rfc2263.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

          wishes to use.




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       -  The contextEngineID is provided by the command generator if it
          wishes to explicitly specify the location of the management
          information it is requesting.

       -  The contextName is provided by the command generator if it
          wishes to explicitly specify the local context name for the
          management information it is requesting.

       -  The pduVersion indicates the version of the PDU to be sent.

       -  The PDU is a value constructed by the command generator
          containing the management operation that the command generator
          wishes to perform.

       -  The expectResponse argument indicates that a response is
          expected.

   The result of the sendPdu interface indicates whether the PDU was
   successfully sent.  If it was successfully sent, the returned value
   will be a sendPduHandle.  The command generator should store the
   sendPduHandle so that it can correlate a response to the original
   request.

   The Dispatcher is responsible for delivering the response to a
   particular request to the correct command generator application.  The
   abstract service interface used is:

       processResponsePdu(              -- process Response PDU
         IN   messageProcessingModel    -- typically, SNMP version
         IN   securityModel             -- Security Model in use
         IN   securityName              -- on behalf of this principal
         IN   securityLevel             -- Level of Security
         IN   contextEngineID           -- data from/at this SNMP entity
         IN   contextName               -- data from/in this context
         IN   pduVersion                -- the version of the PDU
         IN   PDU                       -- SNMP Protocol Data Unit
         IN   statusInformation         -- success or errorIndication
         IN   sendPduHandle             -- handle from sendPDU
              )

   Where:

       -  The messageProcessingModel is the value from the received
          response.

       -  The securityModel is the value from the received response.

       -  The securityName is the value from the received response.



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       -  The securityLevel is the value from the received response.

       -  The contextEngineID is the value from the received response.

       -  The contextName is the value from the received response.

       -  The pduVersion indicates the version of the PDU in the
          received response.

       -  The PDU is the value from the received response.

       -  The statusInformation indicates success or failure in
          receiving the response.

       -  The sendPduHandle is the value returned by the sendPdu call
          which generated the original request to which this is a
          response.

   The procedure when a command generator receives a message is as
   follows:

(1)  If the received values of messageProcessingModel, securityModel,
     securityName, contextEngineID, contextName, and pduVersion are not
     all equal to the values used in the original request, the response
     is discarded.

(2)  The operation type, request-id, error-status, error-index, and
     variable-bindings are extracted from the PDU and saved.  If the
     request-id is not equal to the value used in the original request,
     the response is discarded.

(3)  At this point, it is up to the application to take an appropriate
     action.  The specific action is implementation dependent.  If the
     statusInformation indicates that the request failed, an appropriate
     action might be to attempt to transmit the request again, or to
     notify the person operating the application that a failure
     occurred.

3.2.  Command Responder Applications

   Before a command responder application can process messages, it must
   first associate itself with an SNMP engine.  The abstract service
   interface used for this purpose is:








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       statusInformation =        -- success or errorIndication
         registerContextEngineID(
         IN   contextEngineID     -- take responsibility for this one
         IN   pduType             -- the pduType(s) to be registered
              )

   Where:

       -  The statusInformation indicates success or failure of the
          registration attempt.

       -  The contextEngineID is equal to the snmpEngineID of the SNMP
          engine with which the command responder is registering.

       -  The pduType indicates a Get, GetNext, GetBulk, or Set pdu.

   Note that if another command responder application is already
   registered with an SNMP engine, any further attempts to register with
   the same contextEngineID and pduType will be denied.  This implies
   that separate command responder applications could register
   separately for the various pdu types.  However, in practice this is
   undesirable, and only a single command responder application should
   be registered with an SNMP engine at any given time.

   A command responder application can disassociate with an SNMP engine
   using the following abstract service interface:

       unregisterContextEngineID(
         IN   contextEngineID     -- give up responsibility for this one
         IN   pduType             -- the pduType(s) to be unregistered
              )

   Where:

       -  The contextEngineID is equal to the snmpEngineID of the SNMP
          engine with which the command responder is cancelling the
          registration.

       -  The pduType indicates a Get, GetNext, GetBulk, or Set pdu.

   Once the command responder has registered with the SNMP engine, it
   waits to receive SNMP messages.  The abstract service interface used
   for receiving messages is:

   processPdu(                     -- process Request/Notification PDU
     IN   messageProcessingModel   -- typically, SNMP version
     IN   securityModel            -- Security Model in use
     IN   securityName             -- on behalf of this principal



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     IN   securityLevel            -- Level of Security
     IN   contextEngineID          -- data from/at this SNMP entity
     IN   contextName              -- data from/in this context
     IN   pduVersion               -- the version of the PDU
     IN   PDU                      -- SNMP Protocol Data Unit
     IN   maxSizeResponseScopedPDU -- maximum size of the Response PDU
     IN   stateReference           -- reference to state information
          )                        -- needed when sending a response

   Where:

       -  The messageProcessingModel indicates which Message Processing
          Model received and processed the message.

       -  The securityModel is the value from the received message.

       -  The securityName is the value from the received message.

       -  The securityLevel is the value from the received message.

       -  The contextEngineID is the value from the received message.

       -  The contextName is the value from the received message.

       -  The pduVersion indicates the version of the PDU in the
          received message.

       -  The PDU is the value from the received message.

       -  The maxSizeResponseScopedPDU is the maximum allowable size of
          a ScopedPDU containing a Response PDU (based on the maximum
          message size that the originator of the message can accept).

       -  The stateReference is a value which references cached
          information about each received request message.  This value
          must be returned to the Dispatcher in order to generate a
          response.

   The procedure when a message is received is as follows.

(1)  The operation type is determined from the ASN.1 tag value
     associated with the PDU parameter.  The operation type should
     always be one of the types previously registered by the
     application.

(2)  The request-id is extracted from the PDU and saved.





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(3)  If the SNMPv2 operation type is GetBulk, the non-repeaters and
     max-repetitions values are extracted from the PDU and saved.

(4)  The variable-bindings are extracted from the PDU and saved.

(5)  The management operation represented by the SNMPv2 operation type
     is performed with respect to the relevant MIB view within the
     context named by the contextName, according to the procedures set
     forth in [RFC1905].  The relevant MIB view is determined by the
     securityLevel, securityModel, contextName, securityName, and SNMPv2
     operation type.  To determine whether a particular object instance
     is within the relevant MIB view, the following abstract service
     interface is called:

         statusInformation =      -- success or errorIndication
           isAccessAllowed(
           IN   securityModel     -- Security Model in use
           IN   securityName      -- principal who wants to access
           IN   securityLevel     -- Level of Security
           IN   viewType          -- read, write, or notify view
           IN   contextName       -- context containing variableName
           IN   variableName      -- OID for the managed object
                )

     Where:

       -  The securityModel is the value from the received message.

       -  The securityName is the value from the received message.

       -  The securityLevel is the value from the received message.

       -  The viewType indicates whether the PDU type is a read or write
          operation.

       -  The contextName is the value from the received message.

       -  The variableName is the object instance of the variable for
          which access rights are to be checked.

     Normally, the result of the management operation will be a new PDU
     value, and processing will continue in step (6) below.  However, at
     any time during the processing of the management operation:

       -  If the isAccessAllowed ASI returns a noSuchView,
          noAccessEntry, or noGroupName error, processing of the
          management operation is halted, a PDU value is contructed
          using the values from the originally received PDU, but



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          replacing the error_status with an authorizationError code,
          and error_index value of 0, and control is passed to step (6)
          below.

       -  If the isAccessAllowed ASI returns an otherError, processing
          of the management operation is halted, a different PDU value
          is contructed using the values from the originally received
          PDU, but replacing the error_status with a genError code, and
          control is passed to step (6) below.

       -  If the isAccessAllowed ASI returns a noSuchContext error,
          processing of the management operation is halted, no result
          PDU is generated, the snmpUnknownContexts counter is
          incremented, and control is passed to step (6) below.

       -  If the context named by the contextName parameter is
          unavailable, processing of the management operation is halted,
          no result PDU is generated, the snmpUnavailableContexts
          counter is incremented, and control is passed to step (6)
          below.

(6)  The Dispatcher is called to generate a response or report message.
     The abstract service interface is:

     returnResponsePdu(
       IN   messageProcessingModel   -- typically, SNMP version
       IN   securityModel            -- Security Model in use
       IN   securityName             -- on behalf of this principal
       IN   securityLevel            -- same as on incoming request
       IN   contextEngineID          -- data from/at this SNMP entity
       IN   contextName              -- data from/in this context
       IN   pduVersion               -- the version of the PDU
       IN   PDU                      -- SNMP Protocol Data Unit
       IN   maxSizeResponseScopedPDU -- maximum size of the Response PDU
       IN   stateReference           -- reference to state information
                                     -- as presented with the request
       IN   statusInformation        -- success or errorIndication
            )                        -- error counter OID/value if error

     Where:

       -  The messageProcessingModel is the value from the processPdu