New XSLT2 implementation of ISO Schematron: SchXslt

There is a promising looking new implementation of Schematron for XSLT2 up at GitHub, the Open Source SchXslt project.  Kudos to David Maus for developing this, and making it available. It is intended as a drop-in replacement for the most common skeleton implementation (also on GitHub at Schematron), so it…

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Schematron reimagined for JSON/JSONPath

On GitHub you can find jsontron which is Schematron  moved out of the XML/XSLT/XPath ecosystem and applied to the JSON/JavaScript/JSONPath ecosystem.  What is particularly pleasing to me is that this seems to be a really full implementation of ISO Schematron, including phases (not abstract rules and abstract patterns, no biggie.) It…

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Assertions in Java

In Schematron, an assertion is a positive natural language statement about some aspect of a pattern that is expected to be found in an XML document.  It is implemented (to whatever extent possible) with the assert test. However, in programming languages, assertions have a wider range of meaning. (To the…

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The Most Common Programming Error with Schematron

Schematron is a small, simple language, by design.  The complexity is not in the elements, but sloughed off to the XPaths. But if there is one mistake that I sometimes see developers make, it is this: people think that all the rules in a pattern will be tried.  In fact,…

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Sorting out Log4J 2.0’s strict schemas

Log4J version 2.0 has two dialects of its XML configuration language: concise and strict. Concise mode is fairly well document and freeform. It uses the reflection API and plugins, so that if there is a plugin available, you can just call its name directly.  So there is no schema: the…

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The most interesting Class of Computer Languages

In the previous blog  (XML as a canary in the mine: can Intel IPSC help stagnant C get its mojo back?), I mentioned three classes of languages that are thriving, plus one that I suggest is not. But that leaves out what I think is the most interesting class of…

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Using XPath to make Assertions is now a common technique

The idea of using XPath in a schema language about structured data probably first came up with Dave Raggett’s Assertion Grammars. This was a recasting DTDs that allowed (I don’t know if this part was ever implemented) the context element to specified using an XPath: called Conditions. I think of…

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How many developers think different?

The StackOverflow yearly survey came out today. This week I have been writing some posts thinking about what modes of thinking, jobs, technologies, debugging strategies might be suitable for developers with smaller working memories or below average short-term-memory-consolidation.  And I have suggested that the emphasis in the hiring exams of…

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Alan Turing and Tony Hoare on Assertions

Schematron is a language for making assertions about whole XML documents, that each part of various patterns must be present. Schematon (and the other XML schema languages starting with DTDs) are a little special in that they are geared for assertions to be made on large complex data structure, but…

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