在急難救援的環境中最重要的就是急救資料分享，且急救資料分享會影響到整個救援行動的成敗，然而在急難救援環境中急救資料分享是相當困難的，因為在救災現場可能沒有通訊設備。
在急難救援的環境中，一般來說同一地點內的網路情況是相對穩定的，而不同地點間的網路是相對較不穩定的，而網路分割的情況有可能發生在不同的地點間。急難救援可以採用在資料網格中的常見的複製技術來提高急救資料分享的效率。但如何維持急救資料的多份副本間的一致性就成為另一個要解決的問題。
在本文中我們提出了「海鷗」系統可以在急難救援的環境中透通的維持急救資料的多份副本間資料內容的一致性。海鷗系統在地點間採用樂觀複製(Optimistic replication)技術來提供高程度的可得性，相對的在地點內採用悲觀複製(Pessimistic replication)技術來提供較嚴格的一致性。同時，海鷗系統採用了動態調整一致性單位的方式來提高效能，因為動態調整一致性單位在偽分享(false sharing)的情況下，可以達到更高程度的平行度。最後，海鷗系統採用了透通的資料一致性管理機制，因此使用者不需要修改原有的程式就可以在海鷗系統上順利執行。

In the scenario of the emergency and rescue operations, information sharing is the most important factor that affects the success and failure of the entire operation. However, efficient information sharing is difficult to achieve in such a scenario because there is no communication infrastructure existed at the disaster sites.
Generally Speaking, the network condition is relatively reliable in the intra-site environment and relatively unreliable in the inter-site environment. Moreover, the network partitioning problem may occur between two sites. Therefore, the replication technique in data grid should be used in emergency and rescue application for improving the efficiency of the information sharing. However, the data consistency problem occurs between replicas.
In this context, we propose a middleware called Seagull that can transparently manage the data consistency, designated as Seagull for the situation of the emergency and rescue applications. Seagull adopts the optimistic replication technique that provides high availability, and adopts the pessimistic replication technique in the intra-site environment that provides strong consistency. Moreover, it adopts an adaptive consistency granularity strategy that achieves the better performance of the consistency management because this strategy provides higher parallelism when the false sharing happens. Lastly, Seagull adopts the transparency data consistency management scheme, and thus the users do not need to modify their source codes to run on the Seagull.

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[30] Fuse http://fuse.sourceforge.net/
[31] WANem http://wanem.sourceforge.net/
[32] Ubuntu http://www.ubuntu.com/