Ciao Barbara,
the image below is enough up-to-date to describe the current integration architecture. Basically it relies on the REST APIs exposed by ESRI ArcGIS. Map tiles are downloaded from the browser via HTTP.
PS: in the old Spatial versions, the integration was at the db level; so don't take into account the green area of the image ;-)

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Diego Visentin
EAM BU Director
Tempestive S.p.A.
Pordenone
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