Today: September 25, 2021 3:46 pm
A collection of Software and Cloud patterns with a focus on the Enterprise

Tag: object oriented design


A few days ago I wrote about how to structure version details in MongoDB. In this and subsequent articles I’m going to present a Java based approach to working with that revision data. I have published all this work as an open source repository on github. Feel free to fork it: https://github.com/dwatrous/mongodb-revision-objects Design Decisions To begin with, here are a few design rules that should direct the implementation: Program to interfaces. Choice of datastore or other technologies should not be visible in application code Application code should never deal with versioned objects. It......

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Last week I spent way too much time integrating Apache Wicket and Google Guice. Yikes! The most difficult part for me was getting the initialization to happen in the right order. A big Thank You to Dan Retzlaff on the Wicket list for helping work through these details. The details below were applied to a Wicket quickstart project for Wicket 6.0.0. Design Decisions It was important to me to keep the application tier separate from web tier. I actually maintain each in a separate repository. I have several motivations for this, such as:......

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The information below was delivered to one of my programmers as direction for how to implement a rather big change in an existing software product that I sell. I thought it was potentially useful to a broader audience, so I’m posting it here: …The rest of this is rather complicated to explain online. I’ll do my best. I’m going to look at this in a simplistic way and let you work through the details. First imagine that we have an Authorize.net processing class based largely on their API. class AuthnetProcessAIMPayment { protected $apiKey;......

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Java, Wicket and Hibernate on EC2 (pre-interview project)

Over the weekend I put together a project as a precursor to an interview. I really like interviews where I have a chance to solve a problem that’s more meaningful than generating a random number efficiently. The pre-interview question came in the form of a sketch of the application. This worked out great since I suggest always starting with a sketch drawn by hand. Here’s what they wanted: Choice of technology The instructions indicated that I could use any technology that I was familiar with, as long as I included the libraries necessary......

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Software licensing: The value of good books

I have a large budget for books (but thanks to Amazon it doesn’t have to be as big as it could be). Sure it’s true that most of the information in programming books is online and available for free. There may even be substance to the argument that most books are out of date as soon as they hit the shelf because technology moves so fast. Oh well. I get huge value from books. They save me many hours of time that I might spend scouting around for a snippet here or an......

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In the current series of articles I’ve been talking about development of a system to enable premium wordpress plugins to be protected by licenses. While working on the design and going through a brain storming session yesterday with a colleague I had two small realizations. The first is that from the beginning I have planned to keep the WordPress coupling separate from the main licensing API. In fact, I haven’t planned to include any WordPress specific or shopcart type features in the API. This provides me with some benefits. One is that it......

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WordPress plugin licensing: API and class diagram

In the first article in this series, I sketched out some of the basic design ideas for the wordpress plugin licensing system. The next step is to come up with some more concrete details about how the application will work, what information it will manage and what the interfaces will look like when accessing it. I really like using the UML as I flesh out a design. In particular I find the class diagram and activity diagram useful. I frequently make use of stereotypes to extend the meaning of my classes. I’m not......

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Programming has evolved in very significant ways over the last few decades. There have been some significant strides forward in terms of language structure, reduced complexity and programmer productivity. One of these shifts was from procedural style programming using a language like C to object oriented programming using a language like C++. Most modern languages support objects, inheritance and other object oriented constructs. However, not all programmers use these the right way. As a matter of course, most introductory material in programming is procedural in style (a linear sequence of commands). It’s important......

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