XSLTTransform

XSLTTransform is a generic AWS Lambda function designed specifically for Kinesis Data Firehose Data Transformation.

XSLTTransform uses Saxon-HE 9.9 processor to perform an XSLT 3.0 transformation of input records to output records. XSLT 1.0 and 2.0 stylesheets should be backwards-compatible. Naturally, the input records have to be XML. JSON can work too, if you use a 3.0 stylesheet and its JSON processing features.

Passing a map of stylesheet parameters is supported. Environment variables can be retrieved using System.getenv() and forwarded as stylesheet parameters.

Usage

The XSLT stylesheet is user-defined and has to be supplied to the function. It can be done by extending the XSLTTransform base class and overriding its constructor with stylesheet and parameter map as arguments.

The simplest way to embed a stylesheet is to put it under /src/main/resources, from where it can be read using getResourceAsStream(). That way the stylesheet is built into the function JAR itself. Alternatively, it should be possible to load it from S3.

In AWS Lambda configuration, specify transformRecords method (which is inherited by your subclass) as the function handler.

Example

The following example shows /src/main/resources/custom.xsl used as the XSLT stylesheet, as well as my-param stylesheet parameter initialized with the value of MY_PARAM environment variable.

package custom;

import com.atomgraph.etl.aws.kinesis.transform.XSLTTransform;
import java.util.Collections;
import javax.xml.transform.stream.StreamSource;
import net.sf.saxon.s9api.QName;
import net.sf.saxon.s9api.SaxonApiException;
import net.sf.saxon.s9api.XdmAtomicValue;

public class CustomXSLTTransform extends XSLTTransform
{
    
    public CustomXSLTTransform() throws SaxonApiException
    {
        super(new StreamSource(CustomXSLTTransform.class.getResourceAsStream("/custom.xsl")),
            Collections.singletonMap(new QName("my-param"), new XdmAtomicValue(System.getenv("MY_PARAM"))));
    }

}

The function handler would be custom.CustomXSLTTransform::transformRecords in this case.

Build

Create a new Java project and include XSLTTransform as dependency in pom.xml:

<dependency>
    <groupId>com.atomgraph.etl.aws.kinesis</groupId>
    <artifactId>XSLTTransform</artifactId>
    <version>1.0.0-SNAPSHOT</version>
</dependency>

You might also need to add the maven-shade-plugin in the <build> section, as per Creating a .jar Deployment Package Using Maven without any IDE (Java).

Package the extended function for upload to AWS Lambda by running mvn package.