We present TEMPOS: a set of models and languages supporting the manipulation of temporal data on top of object DBMS. The proposed models exploit object-oriented technology to meet some important, yet traditionally neglected design criteria related to legacy code migration and representation independence. Two complementary ways for accessing temporal data are offered: a query language and a visual browser. The query language, namely TEMPOQL, is an extension of OQL supporting the manipulation of histories regardless of their representations, through fully composable functional operators. The visual browser offers operators that facilitate several time-related interactive navigation tasks, such as studying a snapshot of a collection of objects at a given instant, or detecting and examining changes within temporal attributes and relationships. TEMPOS models and languages have been formalized both at the syntactical and the semantical level and have been implemented on top of an object DBMS. The suitability of the proposals with regard to applications' requirements has been validated through concrete case studies.

This paper presents a language for expressing temporal pattern-matching queries, and a set of temporal grouping operators for structuring histories following calendar-based criteria. Pattern-matching queries are shown to be useful for reasoning about successive events in time while temporal grouping may be either used to aggregate data along the time dimension or to display histories. The combination of these capabilities allows to express complex queries involving succession in time and calendar-based conditions simultaneously. These operators are embedded into the TEMPOS temporal data model and their use is illustrated through examples taken from a geographical application. The proposal has been validated by a prototype on top of the O 2 DBMS. Keywords: temporal databases, temporal object model, temporal query language, pattern-matching queries, temporal grouping, calendar, granularity, O 2 . 1 Introduction In most modern DBMS, time is one of the primitive datatypes provided for d...