Components

The Components section of the Toolbox contains flow components such as Event Log, Message Queue and Processes.

Background Worker

The BackgroundWorker component executes an operation on a separate, dedicated thread. Operations like downloads and database transactions that take time can cause your user interface to appear unresponsive. The BackgroundWorker component will execute a time-consuming operation in the background, listen for events that report the progress of your operation and signal when your operation is finished - without an unresponsive user interface.

See BackgroundWorker.

Error Provider

The ErrorProvider component provides indication that a control on a form has an associated error. An error description and an associated icon can be configured for the component to 'flash' in a configurable BlinkStyle and BlinkRate. A ToolTip can also be configured to display the error description when a user hovers over the icon.

An error provider can be preferable to a message dialog in some situations, because once a dialog is dismissed, the message is no longer visible. The ErrorProvider component displays an icon next to the control that is in error for as long as the error has not been addressed. The error message can be displayed on hover.

See ErrorProvider.

Event Log

The EventLog component provides interaction with Windows® event logs which record information about important software or hardware events. The component lets you read existing logs, write entries to logs, create or delete event sources, delete logs, and respond to log entries. New logs can also be created when creating an event source.

Windows provides three default event logs: Application, System, and Security. Security logs are read-only. Micromine Geobank keeps an event log for the Job Scheduler, among other events.

See EventLog.

File System Watcher

The FileSystemWatcher component monitors the file system notifications and raises a notification event when a directory, or file in a directory, changes. You can use a FileSystemWatcher to look for changes in files or subdirectories in a specified directory on a local computer, network drive or remote computer.

The Filter property for the component can be set to empty ("") or a wildcard ("*.*") to watch for changes in all files. Watching a specific file is achieved with a Filter property set to the file name. Changes in certain types of files can be watched with an extension Filter - for example, "*.dat" to watch for changes in data files.

The NotifyFilter property for the component determines the kind of change to be watched. For example, changes in the LastWrite date and time, or the Size of files or directories can be watched with the NotifyFilter.

Renaming, deletion or creation of files or directories can be watched with the Changed, Created, Deleted and Renamed events and specific parameters.

See FileSystemWatcher.

Help Provider

The HelpProvider component provides pop-up or online Help for controls on a form. The component instance has a collection of references to controls associated with it. The HelpNamespace property associates a Help file with a HelpProvider.

The HelpProvider is associated with a control using the Help options in the Misc properties for the control - for example, HelpNavigator.

See HelpProvider.

Image List

The ImageList component is used to manage a collection of images. ImageList can be used by controls such as a ListView to select the icons and other images required for display.

The ImageList properties (ImageList, SmallImageList, StateImageList and LargeImageList) for the associated controls can be set to the relevant ImageList to configure the display.

See ImageList.

Message Queue

The MessageQueue component provides access to a queue on a Message Queuing server. Applications can communicate across networks and systems to send, receive, or read (peek) messages from queues. A path to an existing resource can be set in the MessageQueue, or a new queue can be created.

The MessageQueue component supports synchronous and asynchronous message retrieval. Synchronous methods, Peek and Receive delay the process for a specified time for a new message to arrive in the queue. Asynchronous methods, BeginPeek and BeginReceive, allow the main application tasks to continue separately until a message arrives in the queue. Both methods work by using callback objects and state objects to communicate information.

See MessageQueue

Performance Counter

The PerformanceCounter component provides an instance of a Windows NT performance counter. The component can be used for reading predefined or custom counters and publishing (writing) performance data to custom counters. Performance that can be data collected includes busy time for a processor, memory usage, or the size of data (in bytes) received over a network.

The registry stores the names of all available counters, each of which is related to a specific area of system functionality. For the component, the counter information must include the category for which the counter measures data. The categories for a computer relate to a functional element within the computer and include hardware like disks and memory, and system categories such as processes. A set of standard counters is assigned to each available category.

See PerformanceCounter.

Process

The Process component provides access to local and remote processes and can be used to start and stop local system processes. The Process component can provide a list of the processes that are running, or a new process can be initiated.

Once initialised, the Process component can obtain information about the running processes including the loaded modules (.dll and .exe files), and performance information such as the amount of memory being used.

See Process.

Serial Port

The SerialPort component is used to control a serial port file resource. The component provides synchronous and event-driven I/O, access to pin and break states, and access to serial driver properties.

See SerialPort.

Timer

The Timer component generates an event after a set interval, with an option to generate recurring events. The server-based component raises an Elapsed event in your application, once or repeatedly, after the number of milliseconds specified in the Interval property have passed.

For example, for a critical server that must be running uninterrupted, a service using a Timer component can be created to check the server periodically to ensure it is running. If the Elapsed even occurs after the Timer interval, the service can attempt to restart the server or notify an administrator.

See Timer.