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<FONT COLOR="#000077">Teach Yourself Oracle 8 In 21 Days</FONT></H1>
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<H1><FONT COLOR="#000077">- Day 21-<BR>
Exploring the Web Publishing Assistant and Network Computing Architecture</FONT></H1>
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<P>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.
<H2><FONT COLOR="#000077"><B>The Web Publishing Assistant</B></FONT></H2>
<P>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.</P>
<P>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.
<DL>
<DD><B>1.</B> 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.
</DL>
<P><A NAME="01"></A><A HREF="01.htm"><B>Figure 21.1.</B></A><B></B></P>
<P><I>The initial screen of the Oracle Web Publishing Assistant.</I></P>
<DL>
<DD><B>2.</B> 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.
</DL>
<P><A NAME="02"></A><A HREF="02.htm"><B>Figure 21.2.</B></A><B></B></P>
<P><I>The main screen of Web Publishing Assistant; no Web pages have been created,
so none are defined.</I></P>
<DL>
<DD><B><I><BR>
</I>3.</B> 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.<BR>
<B></B>
<P><B>4.</B> 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).
</DL>
<UL>
<LI>Username--The username that will be used on all queries to access data for this
Web page.
<P>
<LI>Password--The password associated with that username.
<P>
<LI>Database--The name of the database that will be accessed.
</UL>
<BLOCKQUOTE>
<P>
<HR>
<FONT COLOR="#000077"><B>NOTE:</B></FONT><B> </B>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.
<HR>
</BLOCKQUOTE>
<DL>
<DD><B>5. </B>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.
</DL>
<BLOCKQUOTE>
<P>
<HR>
<FONT COLOR="#000077"><B>NOTE:</B></FONT><B> </B>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.
<HR>
</BLOCKQUOTE>
<P><A NAME="03"></A><A HREF="03.htm"><B>Figure 21.3.</B></A><B></B></P>
<P><I>The first screen of the Create Web Page wizard.</I></P>
<BLOCKQUOTE>
<P>
</BLOCKQUOTE>
<P><A NAME="04"></A><A HREF="04.htm"><B>Figure 21.4.</B></A><B></B></P>
<P><I>The second screen of the Create Web Page wizard.</I></P>
<DL>
<DD><B><I><BR>
</I>6. </B>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:
</DL>
<UL>
<LI>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.
<P>
<LI>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.
</UL>
<P><A NAME="05"></A><A HREF="05.htm"><B>Figure 21.5.</B></A><B></B></P>
<P><I>The third screen of the Create Web Page wizard.</I></P>
<DL>
<DD><B>7. </B>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.
</DL>
<P><A NAME="06"></A><A HREF="06.htm"><B>Figure 21.6.</B></A><B></B></P>
<P><I>The final screen of the Create Web Page wizard.</I></P>
<DL>
<DD><B>8. </B>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.
</DL>
<P><A NAME="07"></A><A HREF="07.htm"><B>Figure 21.7.</B></A><B></B></P>
<P><I>Summary of the actions taken by the Create Web Page wizard.</I></P>
<DL>
<DD><B>9.</B> 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.
</DL>
<P><A NAME="08"></A><A HREF="08.htm"><B>Figure 21.8.</B></A><B></B></P>
<P><I>The main page of the Web Publishing Assistant; note that the new Web page appears
on this screen.</I></P>
<DL>
<DD><B>10.</B> 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.
</DL>
<P><A NAME="09"></A><A HREF="09.htm"><B>Figure 21.9.</B></A><B></B></P>
<P><I>The Web page created by the Web Publishing Assistant. Note the added graphics.</I></P>
<P>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.
<H2><FONT COLOR="#000077"><B>The Network Computing Architecture</B></FONT></H2>
<P>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.</P>
<P>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.</P>
<P>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.
<H3><FONT COLOR="#000077"><B>NCA Standards</B></FONT></H3>
<P>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.
<H4><FONT COLOR="#000077"><B>CORBA 2.0</B></FONT></H4>
<P>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.</P>
<P>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.
<H4><FONT COLOR="#000077"><B>HTTP/HTML</B></FONT></H4>
<P>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.</P>
<P>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.</P>
<P>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.</P>
<P>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.
<H3><FONT COLOR="#000077"><B>NCA Components</B></FONT></H3>
<P>The NCA is made up of various components that work together to form the architecture.
These components include
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