XML Reference Guide

Mar 14, 2003

␡

⎙ Print

< Back Page 250 of 278 Next >

One thing about being a developer is that there are always lots of things to keep track of. Maybe its your "to do" list, or a list of items that need to be fixed, or a list of resource materials to keep track of ... notice a pattern here?

It seems like the first step in almost everything I do is to make a list that breaks a large task (or block of information) into something more manageable. More often than not, that involves making an outline.

Now, I don't know whether they're still teaching outlines in school -- I had to explain them to my teenage son this past week -- but they typically involve multiple levels of information, such as:

Overview

What is XML?

Table of Contents

Programming with XML

The Document Object Model

DOM and Java
DOM and .NET

Simple API for XML

SAX and Java
SAX and .NET

XML in Use: New Languages

DocBook
SVG

Additional Resources

Frequently Asked Questions

Now, you probably know that DOM and SAX are related to Programming, while DOM and Java and DOM and .NET are related to DOM. DOM and Java isn't related to SAX, of course.

In outlining, these relationships are expressed as parent-child relationships, and they translate perfectly into the parent-child relathiponships between elements. For example, I can create an outline like so:

<opml version="1.0">
<body>
<outline text="Overview">
   <outline text="What is XML?"/>
</outline>
<outline text="Table of Contents">
   <outline text="Programming">
      <outline text="DOM">
         <outline text="DOM and Java"/>
         <outline text="DOM and .NET"/>
      </outline>
      <outline text="SAX">
         <outline text="SAX and Java"/>
         <outline text="SAX and .NET"/>
      </outline>
   </outline>
   <outline text="XML in Use: New Languages">
      <outline text="DocBook"/>
      <outline text="SVG"/>
   </outline>
</outline>
<outline text="Additional Resources">
   <outline text="Frequently Asked Questions"/>
</outline>
</body>
</opml>

Just as it is conceptually, the element representing DOM is the parent of the element representing DOM and Java. In fact, this is a specific XML vocabulary called Outline Processor Markup Language, or OPML, which is designed to work with outliners.

Never heard of an outliner? Sure you have. Ever created an outline in Microsoft Word by using the Heading styles? How about navigated your hard drive using Windows Explorer? Those are both outliners, in that they organize information into a hierarchy and enable the user to decide which sections should show more detail.

There was a time when outliners came as separate products, such as MORE and ThinkTank, but now they're built into many products and systems, and with their place as the backbone of applications such as the popular Radio Userland they're gaining popularity in the blogging world. For example, Blogrolling.com, which provides an easy way for bloggers to maintian a list of sites they recommend, allows users to directly import OPML files. The Frontier server automatically detects whether a browser is better off receiving OPML directly or a version transformed into HTML, and returns the appropriate version.

So let's take a look at creating these files.

At it's heart, OPML is remarkably simple. As in the previous listing, an outline is basically outline elements within outline elements. An outline processor such as JOE can read this file and act accordingly.

(This structure, by the way, makes it convenient to include one outline within another.)

By adding some optional metadata elements, we can make this outline even more useful:

<?xml version="1.0" encoding="ISO-8859-1"?>
<opml version="1.0">
<head>
   <title>The InformIT XML Reference Guide</title>
   <dateCreated>Wed, 3 Dec 2003 05:02:23 GMT</dateCreated>
   <dateModified>Wed, 3 Dec 2003 05:02:23 GMT</dateModified>
   <ownerName>Nicholas Chase, Guide</ownerName>
   <ownerEmail>informit@nicholaschase.com</ownerEmail>
   <expansionState>2,3,4</expansionState>
   <vertScrollState>1</vertScrollState>
   <windowTop>100</windowTop>
   <windowLeft>100</windowLeft>
   <windowBottom>300</windowBottom>
   <windowRight>300</windowRight>
   <applyStyleForComments>true</applyStyleForComments>
   <applyStyleForEditability>true</applyStyleForEditability>
   <applyStyleForMoveability>true</applyStyleForMoveability>
</head>
<body>
<outline text="Overview">
   <outline text="What is XML?"/>
</outline>
<outline text="Table of Contents">
   <outline text="Programming">
      <outline text="DOM">
         <outline text="DOM and Java"/>
         <outline text="DOM and .NET"/>
      </outline>
      <outline text="SAX">
         <outline text="SAX and Java"/>
         <outline text="SAX and .NET"/>
      </outline>
   </outline>
   <outline text="XML in Use: New Languages">
      <outline text="DocBook"/>
      <outline text="SVG"/>
   </outline>
</outline>
<outline text="Additional Resources">
   <outline text="Frequently Asked Questions"/>
</outline>
</body>
</opml>

OPML specifies three basic types of optional metadata: identifying information such as title and ownerName, positioning information that's only used when the outline is displayed in its own window, such as windowTop and windowLeft, and information related to the outline itself, such as expansionState and applyStyleForComments. Together, these provide instructions for the processor.

OPML also provides for additonal attributes such as comments.

One common use is for displaying HTML, such as links, so it's improtant to look at a couple of issues that may arise when you try.

Say, for example, that I wanted to create an OPML document out of the blogroll for my personal blog, Chaos Magnet. I'd have to include HTML in the text attribute. If I did that straight, as in:

<?xml version="1.0" encoding="ISO-8859-1"?>
<opml version="1.0">
<body>
   <outline text="<a href='http://xml.informit.com'>The 
       InformIT XML Reference Guide</a>"/>
   <outline text="<a href='http://www.vanguardreport.com'>The 
       Vanguard Science Fiction Report</a>"/>
   <outline text="<a href='xmlhack.com'>XML Hack</a>"/>
   <outline text="<a href='http://www.garybembridge.com/blog.htm'>Gary 
       Bembridge's Weird Stuff</a>"/>
...
</body>
</opml>

we'd have a major problem. In fact, because the first example of OPML I'd ever seen had a construction like this, I'd discounted it as not being "real XML". So what's the problem?

The problem is that well-formed XML can't have a < in an attribute value. All is not lost, however, because you can use XML's predefined entities to solve the problem. This makes the correct version

<?xml version="1.0" encoding="ISO-8859-1"?>
<opml version="1.0">
<body>
   <outline text="&lt;a href='http://xml.informit.com'&gt;The 
      InformIT XML Reference Guide&lt;/a&gt;"/>
   <outline text="&lt;a href='http://www.vanguardreport.com'&gt;The 
      Vanguard Science Fiction Report&lt;/a&gt;"/>
   <outline text="&lt;a href='xmlhack.com'&gt;XML 
      Hack&lt;/a&gt;"/>
   <outline text="&lt;a 
      href='http://www.garybembridge.com/blog.htm'&gt;Gary 
      Bembridge's Weird Stuff&lt;/a&gt;"/>
...
</body>
</opml>

Similarly, you can use the " entity to avoid prematurely closing the text attribte value, as in

<?xml version="1.0" encoding="ISO-8859-1"?>
<opml version="1.0">
<body>
   <outline text="&lt;a href=&quot;http://xml.informit.com&quot;&gt;The 
      InformIT XML Reference Guide&lt;/a&gt;"/>
   <outline text="&lt;a 
      href=&quot;http://www.vanguardreport.com&quot;&gt;The 
      Vanguard Science Fiction Report&lt;/a&gt;"/>
   <outline text="&lt;a href=&quot;xmlhack.com&quot;&gt;XML 
      Hack&lt;/a&gt;"/>
   <outline text="&lt;a 
      href=&quot;http://www.garybembridge.com/blog.htm&quot;&gt;Gary 
      Bembridge's Weird Stuff&lt;/a&gt;"/>
...
</body>
</opml>

And that, in a nutshell, is it. Check out the resources for more information on OPML itself and on uses and other implementations.

< Back Page 250 of 278 Next >

🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Privacy Notice

Overview

Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security

Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children

This site is not directed to children under the age of 13.

Marketing

Pearson may send or direct marketing communications to users, provided that

Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
Such marketing is consistent with applicable law and Pearson's legal obligations.
Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out

Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

As required by law.
With the consent of the individual (or their parent, if the individual is a minor)
In response to a subpoena, court order or legal process, to the extent permitted or required by law
To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
To investigate or address actual or suspected fraud or other illegal activities
To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links

This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020

Email Address