xslt.md

description
This page provides the technical details of the XSLT policy

XSLT

{% hint style="warning" %} This feature requires Gravitee's Enterprise Edition. {% endhint %}

Overview

You can use the xslt policy to apply an XSL transformation to an incoming XML request body or to the response body if your backend is exposing XML content.

This policy is based on the Saxon library.

By default, a DOCTYPE declaration will cause an error. This is for security. If you want to allow it, you can set policy.xslt.secure-processing to false in the Gateway configuration file (gravitee.yml).

Functional and implementation information for the xslt policy is organized into the following sections:

• Examples
• Configuration
• Compatibility Matrix
• Errors

Examples

{% hint style="warning" %} This policy can be applied to v2 APIs and v4 HTTP proxy APIs. It cannot be applied to v4 message APIs or v4 TCP proxy APIs. {% endhint %}

{% tabs %} {% tab title="HTTP proxy API example" %} Remove SOAP elements when calling a WS:

<xsl:stylesheet version="2.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
    xmlns:fn="http://www.w3.org/2005/xpath-functions"
    exclude-result-prefixes="fn xsl">

    <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes" />

    <!-- template to copy elements -->
    <xsl:template match="*">
        <xsl:if test="normalize-space(string(.)) != ''">
            <xsl:element name="{local-name()}">
                <xsl:apply-templates select="@* | node()"/>
            </xsl:element>
        </xsl:if>
    </xsl:template>

    <!-- template to copy attributes -->
    <xsl:template match="@*">
        <xsl:attribute name="{local-name()}">
            <xsl:value-of select="."/>
        </xsl:attribute>
    </xsl:template>

    <!-- template to copy the rest of the nodes -->
    <xsl:template match="comment() | text() | processing-instruction()">
        <xsl:copy/>
    </xsl:template>

    <xsl:template match="soapenv:*">
        <xsl:apply-templates select="@* | node()" />
    </xsl:template>

    <xsl:template match="@xsi:nil[.='true']"/>
</xsl:stylesheet>

{% endtab %} {% endtabs %}

Configuration

Sample policy configuration:

{% code title="Sample Configuration" %}

"xslt": {
    "scope": "RESPONSE",
    "stylesheet": "<xsl:stylesheet \n  version=\"2.0\"\n  xmlns:xsl=\"http://www.w3.org/1999/XSL/Transform\"\n  xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"   xmlns:soapenv=\"http://schemas.xmlsoap.org/soap/envelope/\" xmlns:fn=\"http://www.w3.org/2005/xpath-functions\" exclude-result-prefixes=\"fn xsl\">\n  <xsl:output method=\"xml\" version=\"1.0\" encoding=\"UTF-8\" indent=\"yes\"/>\n\n  <!-- template to copy elements -->\n    <xsl:template match=\"*\">\n<xsl:if test=\"normalize-space(string(.)) != ''\">\n        <xsl:element name=\"{local-name()}\">\n            <xsl:apply-templates select=\"@* | node()\"/>\n        </xsl:element>\n</xsl:if>\n    </xsl:template>\n\n    <!-- template to copy attributes -->\n    <xsl:template match=\"@*\">\n        <xsl:attribute name=\"{local-name()}\">\n            <xsl:value-of select=\".\"/>\n        </xsl:attribute>\n    </xsl:template>\n\n    <!-- template to copy the rest of the nodes -->\n    <xsl:template match=\"comment() | text() | processing-instruction()\">\n        <xsl:copy/>\n    </xsl:template>\n\n  <xsl:template match=\"soapenv:*\">\n    <xsl:apply-templates select=\"@* | node()\" />\n  </xsl:template>\n\n  <xsl:template match=\"@xsi:nil[.='true']\"/>\n</xsl:stylesheet>",
    "parameters": [
        {
            "name": "my-parameter",
            "value": "my-value"
        }
    ]
}

{% endcode %}

By default, a DOCTYPE declaration will cause an error. This is for security. If you want to allow it, you can set policy.xslt.secure-processing to false in the Gateway configuration file (gravitee.yml):

policy:
  xslt:
    secure-processing: false

Phases

The phases checked below are supported by the xslt policy:

v2 Phases	Compatible?	v4 Phases	Compatible?
onRequest	true	onRequest	true
onResponse	true	onResponse	true
onRequestContent	false	onMessageRequest	false
onResponseContent	false	onMessageResponse	false

Options

The xslt policy can be configured with the following options:

Property	Required	Description	Type	Default
scope	true	Execution scope (request or response)	string	RESPONSE
stylesheet	true	XSLT stylesheet to apply	string
parameters	false	Parameters to inject while running XSL transformation	Array of XSLT parameters	-

Compatibility matrix

The following is the compatibility matrix for APIM and the xslt policy:

Plugin Version	Supported APIM versions
2.x	3.x
3.x	4.0+

Errors

HTTP status code	Message
500	Bad stylesheet file or XSLT transformation cannot be executed properly