Triggers are special user defined actions usually in the form of stored procedures, that are automatically invoked by the server based on data related events. It can perform complex actions and can use the full power of procedural languages.
A rule is a special type of trigger that is used to perform simple checks on data.
Transparency really means hiding the network and its servers from the users and even the application programmers.
TP-Lite is simply the integration of TP Monitor functions in the database engines.
TP-Heavy are TP Monitors which supports the Client/Server architecture and allow PC to initiate some very complex multiserver transaction from the desktop.
TP lite, based on stored procedures. TP heavy, based on the TP monitors.
This new model of Client/Server consists of thin, portable, "universal" clients that talk to super fat servers. In the simplest form, a web server returns documents when clients ask for them by name. The clients and server communicate using an RPC-like protocol called HTTP.