将mule消息有效负载转换为snmp陷阱或pdu对象

Question

我已经应用了一个使用snmp4j发送和接收陷阱的示例，一切都很好。
但问题是：
当使用mule esb接收snmp陷阱时，我无法将传入的消息有效负载转换为PDU（或任何snmp4j合适的对象）以从中提取数据，我已经做了很多搜索，但徒劳无功。
有人能帮助我：
将我从udpendpoint收到的mule esb消息有效负载转换为org.snmp4j。从PDU对象中提取陷阱数据吗？
这是我的代码：

public synchronized MuleEvent process(MuleEvent event) throws MuleException {
        byte[] encodedMessage = event.getMessage().getPayload(byte[].class);
        //next line is not working but its only sample of what I Am looking for 
        PDU pdu = new PDU(encodedMessage );
.....

Answer 1

您需要创建一个自定义转换器来转换相关SNMP4J对象中的消息有效负载。或者，如果SNMP4J API足够简单，这可以使用表达式转换器来完成。

Answer 2

当您实现自己的TransportMapping并将其与SNMP4J MessageDispatcherImpl关联时，可以更轻松地将BER流转换为SNMP4J PDU。然后将所有必要的MessageProcessingModels和SecurityProtocols添加到消息调度程序。

最后，将CommandResponder接口的实现添加到消息调度程序中，就完成了。

Answer 3

public class SNMP4JParser implements Callable {

    /**
     * The following objects are all necessary in order to use SNMP4j as a parser for raw messages.
     * This was all inspired by SNMP4j source code, in particular MessageDispatcherImpl.java
     */
    private MessageProcessingModel model = null;
    private MessageDispatcher dispatcher = null;
    private Address listenAddress = null;
    private Integer32 messageProcessingModel = null;
    private Integer32 securityModel = null;
    private OctetString securityName = null;
    private Integer32 securityLevel = null;
    private PduHandle handle = null;
    private StatusInformation statusInfo = null;
    private MutableStateReference mutableStateReference = null;

    /**
     * Taken from org.snmp4j.transport.AbstractTransportMapping class
     */
    protected Integer32 maxInboundMessageSize = new Integer32 ( (1 << 16) - 1 );

    /**
     * Taken from org.snmp4j.MessageDispatcherImpl class
     */
    private int transactionID = new Random().nextInt(Integer.MAX_VALUE - 2) + 1;

    /**
     * Create all objects that SNMP4j needs to parse a raw SNMP message
     */
    public SNMP4JParser()
    {
        model = new MPv1();
        dispatcher = new MessageDispatcherImpl();
        listenAddress = GenericAddress.parse("udp:0.0.0.0/2001");
        messageProcessingModel = new Integer32();
        securityModel = new Integer32();
        securityName = new OctetString();
        securityLevel = new Integer32();
        handle = new PduHandle(transactionID);
        statusInfo = new StatusInformation();
        mutableStateReference = new MutableStateReference();
    }

    /**
     * @see org.mule.api.lifecycle.Callable#onCall(org.mule.api.MuleEventContext)
     */
    @Override
    public Object onCall(MuleEventContext eventContext) throws Exception
    {
        byte[] payloadBytes = eventContext.getMessage().getPayloadAsBytes();
        ByteBuffer buffer = ByteBuffer.wrap(payloadBytes);
        BERInputStream wholeMessage = new BERInputStream(buffer);
        MutablePDU mutablePdu = new MutablePDU();

        int status = model.prepareDataElements(
                dispatcher, 
                listenAddress, 
                wholeMessage,
                messageProcessingModel, 
                securityModel,
                securityName, 
                securityLevel, 
                mutablePdu,
                handle, 
                maxInboundMessageSize, 
                statusInfo,
                mutableStateReference);

        if ( status !=  SnmpConstants.SNMP_MP_OK )
            throw new RuntimeException(
                "Couldn't parse SNMP message. model.prepareDataElements() returned " + status);

        return mutablePdu.getPdu();
    }

}

我用这样的流对其进行了测试（我使用了snmp4j-1.11.5和mule-standalone-3.4.0）

<udp:connector name="connector" doc:name="UDP"/>
<flow name="snmp-demo-trapHandlingFlow" doc:name="snmp-demo-trapHandlingFlow">
    <udp:inbound-endpoint host="0.0.0.0" port="2001" responseTimeout="10000"  doc:name="UDP"/>
    <logger message="TRAP RECEIVED - #[System.currentTimeMillis()]" level="DEBUG" doc:name="Inbound timestamp"/>
    <component class="com.netboss.flow.demo.SNMP4JParser" doc:name="SNMP4JParser"/>
    [...]

它的工作原理。

现在，我意识到还有一些悬而未决的问题：

1. 有没有更好/更有效的方法