Diazo (software)

Last updated
Diazo
Developer(s) Paul Everitt, Laurence Rowe and Martin Aspeli
Stable release
1.1.1 / March 21, 2015;3 years ago (2015-03-21) [1]
Preview release
e917d54922 / May 20, 2015;3 years ago (2015-05-20) [2]
Operating system Cross-platform
Platform Python
License New BSD
Website diazo.org

Diazo, previously named xdv, is a general-purpose, open source website theming tool. It is written in Python and generates XSLT. Diazo creates a separation between theme pages (static HTML) and transformation rules (Diazo's own domain specific language based in XML), allowing web designers to work on templates in plain HTML, without knowledge of XSLT or special template-related codes.

Open-source software software licensed to ensure source code usage rights

Open-source software (OSS) is a type of computer software in which source code is released under a license in which the copyright holder grants users the rights to study, change, and distribute the software to anyone and for any purpose. Open-source software may be developed in a collaborative public manner. Open-source software is a prominent example of open collaboration.

Python is an interpreted, high-level, general-purpose programming language. Created by Guido van Rossum and first released in 1991, Python has a design philosophy that emphasizes code readability, notably using significant whitespace. It provides constructs that enable clear programming on both small and large scales. Van Rossum led the language community until stepping down as leader in July 2018.

XSLT is a language for transforming XML documents into other XML documents, or other formats such as HTML for web pages, plain text or XSL Formatting Objects, which may subsequently be converted to other formats, such as PDF, PostScript and PNG. XSLT 1.0 is widely supported in modern web browsers.

Contents

Diazo creates a themed site by using user-defined rules to combine vanilla content from a dynamic website together with a static HTML theme. The rules file (conventionally named rules.xml) has directives which, for example, may replace the contents of an HTML node in the theme with the contents of one in the content.

Computer software, and sometimes also other computing-related systems like computer hardware or algorithms, are called vanilla when not customized from their original form, meaning that they are used without any customizations or updates applied to them. Vanilla software has become a widespread de facto industry standard, widely used by businesses and individuals. The term comes from the traditional standard flavor of ice cream, vanilla. According to Eric S. Raymond's The New Hacker's Dictionary, "vanilla" means more "default" than "ordinary".

Web server support

The Diazo compiler generates XSLT, which can be deployed on any proxying web server with an XSLT processor such as Apache (using mod_transform), Varnish, or WSGI.

The Apache HTTP Server, colloquially called Apache, is free and open-source cross-platform web server software, released under the terms of Apache License 2.0. Apache is developed and maintained by an open community of developers under the auspices of the Apache Software Foundation.

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The Web Server Gateway Interface (WSGI) is a simple calling convention for web servers to forward requests to web applications or frameworks written in the Python programming language. The current version of WSGI, version 1.0.1, is specified in Python Enhancement Proposal (PEP) 3333.

WSGI also has more direct Diazo support: the DiazoMiddleware filter will compile and cache Diazo themes on the fly.

Nginx has an XSLT processor, [3] but, as of March 2012, it requires the unthemed website (the content) to use strict XHTML. The strict requirement can be relaxed, however, if a patched version of Nginx is used. [4] [5]

History and naming

Diazo was originally a reimplementation of an earlier software called Deliverance. Where Deliverance would handle the HTML transformation in Python, Diazo generates XSLT which can then be used to defer the actual transformation to faster XSLT engines.

The name change to Diazo (from xdv) was announced at the Plone conference 2010. A major motivation for the name change was to reduce ambiguity, as the XDV name was used by both collective.xdv (a Plone-specific theming package, now called plone.app.theming) and by the stand-alone XDV tools (now called Diazo). Also dv.xdvserver was renamed to DiazoMiddleware.

Plone (software)

Plone is a free and open source content management system built on top of the Zope application server. Plone is positioned as an "Enterprise CMS" and is commonly used for intranets and as part of the web presence of large organizations. High-profile public sector users include the U.S. Federal Bureau of Investigation, Brazilian Government, United Nations, City of Bern (Switzerland), New South Wales Government (Australia), and European Environment Agency. Plone's proponents cite its security track record and its accessibility as reasons to choose Plone.

Diazo is based on DVNG, a prototype version of xdv. Diazo originally implemented only a subset of the features in Deliverance, but now has similar features, although their configuration language is not completely compatible. Diazo has become the de facto standard for theming in Plone 4 and is included in Plone 4.2 and later.

Directives

The basic directives of Diazo include: replace (replace a node or attribute in the theme with that from content), before and after (insert a node before or after another), drop (delete a node or attribute), strip (remove a tag but not its child nodes), merge, and copy.

A node, node's children or attribute, can be selected with either XPath selectors or CSS3 selectors. CSS selectors are replaced by the equivalent XPath selector during the pre-processing step of the compiler.

Advanced features include: conditions based on content nodes or paths, with grouping and nesting; multiple, conditional themes; modifying the theme or content on the fly; inline XSL directives; Doctype changes; XInclude protocol.

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References

  1. ↑ https://pypi.python.org/pypi/diazo
  2. ↑ https://github.com/plone/diazo/
  3. ↑ http://wiki.nginx.org/HttpXsltModule
  4. ↑ nginx-xslt-html-parser, Laurence Rowe
  5. ↑ Nginx with HTML xslt support (html-xslt on Google code), patches Nginx 0.7.67 from 15 June 2010
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