Custom Components

Custom components let you extend Nodlyn with your own workflow nodes — proprietary APIs, internal protocols, or business logic — as .NET plugins. Built plugins appear in the Studio palette under the Custom section, with Inspector settings generated automatically from your schema.

When to use

Wrap an internal REST API or legacy system not covered by built-in connectors.
Package domain-specific validation or transformation reusable across workflows.
Ship proprietary logic to customers inside an exported runtime agent (DLLs in plugins/custom/ are bundled automatically).

Official sample project

Start from the reference plugin on GitHub — full source, three example nodes, and step-by-step comments:

Nodlyn.CustomComponent on GitHub

git clone https://github.com/nodlyn-dev/custom-component.git
cd custom-component/Nodlyn.CustomComponent
dotnet build -c Release

The sample includes:

Node	Node type	Type	What it demonstrates
Hello World	`custom.example.helloWorld`	Action	Settings, outputs, minimal executor.
Text Transform	`custom.example.textTransform`	Transform	Reading pipeline input, passing data downstream.
Number Check	`custom.example.numberCheck`	Condition	Threshold comparison, true/false branching.

How plugins work

At startup, Nodlyn scans plugins/custom/ for *.dll files.
Each DLL may define a Connector Definition (DeviceConnectorDefinition) and one or more Executors (CapabilityExecutor).
Capabilities become draggable nodes; node type is {ConnectorId}.{CapabilityId} (e.g. custom.example.helloWorld).
Executors run when the node executes — same engine path as built-in connectors.

Plugins load in an isolated assembly context. A invalid DLL is logged and skipped; other plugins still load. There is no hot reload — restart Studio or the runtime agent after deploying changes.

Quick start (deploy sample)

Build the sample (see above). Output DLL: Nodlyn.CustomComponent/bin/Release/net8.0/Nodlyn.CustomComponent.dll
Copy to your Nodlyn install: plugins/custom/Nodlyn.CustomComponent.dll
Restart the platform (Studio API or runtime agent).
Open the workflow editor — nodes appear under Custom → Example Plugin.

Build your own plugin

1. Connector definition

Create a class extending DeviceConnectorDefinition. Declare identity and capabilities (Inspector fields, security level, inputs/outputs):

ConnectorId — globally unique, e.g. custom.mycompany
DisplayName, Icon, Color, Description — palette appearance
Capabilities — list of CapabilityContract entries with CapabilityId, settings schema, CapabilityType

2. Executor

Create a class extending CapabilityExecutor with matching ConnectorId and CapabilityId:

Read settings from node.Settings (Inspector labels map to setting names).
Read upstream data via ResolveInput(node, context).
Return StepOutcome.Ok(...) with output object for downstream nodes.
For side effects (HTTP, hardware), honour Dry Run via context.ExecutionMode.

3. Project rules

Rule	Detail
References	Reference Nodlyn.Core only — not Nodlyn.Api or Nodlyn.Connectors.
Constructors	Parameterless constructors required (loaded via `Activator.CreateInstance`).
Unique IDs	`ConnectorId` and each `CapabilityId` must not collide with built-in or other plugins.
Validation	If any type in the DLL fails validation, the entire plugin is rejected.
Restart	Deploy DLL → restart — no hot reload.

Inspector setting types

Type	UI control
`text`	Single-line input
`number`	Numeric input
`toggle`	On/off switch (`"true"` / `"false"`)
`select`	Dropdown with `Options`
`textarea`	Multi-line text

Capability types

Type	Use for
`Action`	Operations with side effects
`Condition`	True/false branching
`Transform`	Reshape pipeline data
`Trigger`	Start workflow from external events
`FlowControl`	Delays, forks, merges

Security levels

Level	Behaviour
Safe	No special permission
Sensitive	Credential or confirmation
Dangerous	Operator approval before execution
ArmedRequired	Approval plus arm signal (two-person rule)

Sample node — Hello World properties

From Nodlyn.CustomComponent (Inspector labels):

Property	Type	Description
Your Name	`text`	Name to greet. Required.
Greeting Style	`select`	Friendly, Formal, or Casual.
Include Timestamp	`toggle`	Append ISO timestamp to output.

Outputs: message, greetedAt (when timestamp enabled).

Runtime export

When you export a runtime agent, any DLL present in Studio’s plugins/custom/ at export time is copied into the ZIP under plugins/custom/. The headless runtime loads them the same way — custom nodes work on edge deployments without Studio installed.

If a workflow references a custom node but the DLL is missing on the target machine, Studio shows a missing-component banner until the plugin is deployed.

Related samples on GitHub

Nodlyn.CustomComponent — plugin template (Action, Transform, Condition)
RuntimeIngressConsumer — external HTTP/MQTT/file consumer for deployed agents (not a palette plugin)