Accessing HTML DB (again)
In a browser session,
entering http://server:port/pls/htmldb
should take you to the login page we have seen before.
Note the version number in
the lower right hand corner: 1.6.0.00.87 (at least the 1.6 part should be the
same).
Login as a user and note the
differences. The user interface has a different look and feel, and the upgrade
process, true to form, did migrate existing applications.
How to Implement a Web Service
This example consumes only
six pages in the 2 Day Developer guide, so let's run through this small example
and see just how easy (and accurate) the steps are. The individual sections
(starting on page 6-2) are discussed below.
Section Title: Creating a New Application
The very first step, "From
the Application Builder home page, click Create Application" is incorrect.
The "Create Application" button is at the home page (the page you see
immediately after logging in).
Progress check: On Step 7
(select a theme), there are 12 themes to choose from (the sample says to pick
Theme 2). The workflow process is (as before) shown in the left margin area.
The red border of Theme 1 should look familiar if you have been to the AskTom
Web site.
Section Title: Specifying an Application Proxy Server Address
More than likely, this
section does not apply to you. If you are doing this at home and use Comcast
High-Speed Internet service (as an example), you are not using a proxy server.
Section Title: Searching a UDDI Registry for a Business Name
This section involves
providing input for the UDDI registry used to find a WSDL. UDDI? WSDL? The
explanation of these items in the 2 Day Developer guide is fairly dry. A better
description of what a Universal Description, Discovery, and Integration
registry and a Web Services Description Language document are can be found at
W3Schools (http://www.w3schools.com/wsdl/wsdl_uddi.asp).
This is getting pretty far away from Oracle, but do realize that Oracle
Corporation is a participant in this cross-industry effort to use UDDI. The
example mentioned at the W3Schools site is based on an airline reservation
system, so the applicability of a database (i.e., Oracle) providing the data
should be fairly obvious.
If you follow the steps
exactly as written in the guide (Step 6 - select "IBM UDDI" followed
by "%xMethods%" followed by clicking Search), the end result is:
ORA-20001: The webservice was unreachable because either the
URL you supplied was invalid, or your environment requires a valid proxy server
address for HTTP requests.
A missing bit of information:
what is meant by "select IBM UDDI" is use the oddly designed drop
down menu button to the right of the text field. Click that button and a popup
window with a list of choices appears. That's where/how you select IBM
UDDI v2.
After clicking the menu
button, select IBM UDDI v2:
The location field is then
filled in for you:
At the next step, entering %xMethods%
(note the lowercase "x" after the leading per cent symbol, it kind of
blends in if you don't read that too closely), toggle the xMethods Delayed
Stock Quotes radio button.
The Web Service Summary
gives you an overview of what you just selected.
Your confirmation of
success:
Section Title: Create a Form to Display a Stock Quote
Run through the first six
steps as written. The end result is:
Click Run Page and login
(use the same user you are already logged in as, but why do you have to login
at all at this point?). I used ORCL for Oracle and ran the query.
This completes the first
example shown in the developer guide.
In Closing
Overall, the upgrade process
is fairly straightforward. The use of a script to perform the upgrade is
somewhat of a departure for Oracle as many products use the Universal Installer
or some other GUI interface. As you watch the output or feedback statements
scroll by when htmldbins is running, note that there are over 1000 different
pages being created, which is pretty impressive. It is obvious a significant
amount of work went into the development of HTML DB.
The process shown for
creating a Web service is almost exact with respect to the steps required in
each section. The omission in how to select IBM UDDI is a show stopper, and you
would think that Oracle would follow conventional Web or application design
standards for indicating a drop down menu list, or use a button with a label
saying Select, View, or Browse.
Just for fun, you can
navigate to the icons folder, open the view_small.gif file, rotate it 180
degrees and save it. The icons folder is located under the virtual path ("/i/"
from before) at HTML DB HOME\marvel\images\htmldb\icons. The end result is:
Finally, the odd (and new) part
of the database setup or structure is the "flow" naming, and getting
to a point where most of the Oracle community understands the HTML DB
architecture as well as it understands standard database or application
architecture will take some time which will happen as HTML DB gains more
acceptance and use. In the next article of this series, I will cover another
example from the 2 Day Developer guide and point out some additional resources
for HTML DB.
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