In addition to output, you also have to specify where the data should go into the workflow by adding an element called Workflow Input. This can be done by:
- Right-clicking the input box of the first tool and choosing Connect to Workflow Input. By dragging from the workflow input box to other input boxes several tools can use the input data directly.
- Pressing the button labeled Add Element (or right-click somewhere in the workflow background area and select Add Element from the menu that appears). The input box must then be connected to the relevant tool(s) in the workflow by dragging from the Workflow Input box to the "input description" part of the relevant tool(s) in the workflow.
At this point you have only prepared the workflow for receiving input data, but not specified which data to use as input. To be able to do this you must first save the workflow. When this has been done, the button labeled Run is enabled which allows you to start executing the workflow. When you click on the button labeled Run you will be asked to provide the input data.
Multiple input files can be used when:
- Data is generated within the Workflow
- Data is held within the Workbench
- Data is a combination of the two situations above
It can be useful to rename input elements when working with multiple input files, so that it is easy to discriminate between them when they are shown during workflow execution.
Note: Once the multiple input feature is used in a workflow, it is not possible to run the workflow in batch mode.
You can choose the order in which inputs will be processed by an element by right clicking on the input parameter box at the top of the element and choosing the option Order Inputs. This is most relevant for elements involved in data visualization. The feature Order Inputs is enabled when there are at least two inputs connected to the element (see figure 9.15). A small window will open, in which you can indicate the preferred order of the inputs to that element by moving them up and down in the list (figure 9.16). From this point forward, the order of the inputs is displayed on the branches connecting the inputs to elements.
The feature Order Workflow Inputs allows you to set the order that a user will be asked for each input when they run the workflow. This option is enabled as soon as the workflow has two or more inputs (figure 9.17). Right click on empty space in the Workflow editor to start this tool. A small window will open in which the different inputs can be moved up and down to indicate the desired order (figure 9.18).
The example in figure 9.19 shows how to generate a track list in a workflow. Any track based on a compatible genome can be added to the same track list. This includes reference tracks as well as track results generated by elements of that workflow. In the latter case, only those for which a workflow output element has been configured can be included in a track list.