Attachment Report

Report on Industrial Attachment with Hewlett Packard Labs, Bristol, England Ivan Low Swee Tieng Publishing Systems Solutions Laboratory HP laboratories Bristol HPL-2000-68 7th June, 2000* Baskerville project, E-services, E-speak, XML user interface The Hewlett-Packard Lab’s goal of engaging in world-class research in the interrelated technologies has resulted in a need to invent new solutions to address the challenges of a web economy – from secure e-commerce, high availability systems to electronic content publishing.

The Baskerville Project, a commercial Printing e-Services project done by the Publishing Systems and Solutions Unit in Hewlett-Packard Laboratory, Bristol, sets to create and develop an infrastructure to enable desktop access to commercial printing capabilities. The students’ project, which contributed to part of the Baskerville Project, requires the students to produce components of a workflow concerning outsourced printing. The two main components will involve web front ends to a prototype printing service under development at HP labs.The technical competencies that will be learned by the students include Object Oriented and Java skills, and Internet and e-service technologies. ? Internal Accession Date Only © Copyright Hewlett-Packard Company 2000 NANYANG TECHNOLOGICAL UNIVERSITY Report on Industrial Attachment with Hewlett-Packard Laboratories Bristol, England Prepared By: Low Swee Tieng, Ivan 983330G06 17 May 2000 SCHOOL OF APPLIED COMPUTER ENGINEERING OVERVIEW Overview This report is organized in the following order: Chapter One: Introduction This chapter explains the Purpose, Scope and Limitation.It also gives an introduction to the Company, Hewlett-Packard Lab, including its background, research goals and university partnerships. Chapter Two: Project Background This chapter summarizes the background information of the ‘ Baskerville Project’ as well as the students’responsibilities.

Chapter Three: Training, Research and Implementation This chapter discusses the training and research done by the students, as well as the results of the implementation. Chapter Four: The Attachment Conclusion This chapter gives the overall conclusion of the industrial attachment and further recommendations for improvement.Chapter Five: Bibliography and References This includes the bibliography and references used by the student. TABLE OF CONTENTS Table Of Contents Overview Table of Contents Table of Figures Abstract Acknowledgements i ii v vi vii Chapter One : Introduction 1 2 3 3 4 5 5 6 1. 1 Purpose, Scope and Limitation 1. 2 Company Background 1. 2. 1 Attached Company – Hewlett-Packard 1.

2. 2 Hewlett-Packard Laboratories in Europe 1. 2. 3 Research Goals 1. 2. 4 E-service and Internet Technologies 1. 2. 5 University Partnerships Chapter Two : Project Background 7 8 9 10 2.

The Baskerville Project 2. 2 The Students’Responsibilities 2. 3 The E-services Problem Set Chapter Three : Training, Research and Implementation 13 14 15 15 16 18 24 3.

1 The Text Editing Application 3. 1. 1 The Java Programming Language 3.

1. 2 Object Oriented Programming 3. 1.

3 Graphical User Interface 3. 1. 4 Implementation of the Menu Items 3. 1.

5 Problems and Difficulties Encountered NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT ii ii TABLE OF CONTENTS 3. 1. 6 Recommendations 3.

1. 7 Conclusion 25 26 3. 2 Text Editing Applet 3. . 1 Overview of Applets 3. 2. 2 Standalone and Downloadable Applet Program 3.

2. 3 What Applets Can and Cannot Do 3. 2. 3. 1 Security Restrictions 3. 2. 3. 2 Applet Capabilities 3.

2. 4 Client/Server Computing with Applets and Servlet 3. 2. 4. 1 Servlet Overview 3. 2. 4.

2 Sending User-defined Input to a Web Server 3. 2. 4. 3 Implementation of the Client Interface 3. 2. 4. 4 Implementation of the Web Servlet 3.

2. 5 Java Documentation Comments 3. 2.

6 Unified Modeling Language 3. 2. 7 Problems and Difficulties Encountered 3.

2. 8 Conclusion and Recommendation 7 28 28 29 29 30 31 31 33 34 35 38 40 42 43 3. 3 Text Editing Service 3. 3.

1 E-speak and E-services 3. 3. 1. 1 What is a service? 3. 3. 1.

2 E-Speak Overview 3. 3. 2 The Design Overview 3. 3.

3 The Flow of Events 3. 3. 3. 1 The Step-by-Step Explanation 3. 3.

3. 2 The Flow Charts 3. 3. 4 The Package Structure 3. 3.

4. 1 Implementation of the Class Attributes And Abstract Methods 3. 3. 4. 2 The Subclasses NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 44 45 45 46 50 52 52 57 59 60 62 iii iii TABLE OF CONTENTS 3. 3.

5 The New Package Structure 3. . 6 Implementation of the Servlet Code 3. 3. 7 Problems and Difficulties Encountered 3. 3. 8 Conclusion and Recommendation 66 67 69 70 3. 4 Introduction to the Extensible Markup Language (XML) 3.

4. 1 What is XML? 3. 4. 2 What’ Wrong with HTML? s 3. 4. 3 Replacing HTML with XML 3. 4.

4 XSL: Converting XML to HTML 3. 4. 5 The Implementation of XML 3. 4. 6 Problems Encountered and Conclusion 71 71 72 73 74 76 76 Chapter Four : The Attachment Conclusion 77 78 80 4. 1 Conclusion 4. 2 Other Experiences Gained Chapter Five : Bibliography and References 81 1 82 82 82 5.

1 Java and Object Oriented Programming 5. 2 HTML, XML and XSL 5. 3 E-services and E-speak 5. 4 Unified Modeling Language NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT iv iv TABLE OF FIGURES Table Of Figures Figure 1. 1 Figure 1.

2 Figure 3. 1a Figure 3. 1b Figure 3. 1c Figure 3.

1d Figure 3. 1e Figure 3. 1f Figure 3. 2 Figure 3. 3 Figure 3.

4 Figure 3. 5 Figure 3. 6 Figure 3. 7 Figure 3. 8 Figure 3. 9 Figure 3. 10 Figure 3. 11 Figure 3.

12 Figure 3. 13 Figure 3. 14 Figure 3. 15 Figure 3. 16 Figure 3.

17 Figure 3. 18Hewlett-Packard’ First Product s The Hewlett-Packard Lab in Bristol The Text Editor Application The File Menu The Print Setup Option Flow of Events (Print) The About-about Menu Item The Flow of Events for the Editor Application Overview of Applets Servlet Overview Editor Interface Implementation of Web Servlet Java Document Comments UML Representation of Class Structure The e-speak Infrastructure The Design Overview Step-by-Step Explanation The Flow of Events for User The Flow of Events for Servlet The Package Structure Class Structure The New Package Structure The XSL Processor A Sample of XML Document A Sample of XSL Document 4 18 18 20 21 22 23 28 31 34 35 38 41 48 50 52 57 58 59 60 66 74 75 75 NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 5 v ABSTRACT Abstract The Hewlett-Packard Lab’ goal of engaging in world-class research in the interrelated s technologies has resulted in a need to invent new solutions to address the challenges of a web economy – from secure e-commerce, high availability systems to electronic content publishing.The Baskerville Project, a commercial Printing e-Services project done by the Publishing Systems and Solutions Unit in Hewlett-Packard Laboratory, Bristol, sets to create and develop an infrastructure to enable desktop access to commercial printing capabilities. The students’ project, which contributed to part of the Baskerville Project, allowed the students to acquire the knowledge of Object Oriented Programming and Software Engineering. The Text Editor Application, the initial part of the E-service problem set, served as an introduction to object oriented programming in Java.The Text Editor Applet faces an applet security that severely restricts functionality, particularly in file access and printing. The project introduced the use of servlet to handle these functions remotely instead.

The Text Editing Service then introduced a new electronic service, which goes beyond the simple client/server model. The former employs many small service components and make sure of the e-speak framework to define the text editor service and interface. From the results of the successful project, it is recommended that the Extensible Markup Language, XML, be used in place of the HTML, which has limited internal structure.XSL, a transformation language for transforming a XML document into an HTML document, can be used to convert the Text Editing applet to talk to the e-speak service. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 6 vi ACKNOWLEDGEMENTS Acknowledgements This attachment was possible thanks to the cooperation and support of a number of people, who have enabled the student to gain much more than what the scholastic or industrial aspects of the program could have given.The student is grateful to them all, and would like to express his appreciation to the following people: • Mr.

Tom Gardner, his IA supervisor in Hewlett-Packard Lab, for sharing enthusiastically with him his experiences in programming. The student is sincerely indebted to him for taking great pains to keep him on the right track. His support and assistance contributed to the success of the project. • Dr. Steve Battle (his partner’ supervisor in HP Lab) for being extremely patient and s for providing advice to the student on his final year project. Dr Ian McLoughlin, the student’s supervisor from NTU, who has helped in coordinating with the administration stuffs and provide valuable assistance in his logbook and report writing. The student would also like to express his appreciation to all the staff and colleagues in the PSP departments for their full support and assistance during the attachment, particularly Dr.

Anthony Wiley, the project manager. He would also like to thank his partner Mr Lee Keng Hock for his help and encouragement throughout the entire industrial attachment. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT vii INTRODUCTION Chapter One Introduction This chapter begins with explaining the purpose of the report; follow by its scope and limitations. It then goes on to give a brief introduction on the history of Hewlett-Packard and the attached company, Hewlett-Packard Laboratories, Bristol. This chapter also covers the research goals of Hewlett Packard, as well as a brief explanation on the Eservices and Internet Technologies. This chapter ends by providing an overview of the Hewlett-Packard’ partnership with the universities.

s NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 1 INTRODUCTION 1. 1 Purpose, Scope and Limitation Purpose The Industrial Attachment program fulfils part of the requirement in pursuing the degree of Bachelor of Applied Science (Computer Engineering) in Nanyang Technological University. This report serves to summaries the activities and experiences gained with Hewlett-Packard Laboratories, Bristol England. Scope and Limitations During the attachment, the student was involved in a commercial printing e-Services group project, known as the ‘ Baskerville Project’ This report will only cover parts of the .

roject, which were done by the student. The experience gained during the attachment had helped the students fulfill the objectives of the attachment. However, due to unforeseen circumstances, the commencement of the attachment was delayed. This resulted in a shortage of time for the completion of the project. Therefore, this report will be limited to the stages of implementation prior to the date of reporting.

Further work and research done after the date of reporting are not described fully in this report.The emphasis of this report will be on the research done by the student, in addition to the experience that he gained during the attachment. Certain assumptions need to be made on the reader’ level of familiarity with computing concepts such as object-oriented s programming and software engineering etc.

Frequent references will be made with regards to these concepts. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 2 2 INTRODUCTION 1. 2 Company Background 1. 2. 1 Attached Company – HP HP was founded in 1939 by Bill Hewlett and Dave Packard.The company’ first product, s built in a Palo Alto garage, was an audio oscillator – an electronic test instrument used by sound engineers.

One of HP’ first customers was Walt Disney Studios, which purchased s eight oscillators to develop and test an innovative sound system for the classic movie “Fantasia”. Today, Hewlett-Packard Company is a leading global provider of computing and imaging solutions and services for business and home. One of HP’ major strategies focuses on s capitalizing on the opportunities of the Internet nd the proliferation of electronic services (e-services). Figure 1.

1 HP’ First Product s NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 3 3 INTRODUCTION 1. 2. 2 Hewlett-Packard Laboratories in Europe In September 1984, Hewlett-Packard took the innovative step of starting up a corporate research laboratory in Europe. Hewlett-Packard Laboratories (HPL) is directed by Dick Lampman, with HPL Bristol being HP’ largest research center outside its headquarters s in Palo Alto, California, and employs around 200 researchers – one third of HPL’ total. sSome of HPL’ research focuses on e-services, e-publishing and technologies needed for s next generation digital imaging. Researchers are coming up with new solutions to address the challenges of a web economy – from secure e-commerce, high availability systems to electronic content publishing; from new ways of browsing the web to devices such as mobile phone, to the display, capture and communications technologies that will be used to build future mobile devices. Figure 1.

2 The Hewlett-Packard Lab in Bristol NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 4 4 INTRODUCTION . 2. 3 Research Goals HPLB’ charter is to engage in world-class research in the interrelated technologies that s will enable people to create, manipulate and share electronic information with others wherever they happen to be, for professional and social purposes. 1.

2. 4 E-services and Internet Technologies HPLB is working to deliver the technology requirements for the next chapter of the Internet and creating the architecture and tools for the development and deployment of eservices. The program of research in e-services and Internet technologies encompasses a broad range of activities.HP’ Internet strategy revolves around creating and delivering services over the Net.

It is s built on the vision of e-services and pervasive computing. An e-service is defined as any asset that is made available via the Internet to drive new revenue streams or create new efficiencies. These can be applications, computing resources or services, processes or information. It’ about the Internet working for you, rather than you working the Net. At s HPLabs, they are inventing the technologies to make this vision a reality. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 5 5INTRODUCTION 1. 2. 5 University Partnerships HPLB has an extensive network of relationships with selected departments in leading academic institutions in over 20 countries, and invests considerable resources to support them.

They are important to HPLB because it shares with the academic community a concern to foster innovative research, and to develop the skills and experience of the people involved in its generation and transfer. Over the past 10 years HPLB has built up a portfolio of programmes to encourage collaboration with universities across a broad spectrum of mutually beneficial activities.Every year HPLB hosts about 50 multinational students who work as members of project teams in Bristol to gain industrial experience for their academic qualifications.

Some of them are jointly funded by their government and HP on ‘ industrial PhDs’ designed to forge long-term links between academia and industry. The student population makes a lively contribution to the quality of life at HPLB, and to its international outlook. HPLB’ university relation’ portfolio is structured with independent but complementary s s programmers to help universities get to know HPLB through the route most appropriate to their needs.Peer-to-peer contacts can give rise naturally to opportunities for sustained external research activities where there is a good match of technologies and skills.

NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 6 6 PROJECT BACKGROUND Chapter Two Project BackGround This chapter gives the reader a brief idea of the project which the student was involved in. It explains the purpose and direction of the project, as well as the responsibilities of the students in the project. Finally, this chapter gives a simple E-services problem set, which aims to develop core competencies required to build new electronic services.NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 7 7 PROJECT BACKGROUND 2. 1 The Baskerville Project BackGround Information The ‘Baskerville Project’ is a commercial Printing e-Services project done by the Publishing Systems and Solutions Laboratory in Hewlett-Packard Laboratory, Bristol. The project group consisted of a project manager, 4 other project members, 2 students from Nanyang Technological University and 1 student from Imperial College. Purpose and Direction The purpose of the project is to create and develop an infrastructure to enable desktop access to commercial printing capabilities.NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 8 8 PROJECT BACKGROUND 2.

2 The Students’Responsibilities The two students would produce components of a workflow concerning outsourced printing. The two main components would involve web front ends to a prototype printing service under development at HP labs. The technical competencies required of the students included object-oriented & Java skills, and the understanding of Internet & eService technologies. Individual ResponsibilitiesMr Ivan Low Swee Tieng (Student from Computer Engineering) To develop a user interface to a print service that allows the user to choose the contents they wish to print, to select from a number of print options, and to accept a printing proposal. Mr Lee Keng Hock (Student from Electrical and Electronics Engineering) To develop an interface that allows the user to monitor and manage the progress of a print job. This includes interrogation of the job history and configuration of an email notification system. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 9 9PROJECT BACKGROUND 2.

3 The E-services Problem Sets The aim of these problem sets is to develop core competencies required to build new electronic services. The students were required to try the problem set so as to gain sufficient experience for implementing the ‘Baskerville Project’. Part One: Text Editing Application This exercise provided an introduction to object oriented programming using Java. The objective was to build a simple text editing application.

The editor was to be able to save and load a document to/from file and print the document. This exercise would require the student to install Java Development Kit (JDK) • develop Project Organization Skill • use of the AWT and IO packages NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 10 10 PROJECT BACKGROUND Part Two: Text Editing Applet This exercise provided an introduction to distributed computing. The objective was to convert the text editing application to run as a downloadable applet. This raised issues regarding the applet security, which severely restricts functionality, particularly in file access and printing. These functions might be remotely handled by a servlet. The students were required to set up a Web Server (install Linux/Apache) • learn Client/Server computing with Applets and Servlets (install JDSK) Part Three: Text Editing Service New electronic services go beyond the simple client/server model, employing many small service components.

The e-speak framework would be used to define a text editor service and its interface. The objective was to convert the existing text editing applet & servlet to work in the e-speak framework. This would require • installing e-speak • thinking about Services, Interfaces and Vocabularies NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 11 11 PROJECT BACKGROUNDPart Four: Text Editing The e-speak client cannot be downloaded by a browser for access via the Internet. But a Java applet can speak to an e-speak service using the eXtensible Markup Language, XML.

The objective was to convert the text-editing applet to talk to the existing e-speak service. This would require • installing e-speak Web-Access • using XML NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 12 12 TRAINING, RESEARCH AND IMPLEMENTATION Chapter Three Training, Research and Implementation This chapter covers all the training and experiences that the student has gained during the attachment.The student and his partner have done the implementation of the project, however only that carried out by the student himself will be discussed in detail. The research and implementation done by the student are described in different phrases, according to the E-services problem set. The reader should note that most of the time spent during the attachment was for training and research, followed by the implementation.

Therefore, this chapter will cover the training and exploratory research carried out by the student first, followed by the results of the implementation. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 3 13 TRAINING, RESEARCH AND IMPLEMENTATION 3. 1 The Text Editing Application The Objective The objective of this problem is to build a simple text editing application, which aims to provide an introduction to object oriented programming using Java. The editor should be able to save and load a document to/from file and print the document. Overview The first part of the project, which required the student to create a Text Editor Application, introduced the concept of object oriented programming in Java.

The student made use of the Abstract Windowing Toolkit (AWT) to design the graphical user interface (GUI) for the editor.The editor comprised a frame, menu bar and menu items, and also command buttons, if required. The student also decided on the possible menu items to be included in the program, as well as their individual implementation. Basic Requirements • Java Development Kit (JDK) • Basic Programming Skill • Text Editing software NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 14 14 TRAINING, RESEARCH AND IMPLEMENTATION 3. 1. 1 The Java Programming Language The Java programming language is a state-of-the-art, object-oriented language that has a syntax similar to that of C.The language designers strove to make the Java language powerful, but at the same time, they tried to avoid the excessively complex features that have bogged down other object-oriented languages, such as C++. By keeping the language simple, the designers also made it easier for programmers to write robust, bugfree code.

3. 1. 2 Object Oriented Programming Based on the knowledge of function-oriented C Programming, it is not difficult to write the Editing Application. The challenge, however, is to use a totally new language, Java, and to program using Object Oriented Programming.The main difficulty is how to think in an Object Oriented way.

In Function Oriented Programming, all the user has to do is to write a function to solve a problem. However, in Object Oriented Programming, it is a totally different approach. In Object Oriented Programming, the user will have to think of the problem as a set of objects. Then, the user will have to define the class and the methods, which the object may require, as well as the different attributes and their values. To have a better understanding of object oriented programming in Java, visit the web site at http://web2. ava. sun.

com, which gives an introduction of Java programming. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 15 15 TRAINING, RESEARCH AND IMPLEMENTATION 3. 1. 3 Graphical User Interfaces The first step to any interface program is to create the interface of the program. The interface of the text-editor requires only a frame, a menu bar with some menu items and command buttons. This in turn, requires the Abstract Windowing Toolkit (AWT), which defines all the GUI components in Java.

Note that these components comprise the java. awt package.There are basically four steps to creating a GUI. The steps are listed below with an example given for each of the individual step.

Step 1: Create the component A GUI component can be easily created just like any other object in Java, simply call the constructor. E. g. Button open = new Button (“Open”); Note that the components are typically created in the init () method of an applet or in the constructor of a standalone application (or in a private method invoked by one of those methods). NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 16 16 TRAINING, RESEARCH AND IMPLEMENTATIONStep 2: Add the component to a Container All components must be placed within a container.

Containers in Java are all subclasses of java. awt. Container. E. g. this.

add (open); Step 3: Layout the components within their containers A LayoutManager object can be use to automatically lay out the components of a container according to certain layout rules defined by the particular LayoutManager chosen. E. g. this. setLayout (new BorderLayout (10, 10)); Step 4: Handle the events generated by the components When working with GUI, it is more common to handle the higher-level semantic events that are generated by the components themselves.Java 1. 1 provides different eventhandling models, which can be used.

E. g. public void mouseDragged (MouseEvent e) { NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 17 17 TRAINING, RESEARCH AND IMPLEMENTATION 3. 1. 4 Implementation of the Menu Items The menu bar and its menu items formed the major part of the program. It is the menu items that tell the program what the user wants to do. It is also the main graphical interface for the user. Figure 3.

1a below shows the Text Editor interface implemented by the student. Figure 3. 1a The Text Editor ApplicationThe following sections explain the individual menu items and their functions. Refer to Figure 3. 1b below for the graphical representation of the menu items. Figure 3.

1b The File Menu NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 18 18 TRAINING, RESEARCH AND IMPLEMENTATION File-New This will clear the contents in the editor text area. A new file with no initial filename will be created. File-Open This menu item allows the user to open a file from anywhere within the system. The FileOpen menu item displays an Open Dialog Box for the user to choose the file they want.The user may choose an existing filename or create a new file. File-Save This menu item allows the user to save the file without having to specific the filename. This means that the contents of the editor will be saved into the same file, or rather, the default filename.

File-SaveAs This will be different from Save as this will requires the user to enter a filename. There will be no default filename available. The user normally uses this function instead of the Save function when they want to specify a filename. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 19 19 TRAINING, RESEARCH AND IMPLEMENTATIONFile-Close This will close the existing file.

It will clear all the contents in the text area. File-PrintSetup This will allow the user to define how they want their printer layout to be like. The editor allows the user to specify the type of paper size most suitable for the document, the printing orientation, the number of pages etc. Refer to Figure 3. 1c for the diagram. Figure 3.

1c The Print Setup Option NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 20 20 TRAINING, RESEARCH AND IMPLEMENTATION File-Print This allows the user to print a hardcopy of the contents of the editor.The student has to ensure that the program is able to print according to the user specification. For example, the user may want a margin of 2 inches, a landscape orientation, start printing from page 3 to page 6, and print 4 copies each etc.

A flowchart of how the program takes care of all these is shown in Figure 3. 1d below. Figure 3. 1d Flow of Events (Print) NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 21 21 TRAINING, RESEARCH AND IMPLEMENTATION File-Quit This will exit from the editor. About-about This will display a new window that shows the date and author of the editor.Dialog boxes in Java are implemented using the Dialog class. An information dialog is a dialog box that lets the writer specify the message to be displayed. This dialog box makes use of a MultiLineLabel class that displays multiple static lines of text, which is something that the AWT Label class is incapable of doing.

Much of the code is taken up with the mechanics of breaking the label into separate lines and measuring the size of each of those lines. It made use of the paint () method, getPreferredSize () and getMinimumSize () method. Refer to Figure 3.

1e for the graphical representation of the frame.Figure 3. 1e The About-about Menu item NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 22 22 TRAINING, RESEARCH AND IMPLEMENTATION Flow of Events Figure 3. 1f below shows all the possible flow of events that may occur. The user is allowed to select any of the following commands from the menu. Note that this program only serves as an introduction to the actual project, and at the same time illustrating the concepts of object oriented programming in Java, which is an essential element for the progress of the actual project. Figure 3. 1f The Flow of Events for the Editor ApplicationNANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 23 23 TRAINING, RESEARCH AND IMPLEMENTATION 3.

1. 5 Problems and Difficulties Encountered The main difficulty that the student encountered was the implementation of the program using the concept of Object Oriented. The student, with 4 years of programming experiences in C using Function Oriented concept, found it hard to adapt to using a totally different concept. Although the student was using objects and classes to write a program, there still existed a mixture of both programming concepts.It took the student quite some time to really understand how to make full use of the concept of Object Oriented Programming, such as the superclasses, object and the class hierarchy. Not being able to understand fully the concept of Object Oriented Programming, and also the syntax of Java language, the student also found it hard to organize the program structure in the initial stage. As the student progress further, he started to realize that the code became very long and disorganized.

Many parts of the codes would be redundant if the concept of Object Oriented Programming was used in the first place.Another difficulty encountered by the student was to print the document according to the specification of the user. The student has to ensure that the program is able to print according to the different margins set by the user, the different paper sizes, the different orientation, such as landscape and portrait, and also according to the specified start and end pages. This required the student to have very good knowledge on the superclass Printable in the Java API, as well as the page format, e. g.

the DPI, the font size, font height and font ascent etc. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 24 24TRAINING, RESEARCH AND IMPLEMENTATION 3. 1. 6 Recommendations The first recommendation that the student wished to make is for the writer to have sufficient knowledge of the concept that he is going to use, in this case Object Oriented, before he really start on the actual program.

It is advised that the Unified Modeling Language (UMI) be used at the design stage to get a clearer picture of how the classes and methods are to be defined or constructed. This will help in ensuring that the writer will be able to make full use of each individual class, its properties and methods, and also the advantages of class inheritance, method overridden etc.Another recommendation for the Text Editor application is to use the Java Document Comment. The student did not realize the usefulness of Java Doc, until the later part of the attachment when the supervisor told him. Although the student still managed to use the Java Doc for certain parts of the program codes, implementing it at an earlier stage would have helped the student in debugging, and at the same time, ensured that the supervisor and everyone else had a good understanding of the program. Finally, the student would like to suggest that the program have a help file (if time allowed).A new menu item, called Help, should be included in the menu bar to assist those users who may not have enough computer knowledge. This Editor program should cater to anybody, thus a help file would be helpful.

NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 25 25 TRAINING, RESEARCH AND IMPLEMENTATION 3. 1. 7 Conclusion The implementation of the first part of the project enabled the student to get used to writing a program using the Object Oriented concept and to know more about the new programming language, Java.It was a very useful experience for the student, as Java programming generally improves the programmer’s efficiency. Java is a simple and elegant language with a well-designed, intuitive set of APIs. Programmers are able to write better code with fewer bugs than with other platforms, thus reducing development time. Being able to use the Object Oriented concept to design and implement a problem, the student now found himself more confident in implementing the next stage of the project, which required the student to make use of applet and client/server communication. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 6 26 TRAINING, RESEARCH AND IMPLEMENTATION 3.

2 Text Editing Applet The Objective The objective of this problem was to convert the text editing application to run as a downloadable applet. This part of the project provided an introduction to distributed computing. The student was also able to experience the applet security that severely restricts functionality, particularly file access and printing. A servlet was then introduced to handle this problem. Overview In the second part of the project, the student created a downloadable applet, using the existing Text Editor Application.The current Text Editor Application was only able to run as a standalone program. It was not able to run in any web browser.

To convert it to run as a downloadable applet meant enabling it to run in any web browser. In the later part, the student discovered that the applet had certain security rules, which restricted the functionality of the Editor program. Thus, the student decided to use the servlet to handle that problem. Basic Requirements • Java Servlet Development Kit (JSDK) • Web Server NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 27 27TRAINING, RESEARCH AND IMPLEMENTATION 3. 2.

1 Overview of Applets Every applet is implemented by creating a subclass of the Applet class. The following figure shows the inheritance hierarchy of the Applet class. This hierarchy determines much of what an applet can do and how. Figure 3. 2 Overview of Applets 3.

2. 2 Standalone and Downloadable Applet Program In the previous editor program, the program was only allowed to run as a standalone program. In this part of the project, the text editor was improved so that it could be displayed using any web browser, such as the Internet Explorer.To do this, the program had to be written using Applet. However, there were some security restrictions, which limited the use of applet in certain applications. The next section gives an overview of what an applets can and cannot do.

NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 28 28 TRAINING, RESEARCH AND IMPLEMENTATION 3. 2. 3 What Applets Can and Cannot Do This section gives an overview of both the restrictions applets face and the special capabilities they have. 3.

2. 3. 1 Security Restrictions Every browser implements security policies to keep applets from compromising system security.This section describes the security policies that current browser adhere to. However, the implementation of the security policies differs from browser to browser. Also, security policies are subject to change.

Current browsers impose the following restrictions on any applet that is loaded over the network: • An applet cannot load libraries or define native methods. • It cannot ordinarily read or write files on the host that’ executing it. s • It cannot make network connections except to the host that it came from. • It cannot start any program on the host that’ executing it.

s • It cannot read certain system properties. Windows that an applet brings up look different from windows that an application brings up. Each browser has a SecurityManager object that implements its security policies. When a SecurityManager detects a violation, it throws a SecurityException. The applet can catch this SecurityException and react appropriately. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 29 29 TRAINING, RESEARCH AND IMPLEMENTATION 3. 2.

3. 2 Applet Capabilities The java. applet package provides an API that gives applets some capabilities that applications don’ have.

For example, applets can play sounds, which other programs t cannot do yet.Here are some other things that current browsers and other applet viewers let applets do: • Applets can usually make network connections to the host they came from. • Applets running within a Web browser can easily cause HTML documents to be displayed. • Applets can invoke public methods of other applets on the same page. • Applets that are loaded from the local file system have none of the restrictions that applets loaded over the network do. • Although most applets stop running once you leave their page, they do not have to. To have a better understanding of the applets, please refer to the website at the following URL: http://web2.

ava. sun. com/docs/books/tutorial/applet/index. html Directly or indirectly, this website covers everything one needs to know to write a Java applet. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 30 30 TRAINING, RESEARCH AND IMPLEMENTATION 3. 2.

4 Client/Server Computing With Applets and Servlet Due to the applet security, which severely restricts functionality, the downloadable applet editor program will not be able to access any file, which means that the user will not be able to open, save or print any file. These functions, however, can be remotely handled by a servlet. . 2. 4. 1 Servlet Overview Servlets are modules that extend request/response-oriented servers, such as Java-enabled web servers.

For example, a servlet might be responsible for taking data in an HTML order-entry form and applying the business logic used to update a company’s order database. Figure 3. 3 Servlet Overview NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 31 31 TRAINING, RESEARCH AND IMPLEMENTATION Servlets are to servers what applets are to browsers.

Unlike applets, however, servlets have no graphical user interface.Servlets can be embedded in many different servers because the servlet API, which is used to write servlets, assumes nothing about the server’s environment or protocol. Servlets have become most widely used within HTTP servers; many web servers also support the Servlet API. Other Uses for Servlets Here are a few more applications for servlets: • Allowing collaboration between people.

A servlet can handle multiple requests concurrently, and can synchronize requests. This allows servlets to support systems such as on-line conferencing. • Forwarding requests.Servlets can forward requests to other servers and servlets. Thus servlets can be used to balance load among several servers that mirror the same content, and to partition a single logical service over several servers, according to task type or organizational boundaries. For a more detailed explanation on servlets, the user is advised to refer to the web site at: http://web2. java.

sun. com/docs/books/tutorial/servlets/index. html The Servlets trail teaches one about servlets, the bodies of code that run inside servers and extend their functionality.NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 32 32 TRAINING, RESEARCH AND IMPLEMENTATION 3.

2. 4. 2 Sending User-Defined Input to a Web Server The first thing to do is to get a user input from a web browser to a web server. Fortunately the HTTP protocol provides two main ways to send information to a web server above and beyond the URL of a requested file, that is, the POST and GET methods. The GET Methods The foundation of HTTP/0. 9 (the first implementation of the HTTP protocol) was the definition of the GET method that was used by a web browser to request a specific document.The web browser formulates the actual GET request, sends it to the web server, receives the HTML document back, and then displays the HTML document according to the HTML instructions. Problems With The GET Methods Though the GET method was very useful, a couple of serious problems remained.

First, the GET method only allowed a limited amount of data (1024 characters) to be sent as URL encoded data. If there were too many name/value pairs, some of them would be clipped and data would get lost. Further, since the information was sent as part of the URL, the user could see all of that data.

On the one hand, that made URL’s look really ugly and scary. On the other hand, it meant that the user got to see all of the inner workings of the CGI input. These all changed with the development of HTTP/1.

0. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 33 33 TRAINING, RESEARCH AND IMPLEMENTATION The POST Methods The HTTP/1. 0 protocol was developed from 1992 to 1996 in order to satisfy the need to exchange more than simple text information.

The POST method of input was one of the important changes brought about by the introduction of HTTP/1. 0.The POST method allowed web browsers to send an unlimited amount of data to a web server by allowing them to tag it on to an HTTP request after the request headers as the message body. Typically, the message body would be the old familiar encoded URL string after the question mark (? ).

3. 2. 4. 3 Implementation of the Client Interface An editor interface was created as the client, using HTML. Microsoft FrontPage was use as a straightforward HTML editor.

The editor will only require a Text Input for the filename, a Text Area for the user to edit the text, and a couple of Buttons for the different functions.A menu will no longer be needed. A sample of the editor interface is shown in Figure 3. 4. Figure 3.

4 Editor Interface (Client) NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 34 34 TRAINING, RESEARCH AND IMPLEMENTATION 3. 2. 4. 4 Implementation of the Web Servlet The web servlet is supposed to handle the information sent over by the client.

The client program used the Post method of input to send an unlimited amount of data to the web server, and the servlet used the doPost method to handle the data received. The servlet then determine whether the user wants to open, close, save or print a file at the web browser.The servlet will then create a new HTML form with all the required information and display it on the web browser. The diagrams and explanation below describe how the client activates the servlet to perform the expected task. In Figure 3. 5a below, the Editor Program will only activate the servlet when the user select any of the command buttons below.

Figure 3. 5a Implementation of the Web Servlet: Step 1 NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 35 35 TRAINING, RESEARCH AND IMPLEMENTATION However, the user can also choose to edit the text in the text area or use the browse button to select or view the filename.Both options will not activate the servlet as they do not require any access to file. The servlet will only be activated when the user select a function that required access to any file. When either of the command buttons is selected, the Editor Program (Client) will then send the information to the servlet. The servlet will now determine which button is selected and react accordingly to what the user wanted.

This is shown in Figure 3. 5b below. Figure 3. 5b Implementation of the Web Servlet: Step 2 NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 36 36 TRAINING, RESEARCH AND IMPLEMENTATIONWhen the servlet finished executing the task expected by the user, the servlet will then reprint a new copy of the Editor Interface on the browser and wait for the next command button to be selected. This is again shown in Figure 3. 5c below. Figure 3. 5c Implementation of the Web Servlet: Step 3 This basically complete the second part of the problem set, which is to use the servlet and applet application to create a downloadable Editor Program. The next section will cover two other aspects learned during the implementation of the project: the Java Documentation Comments and the Unified Modeling Language (UML).NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 37 37 TRAINING, RESEARCH AND IMPLEMENTATION 3. 2. 5 Java Documentation Comments Most ordinary comments within Java code explain the implementation details of that code. In contrast, the Java language specification defines a special type of comment known as a doc comment that serves to document the API of the code. A doc comment is an ordinary multiple line comment that begins with /** (instead of the usual /*) and ends with */. The following figures show the implementation of the java doc, as well as the output of the java doc in a web browser.Figure 3. 6a Java Document Comments NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 38 38 TRAINING, RESEARCH AND IMPLEMENTATION Figure 3. 6b The Package Structure Figure 3. 6c Java Method Summary NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 39 39 TRAINING, RESEARCH AND IMPLEMENTATION 3. 2. 6 Unified Modeling Language The UML is the standard language for visualizing, specifying, constructing, and documenting the artifacts of a software-intensive system. It can be used with all processes, throughout the development life cycle, and across different implementation technologies.The UML combines the best of the best from • Data Modeling concepts (Entity Relationship Diagrams) • Business Modeling (work flow) • Object Modeling • Component Modeling In this project, the student made use of the UML modeling elements in class diagrams, that define the classes and their structure and behavior, association, aggregation, dependency and inheritance relationships, multiplicity and navigation indicators and role names. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 40 40 TRAINING, RESEARCH AND IMPLEMENTATION A simple UML model is shown in Figure 3. 7 below.Figure 3. 7 UML Representation of Class Structure In the above example, class Editor is a subclass of Applet. It has two attributes; number and name, and a method call textChange (). It can consist of 0 to infinity number of objects, which is an instance of class InfoDialog. InfoDialog, on the other hand, is a subclass of Dialog. It has two attributes; label and alignment, and a method called setLabel(). This simple example illustrates part of the program code done by the student on the Text Editor Applet. To have a better understanding in UML, please refer to the web site at http://www. ational. com/uml/index. jtmpl NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 41 41 TRAINING, RESEARCH AND IMPLEMENTATION 3. 2. 7 Problems and Difficulties Encountered The first problem that the student encountered was the limitation of the GET method. The client, which is also the web browser, made use of the GET method to communicate with the servlet. The web browser formulates the actual GET request, sends it to a web server, receives the HTML document back, and then displays the HTML document according to the HTML instructions.However, the student did not noticed that the GET request only allowed a limited amount of data (1024 characters) to be send as URL encoded data. Therefore when the user selected a huge file to be saved or print, the servlet was unable to process the request. This problem was solved when the student discovered the new POST method, which was introduced by the HTTP/1. 0. The POST method allowed web browsers to send an unlimited amount of data to a web server by allowing them to tag it on to an HTTP request after the request headers as the message body.For a more detailed explanation on servlets, the reader is advised to refer to the web site at: http://web2. java. sun. com/docs/books/tutorial/servlets/index. html Another problem that the student encountered is changing the output in the HTML interface, after the users made their selection. In HTML, the whole interface has to be reprint by the servlet, even it only consists of a small change in the output. This in fact lengthens the program code, and at the same time, limited the flexibility of the editor interface at run time. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 42 2 TRAINING, RESEARCH AND IMPLEMENTATION 3. 2. 8 Conclusion and Recommendation In this part of the attachment, the student has managed to understand how the client and server can communicate to each other, overcoming the security restrictions imposed by the applet. However, using the HTML form to represent the client application was not a really good way. This is because the HTML form requires the servlet to reprint the whole interface whenever a change needed to be imposed (reflected) on the client interface. This lengthens the servlet program, and is not a good way of organizing the program structure.The alternative method of using Java code to write the applet application may be a better option. The only problem is that it will be more tedious to draw the graphical user interface using Java API, compared to using HTML. However, the Java allowed changes to be made on the interface without reprinting the whole interface. Due to the time constraint, this suggestion is not implemented. Thus, this section can be concluded with the understanding of the application of applets, client/server communication, and the use of servlet to overcome the limitation, or security restrictions of the applets.The next section will cover the next part of the project, which required the student to acquire the knowledge of E-services, E-speak, and XML. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 43 43 TRAINING, RESEARCH AND IMPLEMENTATION 3. 3 Text Editing Service The Objective This part of the project covers both the third and last part of the E-services problem set. These parts of the problem set have been done concurrently by the student and his partner. The objective is to use the e-speak framework to define a text editor service and its interface.The existing text editing applet will be converted to talk to the e-speak service. Overview This is the final part of the problem sets, and it requires the student to acquire the knowledge of e-speak and the XML. New electronic services go beyond the simple client/server model, employing many small service components. This project will use the e-speak framework to define a text editor service and its interfaces. However, the e-speak client cannot be downloaded by a browser for access via the Internet. A Java applet can speak to an e-speak service using the extensible Markup Language, XML.Thus, the textediting applet will be converted to talk to the existing e-speak service. The Requirements • E-speak • E-speak web-access • Understanding of e-services, interfaces and vocabularies • XML / XSL NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 44 44 TRAINING, RESEARCH AND IMPLEMENTATION 3. 3. 1 E-speak and E-services Please note that only the research and training done on the e-speak and services will be covered in this report. The actual implementation of e-speak and services, done by the student’ partner, will not be covered here. s 3. 3. 1. 1 What is a service?A service is traditionally considered to be a stand-alone application with a well-defined interface. For example, an instance of an ERP system, such as a SAP instance, may be considered a service. Similarly, a file system is considered a service. In the e-speak world, a service is not necessarily restricted to a unit such as an application. Instead, the granularity of a service is much smaller. Think differently about what constitutes an e-speak service. Anything that can be described with a unique set of attributes is a service. Functions are invoked directly on this service. Reference for E-service: http://www. hp. om/e-services NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 45 45 TRAINING, RESEARCH AND IMPLEMENTATION 3. 3. 1. 2 E-Speak Overview E-speak is an open software platform designed specifically for the development, deployment and intelligent interaction of e-services. With e-speak, users and e-services can interact regardless of their hardware or operation systems, system management strategies, development environments, or device capabilities. Any service can become manageable by using the e-speak service management framework. Services do not need to explicitly add mechanisms to become manageable.The e-speak event infrastructure enables publish, distribute and subscribe operations across a geographically distributed environment and across multiple protection domains. This event infrastructure coupled with the security and management framework supported in e-speak, provide a comprehensive platform for managing service deployments that require dynamic business collaborations. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 46 46 TRAINING, RESEARCH AND IMPLEMENTATION The e-speak engine is a software that performs the primary e-speak functions of: Discovery Once an e-service is e-speak-enabled, the provider registers it with a host system connected to and accessible by the Internet. During registration, the provider creates a description of the e-service that consists of its specific attributes. Users looking for e-services then describe the type of service they want and e-speak will automatically discover registered services that have the desired attributes. • Negotiation After discovering e-service providers, e-speak negotiates between the requester and the provider to weed out any that offer services outside the criteria of the request. Mediation Once a user and an e-service have been brought together, e-speak is able to continuously monitor service delivery and make adjustments, or “mediate”, in real time. No other Internet technology or standard available today performs this function. • Composition In the near future, e-speak-enabled e-services will be able to combine themselves into more complex, cascading e-services, even-on-the-fly. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 47 47 TRAINING, RESEARCH AND IMPLEMENTATION A Simple Example AThe following section provides a simple example of an e-speak Service written that illustrates some of the basic ideas in the e-speak infrastructure. Client Service DiscoveryA A Client first creates a new connection to an e-speak Core. After connecting to the Core, the Client can look up or register Services. The Client locates a Service that satisfies a constraint expressed with attributes in the default Vocabulary. The result of the find Service is a stub (or proxy) to the Service provider’ Service. Clients can use this stub as s a network object reference and directly invoke methods on the Service (see Figure 3. 8). Figure 3. The e-speak Infrastructure NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 48 48 TRAINING, RESEARCH AND IMPLEMENTATION Client Service Usage A Clients interact with the Service with the set of interfaces for which stubs are available in the Client address space. Clients can preinstall the Service stubs that are generated using the e-speak IDL stub generator, or they may acquire the stub class from the Service provider by other means. When a Client invokes an operation, a well-defined e-speak custom serialization is used to ship the invocation to the target Service through the mediating e-speak infrastructure.In so doing, all method invocations are effectively mediated. Reference for E-speak: http://www. e-speak. net NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 49 49 TRAINING, RESEARCH AND IMPLEMENTATION 3. 3. 2 The Design Overview The Text Editor program was rebuilt using e-speak and HTML. It looked like the old Text Editor, but was much better. The student looked at the front-end which has to work out what goes into the dialog box using information from the print service. His partner, on the other hand, built the back-end services and worked out how to talk to them.Figure 3. 9 The Design Overview User: This is a web browser, such as the Internet Explorer, which allows the user to view the software. This is also considered as the client. Print Server: This is the servlet where the program codes of both the student and his partner will speak to each other. Print Gateway: This is where all the print services are located. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 50 50 TRAINING, RESEARCH AND IMPLEMENTATION The whole idea can be better explained by looking at the Figure 3. 9 provided above.First, the student and his partner decided on the (java) interface between the two work packages. A package structure has to be worked out in which each work-package is a java sub-package. The student had to work out the minimal requirements and dependencies between the two packages. The servlet is the point of interaction between the two packages, as both the student and his partner will be coding part of the servlet. Next, the student’ partner implemented a print server based on the existing printing s code. The print server can also be asked to list its print options that will go into the dialog box.He also implemented a file service for storing and saving text files. The file service can be asked to list the files it already contained so that the student can browse them remotely. He also wrote the part of the servlet code that finds the services and mediates between them and the student’ code. s As for the student himself, he reused his existing editor’ interface to allow the user to s browse and open existing files, and create, edit, save files. When the user prints a file, the servlet requests the printing options, and builds the corresponding dialog box.The options chosen by the user are passed to the servlet when the user starts the print. The main idea is that the dialog is not hard-coded but is extensible at run-time. The aim is to look at several different ways of doing this, from HTML forms generated dynamically in the servlet, to an XML representation of the dialog box transformed in to HTML using XSL either in the servlet or the client, if time permits. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 51 51 TRAINING, RESEARCH AND IMPLEMENTATION 3. 3. 3 The Flow Of EventsNote that for the implementation of the design, the Text Editor Applet was used to simulate the web browser application, which is also the client, in this case. 3. 3. 3. 1 The Step-by-Step Explanation Section 3. 3. 3. 2 contains the flowcharts for both the client and the servlet. Please refer to the flowcharts in the next section, along with the step-by-step explanation. Step 1: The User Initiation The user selects a file or creates a new text by editing in the text area of the Text Editor. The user then presses the Printer Setup button. Please refer to Figure 3. 10a.Figure 3. 10a The User Initiation NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 52 52 TRAINING, RESEARCH AND IMPLEMENTATION Step 2: Client-Servlet Communication This will activate the servlet, which will immediately get a list of print options from the print server through the use of an object, which is an instance of a package structure. The structure of this package will be explained in the next section. Also take note that as shown in Figure 3. 9, there are actually three ways, which the Editor applet (client) can communicate to the servlet.The first method uses the HTML form to display the interface onto the browser and to pass information. The second method uses the Java operating system code to create the interface, and the last method creates a XML document and uses the XSL transformation language to transform it into a HTML document, which can be display in the web browser. Step 3: Servlet Execution Based on the set of print options obtained from the print service, the servlet will now decide what format will be used to display the print option, for example using a select button, a text area, or an option button.The servlet will then display the print options on the browser to allow the user to make their choice. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 53 53 TRAINING, RESEARCH AND IMPLEMENTATION Step 4: The User Selection Based on the available print options provided by the program, the user will then proceed to make their choice. When the user selects the Submit button, all the information will be send to the servlet. This is shown in Figure 3. 10b. Figure 3. 10b The User SelectionTake note that the above presentation of the print options is decided by the package structure, which will be discussed in the later part of the report. However, the representation of the interface is not an important part at this point in time. This is because the focus is on the implementation of the program and its functionality. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 54 54 TRAINING, RESEARCH AND IMPLEMENTATION Step 5: The Servlet Validation of the Information The servlet will now check if all the values entered by the user are valid.If any of the data is invalid, the servlet will print the error message accordingly. This is shown in Figure 3. 10c below. Figure 3. 10c The Servlet Validation of the Information The user, after being prompted by the program, is expected to make the changes. Possible errors that can be detected by the program include: • Keying in of non-number input into a numeric text box; that is, a text box that only allows numbers. • No input in the text box, or rather, an empty field. • Using of space in the beginning of the text field. E. g. Name:NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 55 55 TRAINING, RESEARCH AND IMPLEMENTATION Step 6: Finalization of the Information If there is no error, the servlet will now display a copy of the finalize choices made by the user (refer to Figure 3. 10d), and at the same time, create an object that contains all the printing information, and send it back to the Print Service Provider (PSP). Figure 3. 10d Finalization of the Information When the user selects the Finish button, the user will go back to the Text Editor, and the user has just completed his request for the print service.The following section shows the flow charts for the flow of events for both the user (client) and the servlet. NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 56 56 TRAINING, RESEARCH AND IMPLEMENTATION 3. 3. 3. 2 The Flow Charts Figure 3. 11 shows a flow chart on how the user (client) activates the servlet. Figure 3. 12 shows how the servlet reacts to the client and performs the necessary execution as well as it creates the user interface and communicates between the client (web browser) and the print service. Figure 3. 1 The Flow of Events for User NANYANG TECHNOLOGICAL UNIVERSITY OVERSEAS INDUSTRIAL ATTACHMENT REPORT 57 57 TRAINING, RESEARCH AND IMPLEMENTATION Figure 3. 12 The Flow of Events for Servlet NANYANG TECHNOLOGI