INTERNET-DRAFT V. Ryan Expires 15 December, 1999 R. Lee S. Seligman Sun Microsystems, Inc. 12 June, 1999 Schema for Representing CORBA Object References in an LDAP Directory Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright (C) The Internet Society (1999). All Rights Reserved. Please see the Copyright section near the end of this document for more information. Abstract CORBA [CORBA] is the Common Object Request Broker Architecture defined by the Object Management Group. This document defines the schema for representing CORBA object references in an LDAP directory [LDAPv3]. 1. Introduction This document assumes that the reader has a general understanding of CORBA. Ryan, et. al. [Page 1] INTERNET-DRAFT Schema for CORBA Object Reference June 1999 Traditionally, LDAP directories have been used to store data. Users and programmers think of the directory as a hierarchy of directory entries, each containing a set of attributes. You look up an entry from the directory and extract the attribute(s) of interest. For example, you can look up a person's telephone number from the directory. Alternatively, you can search the directory for entries with a particular set of attributes. For example, you can search for all persons in the directory with the surname "Smith". CORBA applications require access to CORBA objects. Traditionally, CORBA applications have used the COS Naming service for storage and retrieval of CORBA object references. When deployed in environments with a directory, CORBA applications should be able to use the directory as a repository for CORBA object references. The directory provides a centrally administered, and possibly replicated, service for use by CORBA applications distributed across the network. For example, an application server may use the directory for "registering" CORBA objects representing the services that it manages, so that a client can later search the directory to locate those services as it needs. The motivation for this document is to define a common way for applications to store and retrieve CORBA object references from the directory. Using this common schema, any CORBA application that needs to read or store CORBA object references in the directory can do so in an interoperable way. Note that this schema is defined for storing CORBA "object references," not CORBA objects in general. There might be other ways to store CORBA objects in an LDAP directory but they are not covered by this schema. 2 Representation of CORBA Object References This document defines schema elements to represent a CORBA object reference in LDAP directory. Applications in possession of a reference to an object can invoke calls on that object. Such a reference is termed an "interoperable object reference," or IOR. Access to CORBA objects by using IORs is achieved transparently to the application, by means of the Internet Inter-ORB Protocol. A CORBA object reference is represented in the directory by the object class corbaObjectReference. corbaObjectReference is a subclass of the abstract corbaObject object class. corbaObjectReference is an auxiliary object class, which means that it needs to be mixed in with a structural object class. Ryan, et. al. [Page 2] INTERNET-DRAFT Schema for CORBA Object Reference June 1999 The object class corbaContainer represents a directory entry dedicated to storing a CORBA object. It is a structural object class. corbaContainer is not required when a subclass of corbaObject (such as corbaObjectReference) is mixed in with another structural object class. The definitions for the object classes corbaObject, corbaObjectReference, and corbaContainer are presented in Section 4. The corbaObject class has two optional attributes: corbaRepositoryId and description. corbaRepositoryId is a multivalued attribute that is used to store the repository ids of the interfaces implemented by a CORBA object. description is used to store a textual description of a CORBA object. The corbaObjectReference class has one mandatory attribute: corbaIor. corbaIor is used to store the object's stringified IOR. corbaIor and corbaRepositoryId are defined in Section 3; description is defined in [v3Schema]. 3 Attribute Type Definitions The following attribute types are defined in this document: corbaIor corbaRepositoryId 3.1 corbaIor This attribute stores the string representation of the interoperable object reference (IOR) for a CORBA object. An IOR is an opaque handle for the object which contains the information necessary to locate the object, even if the object is in another ORB. This attribute's syntax is 'IA5 String' and its case is insignificant. Ryan, et. al. [Page 3] INTERNET-DRAFT Schema for CORBA Object Reference June 1999 ( 1.3.6.1.4.1.42.2.27.4.1.14 NAME 'corbaIor' DESC 'Stringified interoperable object reference of a CORBA object' EQUALITY caseIgnoreIA5Match SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 SINGLE-VALUE ) 3.2 corbaRepositoryId Each CORBA interface has a unique "repository id" (also called "type id") that identifies the interface. A CORBA object has one or more repository ids, one for each interface that it implements (for example, as a result of interface inheritance). The format of a repository can be any string, but the OMG specifies four standard formats: a. IDL-style IDL:Prefix/ModuleName/InterfaceName:VersionNumber For example, the repository id for the "NamingContext" in OMG's COS Naming module is: "IDL:omg.org/CosNaming/NamingContext:1.0". b. RMI-style RMI:ClassName:HashCode[:SUID] This format is used by RMI-IIOP remote objects [RMI-IIOP]. "ClassName" is the fully qualified name of the class (for example, "java.lang.String"). "HashCode" is the object's hash code (that is, that obtained by invoking the "hashCode()" method). "SUID" is the "stream unique identifier", which is a 64-bit number that uniquely identifies the serialization version of the class; SUID is optional in the repository id. c. DCE-style DCE:UUID This format is used for DCE/CORBA interoperability [CORBA-DCE]. "UUID" represents a DCE UUID. d. "local" Ryan, et. al. [Page 4] INTERNET-DRAFT Schema for CORBA Object Reference June 1999 This format is defined by the local Object Request Broker (ORB). The corbaRepositoryId attribute is a multivalued attribute; each value records a single repository id of an interface implemented by the CORBA object. This attribute need not contain a complete list of the interfaces implemented by the CORBA object. This attribute's syntax is 'Directory String' and its case is significant. ( 1.3.6.1.4.1.42.2.27.4.1.15 NAME 'corbaRepositoryId' DESC 'Repository ids of interfaces implemented by a CORBA object' EQUALITY caseExactMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 ) 4 Object Class Definitions The following object classes are defined in this document: corbaContainer corbaObject corbaObjectReference 4.1 corbaContainer This structural object class represents a container for a CORBA object. ( 1.3.6.1.4.1.42.2.27.4.2.10 NAME 'corbaContainer' DESC 'Container for a CORBA object' SUP top STRUCTURAL MUST ( cn ) ) Ryan, et. al. [Page 5] INTERNET-DRAFT Schema for CORBA Object Reference June 1999 4.2 corbaObject This abstract object class is the root class for representing a CORBA object. ( 1.3.6.1.4.1.42.2.27.4.2.9 NAME 'corbaObject' DESC 'CORBA object representation' SUP top ABSTRACT MAY ( corbaRepositoryId description ) ) 4.3 corbaObjectReference This auxiliary object class represents a CORBA object reference. It must be mixed in with a structural object class. ( 1.3.6.1.4.1.42.2.27.4.2.11 NAME 'corbaObjectReference' DESC 'CORBA interoperable object reference' SUP corbaObject AUXILIARY MUST ( corbaIor ) ) 5. Security Considerations Obtaining a reference to an object and storing it in the directory may make a handle to the object available to a wider audience. This may have security implications. 6. Acknowledgements We would like to thank Sanjeev Krishnan of Sun Microsystems, Simon Nash of IBM, and Jeffrey Spirn of Oracle for their comments and suggestions. 7. Copyright Copyright (C) The Internet Society (1999). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it Ryan, et. al. [Page 6] INTERNET-DRAFT Schema for CORBA Object Reference June 1999 or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 8. References [CORBA] The Object Management Group, "Common Object Request Broker Architecture Specification 2.2," http://www.omg.org [CORBA-DCE] Distributed Systems Technology Center and Digital Equipment Corporation, "DCE/CORBA Interworking Specification," May 1998. http://www.omg.org/library/schedule/DCE_CORBA_Interworking_RFP.html [LDAPv3] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access Protocol (v3)," RFC-2251, December 1997. http://www.ietf.org/rfc/rfc2251.txt [RMI-IIOP] IBM and Java Software, Sun Microsystems, Inc., "RMI over IIOP," June 1999. http://java.sun.com/products/rmi-iiop/index.html [v3Schema] M. Wahl, "A Summary of the X.500(96) User Schema for use with LDAPv3," RFC-2256, December 1997. http://www.ietf.org/rfc/rfc2256.txt 9. Authors' Addresses Ryan, et. al. [Page 7] INTERNET-DRAFT Schema for CORBA Object Reference June 1999 Rosanna Lee Sun Microsystems, Inc. Mail Stop UCUP02-206 901 San Antonio Road Palo Alto, CA 94303 USA +1 408 863 3221 rosanna.lee@eng.sun.com Vincent Ryan Sun Microsystems, Inc. Mail Stop EDUB03 901 San Antonio Road Palo Alto, CA 94303 USA +353 1 819 9151 vincent.ryan@ireland.sun.com Scott Seligman Sun Microsystems, Inc. Mail Stop UCUP02-209 901 San Antonio Road Palo Alto, CA 94303 USA +1 408 863 3222 scott.seligman@eng.sun.com 10. Appendix - LDAP Schema -- Attribute types -- ( 1.3.6.1.4.1.42.2.27.4.1.14 NAME 'corbaIor' DESC 'Stringified interoperable object reference of a CORBA object' EQUALITY caseIgnoreIA5Match SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 SINGLE-VALUE ) ( 1.3.6.1.4.1.42.2.27.4.1.15 NAME 'corbaRepositoryId' DESC 'Repository ids of interfaces implemented by a CORBA object' EQUALITY caseExactMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 ) -- from RFC-2256 -- Ryan, et. al. [Page 8] INTERNET-DRAFT Schema for CORBA Object Reference June 1999 ( 2.5.4.13 NAME 'description' EQUALITY caseIgnoreMatch SUBSTR caseIgnoreSubstringsMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.15{1024} ) -- Object classes -- ( 1.3.6.1.4.1.42.2.27.4.2.9 NAME 'corbaObject' DESC 'CORBA object representation' SUP top ABSTRACT MAY ( corbaRepositoryId description ) ) ( 1.3.6.1.4.1.42.2.27.4.2.10 NAME 'corbaContainer' DESC 'Container for a CORBA object' SUP top STRUCTURAL MUST ( cn ) ) ( 1.3.6.1.4.1.42.2.27.4.2.11 NAME 'corbaObjectReference' DESC 'CORBA interoperable object reference' SUP corbaObject AUXILIARY MUST ( corbaIor ) ) -- Matching rule from ISO X.520 -- ( 2.5.13.5 NAME 'caseExactMatch' SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 ) Ryan, et. al. [Page 9]