JsonMethodCallMarshalFilter.java

/**
 * Licensed to the Austrian Association for Software Tool Integration (AASTI)
 * under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright
 * ownership. The AASTI licenses this file to you under the Apache License,
 * Version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.openengsb.core.common.remote;

import java.io.IOException;
import java.util.Map;

import org.openengsb.core.api.remote.FilterAction;
import org.openengsb.core.api.remote.FilterConfigurationException;
import org.openengsb.core.api.remote.FilterException;
import org.openengsb.core.api.remote.MethodCall;
import org.openengsb.core.api.remote.MethodCallMessage;
import org.openengsb.core.api.remote.MethodResultMessage;
import org.openengsb.core.util.JsonUtils;

import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * This filter takes a JSON-serialized {@link MethodCallMessage} and deserializes it. The {@link MethodCallMessage}
 * object is then passed on to the next filter. The returned {@link MethodResultMessage} is than seralized to JSON
 * again.
 * 
 * <code>
 * <pre>
 *      [MethodCallRequest as JSON-string]   > Filter > [MethodCallRequest]     > ...
 *                                                                                 |
 *                                                                                 v
 *      [MethodResultMessage as JSON-string] < Filter < [MethodResultMessage]   < ...
 * </pre>
 * </code>
 */
public class JsonMethodCallMarshalFilter extends AbstractFilterChainElement<String, String> {

    private FilterAction next;

    @Override
    public String doFilter(String input, Map<String, Object> metadata) throws FilterException {
        ObjectMapper objectMapper = JsonUtils.createObjectMapperWithIntroSpectors();
        MethodCallMessage callMessage;
        try {
            callMessage = objectMapper.readValue(input, MethodCallMessage.class);
            MethodCall call = callMessage.getMethodCall();
            Object[] args = call.getArgs();
            for (int i = 0; i < args.length; i++) {
                String className = call.getClasses().get(i);
                Class<?> parameterClass;
                try {
                    parameterClass = getClass().getClassLoader().loadClass(className);
                } catch (ClassNotFoundException e) {
                    throw new FilterException(e);
                }
                args[i] = objectMapper.convertValue(args[i], parameterClass);
            }
            MethodResultMessage returnValue = (MethodResultMessage) next.filter(callMessage, metadata);
            return objectMapper.writeValueAsString(returnValue);
        } catch (IOException e) {
            throw new FilterException(e);
        }
    }

    @Override
    public void setNext(FilterAction next) throws FilterConfigurationException {
        checkNextInputAndOutputTypes(next, MethodCallMessage.class, MethodResultMessage.class);
        this.next = next;
    }

}