ch21.htm

Teach yourself Oracle8 in 21 day

<UL>
	<LI>NCA-compliant applications--These are what the end user sees, and include Web
	browsers, NCA cartridges, and the Oracle Universal Server.
	<P>
	<LI>Cartridges--These pluggable objects provide specific extensible functionality.
	<P>
	<LI>Protocols--These make up the core of the NCA and allow cartridges to exchange
	information via the Inter-Cartridge Exchange (ICX).
</UL>

<H4><FONT COLOR="#000077"><B>Applications</B></FONT></H4>
<P>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:

<UL>
	<LI>Application servers
	<P>
	<LI>Database servers
	<P>
	<LI>Extensible clients
</UL>

<P>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. <B></B></P>

<P><FONT COLOR="#000077"><B>Application Servers</B> </FONT></P>

<P>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. </P>

<P><FONT COLOR="#000077"><B>Database Servers</B> </FONT></P>

<P>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

<UL>
	<LI>Video
	<P>
	<LI>Audio
	<P>
	<LI>Text
	<P>
	<LI>Spatial data
</UL>

<P>These data types, in conjunction with traditional data types, provide a full spectrum
of information to the user. </P>

<P><FONT COLOR="#000077"><B>Clients</B></FONT> </P>

<P>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.</P>
<P>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. <B></B></P>

<P><FONT COLOR="#000077"><B>The Network Computer</B> </FONT></P>

<P>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.</P>
<P>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

<UL>
	<LI>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.
	<P>
	<LI>Phone booths--Replacing traditional phones with phones that allow Web access
	for e-mail or directory information would be great.
	<P>
	<LI>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.
	<P>
	<LI>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
	&quot;Dream for America.&quot;
	<P>
	<LI>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.
</UL>

<H4><FONT COLOR="#000077"><B>Cartridges</B></FONT></H4>
<P>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.</P>
<P>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.</P>
<P>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.
<H4><FONT COLOR="#000077"><B>Protocols</B></FONT></H4>
<P>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.
<H2><FONT COLOR="#000077"><B>Summary</B></FONT></H2>
<P>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.</P>
<P>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.</P>
<P>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.
<H2><FONT COLOR="#000077"><B>What's Next?</B></FONT></H2>
<P>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.</P>
<P>Database technology is an exciting field that changes every day; new products
and new technologies generate tremendous excitement. So above all, <I>enjoy</I>.
<H2><FONT COLOR="#000077"><B>Q&amp;A</B></FONT></H2>

<DL>
	<DD><B>Q What is the Web Publishing Assistant used for?</B>

	<P><B>A</B> The Web Publishing Assistant is used to create static Web pages from
	database data on a regular basis.

	<P><B>Q What is the difference between the Web Publishing Assistant and the Oracle
	Web Application Server?</B>

	<P><B>A</B> 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.

	<P><B>Q What is the NCA?</B>

	<P><B>A</B> 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.

	<P><B>Q What is the NC (Network Computer)?</B>

	<P><B>A</B> The NC is a thin client or computer that is designed to run network applications
	without using local disk storage or an operating system.
</DL>

<H2><FONT COLOR="#000077"><B>Workshop</B></FONT></H2>
<P>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, &quot;Answers.&quot;
<H3><FONT COLOR="#000077"><B>Quiz</B></FONT></H3>

<DL>
	<DD><B>1.</B> What does NCA stand for?<BR>
	<B></B>

	<P><B>2. </B>What does CORBA stand for?<BR>
	<B></B>

	<P><B>3.</B> What is HTTP?<BR>
	<B></B>

	<P><B>4. </B>What is HTML?<BR>
	<B></B>

	<P><B>5. </B>What is a cartridge?<BR>
	<B></B>

	<P><B>6. </B>What is a static Web page?<BR>
	<B></B>

	<P><B>7. </B>What kind of Web pages can you create with the Web Publishing Assistant?<BR>
	<B></B>

	<P><B>8.</B> What is an NC?<BR>
	<B></B>

	<P><B>9. </B>What new types of data can the Oracle Universal Server handle?<BR>
	<B></B>

	<P><B>10.</B> What types of applications would be suitable for an NC?
</DL>

<H3><FONT COLOR="#000077"><B>Exercises</B></FONT></H3>

<DL>
	<DD><B>1.</B> Invoke the Web Publishing Assistant.<BR>
	<BR>
	<B>2.</B> Using the Create Web Page wizard, create a simple Web page.<BR>
	<BR>
	<B>3.</B> Modify this Web page from the Web Publishing Assistant.<BR>
	<BR>
	<B>4. </B>Delete the Web page using the Web Publishing Assistant.
</DL>

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