Build an app interface

Status

What other tools call it

Meridian's classification; an independent blind rating agreed on 86.2% of 312 rows (exact class, version 2).

Background

When to use it

In KNIME, the user of a data app can enter values for parameters on a web page, and those values are injected into the workflow to parameterise its execution.^[2] Reach for an app interface when the same workflow is run again and again by people who should change its inputs, not its logic. (Meridian's view)

In a group of radio buttons only one option can be selected at a time, while several check boxes in a group may be selected.^[3] Pick each control by what its parameter allows: one choice from a list, several choices, a number, a date or free text, so that a value the workflow cannot use is hard to enter. (Meridian's view) In Alteryx Designer, a group of Radio Button tools with no default set gives the default to the first button, and a group with several defaults gives it to the last.^[4] Set every default on purpose rather than leaving the tool to choose one. (Meridian's view)

In Alteryx Designer, the Error Message tool displays an error message in an app when an expression is true, and downstream processing then stops.^[5] Check the user's entries before the workflow acts on them, and stop with a message that says what to change. (Meridian's view)

In Alteryx Designer, a Drop Down list filled with the fields of a connected tool updates in the app only after the original workflow is run manually in Designer.^[6] A Drop Down list in Alteryx Designer that is filled from an external file or database pulls the latest values from it each time the app is run.^[6] When a user picks a file with the File Browse tool in Alteryx Server, the file is copied to the server, and any updates to it change only that copy, not the original file.^[7] In KNIME Analytics Platform, Widget nodes that re-execute downstream nodes when their value changes work only when the Chromium Embedded Framework is the browser for JavaScript views.^[8]

An Alteryx app user can save their selections as an app-values file with the .yxwv extension and open it again for future runs of the same app.^[1] Keep the values a run was made with beside its results, so the result can be traced to its inputs and the run repeated. (Meridian's view)

The method

In a graphical user interface (GUI), a graphical widget, also called a graphical control element or control, is an element of interaction, such as a button or a scroll bar.^[3] The defining characteristic of a graphical widget is to provide a single interaction point for the direct manipulation of a given kind of data.^[3] Implementations of generic widgets are often packaged together in widget toolkits, which programmers use to build GUIs.^[3] In 1988 the term widget is attested in the context of Project Athena and the X Window System.^[3]

In Alteryx Designer, an app is built by adding Interface Tools to a workflow and designing the interface in the Interface Designer.^[1] Each Alteryx app has a series of questions spread across tabs, which the app user must complete to run the app.^[1] In Alteryx Designer, the Action tool updates the configuration of a workflow with values provided by interface questions, when the workflow is run as an app.^[9] Drawing a connection in Alteryx Designer from a Question tool to a workflow tool places a configured Action tool between the two automatically.^[9] The Alteryx Condition tool tests entered values and returns either true or false.^[10] In Alteryx Designer, an Action tool connected to a Condition tool can update the Disable checkbox of a Tool Container based on the condition.^[9] In the Alteryx Interface Designer, tabs organise an analytic app, and the app prompts its user to move from one tab to the next to complete the process.^[11] The Test View of the Alteryx Interface Designer can open a duplicate workflow in a new tab, configured with the values entered for each question.^[11]

In KNIME, each page of a data app depicts the execution of one component, which encapsulates widgets, views and intermediate nodes.^[2] In KNIME, a component's composite view contains the interactive views of the Widget nodes, Interactive Widget nodes and View nodes inside it.^[8] In KNIME, every composite view on the root level of a workflow also defines a web application, accessible through KNIME Hub.^[8] KNIME's Refresh Button Widget adds a button to a component's composite view, and clicking it triggers re-execution of the component's downstream nodes.^[8] The KNIME Refresh Button Widget creates two variables, one counting the refreshes the button has triggered and one holding an ISO formatted timestamp of the last.^[12] KNIME's Interactive Widget nodes filter the data visualised in the View nodes connected to them, for example with a slider over the range of a chosen column.^[8] In KNIME, the Visual Layout Editor arranges Widget and View nodes next to or below each other by drag and drop.^[2]

Compared with the alternatives

In KNIME, Widget nodes, like Configuration nodes, can provide input parameters for other nodes, but unlike Configuration nodes, Widget nodes are shown as widgets in composite views.^[8] Configuration nodes inside a KNIME component let a user configure the component from the outside through its configuration dialog, without changing the nodes inside it.^[8] A configuration dialog suits someone who places the component in a workflow of their own; a widget page suits someone who never opens the workflow at all. (Meridian's view)

In Talend, the tMsgBox component opens a dialog box with an OK button requiring action from the user.^[13] A dialog that asks only for an OK is a checkpoint in a run, not an interface for setting its inputs. (Meridian's view)

Sources

1. [1]Analytic Appsdocumentation
2. [2]Data Apps Beginners Guide | KNIME Documentationdocumentation
3. [3]Graphical widget - Wikipediasecondary source
4. [4]Radio Button Tooldocumentation
5. [5]Error Message Tooldocumentation
6. [6]Drop Down Tooldocumentation
7. [7]File Browse Tooldocumentation
8. [8]Components Guide | KNIME Documentationdocumentation
9. [9]Action Tooldocumentation
10. [10]Condition Tooldocumentation
11. [11]Interface Designer Windowdocumentation
12. [12]Refresh Button Widgetdocumentation
13. [13]tMsgBox component | Talend Components for Jobs Helpdocumentation