Introduction to FRAME Entries in SAS/AF Software John C. Boling, SAS Institute Inc., Cary, NC

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1 Introduction to FRAME Entries in SAS/AF Software John C. Boling, SAS Institute Inc., Cary, NC INTRODUCTION SAS/AF software, announced in 1985, is an application facility for building interactive enterprise information systems. As the user interacts with the application, the application can customize and execute SAS source cod~ interactively, noninteractively, or even on a remote machine. Other source programs such as Basic, Fortran, Cobol, and PUI can also be customized and submitted for execution from the application. Prior to the introduction of the FRAME entry, entries within a SAS/AF application could not easily intermix text and graphics. As a result, SAS/AF entries did not take on a graphical user interface appearance. The FRAME entry, available in Release 6.08 and subsequent releases, supports the intermixing of text and graphics. As a result, SAS/AF applications can now take on a graphical user interface appearance. GRAPHICAL USER INTERFACES Display 2 Example FRAME Entry Graphical User Interfaces are multi-window, graphic-oriented user applications. Typically, they contain window elements such as bit-mapped and structured graphics, icons, pull-down and pop-up menus, command buttons, scroll bars, and sliders. Most also use a mouse device and painter contro1. With GUI-based applications, users typically navigate through the, application by pointing and clicking on their selections wi1h a mouse. OBJECT ORIENTED PROGRAMMING TERMS FRAME entriestake advantage of object-oriented concepts, the latest development in programming and interface techniques. A discussion of some object-oriented terms is helpful to understanding FRAME entries. Object The design of an object-oriented system begins not with the task to be performed but rather the aspects of the real world that need to be modeled in order to pertorm that task. Objects offer a very natural way of breaking down the problem to be solved. Each object has a range of behavior to be modeled, and each has to maintain some information about its own status. Why look for some other way to package procedures and data when the problem has already organized them for you! An object is a software packet containing a collection of related data elements and a set of procedures called methods for operating on those elements. The data within an object can be accessed only by the object's methods. This arrangement, called encapsulation, protects data from corruption by other objects and hides low-level implementation details from other objects and the rest of the system. Display 1 Example FRAME Entry GUI applications are often simpler and quicker to use than command-based interfaces. For example, GUI menu choices can be icons that users select instead of typing numbers or leners on a command line or pressing function keys. GU! applications are also more intuitive. Rather than requiring users to remember a series of commands and options, the interface prompts for the next action or choice. GUI applications enable users to maneuver quickly and easily through a series of tasks using graphical images. Evel)1.hing an object knows is expressed in its instance variables. Everything it can do is expressed in its methods. Once defined, new types of objects can be used as building blocks. This ability to create new, high-level structures on demand and use them to build applications is called data abstraction. This is a key theme because it allows us to think in terms of the problem, the task, the physical process, rather that the data types of the language and the procedural flow. Classes Object-oriented programming supports the repeated use of common objects through the use of classes. A class is a general prototype which describes the characteristics of similar objects. The objects belonging to a particular class are said to be 567

2 instances of that class. Conceptually it may be helpful to think of a class as a rubber stamp template being used to stamp out instances of itself. Classes allow objects to be defined in a very efficient manner. The methods and variables for a class are defined only once, in the.class definition, without repeating them in every instance. The instances contain only the actual variable values. Although it is possible to define classes independently of each other, classes are usually defined as special cases, or subclasses of each other. Through a process called inheritance, all the subclasses for given class can make use of the methods and variables of that class. Inheritance increases the efficiency of the class mechanism even further: behavior that's characteristic of larger groups of objects is programmed only once, in the definition of the higher-level class, and the subclass merely adds to or modifies that behavior as required for their special cases. Subclasses may be nested to any degree, and inheritance will accumulate down through all levels. The resulting treelike structure is known as a class hierarchy. Messages Objects communicate with one another through messages. A message is simply the name of a receiving object together with the name of one of its methods. A message is a request to carry out the indicated method. Any number of objects can include the same method, and each can implement it according to its own unique needs. That allows any given message to be sent to lots of different objects without worrying about how the message will be handled or even knowing what kind of object will receive it. The ability to hide implementation details behind a common message interlace is known as polymorphism. Polymorphism makes the object-approach very flexible because it allows new kinds of objects to be added to a completed system without rewriting existing procedures. Display 3 Region Manager Each region is filled with an object, an instance of a widget class. Each object within the FRAME is assigned and referred to by a unique name. COMPONENTS OF THE FRAME The FRAME entry utilizes a new interactive editing environment and a set of predefined classes. Region Manager, When you edit a FRAME, you use the region manager (an interactive editing environment) for defining rectangular areas within the window called regions. The regions can be moved, copied, resized, repositioned, emptied, and removed. Display 4 Filling Regions Widget Classes The FRAME entry provides a group of predefined classes from which you can create objects. The term widget is often used to describe objects that are a component of a graphical user interface that displays information and/or accepts user entries. When you fill a region with a widget, you are creating an object, an instance of that widget class. Widget Typical Use SAS/GAAPH Output displays stored GRSEG entries (can be hotspotted). Block branches to other application windows (menuing). 568

3 Icon branches to other application windows (menuing). Text Entry provides fm~in the-blank field (single or multiple lines). Text Label provides field labeling. Graphic Text provides labeling and decoration. Push Button issues commands, performs some simple action. Can be used to open a dialog window. Display 6 Example FRAME Entry Other widgets support various graphical widgets and the ability to display table information. Widget Typical Use Graphics real-time generation of plots and charts based on SAS data sets. Extended Table scrollable table of data, output, or graphs. Can be used as a selection list or for data entry. The logical row is composed of other widgets. Display 5 Example FRAME Entry Several widgets enable you to process user selections. Critical Success Factor specialized display for reporting a numeric value within a predefined range. Widget Typical Use Scroll bars vertical and horizontal scroll bars. List Box provides scrollable selection list. Allows multiple selections. Hotspot graphical objects which overlay other objects. Check Box toggles status of item between on and off. Radio Box provides a mutually exclusive selection list Container Box groups other widgets visually. Slider provides numeric selection within a range. Control Object performs a simple action (Le. displaying a selection list). 569

4 Display 8 MAIN.FRAME Entry Display 7 Example FRAME Entry In Release 6.09 an image widget was added to display high-end graph renderings. Release 6.11 will carry a number of new class definitions including catalog entry viewer, command push button, data table, extended input field, extended text entry, external file viewer, image icon, input field, input field label, organizational chart, process flow diagram, report viewer, toolbar, data form, videoplayer, workarea, and the ability to drag and drop. SCREEN CONTROL LANGUAGE SCL Entry FRAME entries are controlled by Screen Control language (Sel) programs which are stored separately from the FRAME in a Sel entry. By default, an Sel entry has the same name as the FRAME. For example, if the FRAME is named MAIN.FRAME, the corresponding Sel entry is named MAIN.SCl. Since SeL programs are stored separately from FRAME entries, you can create more than one FRAME interface that uses the same Sel program without having to duplicate the SCL program for each FRAME entry. The compiled SCl program piggy backs the FRAME it is associated with. Display 9 MAIN.SCL Entry Some FRAME entries do not even require a SCL program because widget attributes and methods allow FRAME entries to perform many tasks without any additional Sel programming statements. SCL Programming Constructs SCl is a programming language designed to facilitate the development of interactive applications. The language combines the syntax of of the DATA step with additional statements and functions that enable developers to control the flow of their applications based on user interaction. Structure sel entries for FRAME entries contain labeled blocks that execute when users perform an action on an object, like selecting it o-r changing its value. Each labeled block begins with a label and ends with a' RETURN statement. SCL statements are executed in sequence within the labeled block. The label for each block of code is the same as the object with'which it is associated. In additional a SCl entry can also have an INIT, MAIN, andlor TERM label. Label Execution INIT executes before the FRAME entry is displayed to the user MAIN executes jf any object is activated after the corresponding object labeled sections have executed. TERM executes when the FRAME is closed by an END or CANCEL command. Methods As part of its object oriented nature, each widget class includes a 570

5 set of methods. These methods define the operations that can be executed by any object you create from that class. Although each widget class includes a set of predefined methods, you can also write your own methods. When you want an object to perlorm an action, you send it the appropriate message. The message is again the name of the receiving object together with the name of one of its methods. To send messages, you use the CALL SEND or CALL NOTIFY routines in the SCL program. For example, the Graphic Text widget class comes with a set of predefined methods or behaviors. Display 11 FRAME in Edit Mode Display 10 Methods for Graphic Text Widget Class Suppose when a user clicks on a graphic text object named TEXT, you want to convert the text to uppercase and change its color and font. The available methods for the graphic text widget class are used. When the user clicks on the object, the TEXT label in the SCL program executes. The CALL NOT! FY function sends messages to the TEXT object to get the current text string value, convert it to uppercase, change its color to CYAN, and change its font to SWISS. leng~h va:ue $25; TEXT: call notify('text', '_GET_TEXT_',value); call notify ('t.ext', '_SET_TEXT_', upcase (value)) ; call notify('text', '_SET_COLOR_', 'cyan'}; call notify('text', '_SET_FONT_','swiss'}; Display 12 FRAME at Display Time re~urn; ILLUSTRATIONS The remainder of this paper examines two FRAME entries, one somewhat simple and the other more complex. Example 1 In this example, 1he FRAME contains five objects. Four of the widgets are graphic text objects and one is a pushbutton object. The female and male pictogram is displayed using a SAS/GRAPH font. When the FEMALE object or MALE object is clicked on, a resized, FSVIEW window displays the appropriate male or female employees from a SAS data set. 571

6 12 sets the position and size of the next window to display 13 displays as a table of rows and columns the "male" employees in a SAS data set 14 sets the color of the MALE object to 'yellow" 15 returns control to the application and refreshes the FRAME Example 2 In this example, the FRAME contains thirteen objects - one pushbutton, two container boxes, three text entries, one slider, three text label, a graphics object, and two control objects. Display 13 SCL Program The source lines in the SeL program perlorm the following functions: Line Function 1 begins the FEMALE label (graphics text widget) 2 sets the color of the FEMALE object to "green~ The graph initially produces a plot of revenue against date for flight "110". The flight number can be changed by entering a new value or using the control object to display a selection list of valid flight numbers. The variable to plot can be changed by entering a new value or using the control object to display a selection list of valid numeric variables. The slider can be adjusted to analyze the data for any week within the quarter time period. The graph re-analyzes the data whenever the flight number, the response variable, or the week value changes. Should the user enter an invalid flight number or invalid response variable, the invalid entry is corrected using selection lists. 3 refreshes the FRAME with the changed color 4 sets the position and size of the next window to display 5 displays as a table of rows and columns the 'female~ employees in a SAS data set 6 sets the color of the FEMALE object to yellow 7 returns control to the application and refreshes the FRAME 9 begins the MALE label (graphics text widget) Display 14 FRAME in Edit Mode 10 sets the color of the MALE object to "green" 11 refreshes the FRAME with the changed color 572

7 6 sets the value of the WEEK object to ~1' (text entry widget) 7 sets the value of the WSUOE object to 1 (slider widget) 8 sets the value of the RESPONSE object to 'REV~ (text entry widget) 9 creates a SAS date value for the variable START 10 creates a variable END 11 sets the minimum value of the WSLIDE object to 1 Display 15 FRAME at Display Time 12 sets the maximum value of the WSUDE object to begins the FL T label 15 subsets the data set according to the value for the FLT object 16 determines the number of observations in the subsetted data 17 begins a DO GROUP if there are no observations in the subset 19 begins the F _ARROW label (control widget) 20 sets the value of the FL T object to a blank Display 16 SeL Program The source lines in the Sel program perform the following functions: removes the current WHERE condition begins a 00 WHILE construct Line Function 23 sets the position and size of the next displayed window 1 begins the INIT label 2 opens the data set the GRAPH object needs (graphics widget) 3 opens the data set for flight departures 4 positions the cursor on the FLT object (text entry widget) sets the value for the FL T object using a selection list of data from a SAS data set terminates the DO WHILE construct terminates the DO GROUP begun on line number 17 5 sets the value of the FL T object to m11 O 573

8 40 begins a DO GROUP ~ the RESPONSE object is blank 41 begins the R_ARROW label (control widget) 42 begins a DO UNTil construct 43 sets the position and size of the next displayed window 44 sets the RESPONSE object to the name of a numeric variable in a SAS data set 45 terminates the DO UNTil construct Display 17 SCL Program (continuation) The source lines in the sel program perform the following functions: 46 terminates the DO GROUP begun on line notifies the GRAPH object to change the dependent variable Line Function 27 begins the WSUDE label 28 sets the WEEK object tn the value of the WSLIDE object 29 constructs a value for NEWSTART 30 creates a value for END 31 subsets the data set using the value for the FlT object and the START and END dates 48 returns control to the application (this RETURN statement terminates the RESPONSE and R_ARROW labels) 49 begins the TERM label 50 closes the data set needed for flight departures 51 closes the data set needed for the GRAPH object 52 terminates the TERM label. 33 notifies the GRAPH object to update itself 34 returns control to the application (this RETURN statement terminates the INIT, FLT. F _ARROW. and WSLIDE labels 35 begins the RESPONSE label SUMMARY The FRAME entry supports the intermixing of text and graphics to compose graphical user interface applications. The FRAME provides a group of predefined classes from which you create objects. The FRAME, predicated on object oriented programming concepts. represents a robust application development environment using such concepts as objects, classes. messages, methods, encapsulation, and polymorphism. 36 determines jf the RESPONSE object is the name of a variable in a SAS data set 37 sets the RESPONSE object to a blank if the variable does not exist 38 sets the RESPONSE object to a blank if the RESPONSE object represents a character variable or the DATE variable 574