com.rabbitmq.tools.jsonrpc
Class JsonRpcClient

java.lang.Object
  com.rabbitmq.client.RpcClient
      com.rabbitmq.tools.jsonrpc.JsonRpcClient

All Implemented Interfaces:

java.lang.reflect.InvocationHandler

public class JsonRpcClient
extends RpcClient
implements java.lang.reflect.InvocationHandler

JSON-RPC is a lightweight RPC mechanism using JSON as a data language for request and reply messages. It is rapidly becoming a standard in web development, where it is used to make RPC requests over HTTP. RabbitMQ provides an AMQP transport binding for JSON-RPC in the form of the JsonRpcClient class. JSON-RPC services are self-describing - each service is able to list its supported procedures, and each procedure describes its parameters and types. An instance of JsonRpcClient retrieves its service description using the standard system.describe procedure when it is constructed, and uses the information to coerce parameter types appropriately. A JSON service description is parsed into instances of ServiceDescription. Client code can access the service description by reading the serviceDescription field of JsonRpcClient instances.

See Also:

call(String, Object[]), call(String[])

Field Summary

ServiceDescription

serviceDescription Holds the JSON-RPC service description for this client.

Constructor Summary

JsonRpcClient(Channel channel, java.lang.String exchange, java.lang.String routingKey)
Construct a new JsonRpcClient, passing the parameters through to RpcClient's constructor.

Method Summary

java.lang.Object	call(java.lang.String[] args) Public API - as call(String,Object[]), but takes the method name from the first entry in args, and the parameters from subsequent entries.
java.lang.Object	call(java.lang.String method, java.lang.Object[] params) Public API - builds, encodes and sends a JSON-RPC request, and waits for the response.
static java.lang.Object	checkReply(java.util.Map<java.lang.String,java.lang.Object> reply) Private API - parses a JSON-RPC reply object, checking it for exceptions.
static java.lang.Object	coerce(java.lang.String val, java.lang.String type) Private API - used by call(String[]) to ad-hoc convert strings into the required data types for a call.
java.lang.Object	createProxy(java.lang.Class klass) Public API - gets a dynamic proxy for a particular interface class.
ServiceDescription	getServiceDescription() Public API - gets the service description record that this service loaded from the server itself at construction time.
java.lang.Object	invoke(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args) Public API - implements InvocationHandler.invoke.
void	retrieveServiceDescription() Private API - invokes the "system.describe" method on the server, and parses and stores the resulting service description in this object.

Methods inherited from class com.rabbitmq.client.RpcClient

checkConsumer, close, getChannel, getConsumer, getContinuationMap, getCorrelationId, getExchange, getReplyQueue, getRoutingKey, mapCall, mapCall, primitiveCall, primitiveCall, publish, setupConsumer, setupReplyQueue, stringCall

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

serviceDescription

public ServiceDescription serviceDescription

Holds the JSON-RPC service description for this client.

Constructor Detail

JsonRpcClient

public JsonRpcClient(Channel channel,
                     java.lang.String exchange,
                     java.lang.String routingKey)
              throws java.io.IOException,
                     JsonRpcException

Construct a new JsonRpcClient, passing the parameters through to RpcClient's constructor. The service description record is retrieved from the server during construction.

Throws:

java.io.IOException

JsonRpcException

Method Detail

checkReply

public static java.lang.Object checkReply(java.util.Map<java.lang.String,java.lang.Object> reply)
                                   throws JsonRpcException

Private API - parses a JSON-RPC reply object, checking it for exceptions.

Returns:

the result contained within the reply, if no exception is found Throws JsonRpcException if the reply object contained an exception

Throws:

JsonRpcException

call

public java.lang.Object call(java.lang.String method,
                             java.lang.Object[] params)
                      throws java.io.IOException,
                             JsonRpcException

Public API - builds, encodes and sends a JSON-RPC request, and waits for the response.

Returns:

the result contained within the reply, if no exception is found

Throws:

JsonRpcException - if the reply object contained an exception

java.io.IOException

invoke

public java.lang.Object invoke(java.lang.Object proxy,
                               java.lang.reflect.Method method,
                               java.lang.Object[] args)
                        throws java.lang.Throwable

Public API - implements InvocationHandler.invoke. This is useful for constructing dynamic proxies for JSON-RPC interfaces.

Specified by:

invoke in interface java.lang.reflect.InvocationHandler

Throws:

java.lang.Throwable

createProxy

public java.lang.Object createProxy(java.lang.Class klass)
                             throws java.lang.IllegalArgumentException

Public API - gets a dynamic proxy for a particular interface class.

Throws:

java.lang.IllegalArgumentException

coerce

public static java.lang.Object coerce(java.lang.String val,
                                      java.lang.String type)
                               throws java.lang.NumberFormatException

Private API - used by call(String[]) to ad-hoc convert strings into the required data types for a call.

Throws:

java.lang.NumberFormatException

call

public java.lang.Object call(java.lang.String[] args)
                      throws java.lang.NumberFormatException,
                             java.io.IOException,
                             JsonRpcException

Public API - as call(String,Object[]), but takes the method name from the first entry in args, and the parameters from subsequent entries. All parameter values are passed through coerce() to attempt to make them the types the server is expecting.

Returns:

the result contained within the reply, if no exception is found

Throws:

JsonRpcException - if the reply object contained an exception

java.lang.NumberFormatException - if a coercion failed

java.io.IOException

See Also:

coerce(java.lang.String, java.lang.String)

getServiceDescription

public ServiceDescription getServiceDescription()

Public API - gets the service description record that this service loaded from the server itself at construction time.

retrieveServiceDescription

public void retrieveServiceDescription()
                                throws java.io.IOException,
                                       JsonRpcException

Private API - invokes the "system.describe" method on the server, and parses and stores the resulting service description in this object.

Throws:

java.io.IOException

JsonRpcException