OBJREF

OBJREF is the name of the structure of marshalled interfaces in COM and DCOM. Because COM interfaces can only be called directly from the context (like a thread, process or machine) where they originated, when they are needed in another context they are marshalled in this structure, which is then passed to the destination context where it is unmarshalled to a proxy that takes care of the necessary communication, for example passing messages or network packets or marshalling other interfaces passed in calls.{{cite web

|url=http://www.informit.com/articles/article.aspx?p=167771&rll=1

|title=The Mechanics of COM+

|access-date=2008-09-07

|author=Tim Ewald

|date=2001-03-06

|work=Informit

|publisher=Pearson Education & Addison-Wesley Professional

}}{{cite web

|url=http://www.winehq.org/pipermail/wine-devel/2005-January/033082.html

|title=More DCOM notes

|access-date=2008-09-07

|author=Mike Hearn

|date=2005-01-22

|work=Wine Developer's List

|publisher=Codeweavers

}}

Format

The layout of the structure is as follows:{{cite web

|url=http://source.winehq.org/source//dlls/ole32/dcom.idl#L133

|title=dcom.idl

|access-date=2008-09-06

|year=2003

|work=Wine

|publisher=CodeWeavers

}}{{cite web

|url=http://members.tripod.com/IUnknwn/showme.htm

|title=ShowMeMyOBJREF

|access-date=2008-09-07

|author=Dharma Shukla

|year=1998

}} (This is example code to inspect the contents of an OBJREF.)

class="wikitable"

!Offset!!Size!!Description

04Signature: 'MEOW'
44Flag indicating the kind of structure
816Interface identifier
colspan=3|Flag = 1: standard
244Flags, mostly reserved for the system, but can be used to turn off pinging objects.{{cite web

|url=http://www.microsoft.com/msj/0398/dcom.aspx

|title=Understanding the DCOM Wire Protocol by Analyzing Network Data Packets

|access-date=2008-09-07

|last=Eddon

|first=Guy

|author2=Eddon, Henry

|date=March 1998

|work=Microsoft Systems Journal

|publisher=Microsoft

}}

284Reference count
328OXID – object exporter identifier{{cite web

|url=http://msdn.microsoft.com/en-us/library/cc232137.aspx

|title=Windows Protocols Master Glossary: O

|access-date=2008-09-06

|work=MSDN

|publisher=Microsoft

|quote=object exporter identifier (OXID): A 64-bit number that uniquely identifies an object exporter within an object server. … object identifier (OID): (1) In the context of an object server, a 64-bit number that uniquely identifies an object.

}}

408OID – object identifier
4816IPID – interface pointer identifier{{cite web

|url=http://msdn.microsoft.com/en-us/library/cc232132.aspx

|title=Windows Protocols Master Glossary: I

|access-date=2008-09-06

|work=MSDN

|publisher=Microsoft

|quote=interface pointer identifier (IPID): A 128-bit number that uniquely identifies an interface on an object within an object exporter.

}}

64variableDUALSTRINGARRAY
colspan=3|Flag = 2: handler (an extension of standard){{cite web

|url=http://msdn.microsoft.com/en-us/library/cc226833.aspx

|title=OBJREF_HANDLER

|access-date=2008-09-06

|work=MSDN

|publisher=Microsoft

}}

6416Class identifier of a class that will be used as a handler for the interface, i.e. sit between the client and the proxy.
80variableDUALSTRINGARRAY
colspan=3|Flag = 4: custom marshalling{{cite web

|url=http://msdn.microsoft.com/en-us/library/cc226834.aspx

|title=OBJREF_CUSTOM

|access-date=2008-09-07

|work=MSDN

|publisher=Microsoft

}}

2416Class identifier of the custom proxy
4040 (reserved value)
444Size of the data below
48variableCustom marshalling data
colspan=3|Flag = 8: extended (also an extension of standard){{cite web

|url=http://msdn.microsoft.com/en-us/library/cc226835.aspx

|title=OBJREF_EXTENDED

|access-date=2008-09-06

|work=MSDN

|publisher=Microsoft

}}

644Signature 'VYSN'
68variableDUALSTRINGARRAY
 41 (historically the number of data elements below, but there always is only a single element)
 4Signature 'VYSN'
colspan=3|Data element used to identify and marshal an envoy context:{{cite web

|url=http://msdn.microsoft.com/en-us/library/cc225397.aspx

|title=Context Properties

|access-date=2008-09-07

|work=MSDN

|publisher=Microsoft

}}{{cite web

|url=http://msdn.microsoft.com/en-us/library/cc225402.aspx

|title=Context Properties and Marshaling

|access-date=2008-09-07

|work=MSDN

|publisher=Microsoft

}}{{cite web

|url=http://msdn.microsoft.com/en-us/library/cc232153.aspx

|title=Windows Protocols Master Glossary: E

|access-date=2008-09-07

|work=MSDN

|publisher=Microsoft

|quote=envoy context: A context that is marshaled and returned to a client as a result of obtaining an object reference.

}}

 16Context identifier{{cite web

|url=http://msdn.microsoft.com/en-us/library/cc232151.aspx

|title=Windows Protocols Master Glossary: C

|access-date=2008-09-07

|work=MSDN

|publisher=Microsoft

|quote=context: A collection of context properties that describe an execution environment. sqq.

}}

 4Size of the data below, excluding padding
 4Size of the data below, including padding
 8nA marshalled envoy context, padded to a multiple of eight bytes

The layout of DUALSTRINGARRAY is:{{cite web

|url=http://msdn.microsoft.com/en-us/library/cc226837.aspx

|title=DUALSTRINGARRAY

|access-date=2008-09-06

|work=MSDN

|publisher=Microsoft

}}{{cite book

|last=Eddon

|first=Guy

|author2=Eddon, Henry

|editor=Stroo, Eric |editor2=Turner, Alice |editor3=Young, Marc |editor4=Chang, Ina

|title=Inside COM+ Base Services

|year=1999

|publisher=Microsoft Press

|location=Redmond

|isbn=0-7356-0728-1

|chapter=Marshaled Interface Pointers

}}

class="wikitable"

!Offset!!Size!!Description

02Total number of entries in the arrays below, including nulls
22Number of entries in the array that represent string bindings
42nString and security bindings

The string bindings are null-terminated records specifying connection information, like IP addresses, and the security bindings are null-terminated records specifying authentication information. Both arrays are null-terminated too.

References