Topic 5: Visual and Script

1. Topic 5: Visual and Script Visual programming

2. Learning outcomes By the end of this topic, you should be able to: 1. Explain visual programming concepts by using the Visual Basic software as an example; 2. Explain the script programming concept as well as the client-server concept; and 3. Differentiate between scripts and object-oriented programming

3. Introduction • Visual and script programming are the programs that will be the main focus in this course. • You will need to understand and be able to use these programs as a means of solving the various problems that you will face later. • Visual and web programming uses algorithms and object orientation. • Both algorithms and object oriented programming were developed to solve problems related to object orientation or normal programming

4. Visual programming • Visual refers to the representation of an object in graphical form. Objects in visual programming are labels, text boxes, buttons and others. These objects are available in the visual programming language. • Graphical representation enables programs to be developed effortlessly. The program also appears more interesting to the user. In visual programming, you are given a special environment during the development of the program. • There are many different types of software that are available in this category. One of them is Microsoft Visual Basic.

5. A Property is something that can be changed. A buttonÊs color or size can be modified. Pictures can also be placed on the button. • Events are actions that take place when the user does something to the object. • In Visual Basic programming, there are a variety of events for each object used. For example, among the events that exist for a control button object are click (), double click (), mouse up () and others.

6. Introduction to visual basics • There are many software that use visual programming concepts, for example Visual C++, Visual J++ and Visual Interdev among others. In visual programming, you will only be using objects that are represented for the purpose of programming. • Among these objects are labels, text boxes, list box control buttons, combo boxes and others.

7. Sample interface (form1)

8. Visual basic criteria • The following are the criteria in Visual Basic: (a) The program development environment is to write and implement a program using Visual Basic. (b) The language contains syntax rules and the appropriate algorithm representation. (c) Support functions and components must be prepared to enable a computer to implement the VB program.

9. Visual basic components • Visual basic is programmed in an IDE (Integrated Development Environment). An IDE can: (i) Contain space to build graphic interface and provide space for the programmer to write either structural or object-oriented programs. (ii) You can build an appropriate sub program that is compatible to the main program developed.

11. Script • Script is a programming concept that is different from structural and objects-oriented programming • Script cannot be used without the support of client-servers. Unlike normal programming languages, script is dependent on Web servers for its implementation. When developing script, testing is conducted in the Web browser that supports it. • Script does not have its own space to build programs. HTML editors that are available in the market, provide the space needed by programmers to place scripts in HTML tag codes

13. Generally, a script program will need at least: (a) A server; and (b) A web browser that supports the script. HTML is the most important code used in building websites. Either server programs or client programs can support static HTML. This is commonly known as script. Among the programming languages that can be used to write scripts are Java Script and VBScript. Scripts can be divided into two types, namely server (normally using CGI) and client. An example of CGI language is Perl and C.

14. Criteria for script programming • Generally, the purpose of a script is to prepare more dynamic HTML documents. • Script can also receive input from users through suitable use of form. It can also confirm whether the data received is useful or not. • Script can be used for the following purposes: (i) Choosing menu's provided in HTML documents. (ii) Detect errors. (iii) Enabling delivery of information forms. (iv) Downloading pictures. (v) Mouse commands and functions

15. Clients – server concept • Earlier, the relationship between script programming and the client-server system was stressed on. The client-server system is more structured compared to normal computing. • The client’s computer will ask the server to perform a specific task. The server will execute the task by generating useful information for the client. • The server may also be a client of other servers. Both the server and the client will perform their own processes. This process can be done by the same computer or by separate computers.

17. Summary • Visual refers to the representation of an object in graphical form. • Objects in visual programming are labels, text boxes, buttons and others. • These objects are available in the visual programming language. • Graphical representations are objects that are designed by the developer of visual language. They are designed by using object-oriented programming techniques. • Graphical representation enables programs to be developed effortlessly. The program also appears more interesting to the user. • In Visual Basic programming, there are a variety of events for each object used. For example, among the events that exist for a control button object are click (), double click (), mouse up () and others.