Setting up connections between elements is the key to controlling where data flows. Elements are connected via their output channels and input channels. These channels are type dependent: only those with a matching type can be connected. Hovering the mouse cursor over an input or output channel will show a toolip with information like the data type required.
Compatible input and output channels can be connected in various ways:
- Click on an output channel, keep the mouse button depressed, and move the cursor to the desired input channel. A green border around the input channel name indicates when the connection has been made and the mouse button can be released. An arrow is drawn, linking the channels, as shown in figure 12.7.
- Use the Connect <channel name> to... option in the right-click menu of an input or output channel. Hover the cursor over this option to see a list of elements in the workflow with compatible channels. Hovering the cursor over any of these items then shows the particular channels that can be connected to, as shown in figure 12.8.
A given output channel can supply its data to multiple other workflow elements, and workflow elements can accept data as input from more than one output channel. This is illustrated in figure 12.9.
Figure 12.9: Input channels can receive multiple connections, and multiple connections can be configured from output channels. Here, two elements are supplying data to the Reads input channel of the Map Reads to Reference element and data from the Reads Track output channel of Map Reads to Reference is being used as input to two elements.
Input and output channels are discussed further in Workflow elements