Schema validation

From COLLADA Public Wiki
Jump to: navigation, search
This article is one several tutorials, guides, and annotated examples available in this wiki.
Multipage tutorials:  • COLLADA DOM user guide
Shorter how-tos:  • Using accessors  • Schema validation • Using URIs
 • Various annotated examples

Instructions for adding a tutorial

[[Category: ]]

The COLLADA format is defined by a W3C schema. If a document doesn't conform to the schema then it isn't valid COLLADA data. This tutorial explains a few different ways to validate a COLLADA document against the COLLADA schema.

Using xmllint

xmllint is a command-line application that can be used to validate an XML document against a W3C schema. xmllint is distributed as part of libxml. You can find binaries for Windows here. Mac OS X and most Linux distributions come with libxml already installed.

To validate the COLLADA document duck.dae against the latest COLLADA 1.4 schema available from Khronos, run the following command:

xmllint --noout --schema duck.dae

You could also copy the schema locally and use your local version:

xmllint --noout --schema colladaSchema.xsd duck.dae

The --noout option prevents superfluous output. If the COLLADA document violates the schema, xmllint outputs an error message.

Using libxml from a C/C++ Application

Using libxml, you can validate a COLLADA document against the schema from a C/C++ application. The following code illustrates how it works.

#include "libxml/xmlschemas.h"

// libxml error handler
void schemaErrorCallback(void*, const char* message, ...) {
  va_list varArgs;
  va_start(varArgs, message);
  vfprintf(stdout, message, varArgs);

// libxml warning handler
void schemaWarningCallback(void* callbackData, const char* message, ...) {

// Returns true if file validated successfully, false otherwise
bool validate(const string& uri) {
  bool result = false;
  if (xmlSchemaParserCtxt* schemaParser = 
     xmlSchemaNewParserCtxt("")) {
    if (xmlSchema* schema = xmlSchemaParse(schemaParser)) {
      if (xmlSchemaValidCtxt* validityContext = xmlSchemaNewValidCtxt(schema)) {
                               /* callback data */ 0);

        // Returns 0 if validation succeeded
        result = xmlSchemaValidateFile(validityContext, uri.c_str(), 0) == 0;

  return result;