RIAs (rich Internet applications) are all the rage now, and for good reason: Given the wide availability of high-speed Internet service, they have the potential to combine the ease-of-access of Web applications with the ease-of-use of desktop applications. Curl, which is a programming language, an IDE, and a runtime engine, was actually ahead of its time back in 2003, when I wrote about Curl 2.0 for Byte.com. However, broadband access wasn't quite so widespread at the time, and the idea of RIAs didn't seem quite so compelling.

The Bottom Line Curl 5.0 Curl, curl.com/ Very Good  8.6 criteria score weight Capability 9 30% Ease of development 8 30% Documentation 8 15% Performance 9 15% Value 9 10% Cost: Curl/Personal, free; Curl/Personal Server, free for Internet use. Curl/Pro, $598 per seat, including Curl/Pro RTE testing license. Enterprise deployment licenses start at $12,000 per URL per year, plus $150 per named user per year. SaaS deployment licenses, $12,000 per URL per year plus $20 per user per year. Internet Pro deployment licenses start at 10 cents an application launch. OEM deployment licenses are a value-based percentage with a floor. Platforms: Windows 98/NT, or later, with IE 5 or later, Netscape 4.7x or 7.2, or Firefox; RedHat 9, SuSE 9, or Turbolinux 10 or 11 with Mozilla, Konqueror or Firefox; Beta viewer (no IDE) for Mac OS X with Safari or Firefox Bottom Line: Curl has several attractive features as an RIA environment, including excellent performance, strong graphics support, and good data handling. Although the Curl language, library, and tools are not hard to learn, they will be new to most programmers. Curl should be on most companies' RIA evaluation lists. About our Reviews and Scoring Methodology

[ See also: InfoWorld Technology of the Year Awards Application Development winners | Screencast: Curl 5.0 ]

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That's all changed. Curl 5.0, available in both a Personal and Pro edition, is now positioned as an industrial-strength RIA platform: It has all the good attributes of RIAs -- Web-enabled, lightweight, and a rich interface -- plus additional characteristics that make it suitable for enterprise use. Curl applications can handle intermittent connectivity, support large data sets, run securely, and present complex user interfaces gracefully.

The commercial Curl I'm writing about here needs to be distinguished from curl or cURL, the command line tool for transferring files with URL syntax, and the bindings for libcurl available for many languages. Curl was originally developed as an MIT research project; this is a spin-off from that project.

So why haven't you heard about Curl? Curl of Cambridge, Mass., was acquired by Sumisho Computer Systems of Japan in 2004, and Curl was primarily marketed in Japan until this spring.

With an 8MB runtime engine, Curl 5.0 falls near the middle of the range of rich Internet clients as far as "heaviness." It falls near the high end of the range when it comes to runtime performance. It has an impressive JIT (just-in-time) compiler with code caching and good support for graphics hardware. This is quite clear from some of the standard Curl demos and samples, especially the ones that demonstrate ray tracing.

Ray tracing is one of the most compute- and graphics-intensive types of applications, and Curl can actually compute and display animated ray-traced scenes at reasonable frame rates. Curl runs hundreds of times faster than JavaScript, and it comes close to native code speed for many applications.

Easy does it
Curl's original design goals were to unify documents and applications; to provide markup, scripting, and object-oriented programming in one environment with high performance; to create interactive UIs with a minimum of code; to support rapid development; and to be a "gentle slope" language. By "gentle slope," Curl's designers mean that all APIs can be extended, simple tasks require only simple code, and the language needs only the minimum of boilerplate code.

In my experience, Curl meets most of these goals at the language level, and the visual layout editor picks up the slack in the area of rapid UI development.