Teach Yourself Oracle 8 In 21 Days
Teach Yourself Oracle 8 In 21 Days
- Day 21-
Exploring the Web Publishing Assistant and Network Computing Architecture
In this final lesson of the book, I will teach you about the Oracle8 Web Publishing Assistant, a new product that provides a simple yet very effective method of publishing database information on the World Wide Web. You will learn how to use the Web Publishing Assistant to create Web pages. I'll also introduce you to the new and exciting world of the Oracle Network Computing Architecture (NCA). Finally, you will learn about some of Oracle's products, including the Web Commerce server, the Web Application server, and data cartridges.
The Web Publishing Assistant
The Web Publishing Assistant is a new product with Oracle8 for NT for publishing Web pages. Rather than being a sophisticated system for creating Web pages on the fly, the Web Publishing Assistant is a lightweight, easy-to-use utility for creating Web pages from database data. These Web pages are static but are re-created on a regular basis, so they remain up to date.
Perform the steps that follow to extract data from an Oracle database and create a static Web page. Later you will take steps to instigate the automatic re-creation of this Web page on a regular basis. This allows you to keep Web page information current without having to access that data online.
- 1. After you invoke the Web Publishing Assistant from the Oracle for Windows NT program group, you will be greeted by the screen shown in Figure 21.1. If you do not wish to see this screen every time you invoke the Web Publishing Assistant, deselect the checkbox at the bottom of the screen.
The initial screen of the Oracle Web Publishing Assistant.
- 2. After you look at the welcome screen, click the OK button to invoke the main screen of the Web Publishing Assistant (shown in Figure 21.2). This screen shows you what active Web pages you have defined; in this case, you have defined no Web pages, so the screen is blank. After you create a Web page, information about the page and its update frequency will be displayed here. Each Web page created by and under the control of the Web Publishing Assistant will have a line of information here, as you will see later in this section.
The main screen of Web Publishing Assistant; no Web pages have been created, so none are defined.
3. To create a new Web page within the Web Publishing Assistant, you can use the Create Web Page wizard. This wizard steps you through the process of creating a new Web page. To invoke the wizard, select Web Page | New or click the New button.
4. Regardless of how you invoked the wizard, you will now see the wizard's first screen. Use this screen to define the database connection that will be used to retrieve the data. This screen requires you to enter the following data. These values will be used for the database connection (see Figure 21.3).
- Username--The username that will be used on all queries to access data for this
- Password--The password associated with that username.
- Database--The name of the database that will be accessed.
NOTE: Access into Oracle is based on username, password, and database (SID). This allows multiple users to create Web pages based on their own access into the Oracle database.
- 5. Use the second screen to define what data will be displayed on the Web page. This can be an entire table, as shown in Figure 21.4, or a query. Queries are useful if you want to use a join operation to display data from multiple tables. You can also accomplish this by accessing a previously created view. For simplicity, I chose the entire table here.
NOTE: To simplify complex table accesses within the Web Publishing Assistant, you can use other means to create a view into these tables. After the view has been created you can use the Web Publishing Assistant and specify that view as the data source.
The first screen of the Create Web Page wizard.
The second screen of the Create Web Page wizard.
6. The third screen, shown in Figure 21.5, is crucial to the operation of the Web Publishing Assistant: This screen is used to define the schedule of the updates. The Web page will be refreshed from data in the database according to this schedule. The schedule that you choose for each Web page should be based upon the following criteria:
- How often the data changes--If the data does not change on a daily basis, it
is not necessary to frequently update the Web page.
- The required accuracy of the data--If this data must always be up to date, the Web Publishing Assistant must refresh that data often. The Web page itself does not automatically identify its refresh time, but you can easily add that information.
The third screen of the Create Web Page wizard.
- 7. The final screen, shown in Figure 21.6, allows you to define the name of the Web page to be created as well as the formatting information. After you create a few pages, you might find you are dissatisfied with the default formatting and want to add your own. Feel free to customize the HTML code to meet your needs.
The final screen of the Create Web Page wizard.
- 8. As with all of the Oracle tools, you are provided with a screen that summarizes the actions taken (see Figure 21.7). However, this step is redundant because scheduling has already occurred and the page has been created.
Summary of the actions taken by the Create Web Page wizard.
- 9. As shown in Figure 21.8, the main screen now shows information about the Web page that was created in the Create Web Page wizard. You can modify or delete this Web page from this screen. You can also refresh the Web page by clicking the Generate button.
The main page of the Web Publishing Assistant; note that the new Web page appears on this screen.
- 10. This new Web page can be added to the path that your Web server uses. You can even add graphics to the page, as shown in Figure 21.9.
The Web page created by the Web Publishing Assistant. Note the added graphics.
I think the Web Publishing Assistant is straightforward, easy to use, and quite effective. You simply rebuild a Web page on a regular basis from data in the database. You can modify the refresh rate and Web page template to suit your needs.
The Network Computing Architecture
The Network Computing Architecture (NCA) is a framework developed in part by Oracle for network computing. The NCA can be used to define applications that can be run either over the Internet or an intranet.
The NCA is a common set of technologies and products designed to help all systems work more closely together. The NCA's purpose is to join database servers, application servers, and Web servers under a common architecture, open to all vendors, that applications can use to communicate with each other.
The NCA consists of many different components, and in this lesson I provide brief overviews of several. Some of these components consist of the standards that make up the NCA such as CORBA 2.0 and HTTP/HTML. Other components consist programming languages such as Java. Still other components consist of distributed objects, data cartridges, thin clients, and so on.
The NCA is based on open standards that are available to all vendors. These standards allow independent programs to work together and to fit into the architecture regardless of who developed them. The main standards that the NCA employs are CORBA 2.0 and HTTP/HTML. Due to the development of a standards-based architecture, all vendors have an equal chance of developing high-quality applications; no vendor receives special advantages.
The Common Object Request Broker Architecture (CORBA) standard is a specification developed by a consortium called the Object Management Group (OMG), which is made up of over 600 companies from all areas of the computer industry. The CORBA standard defines a distributed architecture with an open communication channel between objects. When vendors program to this communication channel, their application can communicate and exchange information with other CORBA-compliant applications.
TCP/IP has been defined as the network-transport protocol for intersystem communication. For communication between different systems, an Internet Object Request Broker has been defined. This Internet Object Request Broker uses TCP/IP as its transport layer. If one adheres to these standards, intersystem and inter-OS communication is possible.
The Hypertext Transport Protocol (HTTP) defines today's World Wide Web. This standard allows Web browsers to communicate with Web servers. This protocol, in conjunction with the Hypertext Markup Language (HTML), is what makes Web browsers work.
HTTP is the specification that defines the communication between servers and browsers. This specification is freely available to all vendors; indeed, it is freely available via the World Wide Web. Simply go to your favorite search engine and search for HTTP.
HTML is the language used to define Web pages. If you look at the source code of a Web page, you will see the HTML code that builds that page.
Web browsers use HTTP to communicate and HTML to define what they will be displaying on the Web page. It is necessary for both of these components to exist for you to properly receive and display World Wide Web information.
The NCA is made up of various components that work together to form the architecture. These components include
- NCA-compliant applications--These are what the end user sees, and include Web
browsers, NCA cartridges, and the Oracle Universal Server.
- Cartridges--These pluggable objects provide specific extensible functionality.
- Protocols--These make up the core of the NCA and allow cartridges to exchange information via the Inter-Cartridge Exchange (ICX).
Applications are the most visible part of the NCA because they are what you, the end user or developer, will work with. The applications that comprise the NCA include but are not limited to the following:
- Application servers
- Database servers
- Extensible clients
These components have one goal: to deliver information to the user. This delivery of information can occur regardless of the operating system of the client or server, and regardless of the brand of Web browser you use, as long as these components meet the specification.
The application server is one of the NCA's key components. An application server is essentially a Web server that supports application cartridges for HTTP/HTML-based programs. You can think of application servers as controlling the application. Application servers, in conjunction with the database servers, provide the application code and data that end-users need and want.
The Oracle Universal Server provides the performance and scalable data storage that today's applications demand. With the advent of the NCA, the Universal Server has been extended to provide many new data types to accommodate the type of corporate data used today. These new data types include
- Spatial data
These data types, in conjunction with traditional data types, provide a full spectrum of information to the user.
Web clients have become fairly standard, but tremendous competition remains as new technologies develop every day. What is important is that along with any proprietary components added to the Web browser, the core standards such as HTML and Java are available. In this way you can develop applications that adhere to these standards without worrying about whether they'll work on certain systems.
I prefer to program to the lowest common denominator by not using proprietary extensions. If you do the same, your application will work on a variety of platforms without requiring major rewriting of code.
The Network Computer
Oracle and others are working on a new type of system called the Network Computer (NC), which is essentially a thin client or Internet Web browser in a box. The NC is very inexpensive and has the advantage of no operating system and no disk drive. Having no OS and no disk drive means that there are fewer parts to break. The component of a computer system that is most likely to fail is the disk drive because disk drives are mechanical and will eventually wear out.
I think the NC will supplement, not supersede, the PC. There are many circumstances where a PC and its local storage are not required, and the NC will work well in those cases. For example, to provide Web access to guests in a hotel, you would not want to place PCs in every room. With a PC you would have to reformat the disk and reload the OS after each guest departed to guarantee that the he or she did not leave any information on the system. Other examples of circumstances where NCs would work nicely include any places where a traditional terminal is in use and more data access is necessary, such as
- Airline terminals--At ticket gates, most airlines still use terminals. Replacing
them with NCs is practical because no local storage is needed and PCs would require
a lot of maintenance. All application access is to the main server, not a local database,
so an NC would be ideal.
- Phone booths--Replacing traditional phones with phones that allow Web access
for e-mail or directory information would be great.
- Retail stores--You could replace traditional cash registers with NC registers.
Information such as inventory in other stores and product descriptions (with graphics)
could be added.
- Schools--Instead of placing expensive PCs in classrooms, NCs could be used. This
would allow each student to access the Internet, which is a goal of Larry Ellison's
"Dream for America."
- Large corporations--Many large corporations do not need each user to have his own personal data storage and an expensive PC. The use of NCs would provide low-cost access to all corporate applications and data.
Cartridges are plug-in applications that are typically specific to a single application. You can provide a wide range of applications by installing several different cartridges that can work together.
Think of a cartridge as an object that might serve one or more purposes. This object uses an Interface Definition Language (IDL) that allows it to identify itself to other objects in a distributed system. A cartridge can be written in a variety of languages, such as Java, Visual Basic, C++, SQL, and so on.
The cartridge itself also uses a software bus called the Inter-Cartridge Exchange (ICX). ICX allows cartridges that are part of a distributed system to communicate with each other. With ICX, a cartridge can communicate with other cartridges, clients, servers, database servers, and so on.
Other key components of the NCA are the components and standards that comprise it, such as TCP/IP, HTML/HTTP, and CORBA 2.0. These were described earlier today in the section on NCA standards.
Today you learned about the Web Publishing Assistant and were introduced to the Oracle Network Computing Architecture (NCA). The Web Publishing Assistant is a new and innovative product that creates Web pages accessible by whatever Web server you use. These static Web pages are periodically updated by the Web Publishing Assistant. The NCA standard specification is designed to join database servers, application servers, and Web servers under a common architecture to allow common access over a network. This infrastructure is open to all vendors to promote a common architecture that applications can use to communicate with each other. In this lesson you were introduced to the NCA and the components that comprise it, such as CORBA, HTTP/HTML, and Java. The NCA is just getting started; you will hear more and more about it in the next few years.
As you have seen in the past 21 days, the Oracle Server product offers a tremendous amount of information and functionality. The purpose of this book has been to introduce the Oracle8 server. Nonetheless, I have tried to be thorough; there was so much information in many cases that I was required to speak at a more advanced level.
I hope these 21 days gave you the knowledge necessary to perform the functions of an Oracle DBA or an informed user, but book knowledge is no substitute for experience. Your next step is to practice and gain experience as an Oracle8 DBA or user.
Because you have finished reading the book, your next step is to practice what you have learned. I hope you have access to an Oracle8 system and can use Enterprise Manager to build databases, tablespaces, and tables. Try different things to see what new skills you can acquire. If you have problems grasping a function or concept, don't give up. If you persevere, you will eventually understand. Fully understanding each component will serve you well in the long run; most aspects of the Oracle RDBMS build on each other.
Database technology is an exciting field that changes every day; new products and new technologies generate tremendous excitement. So above all, enjoy.
- Q What is the Web Publishing Assistant used for?
A The Web Publishing Assistant is used to create static Web pages from database data on a regular basis.
Q What is the difference between the Web Publishing Assistant and the Oracle Web Application Server?
A The Oracle Web Publishing Assistant creates static Web pages from database data whereas the Web Application Server dynamically creates Web pages based on database data.
Q What is the NCA?
A The NCA, or Network Computing Architecture, is a set of standards that defines how computing over the Internet or an intranet will be conducted in the future.
Q What is the NC (Network Computer)?
A The NC is a thin client or computer that is designed to run network applications without using local disk storage or an operating system.
The workshop provides quiz questions to help you solidify your understanding of the material covered and exercises to provide you with experience in using what you've learned. For answers to quiz questions, see Appendix A, "Answers."
- 1. What does NCA stand for?
2. What does CORBA stand for?
3. What is HTTP?
4. What is HTML?
5. What is a cartridge?
6. What is a static Web page?
7. What kind of Web pages can you create with the Web Publishing Assistant?
8. What is an NC?
9. What new types of data can the Oracle Universal Server handle?
10. What types of applications would be suitable for an NC?
- 1. Invoke the Web Publishing Assistant.
2. Using the Create Web Page wizard, create a simple Web page.
3. Modify this Web page from the Web Publishing Assistant.
4. Delete the Web page using the Web Publishing Assistant.
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