XML DTD Validator rule

Use the XML DTD Validator rule to validate a request against an XML Document Type Definition (DTD) schema.

Validates a request against an XML Document Type Definition (DTD) schema. You can upload an XML DTD schema file in the Policy dialog as a valid Swagger XML document. If the request contains a path, parameter, or object that isn't defined in the DTD schema, the client receives a Schema Validation Failed error.
Note: Alternatively, you can use the specification that you upload to create an API.

Policy execution order

The XML DTD Validator rule executes after the request is authenticated. You can use both the XML DTD Validator and XML XSD Validator rule policies concurrently as long as the schemas don't conflict.

Field Description
When this rule should be applied An expression that defines one or more conditions that must be true for the rule to execute.

Example: The expression request.method == "POST" causes the rule to execute only on POST requests.

Edit DTD Launches the XML editor which allows you to define XML. The editor loads an existing XML document if defined previously. The editor lets you save XML in SnapLogic's file system or import existing XML documents from it.

Default value: Empty XML file

Example: 

<!ELEMENT bibliography (book+)>
<!ELEMENT book (title, author*, publisher?, year?, extraAttribute, content, section*)>
<!ATTLIST book ISBN CDATA #REQUIRED>
<!ATTLIST book price CDATA #IMPLIED>
<!ELEMENT title (#PCDATA)>
<!ELEMENT author (#PCDATA)>
<!ELEMENT publisher (#PCDATA)>
<!ELEMENT year (#PCDATA)>
<!ELEMENT extraAttribute (#PCDATA)>
<!ELEMENT content (#PCDATA|extraAttribute)*>
<!ELEMENT section (title, content?, section*)>
Hide/Render WhiteSpace Formats XML with watermarked dots or plain white space between the characters.
Format Code Formats text in XML
Status Specifies whether the rule is enabled or disabled.

Default value: Enabled

Example: Disabled
Description

Required. A brief description of this rule.

Default value: Requests are being validated against the specified DTD

Example: Task XML DTD Validator

Usage Guidelines

Support for inline declared definitions

You can enter a schema by clicking Edit DTD to open the XML editor. If the editor is empty, the rule will evaluate the Document Type Definitions declared inline, as shown in the following example:


<?xml version="1.0"?>
<!DOCTYPE books [
        <!ELEMENT books (book+)>
        <!ELEMENT book (author, title, genre, price, pub_date, review+)>
        <!ATTLIST book id CDATA #REQUIRED>
        <!ELEMENT author (#PCDATA)>
        <!ELEMENT title (#PCDATA)>
        <!ELEMENT genre (#PCDATA)>
        <!ELEMENT price (#PCDATA)>
        <!ELEMENT pub_date (#PCDATA)>
        <!ELEMENT review (#PCDATA)>
        ]>
<books>
    <book id="bk001">
        <author>Famous Author</author>
        <title>Computer Science</title>
        <genre>Education</genre>
        <price>100.00</price>
        <pub_date>2000-10-01</pub_date>
        <review>Test Review</review>
    </book>
</books>

DTD Guidelines

The following guidelines apply DTD schemas entered into the editor and their HTTP clients making the request:

  • HTTP Clients are expected to provide a <!DOCTYPE> tag to indicate validation against Document Type Definitions. Without the tag, validation fails.

  • The parameter just after <!DOCTYPE> is expected to be the same as the outermost tag in the XML. If not, validation fails.

  • Externally referenced DTDs are declared with the following system callout:

    SYSTEM "policy.dtd"

    • <!DOCTYPE outermost_object SYSTEM "external_reference.dtd"> is the standard callout format for specifying DTD validation against external references.

    • For validation against the rule’s Document Type Definitions, HTTP clients are required to specify the SYSTEM declaration.

      • As the API admin, you can instruct clients to use any SYSTEM parameter following the callout. Any value can be specified. See the "policy.dtd" callout.

      • Regardless of the value, the XML DTD Validator uses the definitions specified in the rule to validate external references.


<!DOCTYPE books SYSTEM "policy.dtd">
<books>
    <book id="bk001">
      ...
    </book>
</books>