With this introduction, how are Servlets and EJB's placed? Table 7.1 attempts to uncover this idea.
|Web positioning layer (tier)||More towards backend, but broad based||More towards presentation|
|Primary responsibility||Persistence||Request-response mechanism|
|Nature of functionality||Encapsulate data||Expose data (present)|
|Enabler||Enterprise capability||Multi-threading capability|
|Enterprise concerns||Scalability,transactions, load-balancing,component based model (promoting reusability)||Can act as the controller (C in MVC) in the application|
|Tier||Three or more tier architecture||Two or three tier architecture|
|Nature of application||Requirement for ...|