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Custom Validators

If you need to validate the edited document with a validation engine that is different from the built-in engine, you can configure external validators in the Custom Validation Engines preferences page. After a custom validation engine is properly configured, it can be applied on the current document by selecting it from the list of custom validation engines in the Validation toolbar drop-down menu. The document is validated against the schema declared in the document.

Some validators are configured by default but there are third-party processors that do not support the output message format of Oxygen XML Editor for linked messages:

  • Saxon-EE - Included in Oxygen XML Editor. It is associated to XML Editor and XSD Editor. It is able to validate XML Schema schemas and XML documents against XML Schema schemas. The validation is done according to the W3C XML Schema 1.0 or 1.1. This can be configured in Preferences.
  • MSXML 4.0 (Legacy) - Included in Oxygen XML Editor (Windows edition only). It is associated to XML Editor, XSD Editor and XSL Editor. It is able to validate the edited document against XML Schema, internal DTD (included in the XML document), external DTD or a custom schema type.
  • MSXML.NET (Legacy) - Included in Oxygen XML Editor (Windows edition only). It is associated to XML Editor, XSD Editor and XSL Editor. It is able to validate the edited document against XML Schema, internal DTD (included in the XML document), external DTD or a custom schema type.

  • LIBXML - Not included in Oxygen XML Editor and, depending on your operating system, the libraries need to be downloaded and installed separately from http://xmlsoft.org/downloads.html. Afterward, the PATH environment variable needs to be updated to contain the parent folder of the xmllint executable. Alternatively, you can go to Options > Preferences > Editor > Custom Validation Engines, edit the LIBXML validation engine and set a custom path to the xmllint executable.

    The LIBXML validator is associated with the XML Editor. It is able to validate the edited document against XML Schema, Relax NG schema full syntax, internal DTD (included in the XML document) or a custom schema type. Support for XML Catalogs (the --catalogs parameter) and XInclude processing (--xinclude) are enabled by default in the preconfigured LIBXML validator. The --postvalid parameter is also set by default and it allows LIBXML to validate correctly the main document even if the XInclude fragments contain IDREFS to ID's located in other fragments.

    For validation against an external DTD specified by URI in the XML document, add the --dtdvalid ${ds} parameter manually to the DTD validation command line. ${ds} represents the detected DTD declaration in the XML document.
    CAUTION: File paths containing spaces are not handled correctly in the LIBXML processor. For example, the built-in XML Catalog files of the built-in document types (DocBook, TEI, DITA, etc.) are not handled by LIBXML if Oxygen XML Editor is installed in the default location on Windows (C:\Program Files) because the built-in XML catalog files are stored in the frameworks subfolder of the installation folder and in this case, the file path contains at least one space character.
    Attention: On macOS, if the full path to the LIBXML executable file is not specified in the Executable path text field, some errors may occur during validation against a W3C XML Schema, such as:
    Unimplemented block at ... xmlschema.c

    To avoid these errors, specify the full path to the LIBXML executable file.

A custom validator cannot be applied on files loaded through an Oxygen XML Editor custom protocol plugin developed independently and added to Oxygen XML Editor after installation.