync Configuration

Sending OPC UA Data with GraphQL to Unity…

In a simple setup I have tested to send 2000 value changes per second from an OPC UA server to Unity with GraphQL, the Open-Source Frankenstein Automation Gateway, and the GraphQL for Unity Asset. And it could go up to 10000 value changes per second…

I had one DotNet OPC UA server with a lot of simulated tags with random data. The .Net OPC UA server is the DotNet reference implementation from the OPCFoundation, which can be found here.

On top of that the Open-Source Frankenstein Automation Gateway for GraphQL was running. It is connected to the OPC UA server. It offers a GraphQL interface to the tags of one or more connected OPC UA servers.

In Unity I had used the GraphQL for OPC UA Asset to easily connect to the Gateway, browse the tags, and subscribe to the value changes of 100 tags.

Each tag was changed by the OPC UA server every 45ms. This ends up in a bit more than 2000 value changes per seconds, which were sent from the OPC UA server to the Unity Application.

Here we see the Application running 3 times on my Laptop with an Intel(R) Core(TM) i7-9850H CPU @ 2.60GHz. In the center you see the amount of incoming value changes per second (red number). Around that number, we see some of the values coming in from OPC UA. At the bottom we see the CPU load of the Frankenstein Automation Gateway (java program) and the OPC UA DotNet Server. Both were running on an old Intel(R) Core(TM) i3-6100U CPU @ 2.30GHz.

It was also possible to increase to load up to 10000 value changes per seconds! Sending 100 values every 10ms from OPC UA to Unity…

GraphQL for Unity and how to set headers in code…

If you use the GraqhQL for Unity asset and if you want to set the headers on HTTP or Websockets in the code, then you must use the the GraphQLHttp or GraphQLWebsockets class. At the base class “GraphQL” there is no “Headers” property!

public GraphQLHttp MyGraphQL;

void Start()
    if (MyGraphQL != null)
        MyGraphQL.Headers = new List<Header>()
            new Header() { Key = "token", Value = "secret"}

Then you can also execute a GraphQL query in the code.

MyGraphQL.ExecuteQuery("query { test }", null, (message) =>
    if (message.Type == MessageType.GQL_DATA)
        Debug.Log("Data: " + message.Result.ToString());
        Debug.Log("Error: " + message.Type);

GraphQL on Unity and Result Event for Data and Errors…

The GraphQL for Unity Asset can be used to execute GraphQL queries in Unity. The result is set on properties of Unity objects and there is also a Unity Event on the GraphQL Query Object where user-defined function of a GameObject can be triggered every time when a queries returns data or an error.

public class Sample1 : MonoBehaviour
    public void ResultEvent(GraphQLResult result)
        if (result.Errors.Count==0)
            Debug.Log("Data: " + result.Data.ToString());
            Debug.Log("Error: " + result.Errors.ToString());

Create a GameObject with this class as component and then you can drag and drop this GameObject to the Query GameObject and select the “ResultEvent” method. Every time when the query is executed then this function will be called with the result data (or error data).

GraphQL on Unity & Newtonsoft Reference Error

The GraphQL for Unity Asset uses the Newtonsoft version which is built in newer version of Unity (2020+). If you get an error like this:

Assembly 'Library/ScriptAssemblies/Assembly-CSharp.dll' will not be loaded due to errors: Reference has errors 'GraphQL'.
Assembly 'Assets/GraphQL/Libs/GraphQL.dll' will not be loaded due to errors: 

GraphQL references strong named Newtonsoft.Json Assembly references: Found in project:

Assembly Version Validation can be disabled in Player Settings "Assembly Version Validation"
  • Then you can try to remove NewtonSoft dependency from your project – if you have a dependency. And just use the NewtonSoft version which is already built in and shipped with Unity 2020+. If you use an older version of Unity then you can try to copy the NewtonSoft DLL from 2020 and use this in your older Unity version.
  • Or you can go to Project Settings -> Player -> Other Settings and deactivate “Assembly Version Validation”
  • Install the newtonsoft package from Unity. Go into the package manager and click “+” and then select “Add package from git URL” and fill in “com.unity.nuget.newtonsoft-json”.

GraphQL for Unity and execute a GraphQL Query in Unity with C# Code

With GraphQL for Unity you can execute GraphQL Queries in a Unity way with GameObjects. But with the asset you can also execute queries in Unity with C# code.

Here is a simple example:

public GraphQL Connection;

public void ScriptQuery()
        var query = "query($Token: String!) { doit($Token) { result } } ";
        var args = new JObject
            { "Token", "123" }
        Connection.ExecuteQuery(query, args, (result) =>

Link the Connection variable to your GraphQL GameObject where the connection is set.

Note: the result callback function is called asynchronous and it is not executed in the Game-loop.