JSON Schema Validator

Since Camel 2.20

Only producer is supported

The JSON Schema Validator component performs bean validation of the message body against JSON Schemas v4, v6, v7 and v2019-09 draft using the NetworkNT JSON Schema library (https://github.com/networknt/json-schema-validator).

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-json-validator</artifactId>
    <version>x.y.z</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI format

json-validator:resourceUri[?options]

Where resourceUri is some URL to a local resource on the classpath or a full URL to a remote resource or resource on the file system which contains the JSON Schema to validate against.

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.

Configuring Endpoint Options

Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL as a type safe way of configuring endpoints.

A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.

The following two sections lists all the options, firstly for the component followed by the endpoint.

Component Options

The JSON Schema Validator component supports 2 options, which are listed below.

Name Description Default Type

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

boolean

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

boolean

Endpoint Options

The JSON Schema Validator endpoint is configured using URI syntax:

json-validator:resourceUri

with the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

resourceUri (producer)

Required Path to the resource. You can prefix with: classpath, file, http, ref, or bean. classpath, file and http loads the resource using these protocols (classpath is default). ref will lookup the resource in the registry. bean will call a method on a bean to be used as the resource. For bean you can specify the method name after dot, eg bean:myBean.myMethod.

String

Query Parameters (8 parameters)

Name Description Default Type

allowContextMapAll (producer)

Sets whether the context map should allow access to all details. By default only the message body and headers can be accessed. This option can be enabled for full access to the current Exchange and CamelContext. Doing so impose a potential security risk as this opens access to the full power of CamelContext API.

boolean

contentCache (producer)

Sets whether to use resource content cache or not.

boolean

failOnNullBody (producer)

Whether to fail if no body exists.

boolean

failOnNullHeader (producer)

Whether to fail if no header exists when validating against a header.

boolean

headerName (producer)

To validate against a header instead of the message body.

String

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

boolean

errorHandler (advanced)

To use a custom ValidatorErrorHandler. The default error handler captures the errors and throws an exception.

JsonValidatorErrorHandler

uriSchemaLoader (advanced)

To use a custom schema loader allowing for adding custom format validation. The default implementation will create a schema loader that tries to determine the schema version from the $schema property of the specified schema.

JsonUriSchemaLoader

Example

Assuming we have the following JSON Schema

myschema.json

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "definitions": {},
  "id": "my-schema",
  "properties": {
    "id": {
      "default": 1,
      "description": "An explanation about the purpose of this instance.",
      "id": "/properties/id",
      "title": "The id schema",
      "type": "integer"
    },
    "name": {
      "default": "A green door",
      "description": "An explanation about the purpose of this instance.",
      "id": "/properties/name",
      "title": "The name schema",
      "type": "string"
    },
    "price": {
      "default": 12.5,
      "description": "An explanation about the purpose of this instance.",
      "id": "/properties/price",
      "title": "The price schema",
      "type": "number"
    }
  },
  "required": [
    "name",
    "id",
    "price"
  ],
  "type": "object"
}

we can validate incoming JSON with the following Camel route, where myschema.json is loaded from the classpath.

from("direct:start")
  .to("json-validator:myschema.json")
  .to("mock:end")

If you use the default schema loader, it will try to determine the schema version from the $schema property and instruct the validator appropriately. If it can’t find (or doesn’t recognize) the $schema property, it will assume your schema is version 2019-09.

If your schema is local to your application (e.g. a classpath location as opposed to URL), your schema can also contain $ref links to a relative subschema in the classpath. Per the JSON schema spec, your schema must not have an $id identifier property for this to work properly. See the unit test and schema for an example.

Spring Boot Auto-Configuration

When using json-validator with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-json-validator-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 3 options, which are listed below.

Name Description Default Type

camel.component.json-validator.autowired-enabled

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

Boolean

camel.component.json-validator.enabled

Whether to enable auto configuration of the json-validator component. This is enabled by default.

Boolean

camel.component.json-validator.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean