Camel development series 10

Hello everyone,

Well as usual it has been a long time since I wrote here but I thought a new year has started so a nice and simple update would be good.

This time I will keep it simple and instead show how you can verify json messages against a given schema in your Camel route.

The aim is thus:

Given a json message and a predefined json schema, we want to validate the message against the schema and return the result of the validation.

Camel route

Assuming you have create a Camel route here is how my (very) basic code looks like:

package org.souciance.integration.validate;

import org.apache.camel.builder.RouteBuilder;
import org.apache.commons.io.IOUtils;

import java.nio.charset.Charset;

public class CamelValidateJson extends RouteBuilder {

@Override
public void configure() throws Exception {
ClassLoader classLoader = getClass().getClassLoader();
String schema = IOUtils.toString(classLoader.getResourceAsStream("jsonvalidate/schema.json"), Charset.defaultCharset());
String json = IOUtils.toString(classLoader.getResourceAsStream("jsonvalidate/data.json"), Charset.defaultCharset());
from("timer://cameldemoValidateJson?repeatCount=1").routeId("ValidateJson")
.setBody(constant(json))
.setProperty("Schema", constant(schema))
.bean(ValidateJson.class, "isValidJson")
.choice()
.when(header("isValid")
.isEqualTo(true))
.log("Valid json!")
.when(header("isValid")
.isEqualTo(false))
.log("Invalid json!")
.end()
.end();
}
}

I have kept the steps very simple. The idea is to focus on the schema validation and nothing else so I am manually loading the data and the schema file. You could off course inject the schema path via some variable or some other way.

I then start the route via  timer, again this is to keep it simple.

I then create an exchange property called ”Schema” and insert the schema in it.

Then I call a bean using .bean and as parameters give the bean class and bean method.

The bean will return the result of the validation inside a header.

I use the choice() and when() to log the result.

The bean code looks like this:

package org.souciance.integration.validate;

import com.fasterxml.jackson.databind.JsonNode;
import com.github.fge.jackson.JsonLoader;
import com.github.fge.jsonschema.core.exceptions.ProcessingException;
import com.github.fge.jsonschema.core.report.ProcessingReport;
import com.github.fge.jsonschema.main.JsonSchemaFactory;
import com.github.fge.jsonschema.main.JsonValidator;
import org.apache.camel.Exchange;

import java.io.IOException;

/**
* Created by moeed on 2017-01-15.
*/
public class ValidateJson {
/**
* Method to jsonvalidate some json data based on a json schema
* @throws IOException
* @throws ProcessingException
*/
public static void isValidJson(Exchange exchange) throws IOException, ProcessingException {
final JsonNode data = JsonLoader.fromString(exchange.getIn().getBody().toString());
final JsonNode schema = JsonLoader.fromString(exchange.getProperty("Schema").toString());

final JsonSchemaFactory factory = JsonSchemaFactory.byDefault();
JsonValidator validator = factory.getValidator();

ProcessingReport report = validator.validate(schema, data);
System.out.println(report);
if (!report.toString().contains("success")) {
report.toString();
exchange.getIn().setHeader("isValid", false);
}
else {
exchange.getIn().setHeader("isValid", true);
}

}
}

The method isValidJson is very simple. It receives the exchange. It extracts the json data from the body and the json schema from the exchange property.

Now to the main part. I use the json schema library to do the actually schema validation. If the validation is false I update the exchange header and if it is successful I also update the exchange header.

If you log the output after running it with intentionally bad data for a given a schema you will see something like this:

com.github.fge.jsonschema.core.report.ListProcessingReport: failure
--- BEGIN MESSAGES ---
error: object has missing required properties (["age"])
level: "error"
schema: {"loadingURI":"#","pointer":"/items"}
instance: {"pointer":"/7"}
domain: "validation"
keyword: "required"
required: ["_id","about","address","age","balance","company","email","eyeColor","favoriteFruit","friends","greeting","guid","index","isActive","latitude","longitude","name","phone","picture","range","registered","tags"]
missing: ["age"]
--- END MESSAGES ---

As you can see I did not have the property ”age” so the validation failed. With the age property put back in the data the output will simply be ”success”.

This is just simple way of doing json validation in your Camel routes. You can use it whilst doing rest calls or simple file based data manipulation. For more info here is the source code on my github:

https://github.com/SoucianceEqdamRashti/Integration/tree/master/CamelDemo/src/main/java/org/souciance/integration/validate