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This component provides a configurable view of the workflow in graphical form. In addition, the diagram can be used to construct and edit workflows. Workflow inputs, outputs and processors appear as coloured boxes with arrows between them to represent data and control links. Options are available to configure the layout and level of detail shown, and the resultant diagram may be saved to disc in a number of different formats.


Toolbar

The Toolbar provides quick access to configuring the workflow view. The icons in the toolbar correspond to the following commands:

Icon

Command

Resets the workflow so that it is centred and fits in diagram window

Magnifies the view of the workflow diagram

Minimizes the view of the workflow diagram

Configures the view of the workflow diagram to show no service ports

Configures the view of the workflow diagram to show all service ports

Configures services in the workflow to be displayed as circles

Displays the workflow in a vertical fashion

Displays the workflow in a horizontal fashion

Expands nested workflows in the diagram


Diagram configuration

Diagram views have a number of settings for displaying ports associated with services. The workflow diagram above shows services with no ports which is useful to get a view of the overall structure of the workflow. However, it is not possible to see exactly where the data links are connecting. This additional information can be enabled by clicking on the 'Display all service ports' icon. This will result in the following workflow diagram:

Data links now connect explicitly to particular inputs and outputs. In this vertical view, the outputs of each processor are below the processor name and the inputs above. The display all ports view is often rather unwieldy when there is a large number of ports associated with a processor, e.g. Soaplab services. In these cases, the layout of the workflow diagram can be switched to 'Horizontal' by clicking on the icon on the toolbar:

Clicking on the icon configures the diagram to only show the structure of the workflow:

Processor colours

Colour is used both in the diagram and explorer views to denote the type of service processor. The diagram below shows a workflow including a number of different types of processors:

There are 11 different processor types in Taverna which are coloured as follows:

Type

Description

A user editable scripting operation using interpreted Java

A sub-workflow exposed as a single operation

A user editable scripting operation using the R programming language

An operation for loading spreadsheet data in CSV and Excel format

A local operation to emit a single constant string

A local operation to extract data from XML data

A local operation coded as a Java class

A configurable parameterised query over a Biomart data warehouse dataset. See link

A service wrapper around a legacy commandline tool such as the EMBOSS tool set

A processor accessing a standard SOAP service

A processor accessing a RESTful web service

Tool service

Other elements of the workflow are coloured as follows:

Element

Description

Input port

Output port

Merge

XML Splitter

Workflow editing

The workflow diagram is interactive in nature allowing pipelines to be built by linking processors to one another by, and thereby defining how data flows from step to step. This is achieved by pressing the left button of the mouse whilst the desktop arrow is hovering on a workflow input port or the output port of a processor which will result in an arrow. This arrow can be directed to the input port of another processor or a workflow output port, as shown below, that will be instantiated on release of the mouse button:

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