presented by: Irene Genitsaridh Univ. of Crete hy561 April 28, 2009. AXML. The Active XML project: an overview Serge Abiteboul · Omar Benjelloun · Tova Milo Lazy Query Evaluation for Active XML
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The service invocation is done using the SOAP protocolthe result of this invocation is used to enrich the document.
The same document at different times will have different semantics.
The schema distinguishes between accepting a concrete type, e.g., a temperature element, and accepting a service call returning data of this particular type.
The actual syntax in the system is an extension of XML Schema.
Query: /goingOut/movies//show[title= "The Hours"]/schedule.
Identifying in advance a tight superset of the
service calls that should actually be invoked to answer a query.
Correct, but usually inaccurate. Ignores filtering conditions in the path from the root or in other branches that could make some of the functions irrelevant (e.g. there is no chance that a getNearbyRestos() function node under a hotel is relevant, if the hotel rating is not “*****”).
Constructing one linear path query per node.
Instead of constructing one linear path query per node in the query, it is used an algorithm called NFQ that includes the ﬁltering conditions from the original query.
In Contrast with Linear Path Queries, now the function nodes that are relevant for a query q are precisely the ones retrieved by the NFQs of q.
calls are analyzed to derive an eﬃcient sequence of call invocations appropriate to answer the query.
path extents: for each path
we keep pointers to the
corresponding function call
nodes in the document.
The arguments of a service call are specified as children of the call element. In the simplest case, an argument is plain XML. More generally, arguments can be AXML data, and therefore may themselves contain service calls.
A special attribute of the call element.
A special attribute
of the call element.