rfc2982.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

     naming the data type of the parameter in the parameter's position
     in the parameter list.  The parameter must be of the type indicated
     and generally may be a constant, a MIB object, a function, or an
     expression.

     counter32(integer) - wrapped around an integer value counter32
     forces Counter32 as a data type.

     counter64(integer) - similar to counter32 except that the
     resulting data type is 'counter64'.

     arraySection(array, integer, integer) - selects a piece of an
     array (i.e. part of an OCTET STRING or OBJECT IDENTIFIER).  The
     integer arguments are in the range 0 to 4,294,967,295.  The
     first is an initial array index (one-dimensioned) and the second
     is an ending array index.  A value of 0 indicates first or last
     element, respectively.  If the first element is larger than the
     array length the result is 0 length.  If the second integer is
     less than or equal to the first, the result is 0 length.  If the
     second is larger than the array length it indicates last
     element.

     stringBegins/Ends/Contains(octetString, octetString) - looks for
     the second string (which can be a string constant) in the first
     and returns the one-dimensioned arrayindex where the match began.
     A return value of 0 indicates no match (i.e. boolean false).

     oidBegins/Ends/Contains(oid, oid) - looks for the second OID
     (which can be an OID constant) in the first and returns the
     the one-dimensioned index where the match began. A return value
     of 0 indicates no match (i.e. boolean false).

     average/maximum/minimum(integer) - calculates the average,
     minimum, or maximum value of the integer valued object over
     multiple sample times.  If the object disappears for any
     sample period, the accumulation and the resulting value object
     cease to exist until the object reappears at which point the
     calculation starts over.

     sum(integerObject*) - sums all available values of the
     wildcarded integer object, resulting in an integer scalar.  Must
     be used with caution as it wraps on overflow with no
     notification.

     exists(anyTypeObject) - verifies the object instance exists. A
     return value of 0 indicates NoSuchInstance (i.e. boolean
     false)."



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    ::= { expExpressionEntry 3 }

expExpressionValueType OBJECT-TYPE
    SYNTAX      INTEGER { counter32(1), unsigned32(2), timeTicks(3),
                 integer32(4), ipAddress(5), octetString(6),
                 objectId(7), counter64(8) }
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
     "The type of the expression value.  One and only one of the
     value objects in expValueTable will be instantiated to match
     this type.

     If the result of the expression can not be made into this type,
     an invalidOperandType error will occur."
    DEFVAL      { counter32 }
    ::= { expExpressionEntry 4 }

expExpressionComment OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
     "A comment to explain the use or meaning of the expression."
    DEFVAL      { ''H }
    ::= { expExpressionEntry 5 }

expExpressionDeltaInterval OBJECT-TYPE
    SYNTAX      Integer32 (0..86400)
    UNITS       "seconds"
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
     "Sampling interval for objects in this expression with
     expObjectSampleType 'deltaValue'.

     This object has no effect if the the expression has no
     deltaValue objects.

     A value of 0 indicates no automated sampling.  In this case
     the delta is the difference from the last time the expression
     was evaluated.  Note that this is subject to unpredictable
     delta times in the face of retries or multiple managers.

     A value greater than zero is the number of seconds between
     automated samples.

     Until the delta interval has expired once the delta for the



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     object is effectively not instantiated and evaluating
     the expression has results as if the object itself were not
     instantiated.

     Note that delta values potentially consume large amounts of
     system CPU and memory.  Delta state and processing must
     continue constantly even if the expression is not being used.
     That is, the expression is being evaluated every delta interval,
     even if no application is reading those values.  For wildcarded
     objects this can be substantial overhead.

     Note that delta intervals, external expression value sampling
     intervals and delta intervals for expressions within other
     expressions can have unusual interactions as they are impossible
     to synchronize accurately.  In general one interval embedded
     below another must be enough shorter that the higher sample
     sees relatively smooth, predictable behavior.  So, for example,
     to avoid the higher level getting the same sample twice, the
     lower level should sample at least twice as fast as the higher
     level does."
    DEFVAL      { 0 }
    ::= { expExpressionEntry 6 }

expExpressionPrefix OBJECT-TYPE
    SYNTAX      OBJECT IDENTIFIER
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
     "An object prefix to assist an application in determining
     the instance indexing to use in expValueTable, relieving the
     application of the need to scan the expObjectTable to
     determine such a prefix.

     See expObjectTable for information on wildcarded objects.

     If the expValueInstance portion of the value OID may
     be treated as a scalar (that is, normally, 0) the value of
     expExpressionPrefix is zero length, that is, no OID at all.
     Note that zero length implies a null OID, not the OID 0.0.

     Otherwise, the value of expExpressionPrefix is the expObjectID
     value of any one of the wildcarded objects for the expression.
     This is sufficient, as the remainder, that is, the instance
     fragment relevant to instancing the values, must be the same for
     all wildcarded objects in the expression."
    ::= { expExpressionEntry 7 }

expExpressionErrors OBJECT-TYPE



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    SYNTAX      Counter32
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
     "The number of errors encountered while evaluating this
     expression.

     Note that an object in the expression not being accessible,
     is not considered an error. An example of an inaccessible
     object is when the object is excluded from the view of the
     user whose security credentials are used in the expression
     evaluation. In such cases, it is a legitimate condition
     that causes the corresponding expression value not to be
     instantiated."
    ::= { expExpressionEntry 8 }

expExpressionEntryStatus OBJECT-TYPE
    SYNTAX      RowStatus
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
     "The control that allows creation and deletion of entries."
    ::= { expExpressionEntry 9 }

--
-- Expression Error Table
--

expErrorTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF ExpErrorEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
     "A table of expression errors."
    ::= { expDefine 2 }

expErrorEntry OBJECT-TYPE
    SYNTAX      ExpErrorEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
     "Information about errors in processing an expression.

     Entries appear in this table only when there is a matching
     expExpressionEntry and then only when there has been an
     error for that expression as reflected by the error codes
     defined for expErrorCode."
    INDEX       { expExpressionOwner, expExpressionName }



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    ::= { expErrorTable 1 }

ExpErrorEntry ::= SEQUENCE {
    expErrorTime       TimeStamp,
    expErrorIndex      Integer32,
    expErrorCode       INTEGER,
    expErrorInstance   OBJECT IDENTIFIER
}

expErrorTime OBJECT-TYPE
    SYNTAX      TimeStamp
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
     "The value of sysUpTime the last time an error caused a
     failure to evaluate this expression."
    ::= { expErrorEntry 1 }

expErrorIndex OBJECT-TYPE
    SYNTAX      Integer32
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
     "The one-dimensioned character array index into
     expExpression for where the error occurred.  The value
     zero indicates irrelevance."
    ::= { expErrorEntry 2 }

expErrorCode OBJECT-TYPE
    SYNTAX      INTEGER {
          invalidSyntax(1),
          undefinedObjectIndex(2),
          unrecognizedOperator(3),
          unrecognizedFunction(4),
          invalidOperandType(5),
          unmatchedParenthesis(6),
          tooManyWildcardValues(7),
          recursion(8),
          deltaTooShort(9),
          resourceUnavailable(10),
          divideByZero(11)
          }
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
     "The error that occurred.  In the following explanations the
     expected timing of the error is in parentheses.  'S' means
     the error occurs on a Set request.  'E' means the error



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     occurs on the attempt to evaluate the expression either due to
     Get from expValueTable or in ongoing delta processing.

     invalidSyntax       the value sent for expExpression is not
                    valid Expression MIB expression syntax
                    (S)
     undefinedObjectIndex     an object reference ($n) in
                    expExpression does not have a matching
                    instance in expObjectTable (E)
     unrecognizedOperator     the value sent for expExpression held an
                    unrecognized operator (S)
     unrecognizedFunction     the value sent for expExpression held an
                    unrecognized function name (S)
     invalidOperandType  an operand in expExpression is not the
                    right type for the associated operator
                    or result (SE)
     unmatchedParenthesis     the value sent for expExpression is not
                    correctly parenthesized (S)
     tooManyWildcardValues    evaluating the expression exceeded the
                    limit set by
                    expResourceDeltaWildcardInstanceMaximum
                    (E)
     recursion      through some chain of embedded
                    expressions the expression invokes itself
                    (E)
     deltaTooShort       the delta for the next evaluation passed
                    before the system could evaluate the
                    present sample (E)
     resourceUnavailable some resource, typically dynamic memory,
                    was unavailable (SE)
     divideByZero        an attempt to divide by zero occurred
                    (E)

     For the errors that occur when the attempt is made to set
     expExpression Set request fails with the SNMP error code
     'wrongValue'.  Such failures refer to the most recent failure to
     Set expExpression, not to the present value of expExpression
     which must be either unset or syntactically correct.

     Errors that occur during evaluation for a Get* operation return
     the SNMP error code 'genErr' except for 'tooManyWildcardValues'
     and 'resourceUnavailable' which return the SNMP error code
     'resourceUnavailable'."
    ::= { expErrorEntry 3 }

expErrorInstance OBJECT-TYPE
    SYNTAX      OBJECT IDENTIFIER
    MAX-ACCESS  read-only



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    STATUS      current
    DESCRIPTION
     "The expValueInstance being evaluated when the error
     occurred.  A zero-length indicates irrelevance."
    ::= { expErrorEntry 4 }

--
-- Object Table
--

expObjectTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF ExpObjectEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
     "A table of object definitions for each expExpression.

     Wildcarding instance IDs:

     It is legal to omit all or part of the instance portion for
     some or all of the objects in an expression. (See the
     DESCRIPTION of expObjectID for details.  However, note that