[pragma]

I am proud to announce the addition of this project, DSP, to dsource.org.

Many thanks to Brad, our humble host.

Status:
At present, the project stands as a proof-of-concept for using D as a dynamic web programming language, as embedded in HTML. This technology is very similar to ASP, PHP and Cold Fusion, but truely borrows most of its inspiration from JSP.

The engine is running as an apache plugin coded mostly in D, that parses and transforms requests for .dsp pages into servlet .dll files. These are then loaded and executed as a part of the engine to complete the request. The dll is then kept in an in-memory cache which is then replaced with another build once any of its dependencies (the originating .dsp file for instance) is modified. Right now it also only compiles on Win32, with plans to replace the OS-specific bits with Matthew's Loader interface.

Design:
The DSP Engine itself utilzes the same compile-on-demand semantics that JSP uses. This means that the first hit to a page will always be the longest, with subsequent hits running as fast as the compiled code. Fortunately for us, Walter's D compiler runs amazingly fast, leaving us with a technology that could possibly run circles around JSP.

The core of the DSP engine is a flexible parser/processor which converts the syntax of a .dsp file into a servlet .d file, suitable for compilation into a .dll or .so. The parser itself is not an XML parser, as .dsp's do not have to be well formed documents.

The DSP offers a combination of JSP-like elements ("<? ?>" and "<@page >") as well as reundant, valid xml-style elements ("<dsp:output />" and "<dsp:page />"). This non-orthogonal approach to the dsp grammar was done to allow .dsp documents to be both familiar to JSP/ASP/PHP programmers, yet provide an alternate syntax should the .dsp need to validate as XML. The latter is a key design point since .dsp expressed as XML can be easily pre-processed by XSLT, or any XML-aware server plugin. Plus, the document is more explicit and readable.

Planning:
The next stage involve refactoring the implementation using the Concurrent and Mango D libraries. This should make for a very solid alpha release. At a minimum should feature bare-bones servlet support. possibly with application-level objects to provide context for sessions and the like.

Already working:
- Apache plugin (prototype RAD)
- Conversion of .dsp requests into (re)usable servlet libraries.
- Recompilation of servlet libraries on demand.
- Servlet compilation dependency model

Already somewhat working:
- Nested Servlets (or "custom tags" if you will).
- Application-level objects (ties into per-dir config for apache)
- Proper Read-Write locking for the servlet library cache
- ASPX style Code Behinds (allows for MVC-style designs)

Some planned features:
- Mango-based implemenation
- All-Encompassing DSP Langauge Spec and Best Practices

For those interested, code updates are soon to follow. Please be patient. Thank you.

Please feel free to write to the group or email me if you have any comments or questions.
_________________
-- !Eric.t.Anderton at gmail

[jcc7]

This sounds like an interesting project. If D replaces C++, then DSP can replace JSP. Sounds like a plan to me.

[pragma]

[quote="jcc7"]This sounds like an interesting project. If D replaces C++, then DSP can replace JSP. Sounds like a plan to me. [/quote]

That's pretty much the idea. I can only hope that this, when completed, will ultimately accelerate D's adoption by the masses as a serious replacement for C++.
_________________
-- !Eric.t.Anderton at gmail

[kris]

I don't really have anything specific to add, other than I think this is a truly cool project ... this is the kind of grass-roots shot-in-the-arm that D would need to gain wider adoption. Great idea Eric!

[pragma]

[svanleent]

I am glad to read that DSP is/will be(ing) designed to use XML (next to PHP/ASP layout). A note for thought, JSPX (or JSP documents) are also written in XML. Perhaps a good idea to look at their design as well as JSF (Java Server Faces).

DSP is a great step making D an industry platform, keep on the good work!
_________________
How C++ became ancient

[pragma]

[bmn24]

Why in God's name would anybody ever write something like this for Apache on Win32? That's about the most unlikely combination of web server/OS imaginable.

[larsivi]

Shows what you know then, Apache on Windows is very common.