[CAMEL-8273] More flexible selection of default documentType in XPath expressions

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Abandoned
• Fix Version/s: Future
• Component/s: camel-core
• Patch Info: Patch Available
• Estimated Complexity: Unknown
• Assignee: Unassigned
• Reporter: Stephan Siano
• Created: 23/Jan/15 12:09
• Updated: 06/Aug/19 05:24
• Resolved: 06/Aug/19 05:24

Description

In the current implementation of XPath if no documentType is defined (likely in most cases) the document used for XPath evaluation is parsed into a (DOM) Document using the JDK XML parser before applying the XPath expression on it.

For large documents this might be resource intensive, especially if the XPath is evaluated using a more efficient parser like Saxon.

With the current implementation it is possible to workaround this by setting a documentType attribute to the XPath expression, but doing this efficiently requires some internal knowledge about the previous component in the camel route (which type it creates) and the qualities of the used XML parser (e.g. the JDK parser accepts only InputSource and Node as input types for XPath evaluation whereas Saxon does also support other types like SAXSource).

The attached patch will make the data type used by default for XPath evaluation more flexible (depending on the type of the input).

There are two cases to differentiate:
documentType is set on the XPath expression:
current implementation:
1. try to convert to the documentType
2. if that fails do some extra conversions for some additional data types (WrappedFile, BeanInvocation, String)
3. if that fails throw an exception
new implementation:
1. try to convert to the documentType
2. if that fails, use the message if it is of type Node, InputSource or DOMSource or do some type conversions for specific data types (WrappedFile, BeanInvocation, String, InputStream, Reader, byte[]...)
3. if that fails throw an exception

documentType is not set on the XPath expresson
old implementation:
this is actually the same as if documentType was set to Document
new implementation:
1. Use the message if it is of type Node, InputSource or DOMSource or do some type conversions for specific data types (WrappedFile, BeanInvocation, String, InputStream, Reader, byte[]...) (to InputSource)
2. If the old message is not of one of the types above, convert to DOM Document
3. If this fails throw an Exception