multi-tier

Multi-tier and/or ditstributed apps, do they have the same meaning ? When we talk about layers in these apps, is it physical layers (database, browser, web server,...) or logical layers (data access layer, business layer,...) ? Maybe these two sentences do convey intuitively the distinction between distributed and multi-tier : Distributed : You replicate the processing amongst nodes Multi-tier : You split the processing amongst tiers In one case, the same processing is replicated over several nodes. In the other case, each tier has a distinct responsibility and the processing running on each

After reading some of the Q/As here on stackoverflow, I am still confused about the correct implementation of DTOs in my web application. My current implementation is a (Java EE based) multi-tier architecture (with persistence, service and presentation layer) but with a "common" package used by all layers, containing (amongst others) domain objecs. In this case the layers can not really be considered as independent. I am planning to remove the common package step by step, but I encounter various challenges/questions: Assume the persistence layer would use a class myproject.persistence.domain

I have a Windows Service that performs a number of periodic activities, and I want to change the settings of this service from a Windows Forms app. I'm not sure, though, about the best way to make sure the service has the most updated user preferences in it (how often to run, what folders to use for things, whatever else the user can specify). The user can change settings any time, at will, and I'd like the service know about it almost immediately. Here are the options I'm weighing: The form and service share use the same "Settings" object from a third, shared project, and the form uses a WCF

On a multi-tier application, I need to simulate various TCP/IP errors to test some reconnection code. Does anyone know of any tools (Windows based) I can use for this purpose? Thanks. Try netwox (formerly lcrzoex.) If it won't do it, it can't be done. It contains >200 tools. Scapy allows you to control every aspect of the packets, and randomly modify ("fuzz") the ones you don't want to control. If you're a command-line kind of guy, it's a great tool. Clumsy is a good tool for TCP error simulation on Windows. It can simulate (copy-pasted from link above): Lag, hold the packets for a short

It's considered good practice to have an exception for each layer of application (i.e. PresentationException , ServiceException , PersistenceException etc). But what if my service-layer directly calls DAO methods (methods of persistence layer) without additional operations. Like this: public class MyService { private IPersonDAO dao = new PersonDAO(); public void deletePerson(int id) { dao.deletePerson(id); } } Should I wrap this DAO method invocation with a try-catch block and rethrow possible exceptions as ServiceException ? Should each DAO method throw only PersistenceException ? Well your