...Reflection

This work is partially supported by Agilent Laboratories and Lombard Odier & Co.

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...:

Time decoupling: the interacting parties do not need to be up at the same time. Space decoupling: the interacting parties do not need to know each other.

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...pattern

In [Car98], the notion of pattern is used in a different sense, namely to express event-correlation: a notification is triggered upon arising of a combination of several elementary events.

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...language,

A similar mismatch has been largely discussed in the domain of object-oriented databases, where two separate languages coexist; one for the definition of data and another one for the querying of data [BZ87].

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...GRYPHON [BCM+99,SBS98],

In GRYPHON, reflection is also used ([SBS98]), but not for the expression of subscription patterns: the GRYPHON system uses the same information dissemination mechanisms it offers to applications (which is its primary concern) for internal protocol communication.

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...returned.

With k = 0, the object m itself is accessed as a whole. i_l=0 means that M_i is an argument-less method. We do not consider side-effects of the access methods M_i.

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...API.

JAVA 1.3 integrates a limited mechanism for computational reflection with the java.lang.reflect.Proxy class.

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...invocation.

Note that with JAVA method objects, a native value is wrapped by an instance of its corresponding object type, which makes the nesting of invocations even simpler.

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...errors.

To verify whether a given reified type conforms to another one, we mainly rely on the isAssignableFrom() method in class java.lang.Class.

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...TIGUKAT [SO95].

The major difference between queries in an object database and the filtering of messages by a middleware is the duration of a query. With a middleware system based on content-based publish/subscribe, the query is expressed for future objects. In object databases, queries are performed on a snapshot of the system, but the expression of the query can be made similarly. [PO93] also describes the use of reflection for a closer integration of the language with TIGUKAT.

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...interface,

The counterpart to the well-known Magnitude type in SMALLTALK [GR83].

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...implement.

This counteracts JAVA's lack for operator overloading (as provided for instance by C++ [Str97]).

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...optimizations.

In a companion paper [EGS00b] we introduce type-based publish/subscribe: a static classification scheme based on the types of message objects. The type-based publish/subscribe scheme ensures type safety, and thus enforces optimizations through the inherent knowledge of types and makes type checks and casts inside the application code superfluous.

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...[TCKI00].

[KMS98] terms this technique (runtime) linguistic reflection, which is seen as a synonym of structural reflection.

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...s.

Our system relies on a hierarchical topology of message brokers, among which membership information is split up. A single process rarely has knowledge of more than 100 participants.

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