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Web Services Essentials

By Mike Kaltschnee

 

When the company I work for said they were working on a new technology called Web services, I turned to O'Reilly & Associates to learn more about how they worked. They publish a book called Web Services Essentials, by Ethan Cerami (ISBN # 0596002246, 304 pages, $29.95). Remember that DACS members get a 20% discount on O'Reilly books (send me an e-mail for the secret code). My bookshelf is filled with many of the O'Reilly animal-covered books that have helped me keep up with technology over the years.

A Web service is a program that is run on a Web server, typically by another Web server. Web services are self-describing and discoverable, which means there should be little or no human intervention when someone wants to access your Web service (unless there is a fee or license agreement required for use). Web services are a way for Web servers to communicate, typically using XML (extensible markup language). The final part of Web services is the transport layer, usually HTTP (hypertext transfer protocol -- the same protocol used to view Web pages, hence the "http://" in http://www.dacs.org), but can also be SMTP, FTP, or even BEEP.

Web services work across virtually any platform on the Internet, including Windows, Sun, Apple, Unix, Linux, etc. Virtually every programming language has been enabled to work with Web services. Microsoft's .Net is based around Web services, demonstrating how important this technology is and will be in the future.

Both Google and Amazon have made Web services available. When you visit Amazon.com, you are running programs on their Web server from your Web browser to search and order books. Amazon made some of their programs available to other companies, who are doing very interesting things with the Amazon Web services. One example of how powerful this concept can be is www.Yes.net, which enables you to buy music that is playing on your local radio station at Amazon - while you're listening!

In the case of my company, we've developed Web services our partners can use to get access to our images (I work for the stock photography agency www.IndexStock.com). Our partners are printers, software developers, and companies that use photos as part of their product offering. In the old days, we used to send photos on CD to them, and they would add them to their product. This was time-consuming and limiting -- we have 650,000 photos, and it would be hard to send all of them to all of our partners.

We have set up two Web services, “Image Search” and “Image Download.” One of our business partners can add a search Web Service in as little as a few days to their product, giving them access to all or part of our image collection. We have more than a terabyte of photos, so the partner is saving time and storage costs by using the Web service. Once an image is needed, they can use our Image Download Web Service to access the photo at a variety of sizes.

I picked up Ethan's book with high expectations. O'Reilly books are typically the best on a topic, and I wasn't let down. Ethan spends a lot of time going over the intricacies of the four major Web service components: XML-RPC (XML remote procedure call), SOAP (simple object access protocol), WSDL (Web service description language), and UDDI (universal description, discovery and integration). The examples are well thought-out and he explains key topics clearly.
The major issue I have with this book is the heavy use of Java, which I have only a tiny bit of experience with. With more than 90% of computers today running some form of a Microsoft operating system, I expected more .Net examples. If you are interested in a more detailed book, you have several choices for specialized .Net, Perl, or even Macromedia Flash Remoting, all available on www.ora.com.

This book is for people with a technical or programming background, and I recommend learning more about XML before venturing into the interesting world of Web services. More information on Web services can be found at:

Web services are changing my job, making it faster and easier for our partners to get access to our images (and making it faster and easier for us to sell more photos). I like where all of this technology is going!


MIKE can be reached by e-mail: mikek@demorgan.com. He hasn’t setup a personal UDDI service — yet.

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