New version page

OCI-based Group Communication Support in CORBA

Upgrade to remove ads

This preview shows page 1-2-3-24-25-26 out of 26 pages.

Save
View Full Document
Premium Document
Do you want full access? Go Premium and unlock all 26 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 26 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 26 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 26 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 26 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 26 pages.
Access to all documents
Download any document
Ad free experience

Upgrade to remove ads
Unformatted text preview:

IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTESMS, 2004 1 Abstract—Group communication is a useful mechanism guaranteeing the consistency among replicated objects. The existing approaches do not allow transparent plug-in of group communication protocols into CORBA. They either require modification of CORBA or OS, or provide no room for incorporating group communication transport protocols into CORBA. We propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. We extend the Open Communications Interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. We define Group Communication Inter-ORB Protocol (GCIOP) as a group communication instantiation of General Inter-ORB Protocol (GIOP) that encapsulates underlying group communication protocols. The proposed scheme can be exploited for fault tolerant CORBA (FT CORBA). Experiment results show that group object invocation using the proposed scheme does not incur performance degradation as the number of members in a group increases. Index Terms— Group communication, CORBA, Open communications interface, FT CORBA. I. INTRODUCTION bject replication is a technique to enhance fault tolerance and high availability [7]. An object group is a collection of object replicas that cooperatively works for a common task [10]. Here consistent state of an object group needs to be maintained for constructing high available and fault-tolerant distributed applications. Group communication service (GCS) is a useful mechanism guaranteeing the consistency of the states of all the member objects. It maintains a view, a list of the currently active and connected members in an object group, and also informs the running objects of the updated view whenever it changes. The consistency can be guaranteed by reliable delivery of messages to the members in the current view. There have been several approaches for supporting group communication service in CORBA. In general, they can be categorized into three approaches – integration, service, and interception approach. An example of each of the three approaches is Electra [15], Object Group Service (OGS) [4], and Eternal [19, 22], Manuscript received December 8, 2002. This work was supported in part by the National Research Laboratory Program funded by Ministry of Science and Technology, the Republic of Korea under Grant 2EG1900. A preliminary version of this paper appeared in [14] and [21]. D. Lee, D. Nam, and C. Yu are with the School of Engineering, Information and Communications University, 58-4 Hwaam-dong, Yuseong-gu, Daejeon, 305-732 Korea. Tel.: +82 42 866 6113, Fax: +82 42 866 6243 (e-mail: {dlee, paichu, cyu}@ icu.ac.kr). H.Y. Youn is with the School of Electrical and Computer Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon 440-746 Korea. (e-mail: [email protected]). OCI-based Group Communication Support in CORBA Dongman Lee, Member, IEEE Computer Society, Dukyun Nam, Hee Yong Youn, Senior Member, IEEE, and Chansu Yu, Member, IEEE OIEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTESMS, 2004 2 respectively. In the integration approach, the GCS module is an integral part of Object Request Broker (ORB), and thus introducing a new GCS requires modification of ORB. The service approach provides group communication as Object Service [5] on top of CORBA, leveraging the CORBA’s point-to-point communications, General Inter-ORB Protocol (GIOP). That is, no room exists for group communication transport protocols to be incorporated into CORBA. The interception approach supports the group communication service by intercepting the system calls related to group communications using an interceptor. It does not allow CORBA objects to directly exploit the underlying group communication services since the interceptor is not part of CORBA. In summary, the existing approaches do not support transparent plug-in of group communication protocols into CORBA, and thus CORBA application programmers cannot directly exploit the protocols. There must be a generic group communication framework that allows transparent plug-in of various group communication protocols via a standard CORBA interface. In this paper we propose a mechanism that allows such framework with no modification of existing CORBA. We leverage the OCI (Open Communications Interface) [1] to support interoperability, reusability of existing group communication, and independency on ORB and OS. We add new operations into the existing OCI by which an object group can be managed and invocations are made to the group. We define Group Communication Inter-ORB Protocol (GCIOP) as a group communication instantiation of General Inter-ORB Protocol (GIOP) that encapsulates underlying group communication protocols. We then add group communication Info Object to the OCI and extend the interfaces of the OCI to support group semantics. The existing OCI consists of a Connector, Connector Factory, Acceptor, and Transport module [1, 10]. The existing group communication basically requires group address expansion, delivery ordering, and state transfer [2]. To satisfy these requirements of group communication, a group name, ordering type, and state are saved in the Info object. We add an attribute to Connector’s Transport Info for setting the ordering-type and add group maintenance operations to Acceptor. The proposed design can be used to wrap or embed various group communication protocols without any modification of ORB and the OCI. We devise a group Interoperable Object Reference (IOR) for GCIOP in order to support the non-FT CORBA compliant systems which do not support group object references. The proposed scheme can be exploited for the fault tolerant infrastructure based on the FT-CORBA standard [25]. The Interoperable Object Group Reference (IOGR) as a group reference is used instead of the GCIOP-based IOR when the proposed scheme is used by FT CORBA. ForIEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTESMS, 2004 3 composing and invoking an object group except resolving the IOGR, the proposed scheme can be directly adapted to the FT CORBA standard. A part for resolving the IOGR should be included in the Connector Factory. We implement the proposed scheme on


Download OCI-based Group Communication Support in CORBA
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view OCI-based Group Communication Support in CORBA and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view OCI-based Group Communication Support in CORBA 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?