Konduit Serving supports data transformations defined by the DataVec vectorization and ETL library.
import ai.konduit.serving.InferenceConfiguration;
import ai.konduit.serving.config.ServingConfig;
import ai.konduit.serving.configprovider.KonduitServingMain;
import ai.konduit.serving.pipeline.step.TransformProcessStep;
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.JsonNode;
import com.mashape.unirest.http.Unirest;
import com.mashape.unirest.http.exceptions.UnirestException;
import org.datavec.api.transform.TransformProcess;
import org.datavec.api.transform.schema.Schema;

A reference Java project is provided in the Example repository ( ) with a Maven pom.xml dependencies file. If using the IntelliJ IDEA IDE, open the java folder as a Maven project and run the main function of InferenceModelStepDataVec the class.

Data transformations with DataVec

Schema (source)

A Schema specifies the structure of your data. In DataVec, a TransformProcess requires the Schema of the data to be specified. Both schema and transform process classes come with a helper Builder class which are useful for organizing code and avoiding complex constructors.

Schema objects have a number of methods that define different data types for columns: addColumnsString(), addColumnInteger(), addColumnLong(), addColumnFloat(), addColumnDouble() and addColumnCategorical().

TransformProcess (source)

TransformProcess provides a number of methods to manipulate your data. The following methods are available in the Datavec API:

  • Reduce the number of rows: filter()

  • General data transformations: replaceStringTransform(), replaceMapTransform(),

  • Type casting: stringToTimeTransform(), transform(), categoricalToInteger(),

  • Combining/reducing the values in each column: reduce()

  • String operations: appendStringColumnTransform(), toLowerCase(), toUpperCase(), stringRemoveWhitespaceTransform(), replaceStringTransform(), stringMapTransform()

  • Column selection/renaming: removeColumns(), removeAllColumnsExceptFor(), renameColumn()

  • One-hot encoding: categoricalToOneHot(), integerToOneHot()

In this short example, we append the string two to the end of values in the string column first. As an initial step, define the input and output Schema with string column:

Schema inputSchema = new Schema.Builder()
Schema outputSchema = new Schema.Builder()
TransformProcess transformProcess = new TransformProcess.Builder(inputSchema).
appendStringColumnTransform("first", "two").build();

Configure the step

The TransformProcess can now be defined in the Konduit Serving configuration with a TransformProcessStep. Here, we

  • configure the inputs and outputs: the schema, column names and data types should be defined here.

  • declare the TransformProcess using the .transformProcess() method.

Note that Schema data types are not defined in the same way as PythonStep data types. See the source for a complete list of supported Schema data types:

  • NDArray

  • String

  • Boolean

  • Categorical

  • Float

  • Double

  • Integer

  • Long

  • Bytes

You should define the Schema data types in TransformProcessStep() as strings.

TransformProcessStep transformProcessStep = new TransformProcessStep(transformProcess, outputSchema);

Configure the server

Configure the Server using ServingConfig to define the port using the httpPort argument.

int port = Util.randInt(1000, 65535);
ServingConfig servingConfig = ServingConfig.builder()
InferenceConfiguration inferenceConfiguration = InferenceConfiguration.builder()

The inferenceConfiguration is stored as a JSON File.

File configFile = new File("config.json");
FileUtils.write(configFile, inferenceConfiguration.toJson(), Charset.defaultCharset());


The Client should be configured to match the Konduit Serving instance. As this example is run on a local computer, the server is located at host 'http://localhost' and port port. And Finally, we run the Konduit Serving instance with the saved config.json file path as configPath and other necessary server configuration arguments.. Recall that the TransformProcessStep() appends a string two to strings in the column first.

A Callback Function onSuccess is implemented in order to post the Client request and get the HttpResponse, only after the successful run of the KonduitServingMain Server.

.onSuccess(() -> {
try {
HttpResponse<JsonNode> response ="http://localhost:%s/raw/json", port))
.header("Content-Type", "application/json")
.body("{\"first\" :\"value\"}").asJson();
} catch (UnirestException e) {
.runMain("--configPath", configFile.getAbsolutePath());

Confirm the output

After executing the above, in order to confirm the successful start of the Server, check for the below output text:

Jan 08, 2020 1:36:01 PM ai.konduit.serving.configprovider.KonduitServingMain
INFO: Deployed verticle ai.konduit.serving.verticles.inference.InferenceVerticle

The Output of the program is as follows:


The complete inference configuration in JSON format is as follows:

SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]
"memMapConfig" : null,
"servingConfig" : {
"httpPort" : 15614,
"listenHost" : "localhost",
"logTimings" : false,
"outputDataFormat" : "JSON",
"uploadsDirectory" : "file-uploads/"
"steps" : [ {
"@type" : "TransformProcessStep",
"inputColumnNames" : {
"default" : [ "first" ]
"inputNames" : [ "default" ],
"inputSchemas" : {
"default" : [ "String" ]
"outputColumnNames" : {
"default" : [ "first" ]
"outputNames" : [ "default" ],
"outputSchemas" : {
"default" : [ "String" ]
"transformProcesses" : {
"default" : {
"actionList" : [ {
"transform" : {
"@class" : "org.datavec.api.transform.transform.string.AppendStringColumnTransform",
"columnName" : "first",
"toAppend" : "two"
} ],
"initialSchema" : {
"@class" : "org.datavec.api.transform.schema.Schema",
"columns" : [ {
"@class" : "org.datavec.api.transform.metadata.StringMetaData",
"name" : "first"
} ]
} ]