Define custom objects as Java services

What is to be implemented as a Service ?

Other pages demonstrate how to manually add Marshaller/Unmarshaller/MethodConf/EvaluatorValueLogic to configuration.

Custom (and default) implementations of those interfaces can be seen as providers for them. Implementations can be installed in the form of extensions.

To pass implementations as service providers, place provider-configuration files under a directory in the resource directory META-INF/services. The directory’s name is the fully qualified binary name of the interface/service’s type.

The directory contains a list of files. Each file represents an implementation of the interface, with a fully qualified binary name, and with parameters of its own.

File parameters

Each file contains a number of parameters to define an implementation/service provider.

There are several possible parameters:

• className: binary fully qualified name of current implementation.
• singleton: boolean to indicate if Scala object, otherwise Scala class.
• codename: Type codename that this implementation should be associated with. See Types
• constructorArgNames: list of constructor argument names in single a String, separated by sep.
• sep: string separator in constructorArgNames.

You must also provide Constructor arguments in the file in the form argumentName=argumentValue.

How to declare a Marshaller as a service

Just add a directory named com.celadari.jsonlogicscala.serialize.Marshaller in your META-INF/services/ directory.

project
│   ...
│   build.sbt
│
└───META-INF
│   │   ...
│   │   ...
│   │
│   └───services
│       │   file111.txt
│       │   file112.txt
│       │   ...
│       └───com.celadari.jsonlogicscala.serialize.Marshaller
│           │   codenameCustomClassA
│           │   codenameCustomClassB
│           │   ...
└

Example

You may implement the following class

// package com.myownpackage.definitions
class A(...)

// package com.myownpackage.marshallers
class MarshallerClassA(param1: Int, param2: String) extends Marshaller {
  def marshal(value: Any): JsValue = {
    value match {
      case a: A => ...
      case _ => throw ...
    }
  }
}

Instead of passing it manually to Serializer.createConf, you can just define file classA in the directory META-INF/services/com.celadari.jsonlogicscala.serialize.Marshaller/

className=com.myownpackage.marshallers.MarshallerClassA
singleton=false
param1=45
param2="My own parameter"
constructorArgNames=param1;param2
sep=;
codename=classA

How to declare a Unmarshaller as a service ?

Just add a directory named com.celadari.jsonlogicscala.deserialize.Unmarshaller in your META-INF/services/ directory.

project
│   ...
│   build.sbt
│
└───META-INF
│   │   ...
│   │   ...
│   │
│   └───services
│       │   file111.txt
│       │   file112.txt
│       │   ...
│       └───com.celadari.jsonlogicscala.deserialize.Unmarshaller
│           │   codenameCustomClassA
│           │   codenameCustomClassB
│           │   ...
└

Example

You can implement the following class:

// package com.myownpackage.definitions
class A(...)

// package com.myownpackage.unmarshallers
class UnmarshallerClassA(param1: Int, param2: String) extends Unmarshaller {
  def unmarshal(jsValue: JsValue): Any = {
    val constructorArg1 = (jsValue \ ...).as[...]
    ...
    val constuctorArgN = (jsValue \ ...).as[...]
    new A(constuctorArg1, ..., constuctorArgN)
  }
}

Instead of passing it manually to Deserializer.createConf, you can just define the file classA in the directory META-INF/services/com.celadari.jsonlogicscala.deserialize.Unmarshaller/

className=com.myownpackage.unmarshallers.UnmarshallerClassA
singleton=false
param1=45
param2="My own parameter"
constructorArgNames=param1;param2
sep=;
codename=classA

How to declare an EvaluatorValueLogic as a service

Just add a directory named com.celadari.jsonlogicscala.evaluate.EvaluatorValueLogic in your META-INF/services/ directory.

project
│   ...
│   build.sbt
│
└───META-INF
│   │   ...
│   │   ...
│   │
│   └───services
│       │   file111.txt
│       │   file112.txt
│       │   ...
│       └───com.celadari.jsonlogicscala.evaluate.EvaluatorValueLogic
│           │   codenameCustomClassA
│           │   codenameCustomClassB
│           │   ...
└

Example

You can implement the following classes, replacing objects A with objects B before evaluation.

// package com.myownpackage.definitions
class A(...)
class B(...)

// package com.myownpackage.evaluators
class EvaluatorValueLogicClassA(param1: Int, param2: String) extends EvaluatorValueLogic {
  def evaluateValueLogic(value: Any): Any = {
    new B(...)
  }
}

Instead of passing it manually to EvaluatorLogicConf.createConf, you can just the define file classA in the directory META-INF/services/com.celadari.jsonlogicscala.evaluate.EvaluatorValueLogic/

className=com.myownpackage.evaluators.EvaluatorValueLogicClassA
singleton=false
param1=45
param2="My own parameter"
constructorArgNames=param1;param2
sep=;
codename=classA

How to declare MethodConf as a service

Just add a directory named com.celadari.jsonlogicscala.evaluate.MethodConf in your META-INF/services/ directory.

project
│   ...
│   build.sbt
│
└───META-INF
│   │   ...
│   │   ...
│   │
│   └───services
│       │   file111.txt
│       │   file112.txt
│       │   ...
│       └───com.celadari.jsonlogicscala.evaluate.MethodConf
│           │   codenameCustomOperatorA
│           │   codenameCustomOperatorB
│           │   ...
└

Example:

You can implement following classes, replacing objects A with objects B before evaluation.

// package com.myownpackage.operators
object OperatorA extends Operator {
  ...
}

Instead of passing it manually to EvaluatorLogicConf.createConf, you can just define file classA in the directory META-INF/services/com.celadari.jsonlogicscala.evaluate.MethodConf/

className=com.myownpackage.operators.OperatorA
singleton=true
codename=operator_a