Viz Arc User Guide

Version 1.7 | Published November 15, 2022 ©

Data Integration

When running Viz Arc, a SignalR Hub waits for incoming connections internally. The Arc Web Server Port can be configured, see General Settings. The hub where the various methods can be invoked by clients is called VizArcHub.

Information: To use an external application running a SignalR client, please use a .NET 6.0 based project.

The server supports the following methods

  • setStringVariable (string varName, string value)

  • setJSONVariable (string varName, string json)

Those two methods allow clients to set simple variable names with either a string value or a JSON string. Viz Arc scripts is notified of variable changes and can process their value. The following code sample shows client setting variables in Viz Arc:

C# client sample
using Microsoft.AspNetCore.SignalR.Client;
// create VizArcHub connection on localhost and default port 5004
HubConnection connection = new HubConnectionBuilder()
// connect
await connection.StartAsync();
// set some DataMap variable
await connection.InvokeAsync("setStringVariable", "hello", "world!");

In any Viz Arc script, the values above can be read, as in the following simple sample:

Viz Arc script
Global.OnInit = function () {
Console.WriteLine( "data " + GetData("hello"))
Console.WriteLine( "json " + GetData("jsonData").ToString())
Console.WriteLine( "name is " + GetData("jsonData").Name.ToString())
// subscribe to all DataMap variable changes
Global.OnDataMapValueChanged = function (varName) {
Console.WriteLine( varName + " changed to "+ GetData(varName).ToString())
if( varName == "jsonData" )
Console.WriteLine( "nams is " + GetData("jsonData").Name.ToString())

The method GetData returns the currently set value of the variable.

MQTT Broker

When the MQTT broker port is configured, an internal MQTT broker starts on Viz Arc startup. All topic changes are transmitted to the DataMap using the MQTT topic as the key and the topic's payload as value.


To test the integration you can wither use the MQTT Explorer (this tool can be useful to monitor Viz Arc's MQTT broker as well) or a .NET core project using the following C# code:

Sample C# snippet for publishing a MQTT topic to Viz Arc
// using nuget package MQTTnet.AspNetCore and MQTTnet.Extensions.ManagedClient
using MQTTnet;
using MQTTnet.Client;
using MQTTnet.Client.Options;
// ...
var factory = new MqttFactory();
IMqttClient mqttClient = factory.CreateMqttClient(); // create MQTT client
var options = new MqttClientOptionsBuilder().WithTcpServer("localhost", 1883).Build(); // create connection options
var connResult = mqttClient.ConnectAsync(options, CancellationToken.None).Result; // connect to VizArc's MQTT broker
var message = new MqttApplicationMessageBuilder().WithAtLeastOnceQoS().WithTopic("local/news/breaking").WithPayload("breaking news").Build(); // create message
var result = mqttClient.PublishAsync(message, CancellationToken.None).Result; // publish the message
Viz Arc JavaScript sample to receive and read MQTT topics through the DataMap
var listenTopic = "local/news/breaking"
Global.OnInit = function ()
Global.OnDataMapValueChanged = function (varName)
if( varName == listenTopic )
news.Value = GetData(listenTopic)

The script above listens to changes on the "local/news/breaking" topic and updates a text box accordingly.

TCP Server

Viz Arc starts up a TCP server which can be used to set and get DataMap variables. The port of the server can be configured, see General Settings.

You can set DataMap variables using a command string from a Viz Engine script:

Set DataMap
System.TcpSendAsync("resultSetDM", "localhost", 9204, "ARC*DATAHUB SET key|someValue 1.0 1.0 1.0", 1000)

The command above sets the variable key to the value someValue 1.0 1.0 1.0. The | character separates the key from the value. This value can then be further processed in Viz Arc.

To read back a value from the DataMap in Viz Arc you can use the GET command like in the sample below.

Get DataMap
Dim ret = System.TcpSend("localhost", 9204, "ARC*DATAHUB GET key", 1000)

The Viz Engine script variable ret contains the value of key.

You can execute an action using a command string from a Viz Engine script:

Set DataMap
System.TcpSendAsync("resultSetActionName", "localhost", 9204, "ARC*ACTION EXECUTE loadSceneA", 1000)
System.TcpSendAsync("resultSetActionGUID", "localhost", 9204, "ARC*ACTION EXECUTE 49c525fa-0ce8-46e1-bae4-acfb4abdb629", 1000)

The commands above search for actions loadSceneA by name and 49c525fa-0ce8-46e1-bae4-acfb4abdb629 by GUID and execute them if they can be found in the current project.

DataMap Linking

Some scripting UI components like Text, Int or Double have the properties Linked Data Key and Linked Data Query.


The Data Key entry can accept any key name used in a DataMap entry. As an example add a key matchResult using the web UI to insert key/value pairs on Viz Arc.


Enter matchResult as Linekd Data Key and the text value updates to the previously entered data.


For more complex data structures such as .json strings, the Linked Data Query can be used.

json sample data
"Home":"City A",
"Away":"City B",
"Home":"FC A",
"Away":"FC B",

The DataMap after adding the above .json using the matches key.


Enter a JSONPath string $[0].HomeScore to get the home score of the first .json array element.


Instead of using constant values for indexing the .json array a variable can be used instead. A variable must be enclosed in % character and should be the ID of an existing scripting UI element.


$[%dropdown_0%].HomeScore gets resolved to $[1].HomeScore as the dropdown value of the dropdonw_0 component is 1.