General Action and Filetype Concepts

In many cases, Create Action will easily integrate your application into HP VUE. However, the action and filetype database provides additional functionality. To take full advantage of its features, it is helpful to understand some basic concepts. You can use these concepts to design how the application will be integrated into HP VUE.

Basic concepts of actions and filetypes

Actions replace command lines. Actions provide a visual representation of a command. The action definition specifies the command to be executed when the action is invoked, and connects the command with a visual representation (an icon). That icon becomes a graphical user interface for the command.

Figure 19-2 Actions provide icons that start applications and execute commands.

Filetypes connect applications with their data. A filetype provides both a visual and behavioral distinction for data files:

It defines a unique icon for the file in File Manager windows.
It can have a custom Actions menu for tasks you do with the data files.
It provides "context-sensitivity" for actions. For example, you can write different versions of the Print action for different filetypes; this creates a filetype-sensitive Printer control for the Front Panel.

Actions can be used different ways. Once you've created an action for an application, you can set up your environment to start the application from:

A toolbox.
The Front Panel or one of its subpanels.
The Window and Workspace menus.
By creating a filetype, you can start the application from a File Manager view of one of the application's data files.

Actions and filetypes have scope. Scope defines who can create and use actions and filetype:

Personal actions and filetypes are configured in a subdirectory of the home directory. Therefore, they can be created by an individual user and are available only to that user.
General (system-wide) actions and filetypes are created in a directory generally restricted to system admininstrators (superusers). These are available to all users on a system.
Exported actions and filetypes are available to other systems. This allows the system administrator to create and maintain one set of actions and filetypes on a central host.

Actions are network transparent. Actions let you start an application exactly the same way regardless of where in the network it resides:

An action definition specifies where to execute the application. The user doesn't have to worry about such things as host permissions, remote shells, or proper search paths each time the application is started.
The action can specify a remote directory as the default data location.
Actions can be defined remotely. An application server can provide both the application and the action, thus centralizing administration.

See Also.

“Creating a Simple Filetype” and “Creating Filetypes” covers creating filetypes.
“Creating Actions Manually” covers writing actions by manually editing database files.
These topics cover networking with actions:

Preparing to Integrate an Application Into HP VUE

Before writing filetypes and actions, there are some design issues to consider.

Defining the scope. The scope of the action is determined by the database in which it is defined:

Personal database: for user-specific actions.
General database: for system-wide actions.
Exported database: for actions to be exported to other systems. Your database can also include imported actions—actions located on remote systems.

Connecting applications with data. If an application uses data files, you may want to create a filetype for the application. At the very least, the filetype can provide a unique icon in File Manager.

The next thing you need to know is whether or not the application can be started with a file argument. This depends on the syntax of the command to start the application. For example, Text Editor can be started with an empty tablet or with a file argument.

   vuepad [filename]

Some applications require that data be loaded into the application after the application is started. In this case, no file argument is allowed on the command line.

Commands without file arguments. You can provide these behaviors:

The data file can have its own icon (filetype). Item help on the data file can identify the application.
The application can be started by double-clicking its icon in a toolbox.

Commands with file arguments. You can provide these behaviors:

The data file can have its own icon (filetype). You can add the applications to the File Manager Actions menu for the filetype.
The application can have an icon in a toolbox. The application can be started by:
- Double-clicking its icon in a toolbox or the Front Panel. The action displays a prompt for the file argument.
- Dragging a file of the correct filetype to the application icon.
- Selecting a datafile and then choosing the application from the Action menu.

See Also.

“The local database directories” covers the locations of local database files.
These topics cover networking with actions:

General Action and Filetype Concepts

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Basic concepts of actions and filetypes

Preparing to Integrate an Application Into HP VUE