CORBA 環境上的物件查詢服務

Abstract

隨著物件導向與分散式計算之成熟, 在分散式物件環境上發展系 統與軟體已經成為一項熱門的趨勢. 而由 OMG (Object Management Group) 所提出的分散式物件環境架構 CORBA (Common Object Request Broker Architecture) 已經成為一個廣受業界重視與接受的工業標準. CORBA 的物件查詢服務是 OMG 於 1995 年所提出的一項共通物件服務規 格(COSS). 它提供一個簡單易用的界面使得客戶端能夠找出屬性符合查詢 條件的物件. 一個查詢條件可以由下面兩種語言寫成:SQL或是ODMG所制定 的物件查詢語言(OQL). 本篇論文在 CORBA 所提供的物件連結之 環境下發展與實作物件查詢服務. 此物件查詢服務可連接關聯式資料庫和 物件導向資料庫. 不管使用者所發出的查詢條件為SQL或是OQL, 我們都能 為其取得符合查詢條件的結果, 並將此結果轉譯成具有平台獨立性和程式 語言獨立性的CORBA物件. 這些CORBA物件能夠在CORBA的ORB上流動, 並且 可以由不同的CORBA應用程式分享與共用. The Common Object Request Broker Architecture (CORBA) defined bythe Object Management Group (OMG) has become an emerging industry standardof distributed objects technology. It provides the interconnection busbetween distributed objects and a mechanism to develop platform- and language-independent distributed applications. The Object Query Service (OQS) proposed by OMG defines a very general facility for querying collections of objects. Through OQS, clients can use a simple interface to find objects whoseattributes meet the search criteria specified by a query. The query can be formulated using either SQL query or ODMG's OQL. In thesis, we design and implement the Object Query Service based onCORBA. Our Query Service acts as a middleware to both relational databases and object-oriented databases. Clients are able to issue either SQL query or OQL query, and our OQS will retrieve and translate the results into CORBA objects that have both platform- and language-independent properties. TheseCORBA objects can be passed anywhere on the ORB and they can be shared by different application objects.