org.snmp4j.agent.mo
Class MOScalar<V extends org.snmp4j.smi.Variable>

java.lang.Object
  org.snmp4j.agent.mo.MOScalar<V>

All Implemented Interfaces:

ManagedObject, ManagedObjectValueAccess, MOScope, RegisteredManagedObject, SerializableManagedObject

Direct Known Subclasses:

AgentppSimulationMib.AgentppSimDeleteRow, AgentppSimulationMib.AgentppSimDeleteTableContents, DateAndTimeScalar, DisplayStringScalar, EnumeratedScalar, NotificationLogMib.NlmConfigGlobalAgeOut, NotificationLogMib.NlmConfigGlobalEntryLimit, SnmpTsmMib.SnmpTsmConfigurationUsePrefix, SNMPv2MIB.SysUpTimeImpl, TestAndIncr, TimeStampScalar

public class MOScalar<V extends org.snmp4j.smi.Variable>
extends java.lang.Object
implements ManagedObject, MOScope, SerializableManagedObject, ManagedObjectValueAccess

The MOScalar class represents scalar SNMP managed objects.

Version:

1.4

Author:

Frank Fock

Constructor Summary

MOScalar(org.snmp4j.smi.OID id, MOAccess access, V value)
Creates a scalar MO instance with OID, maximum access level and initial value.

Method Summary

void	addMOChangeListener(MOChangeListener l) Adds a MOChangeListener that needs to be informed about state changes of this scalar.
void	addMOValueValidationListener(MOValueValidationListener l) Adds a value validation listener to check new values.
protected int	changeValue(V value) Changes the value of this scalar on behalf of a commit or undo operation.
protected boolean	checkRequestScope(SubRequest request) Checks whether the request is within the scope of this scalar or not.
void	cleanup(SubRequest request) Cleansup a (sub)request and frees all resources locked during the preparation phase.
void	commit(SubRequest request) Commits a previously prepared SET (sub)request.
boolean	covers(org.snmp4j.smi.OID oid) Checks if this scope covers the supplied OID.
org.snmp4j.smi.OID	find(MOScope range) Finds the first object ID (OID) in the specified search range.
protected void	fireAfterMOChange(MOChangeEvent changeEvent)
protected void	fireAfterPrepareMOChange(MOChangeEvent changeEvent)
protected void	fireBeforeMOChange(MOChangeEvent changeEvent)
protected void	fireBeforePrepareMOChange(MOChangeEvent changeEvent)
protected void	fireValidate(MOValueValidationEvent validationEvent)
void	get(SubRequest request) Processes a GET request and return the result in the supplied sub-request.
MOAccess	getAccess() Gets the access object for this scalar.
org.snmp4j.smi.OID	getID() Gets the unique object ID of the managed object.
org.snmp4j.smi.OID	getLowerBound() Gets the lower bound OID of the scope.
org.snmp4j.smi.OID	getOid() Gets the instance OID of this scalar managed object.
MOScope	getScope() Returns the scope of OIDs that are covered by this scalar's object registration.
MOScope	getSingleInstanceScope() Returns a scope that covers only the scalar instance itself without any possible OIDs down in the tree or at the same level.
org.snmp4j.smi.OID	getUpperBound() Gets the upper bound OID of the scope.
V	getValue() Returns the actual value of this scalar managed object.
org.snmp4j.smi.Variable	getValue(org.snmp4j.smi.OID instanceOID) Returns the variable (a copy thereof) with the specified instance OID managed by this ManagedObject.
boolean	isCovered(MOScope other) Checks whether the supplied scope is covered by this scope.
boolean	isLowerIncluded() Indicates whether the lower bound OID is included in the scope or not.
boolean	isOverlapping(MOScope other) Checks whether the supplied scope overlap with this one, thus sharing at least one OID with the supplied one.
boolean	isUpperIncluded() Indicates whether the upper bound OID is included in the scope or not.
int	isValueOK(SubRequest request) Checks whether the new value contained in the supplied sub-request is a valid value for this object.
boolean	isVolatile() Tests if this instance of a SerializableManagedObject should be serialized or deserialized through persistent storage load or save operation.
void	load(MOInput input) Loads the content of the managed object from the specified input (stream).
boolean	next(SubRequest request) Finds the successor instance for the object instance ID (OID) given by the supplied sub-request and returns it within the supplied sub-request object.
void	prepare(SubRequest request) Prepares a SET (sub)request.
void	removeMOChangeListener(MOChangeListener l) Removes a MOChangeListener.
void	removeMOValueValidationListener(MOValueValidationListener l) Removes a value validation listener
void	save(MOOutput output) Saves the (non-volatile) content of this managed object to the specified output (stream).
int	setValue(V value) Sets the value of this scalar managed object without checking it for the correct syntax.
boolean	setValue(org.snmp4j.smi.VariableBinding newValueAndInstancceOID) Sets the value of a particular MIB object instance managed by this ManagedObject.
void	setVolatile(boolean isVolatile) Sets the volatile flag for this instance.
java.lang.String	toString()
protected java.lang.String	toStringDetails()
void	undo(SubRequest request) Compensates (undo) a (sub)request when a commit of another subrequest failed with an error.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

MOScalar

public MOScalar(org.snmp4j.smi.OID id,
                MOAccess access,
                V value)

Creates a scalar MO instance with OID, maximum access level and initial value.

Parameters:

id - the instance OID of the scalar instance (last sub-identifier should be zero).

access - the maximum access level supported by this instance.

value - the initial value of the scalar instance. If the initial value is null or a Counter syntax, the scalar is created as a volatile (non-persistent) instance by default.

Method Detail

getScope

public MOScope getScope()

Returns the scope of OIDs that are covered by this scalar's object registration. This range is 1.3.6...n <= x < 1.3.6...n+1 where n is the last subidentifier of the OID registered by the corresponding OBJECT-TYPE definition. Prior to version 1.1.2, this method returned a scope equal to the scope now returned by getSingleInstanceScope().

Specified by:

getScope in interface ManagedObject

Returns:

a MOScope that covers the OIDs by this scalar object registration.

getSingleInstanceScope

public MOScope getSingleInstanceScope()

Returns a scope that covers only the scalar instance itself without any possible OIDs down in the tree or at the same level.

Returns:

a scope that covers exactly the OID of this scalar.

Since:

1.1.2

find

public org.snmp4j.smi.OID find(MOScope range)

Description copied from interface: ManagedObject

Finds the first object ID (OID) in the specified search range.

Specified by:

find in interface ManagedObject

Parameters:

range - the MOScope for the search.

Returns:

the OID that is included in the search range and null if no such instances could be found.

get

public void get(SubRequest request)

Description copied from interface: ManagedObject

Processes a GET request and return the result in the supplied sub-request.

Specified by:

get in interface ManagedObject

Parameters:

request - the SubRequest to process.

getAccess

public MOAccess getAccess()

Gets the access object for this scalar.

Returns:

the access instance associated with this scalar.

Since:

1.2

checkRequestScope

protected boolean checkRequestScope(SubRequest request)

Checks whether the request is within the scope of this scalar or not.

Parameters:

request - a SubRequest.

Returns:

true if the request is within scope and false otherwise. In the latter case, the variable of the request is set to Null.noSuchInstance and the request is marked completed.

next

public boolean next(SubRequest request)

Description copied from interface: ManagedObject

Finds the successor instance for the object instance ID (OID) given by the supplied sub-request and returns it within the supplied sub-request object.

Specified by:

next in interface ManagedObject

Parameters:

request - the SubRequest to process.

Returns:

true if the search request found an appropriate instance, false otherwise.

isValueOK

public int isValueOK(SubRequest request)

Checks whether the new value contained in the supplied sub-request is a valid value for this object. The checks are performed by firing a MOValueValidationEvent the registered listeners.

Parameters:

request - the SubRequest with the new value.

Returns:

SnmpConstants.SNMP_ERROR_SUCCESS if the new value is OK, any other appropriate SNMPv2/v3 error status if not.

prepare

public void prepare(SubRequest request)

Description copied from interface: ManagedObject

Prepares a SET (sub)request. This method represents the first phase of a two phase commit. During preparation all necessary resources should be locked in order to be able to execute the commit without claiming additional resources.

Specified by:

prepare in interface ManagedObject

Parameters:

request - the SubRequest to process.

commit

public void commit(SubRequest request)

Description copied from interface: ManagedObject

Commits a previously prepared SET (sub)request. This is the second phase of a two phase commit. The change is committed but the resources locked during prepare not freed yet.

Specified by:

commit in interface ManagedObject

Parameters:

request - the SubRequest to process.

changeValue

protected int changeValue(V value)

Changes the value of this scalar on behalf of a commit or undo operation. Overwrite this method for easy and simple instrumentation. By default setValue(Variable value) is called.

Parameters:

value - the new value.

Returns:

a SNMP error status if the operation failed (should be avoided).

Since:

1.2

undo

public void undo(SubRequest request)

Description copied from interface: ManagedObject

Compensates (undo) a (sub)request when a commit of another subrequest failed with an error. This also frees any resources locked during the preparation phase.

Specified by:

undo in interface ManagedObject

Parameters:

request - the SubRequest to process.

cleanup

public void cleanup(SubRequest request)

Description copied from interface: ManagedObject

Cleansup a (sub)request and frees all resources locked during the preparation phase.

Specified by:

cleanup in interface ManagedObject

Parameters:

request - the SubRequest to process.

getOid

public org.snmp4j.smi.OID getOid()

Gets the instance OID of this scalar managed object.

Returns:

the instance OID (by reference).

getLowerBound

public org.snmp4j.smi.OID getLowerBound()

Description copied from interface: MOScope

Gets the lower bound OID of the scope. Whether the lower bound is included or excluded from the scope's region is determined by MOScope.isLowerIncluded().

Specified by:

getLowerBound in interface MOScope

Returns:

an OID.

getUpperBound

public org.snmp4j.smi.OID getUpperBound()

Description copied from interface: MOScope

Gets the upper bound OID of the scope. Whether the upper bound is included or excluded from the scope's region is determined by MOScope.isUpperIncluded().

Specified by:

getUpperBound in interface MOScope

Returns:

OID

isCovered

public boolean isCovered(MOScope other)

Description copied from interface: MOScope

Checks whether the supplied scope is covered by this scope.

Specified by:

isCovered in interface MOScope

Parameters:

other - the MOScope to check

Returns:

true if the lower bound of other is greater or equal than the lower bound of this scope and if the upper bound of other is lower or equal than the upper bound of this scope.

isLowerIncluded

public boolean isLowerIncluded()

Description copied from interface: MOScope

Indicates whether the lower bound OID is included in the scope or not.

Specified by:

isLowerIncluded in interface MOScope

Returns:

true if the lower bound is included.

isUpperIncluded

public boolean isUpperIncluded()

Description copied from interface: MOScope

Indicates whether the upper bound OID is included in the scope or not.

Specified by:

isUpperIncluded in interface MOScope

Returns:

true if the upper bound is included.

getValue

public V getValue()

Returns the actual value of this scalar managed object. For a basic instrumentation, overwrite this method to provide always the actual value and/or to update the internal value member and then call super.getValue() in the derived class.

Returns:

a non null Variable with the same syntax defined for this scalar object.

isVolatile

public boolean isVolatile()

Description copied from interface: SerializableManagedObject

Tests if this instance of a SerializableManagedObject should be serialized or deserialized through persistent storage load or save operation.

Specified by:

isVolatile in interface SerializableManagedObject

Returns:

true if SerializableManagedObject.load(org.snmp4j.agent.io.MOInput) and SerializableManagedObject.save(org.snmp4j.agent.io.MOOutput) should not be called through a persistent storage operation and false if these method should be called.

setValue

public int setValue(V value)

Sets the value of this scalar managed object without checking it for the correct syntax.

Parameters:

value - a Variable with the with the same syntax defined for this scalar object (not checked).

Returns:

a SNMP error code (zero indicating success by default).

setVolatile

public void setVolatile(boolean isVolatile)

Sets the volatile flag for this instance.

Parameters:

isVolatile - if true the state of this object will not be persistently stored, otherwise the agent may save the state of this object persistently.

isOverlapping

public boolean isOverlapping(MOScope other)

Description copied from interface: MOScope

Checks whether the supplied scope overlap with this one, thus sharing at least one OID with the supplied one.

Specified by:

isOverlapping in interface MOScope

Parameters:

other - a MOScope.

Returns:

true if there exists at least one OID that is included in both scopes.

addMOValueValidationListener

public void addMOValueValidationListener(MOValueValidationListener l)

Adds a value validation listener to check new values.

Parameters:

l - a MOValueValidationListener instance.

removeMOValueValidationListener

public void removeMOValueValidationListener(MOValueValidationListener l)

Removes a value validation listener

Parameters:

l - a MOValueValidationListener instance.

fireValidate

protected void fireValidate(MOValueValidationEvent validationEvent)

getID

public org.snmp4j.smi.OID getID()

Description copied from interface: RegisteredManagedObject

Gets the unique object ID of the managed object.

Specified by:

getID in interface RegisteredManagedObject

Returns:

an OID.

load

public void load(MOInput input)
          throws java.io.IOException

Description copied from interface: SerializableManagedObject

Loads the content of the managed object from the specified input (stream).

Specified by:

load in interface SerializableManagedObject

Parameters:

input - a MOInput instance.

Throws:

java.io.IOException - if an MOInput operation fails.

save

public void save(MOOutput output)
          throws java.io.IOException

Description copied from interface: SerializableManagedObject

Saves the (non-volatile) content of this managed object to the specified output (stream).

Specified by:

save in interface SerializableManagedObject

Parameters:

output - a MOOutput instance.

Throws:

java.io.IOException - if an MOOutput operation fails.

covers

public boolean covers(org.snmp4j.smi.OID oid)

Description copied from interface: MOScope

Checks if this scope covers the supplied OID.

Specified by:

covers in interface MOScope

Parameters:

oid - an OID.

Returns:

true if oid is greater or equal the scope's lower bound and if it is less or equal its upper bound.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

toStringDetails

protected java.lang.String toStringDetails()

addMOChangeListener

public void addMOChangeListener(MOChangeListener l)

Adds a MOChangeListener that needs to be informed about state changes of this scalar.

Parameters:

l - a MOChangeListener instance.

Since:

1.1

removeMOChangeListener

public void removeMOChangeListener(MOChangeListener l)

Removes a MOChangeListener.

Parameters:

l - a MOChangeListener instance.

Since:

1.1

fireBeforePrepareMOChange

protected void fireBeforePrepareMOChange(MOChangeEvent changeEvent)

fireAfterPrepareMOChange

protected void fireAfterPrepareMOChange(MOChangeEvent changeEvent)

fireBeforeMOChange

protected void fireBeforeMOChange(MOChangeEvent changeEvent)

fireAfterMOChange

protected void fireAfterMOChange(MOChangeEvent changeEvent)

getValue

public org.snmp4j.smi.Variable getValue(org.snmp4j.smi.OID instanceOID)

Description copied from interface: ManagedObjectValueAccess

Returns the variable (a copy thereof) with the specified instance OID managed by this ManagedObject.

Specified by:

getValue in interface ManagedObjectValueAccess

Parameters:

instanceOID - the instance OID of the value. Thus, for scalar values with .0 suffix and for tabular objects with table index suffix.

Returns:

a copy of the requested Variable or null if such a variable does not exist.

setValue

public boolean setValue(org.snmp4j.smi.VariableBinding newValueAndInstancceOID)

Description copied from interface: ManagedObjectValueAccess

Sets the value of a particular MIB object instance managed by this ManagedObject. This is a low level operation, thus no change events will be fired.

Specified by:

setValue in interface ManagedObjectValueAccess

Parameters:

newValueAndInstancceOID - a VariableBinding identifying the object instance to modify by its OID and the new value by its variable part.

Returns:

true if the object instance exists and has been modified successfully, false otherwise.