XML Reference Guide

Mar 14, 2003

␡

⎙ Print

< Back Page 151 of 278 Next >

Almost a decade ago, back when web-based applications were still finding their way, I found myself with a problem. I needed to update a shopping cart page with additional options and prices based on other choices the user had made. Because of customer-sensitive ordering and other factors, generating the changes locally within the browser was impossible; I'd simply have to make a call to the server for the information.

Back then I had a couple of choices. One option was to simply make the user submit the page, and then regenerate it with the correct information. Given that these were the days of dial-up and slow browsers, and that the page itself was very complex, this was not a very attractive option.

The second option was to make a call to the server from within the page. Back then, there was just one way to do it. I rigged up a Java applet that detected the information already in the form, and then used that information to make a call back to the server using an HTTP request. The server sent back a response, which the applet parsed and passed back to another form element using Javascript.

It was ugly, but it worked.

Today we wouldn't have to go through anywhere near as much trouble. Today, rather than wiring together applets and Javascript and waiting for the applet to download, we can simply do everything using Javascript. In fact, today we have the option to do much more, combining JavaScript, HTTP requests, CSS (including DOM-related technologies variously known as DHTML), and XSLT. It's being called a "new approach" to web development, but really, all that's new about it is the name: Ajax, or "Asynchronous JavaScript + XML".

Still, the "asynchronous" part is attractive, and it's making applications much more interactive; the user can simply go about his or her business exploring the page without having to wait for the network operation to finish first. Some good examples of this technique in action include:

Google Suggest analyzes what you've entered as you type, looks up likely choices, and gives you a pull-down list, including the approximate number of results. You then have the option to use your arrow keys to make a choice or to click on a choice.
Backbase includes a number of very cool demos, including a shopping site that displays category products and even enables users to sort items via drag and drop.
Ripped Tickets not only tries to anticipate what you're going to type, but actually looks up the data and displays it on the page as you type and refine your search.
Google Maps is, in some ways, the granddaddy of this technique. Users enter an address and the map appears on the page. Users can also scroll the map, which tries to pre-fetch likely areas. It also uses CSS to provide a pointer that includes a shadow on the actual map. You can also switch back and forth between the map and the satellite image.

OK, so that's what we can do with it, now how does it work?

Let's take the example of Ripped Tickets to start with. I'm not privvy to the inner workings of the site, nor have I sat down and analyzed it -- though that's an option, since this is all in the browser, after all -- but here's how the basic process of using something like this could work:

The page loads. Nothing out of the ordinary here.
The user begins to type in the form box.
The page detects the typing in the form box, either using an event based on the keypress or a timed polling process. (For example, checking the box every second rather than reacting to every keypress of a fast typist.)
JavaScript on the page sends a request to the server with the information the user has already typed and specifies a function to handle the result whenever it comes back. This request is made via either the XMLHttpRequest object (in Mozilla and Safari) or the Microsoft.XMLHTTP ActiveX object (in Internet Explorer).
The JavaScript returns control to the user, who's still free to type more and look around more.
When the response comes back, the function receives it as, say, an XML document.
The script uses XSLT to transform the XML document into the HTML that represents the table.
The script uses the Document Object Model to get a reference to a div element below the search box.
The script uses the Document Object Model to replace the contents of that div with the new results.
The user sees results on the page.

Now, that may seem like a lot going on, but if you visit any of these sites, you'll see that it's not only simple for the user, but much, much, much less disruptive than the old type-submit-wait-read-type cycle.

And really, it's not that difficult to build, when you come right down to it. In the next couple of weeks, we'll build a simple feedreader application that works right in the browser and demonstrates all of these concepts.

< Back Page 151 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