[jira] [Created] (GEODE-3306) Parsing of cache.xml with whitespace fails with Apache Xerces

["Darren Foong (JIRA)" <ji...@apache.org>]

Darren Foong created GEODE-3306:
-----------------------------------

             Summary: Parsing of cache.xml with whitespace fails with Apache Xerces
                 Key: GEODE-3306
                 URL: https://issues.apache.org/jira/browse/GEODE-3306
             Project: Geode
          Issue Type: Bug
          Components: core
            Reporter: Darren Foong
             Fix For: 1.2.0


I am using Geode 1.2.0 and Apache Xerces 2.11.0 (not the one included in the Oracle JDK), and I encountered the following error when I tried to programmatically start a cache:

{noformat}
org.apache.geode.InternalGemFireError: Did not expected a java.lang.StringBuffer on top of the stack.

Exception in thread "main" org.apache.geode.InternalGemFireError: Did not expected a java.lang.StringBuffer on top of the stack.
	at org.apache.geode.internal.Assert.throwError(Assert.java:94)
	at org.apache.geode.internal.Assert.assertTrue(Assert.java:117)
	at org.apache.geode.internal.cache.xmlcache.CacheXmlParser.endRegionAttributes(CacheXmlParser.java:1257)
	at org.apache.geode.internal.cache.xmlcache.CacheXmlParser.endElement(CacheXmlParser.java:2909)
	at org.apache.geode.internal.cache.xmlcache.CacheXmlParser$DefaultHandlerDelegate.endElement(CacheXmlParser.java:3374)
	at org.apache.xerces.parsers.AbstractSAXParser.endElement(Unknown Source)
	at org.apache.xerces.parsers.AbstractXMLDocumentParser.emptyElement(Unknown Source)
	at org.apache.xerces.impl.xs.XMLSchemaValidator.emptyElement(Unknown Source)
	at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
	at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
	at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
	at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
	at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
	at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
	at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
	at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
	at org.apache.xerces.jaxp.SAXParserImpl.parse(Unknown Source)
	at javax.xml.parsers.SAXParser.parse(SAXParser.java:195)
	at org.apache.geode.internal.cache.xmlcache.CacheXmlParser.parse(CacheXmlParser.java:224)
	at org.apache.geode.internal.cache.GemFireCacheImpl.loadCacheXml(GemFireCacheImpl.java:4287)
	at org.apache.geode.internal.cache.GemFireCacheImpl.initializeDeclarativeCache(GemFireCacheImpl.java:1390)
	at org.apache.geode.internal.cache.GemFireCacheImpl.initialize(GemFireCacheImpl.java:1195)
	at org.apache.geode.internal.cache.GemFireCacheImpl.basicCreate(GemFireCacheImpl.java:758)
	at org.apache.geode.internal.cache.GemFireCacheImpl.create(GemFireCacheImpl.java:745)
	at org.apache.geode.cache.CacheFactory.create(CacheFactory.java:173)
	at org.apache.geode.cache.CacheFactory.create(CacheFactory.java:212)
	at server.ServerWhitespace.main(ServerWhitespace.java:8)
{noformat}

However, this does not happen when I don't use Apache Xerces, i.e. I rely on the version in the Oracle JDK (1.8).

After getting the Geode source code and stepping through the parsing using the Eclipse debugger, I realised that there were unexpected StringBuffers pushed onto the parse stack, thus causing the problem.

These StringBuffers were created and pushed by the {{characters()}} method (https://github.com/apache/geode/blob/develop/geode-core/src/main/java/org/apache/geode/internal/cache/xmlcache/CacheXmlParser.java#L3270). Changing the log level to {{TRACE}} and examining the parse stack showed that these StringBuffers contained the whitespace (including newlines) between the XML tags in {{cache.xml}}.

When using the Oracle JDK's version of Xerces, these StringBuffers did not appear on the parse stack despite the whitespace.

I have a proof of concept on GitHub: https://github.com/darrenfoong/geode-parser-poc The {{cache.xml}} file without whitespace between the tags was parsed without errors by both versions of Xerces.

It could be the case that the JDK Xerces strips out whitespace while Apache Xerces doesn't; but this could be implemented in {{characters()}} by only pushing non-whitespace char arrays in the {{else}} block. However, there could be other XML parsing edge cases that I am unaware of.

There should be others who need Apache Xerces for their projects; a fix would be appreciated.



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