Revision 4.2.4
--------------

- SNMPv3 high-level and native API examples reworked and extended to cover
  many use cases.
- The missing functionality of NOTIFICATION-TYPE objects being looked up
  at local Management Instrumentation and attached to TRAP/INFORM message
  by Notification Originator is now fully implemented.
- The missing functionality of passing Response PDU contents of INFORM
  request is now implemented at Notification Originator app. The return
  value of NotificationOriginator.sendNotification is now a composite object
  that includes errorStatus, errorIndex and varBinds.
- The missing functionality of passing lookupNames & lookupValues params
  to Notification Originator is now implemented. It may make sense for
  INFORMs.
- The missing functionality of passing contextName to oneliner
  version of NotificationOriginator.sendNotification is now implemented.
- Oneliner example apps now include cases where non-default SNMP
  ContextEngineId/ContextName/SecurityEngineId is used.
- The contextName parameter of SnmpContext.getMibInstrum made optional.
- AbstractMibInstrumController class added as a base class for all possible
  kinds of Management Instrumentation controllers.
- Report package version on debugging code initialization.
- MibInstrumController.getMibBuilder() added.
- I/O sockets buffer sizes made configurable, minimum default is now 
  forced to be no less than 2**17 (to fit two huge datagrams).
- Catch possible exceptions on pyasn1 encoder invocation.
- VACM modules converted from a function into an object to let it keep
  state (caches) in the future.
- Unnecessary *MibSource explicit initialization calls removed at MibBuilder.
- Example configuration for Net-SNMP's snmptrapd added.
- Cast additionalVarBinds into ObjectIdentifier type at
  NotificationOriginator.sendNotification()
- Standard SNMPv3 Apps hardened to catch protocol-related exceptions and
  report them as errorIndication's.
- Catch and mute possible failure of getsockname(), that seems to happen 
  on Windows only so far.
- Memory leak fixed at oneliner cache of already configured targets.
- Fixes to at AsynNotificationOriginator.sendNotification() to make
  a) the notificationType param mandatory b)t e varBinds param really
  optional
- Fixes to ContextEngineId/ContextName support at the oneliner API: now
  both items should be passed to request PDU through *Cmd() request
  initiation method, the items of authData object should be used only for
  LCD configuration.
- Fix to MibVariable handling of the MIB, <empty-symbol> initializers.
- Fix to outgoing queue processing order at socket transport. Now
  it's a FIFO discipline rather than LIFO.
- Fix to NotificationOriginator's additionalVarBinds parameter - it is
  not mandatory anymore with the oneliner API. Also additionalVarBinds
  defaulted value changed from None to () meaning no var-binds.
- Attempt to convert Windows style EOL into UNIX ones in MIB source
  modules appeared to be unnecessary and even destructive to modules
  data in some cases. So the convertion code removed altogether.
- Fix to isAccessAllowed() error handling at NotificationOriginator. System
  used to crash on access denied condition.
- Fix to NotificationOriginator to make it use system uptime and trap OID
  values from SNMP engine's instrumentation rather then from SNMP context.
- Fix a couple of bugs at MibTable* logic involved for table instances
  creation.
- Fix to Management Instrumentation code to handle cases of non-initialized
  or not-compliant-to-constraints Managed Objects Instances.
- Fix to Management Instrumentation code to make table row removal through
  SNMP working again. Wrong method (instumClone) was probed at terminal
  MIB nodes values instead of the right one (setValue).

Revision 4.2.3
--------------

- SECURITY FIX: USM subsystem did not verify securityLevel of a request
  to an authoritative SNMP engineinbound against auth/priv protocols
  configured for the user in question. That allowed unauthenticated/unciphered
  access to pysnmp-based Agent even if USM user is configured to provide one.
- Oneliner [Asyn]CommandGenerator now supports optional keyword args
  lookupNames, lookupValues that enable response OID / value looked up at
  MIB and reported as a MibVariable container object carrying relevant
  MIB info.
- Oneliner [Asyn]CommandGenerator now supports symbolic MIB object names to be
  passed within a MibVariable container object which would do a deferred
  MIB lookup for name resolution. This is a new and preferred API which
  obsoletes the tuple-based one (it is still suppored though).
- Oneliner CommandGenerator's class attributes lexicographicMode, maxRows
  and ignoreNonIncreasingOid moved to optional keyword args of nextGen() 
  and bulkGen() methods.
- IPv6/UDP and Local Domain Socket transport interfaces added to the
  oneliner API.
- Mib Instrumentation subsystem re-worked to replace excessive
  MibNode's smiCreate()/smiWrite()/smiDestroy() methods with 
  MibScalarInstance's getValue()/setValue()
- MibTree.readTest[Get]Next() reworked to be called uniformely so
  user could tap on these methods at any level of the MIB tree.
- MibTableColumn.getNextNodeWithValue() unpublished API method obsoleted
  and removed for clarity.
- Hex dumps of binary parts of the protocol added to ease system
  operations analysis.
- SnmpEngineId autogeneration does not call DNS resolver but uses
  local hostname not to depend upon local IP availability and performance.
- Example apps reworked, additional SNMPv3 auth/priv protocols and transports
  added.
- Package version is now available as __init__.__version__ and it is 
  in-sync with distutils.
- Package meta-information updated.
- The __init__.py's made non-empty (rumors are that they may be optimized 
  out by package managers).
- Multiple fixes to UNIX domain socket transport to make it fully
  operational again.
- Use sysUpTime value whenever it is included in Notification PDU, otheriwese
  resort to SNMP engine uptime reading.
- SNMPv2c Message is now defined in rfc1901.py what matches standard 
  definition.
- Types defined within SNMPv1/v2c data structures (rfc1157.py/rfc1905.py)
  moved to module scope to become accessible by wrapper routines
  (v1.py/v2c.py). This is used for setting strictly typed default values
  to corresponding SNMP data structures.
- The obsolete and unpublished MibInstrumController.readVarsFast() method
  removed for API clarity.
- MibBuilder now distinguishes case of MIB modules filenames even if
  underlying OS does not.
- LCD configuration caching is implemented at pysnmp.entity.rfc3413.config
  that improves performance of repetitive calls by 10% and might hugely
  improve NotificationOriginator's performance when working on a large
  number of targets.
- A caching maps implemented at rfc2576 subsystem to speed-up communityName
  to/from securityName resolution. The also makes transport tags processing
  better compliant to the standard.
- Community and Transport tags processing changed at the oneliner interface
  to make the whole mechanism more compliant with the standard. Most
  importantly, it is now possible to tag authentication and transport
  information separately.
- The NoSuchInstanceError exception class is no more inherits from
  NoSuchObjectError to make class hierarchy closer to SNMP specification
  which states that these errors are separate and independent.
- The Next & BulkCommandGenerator's split onto single-run and iterative
  impementations. The former just process a single interaction and complete
  while the latter run as many interactions as user callback function
  indicates to.
- The pysnmp.entity.rfc3413.mibvar module is now obsolete by
  pysnmp.entity.rfc3413.oneliner.mibvar featuring basically the same
  features but within a stateful, dedicated object.
- Auth & target configuration container classes moved to their separate
  modules at oneliner API.
- The notificationType parameter of AsynNotificationOriginator.sendNotification
  made defaulted to reflect its optional nature.
- Oneliner UsmUserData, UdpTransportTarget, Udp6TransportTarget instances
  are not hashable anymore as they are intended to act more like a data 
  structure than object.
- Built-in debugger now supports negating debugging categories.
- An async/getgen.py example script added.
- Fix to MIB data reading routine to make it working with possible 
  Windows end-of-line's.
- Fix to CommandGenerator's SNMPv3 engine autodiscovery algorithm
  when retryCount is administratively set to 0.
- Fix to Notification Originator to make it communicating a single
  sendPduHandle to an application even when multiple INFORMs are triggered
  and processed by a single call by way of transport tagging feature.
- Fix to rfc2576:processIncomingMessage() to take SecurityModel into account
  when lookup up SecurityName by CommunityName. This allows mixed SNMPv1/v2c
  communication with the same target.
- Fix to internal MessageProcessing and SecurityModel timers so they become
  dependant on system timer resolution.
- Fix to v1.PDUAPI.setDefaults() method that used to set wrongly typed
  time-stamp component.
- Fix to IPv6 address handling to prevent system from crashing whilst
  running Python3. 
- Fix to SNMPv2 exception objects translation into SNMPv1 PDU and NEXT
  OIDs calculation.
- Fix to MibTree class to properly report noSuchObject & noSuchInstance
  SNMP special values.
- Fix to libsmi2pysnmp tool to make it working again in Python < 2.7
- Fix to exception handling at decodeMessageVersion() caller to prevent
  ASN.1 parsing errors crashing the whole app.
- Fix to GenericTrap type processing at rfc2576:v1Tov2c() which used to
  crash the whole SNMP engine.
- Fix to [possibly uninizilaized] pyasn1 objects printouts at
  MibInstrumController.__indexMib()
- Fix to maxSizeResponseScopedPDU calculation at rfc3414/service.py.
- Dedicated 'withmib' example set is obsolete and removed.
- Another SNMP proxy example app added (1to3.py).
- Fix to MIB modules loading code to make it using __import__() properly.
  This also makes pysnmp working again with Python 3.3rc0.
- Typo fix to snmpInASNParseErrs MIB instance object.
- Typo fix to errind.EngineIdMismatch class and its instance.

Revision 4.2.2
--------------

- Oneliner CommandGenerator can now limit the number of SNMP table
  rows returned by nextCmd()/bulkCmd() methods.
- Oneliner CommunityData configuration object can now be initialized
  with community name only, security name will be chosen automatically.
- Oneliner LCD configuration routines reworked towards clarity. The
  side-effect of this change is that repetitive oneliner call with the same
  securityName and different configuration options will only honor
  the first settings. Previous implementation would override older settings.
- Transport dispatcher now provides its own time expressed in 
  fractions of second. SNMP engine uses this notion of time for
  handling requests timeout to make packet flow time bound
  to async I/O core operations rather than to real time.
- The libsmi2pysnmp tool improved to handle incomplete SMI v1->v2
  conversion performed by smidump. The remaining core SMIv1 modules
  excluded from the core MIB set.
- The pyasn1 constraint and enumeration objects put into ASN1-*
  MIB modules what appears to be more in-line with SMI. Existing
  MIB modules as well as libsmi2pysnmp tool corrected accordingly.
- SMIv1 MIB modules (including RFC1155 and RFC1213) were moved to
  pysnmp-mibs as pysnmp is SMIv2-based.
- The MibBuilder.importSymbols() now takes optional kwargs and
  push them into MIB modules globals(). This is to facilitate
  passing user infomation, such as DB connection handler, to MIB
  module namespace so it could be used by ManagedObjects implementations.
- When running on Python3, SMI will re-raise exceptions with the original
  traceback for easier diagnostics.
- Out of PYTHONPATH MIB paths now supported.
- Added pyasn1 decoder failures diagnistics in debug mode.
- Fix to non-MT-safe class attributes at SNMPv3 MP & SEC modules.
- Fix to ContextName handling in bytes form whilst running Python3. Data
  mismatch error would return otherwise.
- Fix to SNMPv3 MP peer engine ID discovery not to learn and use
  user-specified ContextEngineId.
- Fix to socket.error processing at Py3 on Windows.
- Fix to oneliner GETNEXT/GETBULK implementation to properly support
  ignoreNonIncreasingOIDs option.
- Fix to setEndOfMibError()/setNoSuchInstanceError() at v1 PDU not to
  loose errorIndex.
- Fix to api.v2c.getVarBindTable() to ignore possible non-rectangular GETBULK
  response tables.
- Fix to oneliner getnext/getbulk response table rectangulation procedure
  to gracefully handle an empty column condition.
- Fix to legacy MibBuilder.getMibPath() to prevent it from missing
  .egg-based components in path.
- Fix to oneliner configuration routine that used to implicitly
  tag SNMPv1/v2c auth and transport LCD rows what resulted in
  huge delays when processing incoming messages with large number
  of peers configured.
- Fix to UDP6 transport handling at rfc2576 security module.
- Fix to SnmpEngineID value autogeneration (used to fail on Mac).
- SNMPv2-SMI.ObjectType.__repr__() fixed to do a repr() on its components.
- All SNMPv2-SMI.MibNode-based objects, once exported to a mibBuilder, will
  carry an embedded label symbol.
- Exlicit repr() calls replaced with '%r'
- Fix to error processing at GETNEXT & GETBULK apps response handlers.
- Fix to libsmi2pysnmp to make it supporting long (256+) list of function
  params.
- Fix to libsmi2pysnmp to support inheritance of MIB types.

Revision 4.2.1
--------------

- Support string OIDs at one-liner API.
- Code quality of libsmi2pysnmp tool improved, MIBs re-built.
- SNMP-PROXY-MIB & SNMP-USER-BASED-SM-3DES-MIB added
- v1arch bulkgen.py example added
- Major overhawl for Python 2.4 -- 3.2 compatibility:
  + get rid of old-style types
  + drop string module usage
  + switch to rich comparation
  + drop explicit long integer type use
  + map()/filter() replaced with list comprehension
  + apply() replaced with */**args
  + dictionary operations made 2K/3K compatible
  + division operator made 2K/3K compatible
  + sorting function now operates on key
  + iterators returned by some funcs in py3k converted to lists
  + exception syntax made 2K/3K compatible
  + tuple function arguments resolved to scalars to become py3k compatible
  + BER octetstream is now of type bytes (Py3k) or still string (Py2k)

Revision 4.1.16d
----------------

- Fix to SNMPv1 Trap PDU agentAddress setter shortcut method.

Revision 4.1.16c
----------------

- Missing module import fixed in privacy subsystem

Revision 4.1.16b
----------------

- Oneliner CommandGenerator can now optionally ignore non-increasing OIDs.
- Default CommandResponder now skips non-compliant (Counter64) values
  when responding to a v1 Manager.
- Fix to state information handling at CommandResponder app.
- Fix to Twisted reactor shutdown condition.
- Fix to distutils dependencies syntax.

Revision 4.1.16a
----------------

- Extended Security Options (3DESEDE, AES192, AES256) privacy
  protocols implemented.
- The error-indication codes moved from literals to objects for reliability
  and clarity
- Fix to v1.TrapPDUAPI.getVarBinds() to address PDU component at the right
  position.
- Fix to rfc1902.Bits initialization from named bits sequence.
- Fix to MIB builder by-extension module filtering code to cope with .pyw
  files.
- Internal caches structure improved.
- Sync versions of oneliner apps split off async implementation for clarity.
- Randomize initial in various numeric sequences.
- MsgAndPduDsp expectResponse parameters passing reworked.
- GetNext/GetBulk response processing logic moved to getNextVarBinds()
- Changes towards performance improvement:
  + all dict.has_key() & dict.get() invocations replaced with modern syntax
    (this breaks compatibility with Python 2.1 and older).
  + introduce the MibInstrumControlle.readVarsFast() method (which skips
    the "testing" phase of MIB value readin) for dealing with internal
    configuration (LCD).
  + default debug.logger is now just a zero value instead of an object
    what saves big on frequent calls
  + SNMPv2-SMI columnar indices <-> index values convertion code optimized.
  + pre-compute and re-use some of ASN.1 structures.
  + avoid setting PDU defaults to save on unnecessary initialization.
  + skip ASN.1 types verification where possible.
  + at oneliner Command Generator, avoid looking up pure OID arguments
    at MIB as it's pointless but takes time.
  + cache MIB columnar objects instance ID <-> symbolic index representation
    mapping

Revision 4.1.15a
----------------

- SNMP Proxy example added.
- End-of-MIB condition detection reworked what caused backward
  incompatibility at v1arch GETNEXT API. Previous pysnmp versions
  used value = None in var-binds as returned by getVarBindTable()
  API method. This version uses rfc1905 exception values (v2c/v3)
  or pyasn1 Null (v1).
  Built-in GETNEXT/GETBULK apps now do not require user to track
  end-of-mib conditions anymore -- this is now done automatically.
- CommandResponder API now supports async mode of operation.
- SNMP exception values now exported from rfc1905 module, and made
  pretty printable.
- Lexicographic walking mode is now supported at oneliner CommandGenerator.
- ContextEngineId&ContextName parameters passing implemented at
  v3arch oneliner API.
- Multiple instances of the same transport domain now supported.
- Initial snmpEngineId value generation improved not to accidentally
  collide within an administrative domain.
- MibTableColumn instances now build value-to-column-instance map
  to speedup by-value search.
- SNMPv2-CONF::AgentCapabilities macro implemented.
- The libsmi2pysnmp tool handles some more MACROs.
- Void access control module implemented to let apps disabling [default] VACM.
- Allow standard SNMP apps to choose access control method to use.
- Twisted-based CommandResponder example added.
- Fix/rework of Twisted GETNEXT/BULK CommandGenerator callback API to
  make it simpler and uniform with other CommandGenerators
- Fix to SNMPv3 security module to store peer SNMP engine timeline
  only if taken from an authenticated message. Prior to this fix
  SNMP engine was not been protected from spoofing.
- Fix to $SMIPATH initialization at build-pysnmp-mib.
- Fix to maxSizeResponseScopedPDU calculation.
- Fix to Next/Bulk CommandGenerators to catch a non-increasing OID
  error condition (what prevents looping).
- Fix to Opaque value tagging at rfc1155.Opaque type.
- Fix to handle (fail gracefully) zero-length user password.
- Fix to SNMP error propagation at Twisted driver (SF tracker ID #3054505).
- Fix to Agent-role snmpEngineId discovery procedure that allows
  authenticated ReportPDU generation.
- Fix to SNMPv1 PDU handling at CommandResponder & NotificationReceiver
  apps.
- Fix to CommandResponder app to skip Counter64 SMI values when responding
  to SNMPv1 Manager.
- Fix to protocol translator code (rfc2576) to handle Counter64 type
  in v2c-to-v1 PDU translation.
- Fix to non-response var-binds translation in rfc2576.v2ToV1().
- Fix to wrong exceptions used in pysnmp/entity modules.
- Fix to noauth/nopriv security module so that it would not crash SNMP
  engine if called accidentally.
- Fix to CommandResponder not to return out-of-range errorIndex along
  with genErr
- Fix to GETBULK CommandResponder to do a by-column MIB walk, not by-raw.
- Fix to getVarBindTable() API function logic.
- Fix to example Manager scripts to use errorIndex when available.
- Fix to dummy encryptData()/decryptData() API
- Fix to oneliner GETBULK table collection code to make it stripping
  uneven rows off table tail.

Revision 4.1.14a
----------------

- Fix to maxSizeResponseScopedPDU calculation at USM security module: now
  more precise and robust against screwed values on input.
- Fix to MIB loading logic that used to load same-name modules at
  disticts search paths on each loadModules() call.
- Fix to AsynsockDispatcher.runDispatcher() to make use of optional
  non-default select() timeout value.
- AbstractTransportDispatcher now allows user application registering
  multiple timer callbacks each with dedicated call period.
- Asynsock mainloop default idle period reduced to 0.5 sec for better
  timer resolution.
- Fix to SNMPv1->SNMPv2c error status handling at proxy module. This
  defect may have caused an infinite loop on a multiple var-bind
  SNMPv1 GetNext operation.
- Fix to contextName processing at config.addV1System -- typo rendered
  passed contextName not committed into LCD.
- Fix to unknown ContextName exception handling at CommandResponder App.
- config.addVacmUser() now accepts an optional contextName what makes
  it usable for configuring multiple contextName-bound bases of Managed
  Objects to SnmpEngine.
- MP pending states cache management re-worked so that SNMP engine will
  now handle an unlimited number of pending request/responses.
- Fix to SNMP discovery procedure: include ContentName in SNMP discovery
  messaging.
- Many fixes to AES crypto code that makes it actually working.
- Fix to SNMPv2-SMI createUndo operations.
- Fix to INFORM sending error handling at oneliner.
- Fix to mismatched response PDU handling at CommandGenerator application.
- Debug category 'app' (for Application) added to facilitate
  Standard SNMP Applications debugging.
- The retryCount semantic of CommandGenerator application changed to include
  sole retries and do not include initial request. Thus, retryCount=1 will
  now send up to two packets, not just one as it used to be.
- Debugging printout now escapes non-printable characters.

Revision 4.1.13a
----------------

- UDP over IPv6 transport implemented.
- Fix to MIB tree walking code that used to fail on table columns where
  indices have identical leading parts.
- SNMPv1/v2c snmpCommunityTransportTag-based imcoming message filtering
  implemented (rfc2576).

Revision 4.1.12a
----------------

- API versioning retired (pysnmp.v4 -> pysnmp).
- MIB loading mechanics re-designed to allow ZIP import.
- MIB loader supports code objects (py[co])
- Installer now uses setuptools for package management whenever available.
- The libsmi2pysnmp tool improved to build constraints of more than
  256 items (Python has a limit on the number of function params).
- Missing SNMPTrap PDU API implemented at proto.api.v2c, RFC2576 proxy
  code reworked.
- Fix to sysUpTime OID at SNMPv2 TRAP PDU.

Revision 4.1.11a
----------------

- Twisted integration implemented.
- Attempt to use hashlib whenever available.
- Fix to oneliner Manager code on < Python 2.4.
- Let NotificationReceiver and CommandResponder Apps browsing request details
  (transport information at the moment) at SNMP engine.
- Fix to config.addV1System() to allow multiple systems to co-exist in LCD.
- Fix to wrongly succeeding user-parameters-by-community-name searching code
  in rfc2576 processIncomingMsg() method.
- Do sanity checking on PYSNMP_MODULE_ID, Groups and Notifications in
  libsmi2pysnmp (SF bug #2122489).
- Fix to oneliner Notification Originator that sometimes used to send multiple
  requests at once.
- Oneliners LCD names generation code reworked to avoid accidental clashes.
- Fix and re-work of sysUpTime value management in LCD.
- Fix to pending inform request data caching in mpmod/rfc2576.py -- previous
  code led to cache data corruption on multple outstanding requests.
- In SMI configuration wrapper functions, catch access to non-configured
  entries and raise an exception.
- Allow multuple callback timer functions in all transport dispatchers.
- Fix to libsmi2pysnmp code to preserve more underscored object names and
  to guess the right type between indistinguishable ObjectGroup &
  NotificationGroup
- Fix to MibScalarInstance value setting logic - previous code failed
  when modifying the same OID multiple times within a single SET operation.
- Minor usability improvements to tools/build-pysnmp-mib.
- Made MIB objects unexport feature operational.

Revision 4.1.10a
----------------

- Internal MIB indexing method __indexMib() unmangled to facilitate
  setting up mutex there for sharing MIB stuff between threads.
- Fixed broken IpAddress value handling in SET operation.
- Broken MibBuilder.unloadModules() method now works.
- Use getLabel() SMI object method when building MIB tree (in builder.py)
  in addition to direct attribute access for clearer object protocol.
- The MIB building tools updated to match significantly improved
  smidump tool (libsmi version > 0.4.5).
- Made libsmi2pysnmp tool optionally building MIB text fields into pysnmp
  MIB code (enabled by default) and MibBuilder conditionally loading them 
  up (disabled by default).
- SnmpEngine and MsgAndPduDispatcher constructors now optionally
  take msgAndPduDspr and mibInstrumController class instances
  respectively to facilitate these objects sharing within a process.
- Unique integers, for various parts of the system, are now generated
  by a nextid.py module. This fixes possible issues with duplicate
  request IDs and handlers.
- Built-in MIBs re-generated to include text fields.

Revision 4.1.9a
---------------

- UNSTABLE ALPHA RELEASE.
- At onliner CommandGenerator, close transport on destruction to
  prevent socket leak. Implicit async transports registration at
  default asyncore's socket map has been disabled to avoid side
  effects.
- Fix to rfc2576.v1ToV2c() PDU converter to perform noSuchName error code
  translation.
- Fixes to Notification PDU convertion code at rfc2576 in part of
  snmpTrapOID handling.
- Fix to nonRepeaters object use as sequence slicer (must be int) at
  cmdrsp.CommandResponderApplication
- Make AsynsockDispatcher using its own socket map by default for 
  threading safety. This will break asyncore apps that rely on pysnmp 
  sharing the same socket map with them. A solution would  be to either
  set asyncore map to pysnmp (AsynsockDispatcher.setSocketMap()) or pass
  pysnmp map (AsynsockDispatcher.getSocketMap()) to asyncore.
- Fix to response timeout roundup bug at CommandGenerator and
  NotificationOriginator code.
- Oneline configuration classes made hashable to prevent memory leaks
  when committing them into CommandGenerator/NotificationOriginator
  internal repository.
- Security information is now released properly in all MP modules.
  This might fix a significant memory leak.
- Typo fix to rfc3411 confirmed class PDU members.

Revision 4.1.8a
---------------

- UNSTABLE ALPHA RELEASE.
- SMI/dispatcher timeout convertion multiplier is actually 100 (1/100 sec)
  rather than 1/1000. This fix affects timeouts specified through SMI.
- __repr__() implemented for UdpTransportTarget, CommunityData, UsmUserData
  in oneliner module.
- Automatically initialize table index values on table management
  operations (SF bug ID #1671989).
- Fix to carrier code: ignore BADFD socket error as it may happen upon 
  FD closure on n-1 select() event.
- Fix to MibBuilder.setMibPath() to preserve previously loaded modules
  intact. Otherwise loadModules() called after setMibPath() might fail
  with 'MIB file not found in search path' exception.
- Fix to oneliner classes that now invoke unconfiguration methods on
  destruction. This might have caused memory leaks.
- Automatically initialize SNMP-USER-BASED-SM-MIB::UsmUserSecurityName
  columnar object instance on creation, as stated in DESCRIPTION (SF
  tracker ID #1620392).
- Fix to USM timeframe arithmetics (SF bug #1649032).
- VACM shortcuts merged into universal add/delVacmUser() to let notifications
  and requests to co-exist for the same user.
- At oneliners, build LCD tables keys from a hashed mix of input parameters
  to make sure these automatic entries won't interfere or exceed constraints
  on keys values.
- Made use of notificationType parameter of the sendNotification method
  in NotificationOriginator applications. This parameter used to be
  ignored in the past. Note, that previously used (and ignored) syntax
  has been changed in an incompatible way.
- Allow plain Python values in setCmd() and sendNotification()
  methods in CommandGenerator and NotificationOriginator applications
  respectively.
- Multi-target oneliner API-based example script added.
- Ignore more socket errors in datagram-type async socket code.
- AES cipher now supported (rfc3826).
- Fix to messed up tagIDs of noSuchInstance and noSuchObject types.
- SET Command Responder fixed to obscure access to non-existing variables
  by returning notWritable error (SF bug #1764839).
- AsynsockDispatcher.setSocketMap() method added to facilitate pysnmp
  transport integration into third-party asyncore-based applications.
- Fix to errorIndex generation at CommandResponder application, the value
  should be a one-based.

Revision 4.1.7a
---------------

- UNSTABLE ALPHA RELEASE.
- Low-level debugging facility implemented.
- Support UdpTransportTarget timeout and retries parameters in oneliner API.
- Fix to snmpTrapOID construction at ...proxy.rfc2576.v1ToV2() 
  function.
- Fix to MibViewController.getNodeName() to take MIB module name
  into account (SF bug #1505847).
- Do explicit check for Counter32,Unsigned32,TimeTicks,Counter64 value types
  in MibTableRow index convertion and in TextualConvention.prettyPrint()
  methods (SF bug #1506341). Handle Bits in indices as RFC2578 suggests.
- Apply read-create column status to libsmi2pysnmp-generated code
  whenever MIB text specifies that (SF bug #1508955).
- Honor and apply DISPLAY-HINT specification when building TextualConvention
  class at libsmi2pysnmp.
- Managed Objects Instances files (smi/mibs/instances/) are now 
  double-underscore prefixed to make them imported explicitly by these
  prefixed names. They used to be imported as a side-effect of
  Managed Objects files import what is way too hackerish.
- The libsmi2pysnmp now supports future libsmi bugfix that would generate 
  "ranges" subtree along with the legacy and ambiguous "range" one.
- SMI support for fixed-length string indices implemented (SF bug #1584799,
  #1653908).
- Managed Object Instances may now have smiRead, smiWrite, smiCreate methods
  to support specific value mangling. These methods, if present, would be 
  invoked from SNMP [Agent] core instead of conventional clone() method.
  The reason is to separate trivial value duplication from specific
  Instance value mangling that may have Agent-specific side effects
  (such as RowStatus).
- MIB table row destruction now works (SF bug #1555010).
- LCD unconfiguration functions for oneliners implemented (SF bug #1635270).
- unloadModules() and unexportSymbols() implemented at MibBuilder
- Notification type PDU proxy code fixed to produce symmetrical
  convertion.
- Various SNMP engine-internal caches expiration implemented.
- SMI-level access control now takes effect only if AC object is
  passed to MIB instrumentation API.
- LCD management code now uses generic MIB instrumentation features.
- Fix to oneliner manager code to have individual UdpSocketTransport
  instance per each SnmpEngine. Multithreaded apps might fail otherwise.
  (SF bug ID #1586420).
- Exclude the PYSNMP_MODULE_ID symbol from MIB view index, as it may get
  resolved into OID label instead of actual MIB object name.
- Memory leak fixed in indices.OidOrderedDict implementation.
- Fix to VACM shortcuts to let notifications and requests to co-exist 
  for the same user otherwise.
- Fix to ...oneliner.cmdgen.UsmUserData to support non-default ciphers.
- USM now uses local notion of snmpEngineBoots/Time when authoritative
  and cached estimate otherwise. Also, a security fix applied to to USM 
  time-window verification (SF bug #1649032).
- Fix to notification objects resolution code at
  NotificationOriginator.sendNotification()
- Do not raise securityLevel for USM error reports that lacks user
  information, as these reports could never be ciphered (SF bug #1624720).
- Non-default BULK PDU params now actually applied.
- SnmpEngineID default value generation algorithmic function changed
  to allow multiple SNMP engines running on the same host.
- Documentation updated.
- A handful of minor fixes applied (SourceForge tracker IDs #1537592,
  #1537600, #1537659, #1548208, #1560939, #1563715, #1575697, #1599220,
  #1615077, #1615365, #1616579).

Revision 4.1.6a
---------------

- UNSTABLE ALPHA RELEASE.
- pysnmpUsmSecretAuthKey and pysnmpUsmSecretPrivKey length increased
  up to 256 octets. There seems no limit on this in RFC, though.
- A workaround for probably broken Agents: SNMPv3 Manager code defaults
  ContextEngineId to SecurityEngineId whenever ContextEngineId is not 
  reported by authoritative SNMP engine on discovery.
- Use empty PDU in engine-discovery report at mpmod/rfc3412.py.
- MibBuilder.loadModules() now fails on missing MIB files.
- MibBuilder.exportSymbols() now accepts unnamed objects (likely Managed
  Objects Instances)
- SNMPv2-SMI.MibScalarInstance objects now support create*/destroy*
  Management Instrumentation methods to pass Columnar Object creation and
  removal events. MibTableColumn class invoke these methods accordingly.
- Fix to AsynNotificationOriginator.asyncSendNotification() callback
  formal parameters
- Initial VACM configuration implemented according to rfc3415 Appendix 1
- tools/buildmibs.sh split-up and re-implemented as tools/build-pysnmp-mib
  and pysnmp-mibs/tools/rebuild-pysnmp-mibs for better usability. These
  and libsmi2pysnmp scripts made installable.
- Types/Notifications/Groups exportSymbols() call chunking implemented
  in tools/libsmi2pysnmp
- Initial values specified to pyasn1 types to comply with latest pyasn1 API.
- Documentation improved
- Minor fixes towards Python 1.5 compatibility

Revision 4.1.5a
---------------

- UNSTABLE ALPHA RELEASE.
- Multi-lingual SNMP Trap/Inform Applications completed; examples added
- SMI model re-designed to make a clear separation between
  Managed Objects and their specification (AKA Agent and Manager side)
- SNMP SET Application support completed
- Minor, though backward incompatible, changes to one-liner API
- Many bugfixes

Revision 4.1.4a
---------------

- UNSTABLE ALPHA RELEASE.
- SHA-based authentication fixed and privacy implemented
- ...oneliner.cmdgen.UsmUserData constructor now takes 
  authProtocol and privProtocol parameters in a backward incompatible
  manner.

Revision 4.1.3a
---------------

- UNSTABLE ALPHA RELEASE.
- rfc3413 applications API changes (related to callback function
  behaviour).
- TransportDispatcher now provides "jobs" interface to clients
  for better control of dispatcher's execution.
- Many minor fixes.

Revision 4.1.2a
---------------

- UNSTABLE ALPHA RELEASE.
- Top-level application classes renamed into longer, self descripting names
  for clarity.
- CommandResponder & NotificationOriginator applications now uses 
  stand-alone SnmpContext for application registration.
- Many minor fixes (inspired by testing on WinXP)

Revision 4.1.1a
---------------

- UNSTABLE ALPHA RELEASE.
- SNMPv3 code first published
- SNMP engine and applications implemented on library level
- Major re-design towards SNMPv3-style API.

Release 4.0.2a
--------------

- Adopted to slightly changed asyncore API (as shipped with python 2,4)

Release 4.0.1a
--------------

- Minor bug/typo fixes, mostly in example/ scripts.

Release 4.0.0a
--------------

- UNSTABLE EARLY ALPHA RELEASE.
- Major re-design and re-implementation.
- Rudimental API versioning implemented to let incompatible package
  branches to co-exist within the same Python installation.
- SMI framework designed and implemented. This framework provides 
  1) various access to MIB data 2) a way to implement custom MIB
  instrumentation objects. There's also a tool for building SMI classes
  from libsmi(3) output (smidump -f python).
- ASN.1 subtyping machinery implemented. Now dynamic ASN.1 instances
  subtyping and quering becomes available. Previously, this has been done
  through Python classes inheritance what proved to be a wrong concept.
- ASN.1 codecs framework re-designed and re-implemented aimed at a more
  consistent design and better performance. Highlights include abstract
  codec interface and serialized data caching (at encoder).
- Asn1Item constraints machinery re-implemented based on Mike C. Fletcher's
  design and code. Now various constrains are implemented as stand-alone
  objects serving interested Asn1Object derivatives through some abstract
  protocol (that's probably the Decorator design pattern).
- ASN.1 tagging facility re-implemented along the client-server design
  pattern. Besides this seems to be a more appropriate design, it allows
  an easier way for dynamic subtyping.
