Saxon

First of all, you haven't configured an ErrorListener on your XsltCompiler, which means the errors are going to System.err, which unless you're running from the console, is probably going into some black hole somewhere. The exception only tells you that there was a compilation failure, but the details of the errors are being written elsewhere. Either set an ErrorListener, or redirect System.err to some well-known location like a log file.

Actually, I've just noticed, you use NewXsltCompiler with a capital N, which means this must be on .NET, but the principle is the same. On .NET the XsltCompiler writes errors to a supplied ErrorList object.

I'm afraid the sample code is very ancient; it really shouldn't be necessary to use saxon:stream() when doing streaming any more. And when I run this stylesheet (from Java, I don't have a .NET machine with me today), the error I get is

Static error at char 23 in xsl:value-of/@select on line 2 column 164 XTSE3430: The body of the xsl:source-document instruction is not streamable

• Predicate [fn:exists(...)] at line 2 is not motionless

Now that's not very helpful, because unfortunately there's been a fair bit of code rewriting before the streamability analysis is done. The saxon:stream() instruction gets turned into a call on xsl:source-document, and the expression count(XXX) > 0 gets turned into a call on fn:exists(XXX). But the essence of this is that the stylesheet doesn't satisfy the streamability rules, which basically means that this sample app somehow found it into the release without testing. (A likely explanation is that we changed the sample so it worked but the release process picked up the old version.)

Using xsl:source-document rather than saxon:stream() actually fixes the issue. Changing the stylesheet to this makes it work:

String xsl = "<xsl:transform version='3.0' xmlns:xsl='http://www.w3.org/1999/XSL/Transform' xmlns:saxon='http://saxon.sf.net/'>\n" +
                    " <xsl:template name='main'> " +
                    " <xsl:source-document href='/Users/mike/repo/samples/data/othello.xml'>"
                    + "<xsl:value-of select=\"count(//LINE[count(tokenize(.,'/s')) &gt; 0] )\" />"
                    + "</xsl:source-document>" +
                    " </xsl:template></xsl:transform>";

One other observation, the tokenize() function is clearly intended to tokenize on whitespace, so the regular expression should be \s rather than /s. But in XPath 3.1 white-space tokenization can be achieved more easily with the one-arg version of the tokenize() function.

In order to actually use streaming, the attribute streamable='yes' is also required on the xsl:source-document instruction. When this is added, Oxygen (using Saxon-EE 9.8.0.8) still shows the validation error "The body of the xsl:stream instruction is not streamable * Predicate [fn:exists(...)] at line 11 is not motionless". I believe the required solution is to use copy-of(//LINE) rather than //LINE (see http://www.saxonica.com/documentation/index.html#!sourcedocs/streaming/xslt-streaming). So the new code becomes:

String s = "<xsl:transform version='3.0' xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>\n" +
				" <xsl:template name='main'>\n" +
				"  <xsl:source-document streamable='yes' href='" + new Uri(samplesDir, "data/othello.xml").ToString() + "'>\n" +
				"   <xsl:value-of select=\"count(copy-of(//LINE)[count(tokenize(.)) &gt; 0] )\" />\n" +
				"  </xsl:source-document>\n";
				" </xsl:template>\n" +
				"</xsl:transform>";

Committed in the 9.9 samples. (To be tested!)

Fix also committed in svn/Saxon.Net/ExamplesEE/ExamplesEE.cs (the actual source file!)