DefaultSnmpClient (sdn-apidoc 2.0.0 API)

java.lang.Object
- com.h3c.util.snmp.DefaultSnmpClient

All Implemented Interfaces:

DatagramEngine.Listener, SnmpClient
```
public class DefaultSnmpClient
extends Object
implements SnmpClient, DatagramEngine.Listener
```
The SNMP client is designed to be thread safe. The follow describes each of the 3 types of threads that will use call into an instance of this class:
The Caller's thread (SNMP client) makes a call to sendRequest(SnmpRequest). A caller can only send a request once. If the request is invalid or there is a problem with the engine an exception will be thrown. If the request is valid, the caller will receive a asynchronous notification on the request's listener. Internally, a call will be made to the sendEngine(SnmpRequest) method that is synchronized with respect to this instance.
The Response Worker Thread will call ClientResponseHandler.responseRecieved(SnmpResponse, byte[], InetSocketAddress) when a response is received. A call is then made to checkOut(int) (which is synchronized) to unregister the associated request. If no request ID is found in the map, this response will be dropped because we have no knowledge of the original request. If a matching request is found, the response will be attached to the request and the response will be processed further. Note that the request has already been removed from the request map so there is no possibility for a retry to occur.
The Timeout Worker Thread will periodically check the request map and perform resends or call back request that have exhausted all retry attempts. A call is made to checkAndHandleTimeouts() which will call removeTimedOutRequests(long) according to the timeout check frequency. The handler (which is synchronized) will iterate and remove all requests that have timed out. Any pending requests that arrive in the meantime will be dropped. (The response thread will have to wait for the iteration to complete before attempting to check out the request from the map). The synchronized block is exited and we are left with a list of requests that we now will retry or all the error listener.
In summary, the sendEngine(SnmpRequest), checkOut(int) and removeTimedOutRequests(long) methods are synchronized with respect to one another so that we can treat the request map and request ID allocation safely. This enforces that a request can only be worked on by a single thread at a time.

Constructor Summary

Constructors
Constructor and Description
`DefaultSnmpClient(DatagramEngine datagramEngine)` Constructor.
`DefaultSnmpClient(DatagramEngine datagramEngine, long timeoutCheckFrequencyMillis)` Constructor.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`onReceive(byte[] payload, InetSocketAddress remoteAddress)` Called back when a new datagram arrives.
`void`	`sendRequest(SnmpRequest request)` Main entry point for sending requests to a SNMP server.
`void`	`sendTrap(SnmpTrapRequest trap)` Main entry point for sending traps to a SNMP receiver.
`void`	`stop()` Shutdown the client and underlying engine.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - DefaultSnmpClient
```
public DefaultSnmpClient(DatagramEngine datagramEngine)
```
    Constructor.
    
    Parameters:
    datagramEngine - datagram engine implementation
  - DefaultSnmpClient
```
public DefaultSnmpClient(DatagramEngine datagramEngine,
                 long timeoutCheckFrequencyMillis)
```
    Constructor.
    
    Parameters:
    datagramEngine - datagram engine implementation
    timeoutCheckFrequencyMillis - frequency in milliseconds between request timeout checks.
- Method Detail
  - stop
```
public void stop()
```
    Shutdown the client and underlying engine.
    
    Specified by:
    
    stop in interface SnmpClient
  - sendTrap
```
public void sendTrap(SnmpTrapRequest trap)
```
    Main entry point for sending traps to a SNMP receiver. The caller creates a trap and hands it off to this this method. Once a trap enters this method the caller should not keep a reference to it.
    
    Specified by:
    
    sendTrap in interface SnmpClient
    
    Parameters:
    trap - SNMP trap
    
    Throws:
    
    IllegalArgumentException - if there is a problem with this request
  - sendRequest
```
public void sendRequest(SnmpRequest request)
```
    Main entry point for sending requests to a SNMP server. The caller creates a request and hands it off to this method. Once a request enters this method the caller should not keep a reference to it.
    
    Specified by:
    
    sendRequest in interface SnmpClient
    
    Parameters:
    request - SNMP request (all required fields must be setup properly)
    
    Throws:
    
    IllegalArgumentException - if there is a problem with this request
  - onReceive
```
public void onReceive(byte[] payload,
             InetSocketAddress remoteAddress)
```
    Description copied from interface: DatagramEngine.Listener
    
    Called back when a new datagram arrives.
    
    Specified by:
    
    onReceive in interface DatagramEngine.Listener
    
    Parameters:
    payload - received datagram payload
    remoteAddress - remote socket address for received payload

Class DefaultSnmpClient

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

DefaultSnmpClient

DefaultSnmpClient

Method Detail

stop

sendTrap

sendRequest

onReceive