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Knowing Your Code’s Structure

I haven’t paid much attention to how the classes in my projects communicate with each other. Looking at the package structure, they all look good and well-organized. Then one day, I came across the article Your Code Structure and it made me to seriously think about re-validate my source code.

In the article, Edmund Kirwan used his tool, named Spoiklin Soice, to analyze the modules of JUnit from the early version to the latest one. The result was that as JUnit evolving, its classes had become more tangled and its structure had become a real mess (according to the graph).

This was really interesting because JUnit had been a widely known & used by almost all Java developers and it was developed by the lengedary Kent Beck. In the article, the latest version of JUnit, 4.11, had become really complex due to new features added into the library. I had always thought of JUnit as a powerful and well-tested tool and never paid attention to its structure and design ever since I used it. It could be the case that as time goes by, JUnit would become more and more difficult to extend and mantain due to its complexity.

Well, that was for JUnit, how about my projects? Spoiklin Soice is really interesting tool, I will use it to analyze them to see whether the structure is still controllable.

But what if we knew that the structure of a project had become too complex, what we could do to make it right again? Or there are any principle that we could follow and then keep everything in its right position?

Download and read more about Edmund’s work at his blog: http://edmundkirwan.com/general/spoiklin.html

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Prepare to Getting Real

I’m bored tonight. So I go to my bookmark bar to see whether there is something I can read. Bingo! I came across the @freebook folder and click on Getting Real. This is a free version of 37signal’s book, Getting Real where it talk about how to quickly and efficiently start up a new software product which solve the problem from the begining. Start small, focus and efficient. I will continue to read it tomorrow.

Here is the link to the free book: http://gettingreal.37signals.com

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Agile toolkits

My current company is using Scrum to develop softwares. To me, it is a set of practices and tools which enhances communication, collaboration, trusts, etc between members of a team.
What people are still debating is that, which one, Scrum or Lean is better. I said, why not both? To me, the term Agile has been broaderned to bear many meanings. It points to a lot of processes. But under the hood. It is still 4 statements and 12 principles of Agile Manifesto. Everything else is just a technique. We can decompose Scrum or Lean into techniques and combines several ones to form a new method. To see if it works, we have to try it. But in the end, they are just tools.

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Why there is no SoftHashMap?

The above question bumped into me when I was developing a simple cache using java.util.Map. In the search for the answer, I came across a thread on JavaRanch that had the same question as mine. And there was an answer which had widen my knowledge in soft/weark references in Java.

I quoted the answer here in case the link is inaccessible.

In the few cases, where I used weak references (or soft references), I used the classes, (and queues) directly. Never used the WeakHashMap class. So, never thought about the possibility of the SoftHashMap class. IMO, the WeakHashMap class was written for internal (as support) reasons, and then exposed because others may need it. Maybe that is why SoftHashMap was never written.

In thinking about it a bit more, I don’t think that it is possible to write a SoftHashMap class. Remember that a SoftHashMap isn’t just a WeakHashMap that is using SoftReferences. It has to also not “distrurb” those soft references. Let me explain….

To implement a WeakHashMap, just use WeakReferences on the keys. This means, of course, that you need to do an additional deference to add/remove the key/value pairs. You will also need to attach a ReferenceQueue so that you can detect that a key has been GC’ed — which the WeakHashMap will use to automatically delete the key-value pair.

There is a minor flaw though — particularly if more than one key lands in a bucket. The WeakHashMap needs to deference the key (ie. make it a hard reference temporarily) so that it can use the hashCode() and equals() methods for the operation. This means, that in theory, it is possible for a key (that isn’t referenced by the application) to survive a GC cycle — if by chance theWeakHashMap is doing this operation….. This is probably not a big deal, as the chances are ridiculously low, and it can be picked up on the next GC cycle.

This becomes a major flaw with the SoftHashMap. Remember that SoftReference objects may or may not be GC’ed even if there are no hard references. It is at the whim of the JVM, which decides based on the amount of memory that it needs. The idea is, if there are lots of memory being freed, there is no reason to completely delete a cache that could be useful to the application.

The issue is, the SoftReference determines which instance to GC based on the access — it keeps timestamps of which object has been used and how recent (Least Recently Used). This means, that the temporary conversion of the soft reference to a hard reference (to do the equals()) will affect the LRU. A key that hasn’t been accessed by the application in a very long time, may survive a GC purely because it shares a bucket with a more commonly used key. And unlike the WeakHashMap issue, the chances are not low, and it may not be picked up in the next GC cycle.

Basically, you have a SoftHashMap that has soft references, but isn’t really a soft hash map.

Henry Wong

The link: http://www.coderanch.com/t/487535/Performance/java/WeakHashMap-SoftHashMap

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My father is a …

My father is a writer. A good one. His name is Marc Norman.

He wrote Shakespeare In Love and a hundred other scripts and novels and has two oscars on his mantle.

He told me this about writing…

It’s a full time job. To be successful you must be disciplined. You do it from nine to five, five days a week. Focus on your work for forty hours and put it away at night and on the weekends. When you’re blocked write something else, sonnets, poems, the “other novel”, love letters. The point is you must write full-time. A writer’s talent is a muscle that must be worked out, and like a bicep it will strengthen with use.

Writers write alone, in quiet. Writers don’t write in coffee-shops. Silence is the blank canvas onto which the world of the work is drawn.

I found this on an anwers on Quora: http://www.quora.com/Writing/What-should-everyone-know-about-writing

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SQL isn’t dead. JooQ is a new fresh thing

After working with 3 layers, DAO, JPA and Hibernate and stuff, I think writing native SQL code is going to disappear. However, til today, I just found a new framework that support you to write SQL command by Java code. Their fluent API is so good that it seems identical with real SQL command.

Check out JOOQ – Java Object Oriented Querying;

http://www.jooq.org/

P.s: Guess what! It’s type-safe.

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Bugs lie in uncertain code

Today after having lunch, I went around articles queue in order to read one or some. As reading the Architecture-Breaking Bugs, a lot of articles I had read before came back to my mind.

The content of article was about flaws in the architecture which the engineers often overlooked, turned out disasters. There was a link to another article which told the story of Airline 5 and has it crashed because only 1 bug at 1 line of code. Going through the articles made me remind of “Clean code” of Uncle Bob, “Don’t Assume It, Prove It” of The Pragmactic Programmer.

Why? Because at the time I was reading the article, I had finished basically a feature in my current project, Migration Process. The process is for migrating old workflow cases into new Process Model Version to avoid too many versions running in parallel. My group was barely finished the process on Friday and had to show it to the Product Owner on next Monday. Honestly, the process was untested, and I was sitting there doing nothing. There were a lot of things to be tested, a lot of scenarios to tests, but I chose to test several of them under the assumption the process will work. HOPE!.

God damn it! I had to go back to do something about it.

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The Humble Dialog Box and Ivy Rich Dialogs

Today I’ve read The Humble Dialog Box of Micheal Feather and it is very interesting. The idea of the article is to develop in test-first manner the Model first, all actions, all interactions should be developed and tested against the mockable interface of the View. By doing this, it ends up all the logic are encapsulted in the Model (smart object) and the View provides methods for the Model to update. It is somehow an opposite way of MVC.

After reading the article, it make me start to questioning. The Ivy Framework, the one my company is using as a ground-up for all project, is stating that all Rich Dialogs are developed using MVC. Really? I start doubting from a long time ago if it is true. The Model of the RD is just a simple data structure while all the logic are put in the Logic part and they are tied together very strict. They are hard to test.

So what will I do? I think I should consider whole part of RD is just a View, the model of the RD should be developed first as POJO, then we will start to see the outcome.

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Thoughts when reading How to Win Friends and Influence People

After reading section “Twelve Ways to Win People to Your Way of Thinking”, I recalled that I’ve applied the principle “Start with questions to which the other person will answer yes” months ago with one of my colleagues.

At that time,  my team was working on a project with another team, they started first and later we  joined. At first, the way we created & updated the database actually sucked. The first time when I looked at the sql files, I had no idea how to run those. There were sql files and batch files to run the scripts and one could not know which one to run first just to look at them. So we had to run back and forth to ask the other team for support.

So I decided to sit down and re-wrote all those scripts and batch files with one thing in mind: I just wanted to make me and my team setting up the database as fast as possible. Finally I did came up with a solution and implemented it. But I needed the confirmation of the other team to follow my new way of hanlde updates of database.

I wrote an email to express my solutions and listed what we (both team) could benefit from doing this. The solution was creating two folders: initial and update. The folder initial contained all the scripts up to this time and a batch file to run all those script. And the updates will have sub folders whose name is a combination of both team’s sprint numbers. At every sprint, we put the update scripts into there appropriate sprint folder and I wrote a batch file to run those script at every sprint or run all of them.

The Scrum Master of the other team agreed with most of the points in the email but he still wanted all developers must added the changes into both places, the old scripts and the new scripts,  just to make sure there was no problem.

He, the Scrum Master, was not an easy-going man. So I decided to make an private Skype conversation with him to convince him not doing that. At first he did not agree. He insisted that all developers must do so because that makes everything in sync. The conversation went like this:

Scrum Master (SM): No, we have to keep updating the old script with ALTER and then add the merge the update into the brand_new_update. So if we run the brand_new_update, the customer will have a full database. We just run the old script with the updating parts.

Me: I have a question: If we run all the initial & update script.

So I asked him if we run the initial first and then run all the updates, did it considered the database is up to date. He answer YES. Then I asked him if two solutions results in equivalent