CORBA Record and Replay

1
CORBA Record and Replay

• Irfan Pyarali
• TAO Workshop

2
Motivation for Recording and Replaying CORBA
Traffic

• Recording CORBA Traffic
• Logging
• Debugging
• Auditing
• Tracking
• Replaying CORBA Requests
• Compare original reply with the new reply
• System determinism
• Identify behavior anomalies

3
Where to Record CORBA Traffic
4
CRR Architecture
Client
Server
request replies
Client
request
Logger Manager
Generic Client
new reply
5
How to Record CORBA Traffic

• Recording level
• GIOP level
• Black box testing can be done by recording GIOP
  messages
• Difficult to tell exactly what has changed
• Interceptor level
• Individual parameters can be inspected
• Can tell exactly what has changed
• Filtering what is recorded
• Interfaces
• Implementations (servants)
• Methods
• Clients this might be difficult since servers
  typically do not know which client is issuing the
  request
• Parameter values will probably need a ETCL like
  mechanism

6
What to Record

• CORBA Request
• Interface name
• Operation name
• Operation type oneway or twoway
• IOR
• For each parameter
• Mode in, inout or out
• TypeCode
• Value for in and inout but not out parameters
• Result
• TypeCode
• Exceptions
• TypeCode
• Successful reply
• TypeCode and value for inout, out and result but
  not in parameters
• Failed reply
• TypeCode and value for exception raised

7
Example IDL

• interface Test
• exception error
• long reason
• long method_longs
• (in long a,
• inout long b,
• out long c)
• raises (error)

8
Example Recorded Request (1)
interface Test exception error long reason
long method_longs (in long a,
inout long b, out long c) raises
(error)

• ltrequestgt
• ltinterfacegtIDLTest1.0lt/interfacegt
• ltoperationgtmethod_longslt/operationgt
• ltoperation_typegttwowaylt/operation_typegt
• ltiorgtIOR010000000d0000004...lt/iorgt
• ltparametergt
• ltmodegtINlt/modegt
• lttypecodegt
• ltbasictypegtlonglt/basictypegt
• lt/typecodegt
• ltvaluegt1lt/valuegt
• lt/parametergt
• ltparametergt
• ltmodegtINOUTlt/modegt
• lttypecodegt
• ltbasictypegtlonglt/basictypegt
• lt/typecodegt
• ltvaluegt2lt/valuegt
• lt/parametergt

ltparametergt ltmodegtOUTlt/modegt lttypecodegt
ltbasictypegtlonglt/basictypegt lt/typecodegt
lt/parametergt ltresultgt lttypecodegt
ltbasictypegtlonglt/basictypegt lt/typecodegt
lt/resultgt
9
Example Recorded Request (2)
interface Test exception error long reason
long method_longs (in long a,
inout long b, out long c) raises
(error)
ltraisesgt lttypecodegt ltexceptiongt
ltnamegterrorlt/namegt ltidgtIDLTest/error1.0lt/idgt
ltmembergt ltnamegtreasonlt/namegt
ltbasictypegtlonglt/basictypegt lt/membergt
lt/exceptiongt lt/typecodegt lt/raisesgt lt/requestgt
10
Example Successful Reply

• ltreplygt
• ltreply_statusgtSUCCESSFULlt/reply_statusgt
• ltparametergt
• lttypecodegt
• ltbasictypegtlonglt/basictypegt
• lt/typecodegt
• ltvaluegt7lt/valuegt
• lt/parametergt
• ltparametergt
• lttypecodegt
• ltbasictypegtlonglt/basictypegt
• lt/typecodegt
• ltvaluegt8lt/valuegt
• lt/parametergt
• ltresultgt
• lttypecodegt
• ltbasictypegtlonglt/basictypegt
• lt/typecodegt
• ltvaluegt9lt/valuegt

interface Test exception error long reason
long method_longs (in long a,
inout long b, out long c) raises
(error)
11
Example System Exception
interface Test exception error long reason
long method_longs (in long a,
inout long b, out long c) raises
(error)

• ltreplygt
• ltreply_statusgtSYSTEM_EXCEPTIONlt/reply_statusgt
• ltraisesgt
• ltcomplexvaluegt
• ltidgtNO_IMPLEMENTlt/idgt
• ltminorgt1413545984lt/minorgt
• ltcompletedgtNOlt/completedgt
• lt/complexvaluegt
• lt/raisesgt
• lt/replygt

12
Example User Exception
interface Test exception error long reason
long method_longs (in long a,
inout long b, out long c) raises
(error)

• ltreplygt
• ltreply_statusgtUSER_EXCEPTIONlt/reply_statusgt
• ltraisesgt
• lttypecodegt
• ltexceptiongt
• ltnamegterrorlt/namegt
• ltidgtIDLTest/error1.0lt/idgt
• ltmembergt
• ltnamegtreasonlt/namegt
• ltbasictypegtlonglt/basictypegt
• lt/membergt
• lt/exceptiongt
• lt/typecodegt
• ltcomplexvaluegt
• ltvaluegt-1lt/valuegt
• lt/complexvaluegt
• lt/raisesgt
• lt/replygt

13
Alternate Recording Schemes

• Portable Interceptors pass parameters as Anys
• Interpretive Recursively traverse each parameter
  represented by an Any to find base type and value
• Compile Added new backend to the IDL compiler
  that generates logging code that knows exactly
  the TypeCode and layout of the parameters
• Classic tradeoffs size, speed, requiring updates
  whenever IDL changes

14
Basic Types

• null
• void
• short
• long
• ushort
• ulong
• float
• double
• boolean

• char
• octet
• TypeCode
• objref
• longlong
• ulonglong
• longdouble
• wchar

15
Complex Types

• any Record type of what is in the any
• structure Record the names and types of each
  member
• union Record the discriminator type for each
  member, record the case label, member name, and
  member type
• enumeration Record the enumerators
• string Record the bounds if any
• sequence Record the bound (if any) and the
  element type
• array Record the dimensions and element type
• alias Record the type of the aliased type
• exception Record the names and types of each
  member
• fixed Record digits and scale

16
Generic Client Replaying Requests

• Parses XML representation of CORBA requests
  converting it into CORBA IIOP request using DII,
  replay it, and returning the result in XML
• ACEXML SAX based parser
• Create IOR - tricky if being redirected to
  alternate server
• For each method that needs to be replayed
• Set method
• For each parameter, create TypeCode, and then
  fill in value
• Set TypeCode of return value
• Set TypeCodes of all possible exceptions
• Record new reply from replay
• Compare with original reply to check for
  differences
• Implementation notes
• Creating TypeCode using TypeCode factory
• Union label have values
• Filling values using DynAny
• Anys are very tricky

17
Conclusions and Future Work

• CORBA Record and Replay may become a CORBA
  specification through the C4I Task Force
• Standardization of XML schema
• Integration into Ovation
• Only works with skeletons based servers
• This limitation comes from Portable Interceptors
• Add value type support
• Compiled logging was initially designed for Orbix
  3
• Need to be modified to support CORBA 3 ORBs
• Record QoS properties
• Including real-time and protocol properties
  related to the CORBA traffic