Simeon Simeonov

I’ve been around software for 20 years now. Looking back, I have mixed feelings about the progress we’ve made. The end results have been amazing but the process of building software hasn’t fundamentally changed since the 80s. In fact, I see us make some of the same mistakes over and over again. One of the common anti-patterns is over-relying on tools and frameworks instead of inventing new programming models. Layers of abstraction are fundamental to software. Some layers are defined through programming models, e.g., machine language, assembly language, 3GLs, JSP. Others are defined through a combination of tools and frameworks, e.g., MFC and Visual Studio on top of C++. There is a limit to how high we can raise a level of abstraction through tools and frameworks alone. At some point, a new programming model is the best way forward. Here are some examples: CASE tools ... (more)

XML in Transit: Encoding Data

I just came back from the first face-to-face meeting of the W3C working group on XML Protocol (is it just me, or is the name somewhat odd-sounding?), and I'm wondering what topics to exclude from this column. Yes, that's right - exclude. Encoding data in XML is a difficult topic for many reasons. First, it's one of those technical subjects in which you need to look at lots of XML instance/schema/DTD snippets. Second, the devil is very much in the details and there are lots of them. Last but not least, there are as many ways to encode data in XML as there are data encoding needs. ... (more)

SOAP - What is this thing called SOAP? Here's the Background, Part 1

I wanted to kick off this new column on XML protocols with an introduction to the hot newcomer in this arena - Simple Object Access Protocol (SOAP). Trouble is, there are too many ways to go about the topic. The first version I wrote was a technical introduction to SOAP laced with references to some of the important ongoing debates on XML protocols and XML distributed computing. When I finished I found that the two threads - detailed technical information and higher-level issues - interfered with each other. So I decided to focus on the technology in the next issue and devote thi... (more)

SOAP Part 2

The last edition of the XML in Transit column (XML-J, Vol. 1, issue 4) introduced the Simple Object Access Protocol (SOAP). Instead of dwelling on technical issues, it focused on the driving forces behind the technology. To put SOAP into context we looked at its history, parsed the buzzword-compliant phrase ubiquitous XML distributed computing infrastructure and scoped the SOAP specification within the broader set of standards likely to emerge in this area. One possible layering of SOAP and related specifications is shown in Figure 1. The areas already covered by SOAP are grayed... (more)

Web Services Description Language

It's time to look at the details of the Web Services Description Language (WSDL) specification and, in particular, how abstract information about Web services is represented in XML and which extensibility mechanisms enable the binding of abstract specifications to concrete implementations. We start with a quick review of the WSDL information model. In the last XML in Transit (XML-J, Vol. 2, issue 2), we derived an information hierarchy for describing Web services by asking what, how, and where questions. The what question points us to the abstract specification of a Web service.... (more)