Package com.rabbitmq.tools.jsonrpc

Class JsonRpcClient

java.lang.Object

com.rabbitmq.client.RpcClient

com.rabbitmq.tools.jsonrpc.JsonRpcClient

All Implemented Interfaces:

InvocationHandler

public class JsonRpcClient
extends RpcClient
implements 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

Fields inherited from class com.rabbitmq.client.RpcClient

NO_TIMEOUT

Constructor Summary

Constructors

Constructor	Description
JsonRpcClient(Channel channel, String exchange, String routingKey)
JsonRpcClient(Channel channel, String exchange, String routingKey, int timeout)	Construct a new JsonRpcClient, passing the parameters through to RpcClient's constructor.

Method Summary

Modifier and Type	Method	Description
Object	call(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.
Object	call(String method, Object[] params)	Public API - builds, encodes and sends a JSON-RPC request, and waits for the response.
static Object	checkReply(Map<String,Object> reply)	Private API - parses a JSON-RPC reply object, checking it for exceptions.
static Object	coerce(String val, String type)	Private API - used by call(String[]) to ad-hoc convert strings into the required data types for a call.
Object	createProxy(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.
Object	invoke(Object proxy, Method method, Object[] args)	Public API - implements InvocationHandler.invoke.

Methods inherited from class com.rabbitmq.client.RpcClient

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

Methods inherited from class java.lang.Object

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

Constructor Details

JsonRpcClient

public JsonRpcClient(Channel channel,
 String exchange,
 String routingKey,
 int timeout)
              throws IOException,
JsonRpcException,
TimeoutException

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

Throws:

TimeoutException - if a response is not received within the timeout specified, if any

IOException

JsonRpcException

JsonRpcClient

public JsonRpcClient(Channel channel,
 String exchange,
 String routingKey)
              throws IOException,
JsonRpcException,
TimeoutException

Throws:

IOException

JsonRpcException

TimeoutException

Method Details

checkReply

public static Object checkReply(Map<String,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 Object call(String method,
 Object[] params)
            throws IOException,
JsonRpcException,
TimeoutException

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

TimeoutException - if a response is not received within the timeout specified, if any

IOException

invoke

public Object invoke(Object proxy,
 Method method,
 Object[] args)
              throws Throwable

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

Specified by:

invoke in interface InvocationHandler

Throws:

Throwable

createProxy

public Object createProxy(Class<?> klass)
                   throws IllegalArgumentException

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

Throws:

IllegalArgumentException

coerce

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

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

Throws:

NumberFormatException

call

public Object call(String[] args)
            throws NumberFormatException,
IOException,
JsonRpcException,
TimeoutException

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

NumberFormatException - if a coercion failed

TimeoutException - if a response is not received within the timeout specified, if any

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.