Introduction

singleton design pattern:

we are forcefully restrict an object to do not create more than one instance.

real time example:
 1. connection object: in the connection pool mechanism are the depends.
 2. Actionservlets: structs frame work in the singleton
3. SessionFactory in the hibernate
4.Mailing phases: in the projects, not singleton.


DTO (Data Transfer Object) design pattern

1. where do you use collection in your project?
ans:
 service layer, DAO layer(data Access Object)
DAO: updating, trigger, communicate with the database.
service layer on server locater: is design pattern, is used to third party validation.