How to use the command xml canonic (with examples)

The xml canonic command is used to make XML documents canonical. It takes an XML document as input and produces a canonical version of the document as output. The canonicalization process removes unnecessary white spaces, sorts attributes, and normalizes namespace URIs, among other things.

Use case 1: Make an XML document canonical, preserving comments

Code:

xml canonic path/to/input.xml|URI > path/to/output.xml

Motivation:

This use case is useful when you want to create a canonical version of an XML document while preserving any comments present in the original document. Comments may contain important information about the content of the document or provide context for future reference.

Explanation:

• xml canonic is the command to start the process of making an XML document canonical.
• path/to/input.xml|URI is the path or URI of the XML document you want to make canonical. Replace this with the actual path or URI of your document.
• > is the output redirection operator used to save the canonical version of the document to a file.
• path/to/output.xml is the path to the file where the canonical version of the document should be saved. Replace this with the actual path where you want to save the file.

Example output:

The output of this command will be the canonical version of the input XML document with comments preserved, saved to the specified output file.

Use case 2: Make an XML document canonical, removing comments

Code:

xml canonic --without-comments path/to/input.xml|URI > path/to/output.xml

Motivation:

This use case is useful when you want to create a canonical version of an XML document and remove all the comments present in the original document. Comments are often used to provide additional information or explanations that are not necessary for the canonical representation of the document.

Explanation:

• --without-comments is an option provided by the xml canonic command that instructs it to remove all comments from the XML document during the canonicalization process. By including this option, the resulting canonical version of the document will not contain any comments.
• The remaining parts of the command have the same meaning as in the previous use case.

Example output:

The output of this command will be the canonical version of the input XML document with all comments removed, saved to the specified output file.

Use case 3: Make XML exclusively canonical, using an XPATH from a file, preserving comments

Code:

xml canonic --exc-with-comments path/to/input.xml|URI path/to/c14n.xpath

Motivation:

This use case is useful when you want to make an XML document exclusively canonical, meaning that only the selected portions of the document defined by the provided XPATH expression should be canonicalized. This allows you to apply canonicalization to specific parts of the document while leaving others unchanged. Preserving comments in this case can be helpful to maintain the original context and meaning of the comments.

Explanation:

• --exc-with-comments is an option provided by the xml canonic command that enables the exclusive canonicalization mode. In this mode, only the elements and attributes specified by the provided XPATH expression will be canonicalized, and the rest of the document will remain unchanged. This option also preserves comments in the resulting canonical version of the document.
• path/to/c14n.xpath is the path to a file containing the XPATH expression that specifies the elements and attributes to be exclusively canonicalized. Replace this with the actual path to your XPATH file.

Example output:

The output of this command will be the exclusive canonical version of the input XML document, where only the selected portions defined by the XPATH expression are canonicalized. The resulting document will preserve the comments present in the original document and will be saved to the specified output file.

Use case 4: Display help for the canonic subcommand

Code:

xml canonic --help

Motivation:

This use case is useful when you are unsure of the available options and their usage for the xml canonic command. Running this command displays the help information for the canonic subcommand, providing a quick reference for all the available options and their descriptions.

Explanation:

• --help is an option provided by the xml canonic command that displays the help information for the canonic subcommand.

Example output:

Running this command will display the help information for the canonic subcommand, including the available options and their descriptions. This output will provide guidance on how to use the command effectively.

Conclusion:

The xml canonic command provides a powerful tool for making XML documents canonical. By following the various use cases outlined in this article, you can create canonical versions of XML documents while preserving or removing comments as needed, and even perform exclusive canonicalization on specific parts of the document. The command offers flexibility and customization for your XML canonicalization requirements.