Using XSLTVM

XSLT Virtual Machine is the software implementation of a "CPU" designed to run compiled XSLT code. A concept of virtual machine assumes a compiler compiling XSLT stylesheets to a sequence of byte codes or machine instructions for the "XSLT CPU". The byte-code program is a platform-independent sequence of 2-byte units. It can be stored, cached and run on different XSLTVM. The XSLTVM uses the bytecode programs to transform instance XML documents. This approach clearly separates compile (design)-time from run-time computations and specifies a uniform way of exchanging data between instructions.

A typical scenario of using the package APIs has the following steps:

1. Create/Use an XML meta context object.

   xctx = XmlCreate(,...);

2. Create/Use an XSLT Compiler object.

   comp = XmlXvmCreateComp(xctx);

3. Compile an XSLT stylesheets and cache the result bytecode.

   code = XmlXvmCompileFile(comp, xslFile, baseuri, flags, );

4. Create/Use an XSLTVM object. The explicit stack size setting are needed when XSLTVM terminates with "... Stack Overflow" message or when smaller memory footprints are required (see XmlXvmCreate).

   vm = XmlXvmCreate(xctx, "StringStack", 32, "NodeStack", 24, NULL);

5. Set a stylesheet bytecode to the XSLTVM object.

   len = XmlXvmGetBytecodeLength(code, ); err = XmlXvmSetBytecodeBuffer(vm, code, len);

6. Transform an instance XML document.

   err = XmlXvmTransformFile(vm, xmlFile, baseuri);

7. Clean.

   XmlXvmDestroy(vm);

   XmlXvmDestroyComp(comp);

   XmlDestroy(xctx);