JAJB

Java Architecture for JSON Binding

JAJB provides the simplest, shortest way to call the server side java api from the front end javascript.

First step

1. Create a POJO Service.

package foo;

import com.d_project.jajb.rpc.Callable;

public class MyService {
  @Callable
  public int add(int a, int b) { return a + b; }
}

2. Setup a RPCServlet.

/WEB-INF/web.xml

  <servlet>
    <servlet-name>jajb-rpc</servlet-name>
    <servlet-class>com.d_project.jajb.rpc.RPCServlet</servlet-class>
    <init-param>
      <param-name>services</param-name>
      <param-value>/WEB-INF/services.properties</param-value>
    </init-param>
  </servlet>

  <servlet-mapping>
    <servlet-name>jajb-rpc</servlet-name>
    <url-pattern>/jajb-rpc</url-pattern>
  </servlet-mapping>

/WEB-INF/services.properties

MyService=foo.MyService

3. Call from a client (with jQuery here).

  $.ajax({
    url : 'jajb-rpc',
    method : 'POST',
    type : 'application/json',
    data : JSON.stringify([
      { serviceName : 'MyService', methodName : 'add' }, // opts
      [ 3, 5 ] // args
    ])
  }).done(function(data) {
    console.log(JSON.stringify(data) );
  });

Here is a result.

{"status":"success","result":8}

With jquery-ajax-wrapper.js, call more simply.

  jajb.getService('MyService')('add')(3, 5).done(function(data) {
    console.log(JSON.stringify(data) );
  });

With POJO VO (Value Object)

package foo;

import com.d_project.jajb.JSONField;
import com.d_project.jajb.JSONType;

@JSONType
public class MyVO {

  @JSONField
  private String message;
  public String getMessage() { return message; }
  public void setMessage(String message) { this.message = message; }

  // This property will not be serialized.
  private String notSerializable;
  public String getNotSerializable() { return notSerializable; }
  public void setNotSerializable(String notSerializable) {
    this.notSerializable = notSerializable;
  }
}

package foo;

import com.d_project.jajb.rpc.Callable;

public class MyVOService {
  @Callable
  public MyVO helloVO(MyVO vo) {
    vo.setMessage("hello," + vo.getMessage() +
        "," + vo.getNotSerializable() );
    vo.setNotSerializable("Can you hear me?");
    return vo;
  }
}

  $.ajax({
    url : 'jajb-rpc',
    method : 'POST',
    type : 'application/json',
    data : JSON.stringify([
      { serviceName : 'MyVOService', methodName : 'helloVO' }, // opts
      [ { message : 'abc', notSerializable : 'will be ignored' } ] // args
    ])
  }).done(function(data) {
    console.log(JSON.stringify(data) );
  });

Here is a result.

{"status":"success","result":{"message":"hello,abc,null"}}

Type Mappings

Java to JSON

Java Type	JSON Type
null (Object)	null (Object)
boolean	Boolean
Primitive Number Types	Number
java.lang.Number	Number
java.lang.String	String
Array	Array
java.util.Iterable	Array
java.util.Map	Object
POJO Object	Object

JSON to Java (basic)

JSON Type	Java Type
null (Object)	null (Object)
Boolean	boolean
Number	java.math.BigDecimal
String	java.lang.String
Array	java.util.ArrayList
Object	java.util.LinkedHashMap

JSON to Java (with auto cast by reflection)

JSON Type	Java Type
Number	Primitive Number Types, java.math.BigInteger
Array	Array, java.util.ArrayList
Object	POJO Object