Update index.md

Author: vasile-baluta

docs/index.md

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 # _Introduction_
 
-Eiffel Intelligence is a service that aggregates informations from different events of a flow with the purpose of notifying subscribers when content of interest has been collected from desired events. By flow we mean a chain of Eiffel events that are linked together directly or indirectly. Eiffel Intelligence uses a set of rules to define what information will be extracted from an Eiffel event in the flow and at what location to store this information in the aggregated object.
+Eiffel Intelligence is a service that aggregates informations from different events of a flow with the purpose of notifying subscribers when content of interest has been collected from desired events. The aggregation is stored in a JSON bject. By flow we mean a chain of Eiffel events that are linked together directly or indirectly. Eiffel Intelligence uses a set of rules to define what information will be extracted from an Eiffel event in the flow and at what location to store this information in the aggregated object. Today only one rule set can be run in each instance and the reason is that in an Eiffel domain with million of events flowing we will have multiple extractions and checks for each rule set and multiple rule sets will require large machines and scalability problems.
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+Eiffel intelligence uses subscriptions to notify interested parties when several evens have occured with desired content in each event aggregated in an aggregated object. Every time an aggregated object is updated we check whether any subscription is fulfilled by the curent state of the aggregated object.