Music: My version of Floyd Rose Tremolo Stopper for my Craftsman EG-95 guitar

Just now, I tried to create a Floyd Rose Tremolo stopper from another cheap floyd rose. I used the saddle/intonation screw and i turned out to be working pretty well. :)  No vibrations nor any problems after the modifications. :)

.NET CF / Windows CE Threading

Lately, I was baffled by a problem in my current Windows CE/ Windows Mobile project. The scenario is quite simple:

• I have a Keydown event on my form.
• On the keydown event handler, I need to do some task which just takes around 500msec to complete.
• On that keydown event handler, I placed a C# lock construct to block the incoming keypresses (and with some Application.Doevents to pump the message queue).
• Then I did some destructive testing. The outcome: If I press a lot of key within the 500msec, the application throws an StackOverflowException.
• Next, I used the Monitor.TryEnter/Monitor.Exit so no blocking will occur. I did the same test. The result: StackOverflowException.

It seems to me that the code is being executed again despite it is inside a lock construct. Normally, what I will do on a PC-based .NET application is to set the control's Enabled property to False, then issue an Application.DoEvents before enabling the property again. Doing this in .NET Compact Framework with a device that is not as fast a PC,  gives an undesirable aesthetic effect. Our device's screen painting is quite slow and doing this method grays out the entire form then back to normal again.

Going back to topic and to illustrate my point:

• I created a sample Windows Form Application. Source code
• There is a keydown event. This must display an incrementing number, have a delay of 750msec, increment the counter, then exit the handler.
• The expected behavior is to display incrementing number each time a key is pressed.

I did an experiment using lock (See the function LockingUsingDotNetLock on the source code). If I press keys within 750msec, the textbox will display the same numbers! It must be incrementing! What happened? I would like to admit that I missed a crucial information regarding C# lock. Just yesterday, I researched more about it (Google, MSDN, StackOverflow.com) and found out that C# lock is re-entrant. It will block access to other threads but it can be acquired again and again by the same thread (Re-entrant Mutex).

Now I know the problem. What will be the solution? Here are the solutions that I could think of as of the moment:

• Using ordinary volatile variable for the locking (See the function LockingUsingVolatileVariable on the source code). It is a very simple solution. If I press keys, only one key will register and the incrementing number will display correctly. Most of the time, this is the behavior that we need.
• Using lock, but this time, we spawn another thread inside the handler (See the function LockingUsingDotNetLockOnAnotherThread on the source code). If I press keys, the key's will queue up, and will display incrementing numbers with respect to the 750msec delay in the code.
• Using Monitor.TryEnter and spawn another thread inside the handler (See the function LockingUsingTryMonitorOnAnotherThread on the source code). This will have the same behavior with Solution #1.

Chain Of Responsibility Design Pattern (Minus the repeated codes)

Last week, I studied Chain Of Responsibility Design Pattern. It was a good design pattern, but from the sample codes that I had seen, one common thing is that there are lots of duplicated codes. I would like to improve these and here are my main goals:
- As much as possible, eliminate or minimize the repeated codes.
- The concrete classes must not worry about the successor as much as possible and must not contain if else statements to call the successor's methods in case the caller can not perform the operation.
- If the additional logic statements for handling of next successor will be removed from the concrete classes, it will be easier to reuse those concrete classes.

I uploaded the code on my github. Link

Lessons Learned in Windows Mobile (Windows CE and .NET Compact Framework 2.0) Development Part 1

It has been months since I joined a company whose products revolve around Windows Mobile 5 and we are using .NET Compact Framework 2.0 and C# for the development. So far, the product is still far from over, but in agile sprint point of view, the product is getting better and better everytime we present it to the stakeholders at the end of sprint iterations. As the lead developer of the project, here are the things me and the team had learned so far:

• GUI toolkit. The best I had seen is Resco Mobile Toolkit. I had tried demo versions of different toolkit and this one stands out visually. In my initial assessment, Resco's UI Components are slow in terms of rendering. But I accidentally discovered that by issuing a Control's Refresh method, the rendering is accelerated. Plus, compared to a competitor toolkit, this has so many additional things (WebDav, Audio, Zip, etc). The license fee outweights the advantages. We are currently using this in our project.
• Protobuf-net. DotNET  CF 2.0 doesn't provide binary serialization by default. I am currently using this heavily on my project. https://code.google.com/p/protobuf-net/
• Using SQL CE and .NET Datatables. One of my colleague insisted to create an SQL CE based database on the extracted data from 3 CSV files which is just a couple of size (around 350KB combined size). After the implementation, our system - which has a total of 64MB - got 32MB of free RAM and there is some performance hit when the database is being queried (SQL connection always open). We tried to open and close the connection, but a further performance hit was experienced although the memory consumption is much lower. I tried to use a memory-persisted Datatable and our system got 42MB of free RAM and no performance hit (queries using DataTable's select method). I did a further research and SQL CE takes around 8MB or more once it is instantiated and left open. I perceived that if the data is around byte or just kilobytes in size, it may be a good idea to just use in-memory Datatables. But if the database is very large, let's say in order of 100MB, it is not a good idea to use in-memory Datatables and stick with the file-based database instead. So as a lesson learned, we try to weigh things first and communicate with each other often especially if a sprint product backlog item is in design stage.
• Architecture. Whether we are a fan of MVC (Model View Controller) or MVP (Model View Presenter), there must always be a separation of concern between those things. After doing a trial run for the MVC and MVP architectures, I am currently sticking with MVP in Passive View. If one is not careful though, the Presenter tends to become a God object (which is one of the known problems of Mediator pattern). If we tend to solve it aggressively, we could end up having lots of classes and interfaces, and too many passing of interface parameters and in the end creating more confusion - which sometimes do more harm than good.
• Pinvoke. Pinvoker is a very good Visual Studio plug-in (and it is free!). http://www.pinvoker.com/Downloads.aspx
• Pinvoke with structure arrays. I had problems Pinvoking at structure with another structure array inside. Based from my research, there is no known work around for this and instead I created a Python script to generate elements for this problem.

These are the important things that I had learned so far. The databases part is the most important one. When I previously developed database-based projects on PC, I don't usually care on the memory size of the SQL object. But developing in a constrained environment, we always tend to look on every details which may affect the performance or the memory.

Information Sharing: Fixing debugging problems: Win CE 5.0 device and VS2005 under .NET CF 2.0

This is a short one :)

I had debugging problem today and the fix is to simply install .NET Compact Framework 2.0 Service Pack:
http://www.microsoft.com/en-us/download/details.aspx?id=20943

:)

Craftsman EG-95 Review Part 1

This will be my first time discussing guitars on this blog. :) My motivation for this post is that I saw some people selling their Craftsman EG-95  (maybe because of the problems that I encountered as well). I would like to share the solutions that I compiled to overcome those problems.

Last week (Feb 17 2014), I bought a Craftsman EG-95. This is just an experimental guitar since I don't have any previous experience with Floyd Rose (FR) setups. After trying it, the stock setup gave me some tuning instabilities. Before buying the guitar, the saleman warned me that Craftsman EG-95 is a little problematic and if I could extend my budget, go for the Charvel Desolation Star, which is a very nice guitar but has only one pickup. :(

Since, we engineers love to solve problems (and at the same time cut some cost), I decided to get the Craftsman EG-95. When I came home, the problems had already surfaced. Anyway, since I am a firm believer of the famous quote:
"The more we are exposed to problems, the more we learn. "
I started to dig deeper yesterday and studied the details of the Floyd Rose from the internet and I learned a lot (and still continue learning as of the moment). Here are the things that I leraned:
1. Never adjust the knife edges under pressure. I learned this rule a little late since I adjusted the action of my strings.
2. According to what I read, when the FR is removed, the knife edges should be stable when screwed to its holder since this is very crucial for tuning stability. In the case of EG-95, there is a very big play on the knife edges. So what I did, is to put teflon tape on the screw thread. This solved the play on the knife edges.
There are also tips to put Chapstik on the knife edges' contact to the FR tremolo, but I used petroleum jelly since I dont have any Chapstik at home. :)
3. Using conventional tuning, it will take time to tune the guitar. But when I saw this youtube link , I was able to tune my EG-95 quickly.
4. The thread on some of the saddles are a little bit sensitive. I have two saddles that have lost their screw thread. :( What I did is just bolt cut the long screws and use a metal file to narrow the tip. This solved the problem however I don't like this as a long-term solution. As of the moment, I am still searching for a saddle online since I don't want to replace the whole FR.

After all of this, I tried to play the guitar and it seems that it is more stable than before. Although, I like it to be really rock-stable even when you use the whammy bar intensely. Here are the things I am planning:
1. Add more springs. Currently, it has 3 springs. I read that having 4 to 5 springs can contribute to the tuning stability.
2. The guitar has a 1 year warranty. If the saddles will not be covered by the warranty, I am planning to look for a saddle or worst case, replace the whole FR with a new one.

Despite of the problems encountered, I am happy that it went this way since I know this will be a very valuable learning experience.

Scrum, Scrum Scrum: Just fell in love with Scrum...

Mid-2013, I am targeting for a PMP certification. I already took online basic project management courses and collected books regarding PMP certifications. Last November 2013, our company have knowledge sharing session regarding Scrum and by that time, I never know anything about scrum although I am a little bit familiar with Agile. After the presentation, I was impressed by Scrum framework.

As we have Pluralsight subscription from our company, I watched Pluralsight's Scrum Fundamentals by David Starr. On the first video, I was inspired by how Scrum Framework saved FBI's Sentinel project. I highly recommend to those who are interested in Scrum to watch this as this gives very good, very simple and practical insights regarding the real-world use of Scrum.

After watching Pluralsight's Scrum Fundamental's, I am more eager to get a Scrum Master Certification rather than a PMP certification. Although I know that PMP's are more respected and more recognized but based from my experience as a developer in companies whose processes and guidelines are based from PMBOK, projects do not always go as planned. Here is a good article regarding this. Also, one can clearly see the difference by just reading the Agile Manifesto.

December 2013, I tried scouting for Scrum Certification and I saw the International Scrum Institute. The exam and certification is not that expensive. All the learning materials is free and can be viewed by anyone. I studied all the materials and took the exam in January 2014 and I passed it. I was able to secure a Scrum Master certificate and this is one of the best New Year gift I could give to myself.


Certifications doesn't need to be expensive and I would like to say thanks to International Scrum Institute for making this possible. As the materials can be learned online, I personally don't agree on the way where certifying bodies requires classroom training before taking exams. This isn't a bad thing actually, but I hope that they would realize that there are some people who have the ability to self-study and are more eager to explore things by themselves. I hope this will change in the future.

Good luck to all who wishes to take the exam.