What are Allowed Connections?

Allowed Connections are rules in the metamodel that define which Node Types can be connected by which Relationship Types.

Why They Exist

Without constraints, you could create nonsensical connections like "a Server manages a Building". Allowed Connections prevent this by explicitly defining valid connections.

How They Work

An Allowed Connection is a triple: Source Type → Relationship Type → Target Type

Examples:

Application → runs_on → Server ✅
Person → manages → Person ✅
Server → manages → Person ❌ (not defined, so not allowed)

Setting Up Allowed Connections

First, create your Node Types (e.g., "Application", "Server")
Create your Relationship Types (e.g., "runs_on")
Select the Relationship Type in the Tree View
In the Properties Panel, find the Allowed Connections section
Click + Add to define a new allowed connection
Select the Source Node Type and Target Node Type
Save — now you can draw this relationship on the canvas

Common Issues

"I can't draw a relationship between two nodes" → Check that an Allowed Connection exists for that combination of source type, relationship type, and target type.

"No relationship types appear in the popup" → No Allowed Connections have been defined for the node types you're trying to connect.

Tips

One Relationship Type can have multiple Allowed Connections (e.g., "depends_on" might connect Application→Application AND Application→Service)
Allowed Connections are directional — "A runs_on B" doesn't automatically mean "B runs_on A"
You can see all Allowed Connections for a Relationship Type in its Properties Panel