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Demonstration: active asynchronous transaction management in high-autonomy federated environment using data agents: Global Change Master Directory v8.0

O. Bukhres, S. Sikkupparbathyam, K. Nagendra, Z. Ben Miled, M. Areal, L. Olsen, C. Gokey, D. Kendig, R. Cordova, G. Major, J. Savage
Proceedings 18th International Conference on Data Engineering  
This demonstration focuses on the implementation of an asynchronous transaction protocol [1,6, 8] which satisfies the requirement of replicating DlF entries through the internet across continents in the International Directory Network (IDN). We have designed a Primary Site Distribution protocol which is asynchronous but active i.e. participating sites in the network announce the arrival of new data to other sites in the network. This protocol also addresses the issues involved in dual ownership
more » ... d in dual ownership of entries which is a challenge that faces several emerging distributed transaction management systems [3,4,8]. Abstract The Global Change Master Directory (GCMD) is an earth scie ce information repository that specifically tracks rese rch data on global climatic change. Building a dire tory of Earth science metadata that allows the exc ange of metadata content among partner org nizations is challenging due to the complex issues inv ved in supporting heterogeneous metadata schema, dat base schema, database implementation and platforms. Thi dem{Jnstration presents the design of the MD8 (Ma ter Directory v8.0), which allows automated exc ange of metadata content among earth science coIl borators through a proposed asynchronous dis ibuted transaction protocol. Specifically, the dem nstration will focus on the Local Data Agent (LDA) that captures local database updates and broadcasts them to ther cooperating nodes asynchronously using an Ann uncer. The objective of the new system (MD8) is to promote the current architecture of the GCMD from a client-server architecture to a federated architecture that is totally automated while providing sites participating in the IDN network with the autonomy needed to maintain their local systems. A detailed overview of the design of the MD8 is included in [9]. MD8 Implementation I. Iptroduction The asynchronous transaction model [6] is the model of choice for the MD8 implementation since the data in the various IDN sites need not be synchronized immediately. The temporarily out-of-sync condition of the data is well tolerated. The proposed design also stipulates that only one site (owner of DIF entry or the GCMD) can initiate and complete an insert, update or delete of a given DIF entry. This satisfies the unidirectional update propagation property of asynchronous transactions. However, a locking mechanism is needed for the case of not-in-sync updates that happen simultaneously at the GCMD site as well as the originating site. The asynchronous transaction model was selected because it also improves response time and prevents global deadlock. Furthermore, because the underlying architecture is a federated architecture, complex handshaking procedures associated with the twophase protocol implementations are avoided. T e Global Change Master Directory (GCMD) is a rep itow that contains information on the changing envi onment collected by various agencies including the Uni d -States government agency Global Change Data Cen er !(GCDC) at NASA. Other agencies that actively coIl ct similar type of information include the Canadian, Aus lian, Japanese and Dutch government agencies. The GC D has been in existence for the past II years. It is a data ase that is growing in importance due to the avai ability of recent research on global climate change [2]. urthermore, the GCMD is one of the few organized effo s to create a system that supports uniform storage, acc s and retrieval of change research metadata. At the core of the GCMD is a DIF (Directory Interchange For at). DlF is a standard used to store and transfer data with n the various sites in the IDN network. It consists of a co lection of fields that describes the GCMD data.
doi:10.1109/icde.2002.994744 dblp:conf/icde/BukhresSNBAOGKCMS02 fatcat:qf2iayltwzgwdnxjnb3hvdxcu4