Maps and Entities and JPA, OH MY!

Ryan McCullough Problem Solving, Programming, Technology Snapshot Leave a Comment

A client I’m working with has an email templating system that needs an upgrade! The current design utilizes a denormalized table that needed to grow a column every time a new unique token is needed. After a review of the offerings through JPA, I was happy to see that JPA had some support for java.util.Map through joins through a variety of the @MapKey annotation.

In this post, I’ll demonstrate the less frequently used methodology of applying and populating a Map of entities using a single table and a composite key.

The Data Access Layer, Part 2 – Using the Criteria API

Mark Adelsberger Architecture, Tutorial 3 Comments

In Part One of this series, I reviewed the basic design goals of a Data Access Layer (DAL), those being: Contain all of the information about the persistence mechanism; and Contain none of the business logic. I then discussed what can happen if your application needs to operate on large volumes of data:  performance may demand running more sophisticated queries; …

The Data Access Layer, Part 1 – The Basics (And When Things Aren’t So Basic)

Mark Adelsberger Architecture 5 Comments

Today, I’d like to talk about the data access layer (DAL). I’ll start with a brief review: the motivation behind the DAL, the design principles that define a theoretically “good” DAL, and the relationship between the DAL and modern persistence technologies. Then, I’ll look at how simple DAL designs might start to break down under some workloads. I’ll outline a …