Maintain combines power and simplicity in a single data management facility. It incorporates the following features:

• Object-oriented development. You can define classes and declare objects that model the real-world entities, such as customers and business transactions, with which your enterprise deals. Object-oriented development saves you time by making it easier for you to reuse source code by means of property inheritance and class libraries, and enables you to leverage the powerful Maintain language by creating your own data types.
• Set-based processing. You can manipulate a group of data source records at the same time. You can define the group as a sequential range of records, as all records that satisfy selection criteria, or a combination of the two. For example, with one simple command you can select and retrieve all of the records for the first 100 employees who have the job code A25.
• Record-at-a-time processing. In addition to set-based processing, you can also identify and work with one record at a time.
• Sophisticated graphical user interface (GUI). You can use the Winform Painter to create sophisticated interactive forms, called Winforms, for entering data, displaying information, and selecting options. You can design these Winforms to include user-friendly features such as dialog boxes for requesting special information, check boxes for making choices, list boxes for selecting values, buttons for invoking functions, and entry fields with automatic data validation for entering valid values.
• Triggers and event-driven processing. The flow of control in conventional processing is mostly pre-determined—that is, the application developer determines the few paths that the end user will be able to take through the procedure.

  To make your application more responsive to the end user—using the graphical user interface—Maintain provides triggers and event-driven processing. A trigger is a specified event that invokes or triggers a function. Each time that the event (such as an end user pressing a function key) occurs, the function is invoked. For example, you might create a trigger for retrieving data: it would notice whenever an end user presses the PF7 key while in a Winform at run time, and would react by retrieving the specified data from the data source and displaying it in the Winform for the user to edit.

• Event-driven development. Developing a procedure by writing out sequential lines of code may be sufficient for conventional linear processing, but event-driven processing demands event-driven development. Developing an application in this way enables you to build much of the application's logic around the user interface. For example, you can develop part of the user interface (a Winform), then assign a trigger to a particular Winform event, then specify the action (that is, the function) associated with the trigger, and finally code the function—all from within the Winform Painter.
• Flow-of-control. Maintain provides many different ways of controlling the flow of a procedure, using enhanced versions of commands found in MODIFY as well as entirely new commands and functions. For example, you can transfer control unconditionally to functions, using PERFORM, and to procedures, using CALL; transfer control conditionally using IF; declare functions (also known as cases) with CASE, and simple blocks of code with BEGIN; and loop using REPEAT.
• Transaction Integrity. Maintain enables you to define multiple data source operations as a single transaction, and to ensure that the entire transaction is written to the data source only if all of its component operations were successful. Maintain does this by respecting your DBMS's native transaction integrity strategy.
• Modular processing. You can create several Maintain procedures which work together, one procedure calling another.

These are just some of the features you can use to develop powerful, flexible, and robust data source management applications.