A Connection is a type of Node Property that specifies a security context and often an endpoint for connecting to a data source.
Additionally, only Nodes with a Connection Property can be run at a DropPoint.
A Connection can be set on a Node in 3 ways:
At design time by selecting a Connection from the drop down list
At run time by setting the GUID of a Connection on to the Connection Property. (The Connection GUID is shown in the Connection detail window in Flowgear).
At run time by setting an XML string on to the Connection Property. The XML string must contain a root Node with any name and immediate child Nodes named according to the Properties defined against the Connection. The DropPointId can also be specified in the XML document. For example, the following XML string will initialize a SQL Query Node: