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// Copyright (c) 2007-2020 VMware, Inc. or its affiliates. All rights reserved.
//
// This software, the RabbitMQ Java client library, is triple-licensed under the
// Mozilla Public License 2.0 ("MPL"), the GNU General Public License version 2
// ("GPL") and the Apache License version 2 ("ASL"). For the MPL, please see
// LICENSE-MPL-RabbitMQ. For the GPL, please see LICENSE-GPL2. For the ASL,
// please see LICENSE-APACHE2.
//
// This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND,
// either express or implied. See the LICENSE file for specific language governing
// rights and limitations of this software.
//
// If you have any questions regarding licensing, please contact us at
// [email protected].
package com.rabbitmq.tools.jsonrpc;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.StringRpcServer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
/**
* JSON-RPC Server class.
*
* Given a Java {@link Class}, representing an interface, and an
* implementation of that interface, JsonRpcServer will reflect on the
* class to construct the {@link ServiceDescription}, and will route
* incoming requests for methods on the interface to the
* implementation object while the mainloop() is running.
*
* {@link JsonRpcServer} delegates JSON parsing and generating to
* a {@link JsonRpcMapper}.
*
* @see com.rabbitmq.client.RpcServer
* @see JsonRpcClient
* @see JsonRpcMapper
* @see JacksonJsonRpcMapper
*/
public class JsonRpcServer extends StringRpcServer {
private static final Logger LOGGER = LoggerFactory.getLogger(JsonRpcServer.class);
private final JsonRpcMapper mapper;
/**
* Holds the JSON-RPC service description for this client.
*/
private ServiceDescription serviceDescription;
/**
* The instance backing this server.
*/
private Object interfaceInstance;
public JsonRpcServer(Channel channel,
Class interfaceClass,
Object interfaceInstance, JsonRpcMapper mapper)
throws IOException {
super(channel);
this.mapper = mapper;
init(interfaceClass, interfaceInstance);
}
/**
* Construct a server that talks to the outside world using the
* given channel, and constructs a fresh temporary
* queue. Use getQueueName() to discover the created queue name.
*
* @param channel AMQP channel to use
* @param interfaceClass Java interface that this server is exposing to the world
* @param interfaceInstance Java instance (of interfaceClass) that is being exposed
* @throws IOException if something goes wrong during an AMQP operation
*/
public JsonRpcServer(Channel channel,
Class interfaceClass,
Object interfaceInstance)
throws IOException {
this(channel, interfaceClass, interfaceInstance, new DefaultJsonRpcMapper());
}
public JsonRpcServer(Channel channel,
String queueName,
Class interfaceClass,
Object interfaceInstance, JsonRpcMapper mapper)
throws IOException {
super(channel, queueName);
this.mapper = mapper;
init(interfaceClass, interfaceInstance);
}
/**
* Construct a server that talks to the outside world using the
* given channel and queue name. Our superclass,
* RpcServer, expects the queue to exist at the time of
* construction.
*
* @param channel AMQP channel to use
* @param queueName AMQP queue name to listen for requests on
* @param interfaceClass Java interface that this server is exposing to the world
* @param interfaceInstance Java instance (of interfaceClass) that is being exposed
* @throws IOException if something goes wrong during an AMQP operation
*/
public JsonRpcServer(Channel channel,
String queueName,
Class interfaceClass,
Object interfaceInstance)
throws IOException {
this(channel, queueName, interfaceClass, interfaceInstance, new DefaultJsonRpcMapper());
}
private void init(Class interfaceClass, Object interfaceInstance) {
/**
* The interface this server implements.
*/
this.interfaceInstance = interfaceInstance;
this.serviceDescription = new ServiceDescription(interfaceClass);
}
/**
* Override our superclass' method, dispatching to doCall.
*/
@Override
public String handleStringCall(String requestBody, AMQP.BasicProperties replyProperties) {
String replyBody = doCall(requestBody);
return replyBody;
}
/**
* Runs a single JSON-RPC request.
*
* @param requestBody the JSON-RPC request string (a JSON encoded value)
* @return a JSON-RPC response string (a JSON encoded value)
*/
public String doCall(String requestBody) {
Object id;
String method;
Object[] params;
String response;
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Request: {}", requestBody);
}
try {
JsonRpcMapper.JsonRpcRequest request = mapper.parse(requestBody, serviceDescription);
if (request == null) {
response = errorResponse(null, 400, "Bad Request", null);
} else if (!ServiceDescription.JSON_RPC_VERSION.equals(request.getVersion())) {
response = errorResponse(null, 505, "JSONRPC version not supported", null);
} else {
id = request.getId();
method = request.getMethod();
params = request.getParameters();
if (request.isSystemDescribe()) {
response = resultResponse(id, serviceDescription);
} else if (request.isSystem()) {
response = errorResponse(id, 403, "System methods forbidden", null);
} else {
Object result;
try {
Method matchingMethod = matchingMethod(method, params);
if (LOGGER.isDebugEnabled()) {
Collection parametersValuesAndTypes = new ArrayList();
if (params != null) {
for (Object param : params) {
parametersValuesAndTypes.add(
String.format("%s (%s)", param, param == null ? "?" : param.getClass())
);
}
}
LOGGER.debug("About to invoke {} method with parameters {}", matchingMethod, parametersValuesAndTypes);
}
result = matchingMethod.invoke(interfaceInstance, params);
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Invocation returned {} ({})", result, result == null ? "?" : result.getClass());
}
response = resultResponse(id, result);
} catch (Throwable t) {
LOGGER.info("Error while processing JSON RPC request", t);
response = errorResponse(id, 500, "Internal Server Error", t);
}
}
}
} catch (ClassCastException cce) {
// Bogus request!
response = errorResponse(null, 400, "Bad Request", null);
}
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Response: {}", response);
}
return response;
}
/**
* Retrieves the best matching method for the given method name and parameters.
*
* Subclasses may override this if they have specialised
* dispatching requirements, so long as they continue to honour
* their ServiceDescription.
*/
public Method matchingMethod(String methodName, Object[] params) {
ProcedureDescription proc = serviceDescription.getProcedure(methodName, params.length);
return proc.internal_getMethod();
}
/**
* Construct and encode a JSON-RPC error response for the request
* ID given, using the code, message, and possible
* (JSON-encodable) argument passed in.
*/
private String errorResponse(Object id, int code, String message, Object errorArg) {
Map err = new HashMap();
err.put("name", "JSONRPCError");
err.put("code", code);
err.put("message", message);
err.put("error", errorArg);
return response(id, "error", err);
}
/**
* Construct and encode a JSON-RPC success response for the
* request ID given, using the result value passed in.
*/
private String resultResponse(Object id, Object result) {
return response(id, "result", result);
}
/**
* Private API - used by errorResponse and resultResponse.
*/
private String response(Object id, String label, Object value) {
Map resp = new HashMap();
resp.put("version", ServiceDescription.JSON_RPC_VERSION);
if (id != null) {
resp.put("id", id);
}
resp.put(label, value);
String respStr = mapper.write(resp);
return respStr;
}
/**
* Public API - gets the service description record that this
* service built from interfaceClass at construction time.
*/
public ServiceDescription getServiceDescription() {
return serviceDescription;
}
}