Another thing to check is the Daffodil version you're using. The layer API was overhauled in Daffodil 3.8.0, so if you're using a layer written for the new layer API (which the latest version of IPv4ChecksumLayer is) it won't be found by older versions of Daffodil. You'll either need a newer version of Daffodil or an older version of the layer.

On 2024-10-28 06:26 PM, Mike Beckerle wrote:
It seems to be searching for the right thing, but unable to find it  on the classpath.

Are you perhaps just missing the metadata to tell the Java SPI loader that the class is to be dynamically loaded from your jar?

The jar must have a file:
META-INF/services/org.apache.daffodil.runtime1.layers.api.Layer

The name is the name of the dynamically loaded base class.

That file contains the name of the dynamic class such as:

com.owlcyberdefense.dfdl.IPv4ChecksumLayer

In the EthernetIP project, this META-INF lives under src/main/resources where it gets packaged into the jar file.




On Mon, Oct 28, 2024 at 1:02 PM Mark Kozak <mark.ko...@adeptus-cs.com <mailto:mark.ko...@adeptus-cs.com>> wrote:

    I feel I am so close to the solution and the tip on the DAFFODIL_CLASSPATH
    environment variable was the last missing step. But unfortunately I am still
    getting the following error:

    [error] Schema Definition Error: The dfdlx:layer
    '{urn:com.owlcyberdefense.dfdl.IPv4Checksum}IPv4Checksum' was not found.
    Available choices are:
    {urn:org.apache.daffodil.layers.lineFolded}lineFolded_IMF,
    {urn:org.apache.daffodil.layers.lineFolded}lineFolded_iCalendar,
    {urn:org.apache.daffodil.layers.base64_MIME}base64_MIME,
    {urn:org.apache.daffodil.layers.gzip}gzip,
    {urn:org.apache.daffodil.layers.fixedLength}fixedLength,
    {urn:org.apache.daffodil.layers.byteSwap}twobyteswap,
    {urn:org.apache.daffodil.layers.byteSwap}fourbyteswap,
    {urn:org.apache.daffodil.layers.boundaryMark}boundaryMark

    Here is what've done so far:

    1 - packaged the scala code for IPv4Checksum as a jar file named
    ipv4checksumlayer_2.12-1.0.jar.  Using this code just to see if I can get
    daffodil to see the class
    2 - Verified the jar file contains the class named IPv4ChecksumLayer.class 
in
    the path com\owlcyberdefense\dfdl\
    3 - set the DAFFODIL_CLASSPATH environment variable to the location of the 
jar
    file.
    4 - pasted the following lines into my schema file:

             xmlns:chksum="urn:com.owlcyberdefense.dfdl.IPv4Checksum"
       <xs:import namespace="urn:com.owlcyberdefense.dfdl.IPv4Checksum"
    schemaLocation="IPv4ChecksumLayer.dfdl.xsd"/>

             <sequence  >
               <xs:annotation>
                   <xs:appinfo source="http://www.ogf.org/dfdl/ <http://
    www.ogf.org/dfdl/>">
                     <dfdl:newVariableInstance ref="chksum:IPv4Checksum"/>
                   </xs:appinfo>
               </xs:annotation>
                   <xs:sequence dfdl:ref="chksum:IPv4ChecksumLayer">
                     <xs:sequence>
                       <xs:element name="Checksum" type="chksum:IPv4Checksum"/>
                     </xs:sequence>
                   </xs:sequence>
             </sequence>




    -----Original Message-----
    From: Steve Lawrence <slawre...@apache.org <mailto:slawre...@apache.org>>
    Sent: Friday, October 25, 2024 1:30 PM
    To: users@daffodil.apache.org <mailto:users@daffodil.apache.org>
    Subject: Re: Where to put custom checksum for use as a layer?

    You need to build your layer into a .jar file and then put that on 
Daffodil's
    classpath.

    If you're use the Daffodil CLI, you can add jars to the CLI classpath by
    setting the DAFFODIL_CLASSPATH environment variable, for example:

        export DAFFODIL_CLASSPATH="/path/to/custom/checksum/layer.jar"
        daffodil parse -s schema.dfdl.xsd ...

    If instead you're running TDML tests using SBT, a common technique is to
    publish the layer jar to a local repository, then add it as a dependency to
    the schema project that uses it. For example, you could do this to publish
    locally:

        cd /layer-project
        sbt publishLocal

    And add this to your schema project build.sbt file:

        libraryDependencies ++= Seq(
          "org.example" % "layer-project" % "1.0.0"
        )

    And then just run "sbt test" from the schema project. SBT will find the
    locally published layer and automatically add it to the classpath when 
running
    tests.



    On 2024-10-25 12:51 PM, Mark Kozak wrote:
     > Hello folks,
     >
     > I have a custom checksum calculator I need to run on an entity. I have 
been
     > studying the ethernetIP example <https://github.com/DFDLSchemas/
    ethernetIP <https://github.com/DFDLSchemas/ethernetIP>>
     > and
     > the layers documentation <https://daffodil.apache.org/layers <https://
    daffodil.apache.org/layers>>, but am unable
     > to
     > figure out where to place my scala implementation for it to be found. Is
     > there
     > some documentation I am missing?
     >
     > Thanks as always for the support,
     >
     > Mark
     >
     > Mark Kozak
     >
     > Director of Engineering
     >
     > Adeptus Cyber Solutions
     >
     > Adeptus-CS.com
     >


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