What is Aident CentralLink?

Aident CentralLink lets Business Central cloud call on-premises hardware, file systems, or custom .NET components-securely and without opening inbound firewall ports.

How does it work?

Part	Runs on	Purpose
CentralLink Agent	Windows host in the customer network	Windows service that loads plug-in DLLs and maintains an outbound Hybrid Connection to Azure Service Bus Relay.
Azure Service Bus Relay	Microsoft Azure (PaaS)	Cloud relay that tunnels HTTPS traffic from Business Central to the on-prem Agent-no VPN required.
CentralLink Connector (BC App)	Business Central online tenant	AL extension that authenticates with the Relay and invokes the Agent’s plug-in endpoints.

Only outbound 443 traffic leaves the LAN; the Agent doesn't listen on a public port.

Architecture at a glance

%% System Architecture - Aident CentralLink
graph TD
    %% ===== SaaS =====
    subgraph BC["Business Central (cloud)"]
        Ext["CentralLink Connector<br/>(AL extension)"]
    end

    %% ===== Azure =====
    subgraph Azure["Microsoft Azure"]
        Relay["Azure Service Bus Relay<br/>(Hybrid Connection)"]
    end

    %% ===== On-prem =====
    subgraph OnPrem["Customer network"]
        Agent["CentralLink Agent<br/>(Windows service)"]
        subgraph Plugins["Plug-in DLLs"]
            NetDrive["drive.dll"]
            NetPrinter["printer.dll"]
            Custom["*.dll"]
        end
    end

    %% Flows
    Ext -->|HTTPS| Relay
    Relay <--> |Hybrid Conn.| Agent
    Agent -->|/.netDrive/*| NetDrive
    Agent -->|/.netPrinter/*| NetPrinter
    Agent -->|/&lt;plugin&gt;/*| Custom

Key Features

• Hybrid connection - Azure Service Bus Relay eliminates inbound exposure; all traffic is agent-initiated and TLS-encrypted.
• Plug-in model - Drop in any .NET assembly; methods marked with [PluginMethod] appear instantly as REST endpoints.
• No server code changes - Business Central calls the Relay using standard AL HTTP APIs; no additional middleware.
• Zero VPN footprint - Works in locked-down networks; only outbound port 443 is required.

Installation

Note

The private NuGet feed URL and access token (PAT) will be provided by Customer Service. Replace <private-feed-url> and <PAT> in the commands below.

1. Prepare Chocolatey

https://chocolatey.org/install

# Install Chocolatey (skip if present)
Set-ExecutionPolicy Bypass -Scope Process -Force
iex ((New-Object Net.WebClient).DownloadString('https://community.chocolatey.org/install.ps1'))

# Install the Azure DevOps credential provider
choco install nuget-credentialprovider-vss -y

2. Register the private feed

choco source add `
    --name=CentralLinkFeed `
    --source="<private-feed-url>" `
    --user="AzureDevOps" `
    --password="<PAT>" `
    --priority=1

3. Install the CentralLink Agent

choco install CentralLinkAgent --source=CentralLinkFeed

The installer:

1. Deploys CentralLink Agent.
2. Creates the default plug-in folder C:\ProgramData\Aident\CentralLink\Plugins.

4. Using CentralLink

1. Launch: Start CentralLink using the desktop shortcut.
2. System Tray: Once running, CentralLink will appear in the system tray for quick access.
3. Startup: Startup behavior can be configured in the application settings.

Logs are written to Event Viewer → Applications and Services Logs → CentralLink.

Security & Deployment Notes

• Outbound-only - Agent opens a persistent, secured WebSocket to the Relay; no inbound firewall holes.
• Authentication - Shared Access Signature (SAS) key for the Relay plus BC tenant credentials; rotate on demand.
• Observability - JSON logs integrate with Event Log, ELK, Splunk, or Azure Monitor.
• Upgrades - choco upgrade CentralLinkAgent performs an in-place update with configuration retention.

Developing Plug-ins

using CentralLink;

namespace HelloWorldPlugin
{
    [AgentPlugin("hello")]
    public class HelloWorld : IAgentPlugin
    {
        [PluginMethod("GET")]
        public string SayHello(string name) => $"Hello, {name}!";

        [PluginMethod("POST")]
        public string Echo(string body) => body;
    }
}

• Compile the DLL and drop it into C:\ProgramData\Aident\CentralLink\Plugins.
• Endpoint becomes https://<relay-namespace>.servicebus.windows.net/hello/SayHello.