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    Fragmented OS


    2010 - 03.01

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    Posted in CS, Computer Science, Industry | Comments Off

    So, the Technical Account Manager for Android at Google came for the department’s seminar session. She’s basically in charge of Google’s relationship with manufacturers that use the Android OS. First off, Google is not the soul creator of Android. It’s actually a creation of the Open Handset Alliance, a group of handset manufacturers, software developers, cell phone service companies, etc.

    The Android OS, despite being less than a year and a half old, has fragmented to an appalling degree. Different manufacturers include varied screen sizes, sensors and actuators. So, application developers cannot predict what hardware is available. And consumers cannot easily predict if an application they download will function correctly.

    The operating system itself has even become fragmented. There are five different versions of Android available across different hardware. Developers now have to consider these different versions, not unlike working with different browsers. Developing for the latest version (as Google does), effectively tells anyone with an older version (79.6% of the Android market at the moment) that they’re out of luck.

    I will note that the speaker suggested using version 1.5 or 1.6 rather than 2.1 in developing. On the one hand, that does solve a short term problem of diverse systems. On the other, it makes an unsafe assumption of developers: that we’d want to use an older specification. For most programming languages, it is better practice and makes a person more employable to use the latest standard whenever possible.

    And, there are some genuine reasons for this fragmentation. With more varied hardware, it becomes increasingly difficult to include the appropriate drivers (needing to write one for every new feature for every individual piece of hardware). Some devices do not contain the memory or processing to be upgraded, which effectively keeps them trapped with their original version.

    It’s this fragmentation that will eventually lead to different flavors of the Android OS, more or less defeating the purpose of a unified operating system. Manufacturers may want to consider having an easy Lego-like means of upgrading hardware, but that still does not account for building the drivers (and assumes that manufacturers would even want open hardware).

    Ah well. It was a nice idea.

    Data Structures


    2010 - 02.26

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    Posted in CS, Teaching assistant | Comments Off

    I’m grading for the data structures course this semester. The prof has never taught the course and is reusing assignments from a previous professor’s version of the coursework.

    I spent Monday sick and grading. (I did not receive the assignments to grade until after the department grade-by due date and had to rush.)

    Grading is a very disheartening. The purpose of the assignment was to demonstrate using a queue. Prof said they could use more advanced data structures. The students did not comprehend they were to still follow the queue requirements (enqueue, dequeue, limited access, etc.).

    Out of 70 students only 1 included a queue, reused from recitation. About 20 had included Java’s queue (many of which preceded to use a secondary data structure to do the actual work). The rest used another data structure altogether to reach the same effect: ArrayLists to LinkedLists to HashMaps to trees.

    For people that are not familiar with a queue, this is among one of the simplest data structures to implement. It implements a First In, First Out (FIFO) means of accessing data. One can only access the first (or “top”) Object in the queue; all other contents are inaccessible.

    … I don’t understand the drive of these students to use more complex data structures (and code design) than is necessary. A queue uses notably less memory and has a faster access time these other data structures.

    I read comments that a hash table is more efficient than a queue. Queues have constant time adds (enqueues) and removals (dequeues). A hash table has O(1 + k/n), where k is the number of keys and n is the number of elements; this is between linear and logarithmic time scales (meaning the amount of time to perform an add or removal will increase with an increase in the size of data structure).

    This scares me. There will be (if there aren’t already) computer scientists and programmers making inefficient code because they genuinely believe their way is better.

    … I talked to the prof in charge (who has been out of town this week) about my issues. My actual boss, the Director of Mentoring and Retention, had spoken to him previously about this. (I was actually third to complain about it to her.) And she was not getting through to him; she was even considering going to the department chair.

    After I told the prof what had transpired, the light bulb finally went on for him. Students will not prove they understand concepts unless they are forced to. Getting the right answer is more important than learning, I guess.

    JUnit


    2010 - 02.03

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    Posted in CS, Class | Comments Off

    JUnit is a unit testing framework developed for Java programs. It’s not my favorite thing in the world. For starters, it only tests public methods. Which is a bit of a problem if from a development standpoint; many internal “heavy lifting” methods are not needed by outside classes and should be private. In addition, I cannot use Eclipse, my IDE, to debug as I do with other code.

    For my software engineering course, I am creating a very simple Roman to Arabic numeral converter. (If anyone knows what the unicode character for Roman numeral 5000, a V with a line over it, I would appreciate it for accuracy.) It isn’t the converter program that is important. The purpose is to demonstrate black box testing methodologies: testing without knowledge of the internals of a program.

    I developed a test plan and wrote the test cases in JUnit, as instructed, before proceeding on to writing the actual converter. I then ran my tests. A couple failed and a hand full had an error. I rewrote the code; the class is small enough to justify it, rather than worry about where my sometimes failing  bug was.

    Yet, I still had the same problems. So, I copied the short bits of code into a main() function to use the debugger. The debugger revealed no faults: my system produced the correct output. JUnit had produced a false negative. I didn’t know it could even do that. It did not occur across similar tests with identical assert statements, so I’m not sure what it could be.

    Spring Work


    2010 - 01.26

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    Posted in Class, Miscellaneous, Work | Comments Off

    So, this semester I’m going to have quite a workload. All my courses have a high reading amount. Two require homework and/or a programming assignment each week.

    In addition, I will be grading the first programming course, tutoring a foreign visually impaired student, and doing side research for the Director of Mentoring & Retention. I’m not even sure my workstudy is for this semester, but I’m guessing the Director wants to spend every dime (thereby making sure I get the full employment pay).

    In most semesters, I have done side projects which dabble into my interest. Yet, I’m not sure I will have the time this time. So, I have decided that I will continue watching how this semester goes and then decide whether I have the time.

    If it does work out, I think I would like to do some cell phone programming (probably Android, but maybe the iPhone‘s Objective C). I don’t know what I would want to program though. I would like to involve hardware, like the GPS or accelerometer. I think the best tools are tangible or ubiquitous.

    Compilers, Networks, and Software Engineering


    2010 - 01.21

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    Posted in Class | 1 Comment »

    I have taken two embedded systems courses, and am now in compilers and networking. Despite having my passion in human-computer interactions (HCI), I have taken predominately systems courses for my capstone work (the exception being A.I.). I suppose that’s because I also like ubiquitous computing, the movement towards embedding technology into the world until it becomes invisible.

    Compilers seems useful, but we’re still reviewing context-free grammars, parse trees, etc. from the computing basics. We will be making a compiler for MiniJava. This basically takes a subset of the Java language and produces MIPS, an assembly language.

    Compilers are very involved productions. One needs to know what kind of hardware it is compiled on, what the specification is for the language, etc. I’m not taking it to spit out compilers (there’s compiler compilers for that). It’s better for enforcing appropriate testing and debugging. (I admit to doing a ludicrous all/several test cases after writing my programs. The appropriate method is to do unit/module testing throughout creation.)

    Networking focuses on how the Internet works: how data gets from one machine to another and protocols for different types of data. I’m taking it more for interest in mobile devices. I don’t know if I’ll get a full answer to these, but it is best to know why I’m doing something:

    • How do cellphones, laptops, etc. protect data when it is on a wireless network? (Someone else can grab the bits I send from out of the air.)
    • What types of machines make up the Internet? What is the ratio between embedded systems and standard computers?
    • With the imminent death of the Internet, what comes next? (We’re running out of IPv4 addresses, and IPv6 adoption has been quite unsuccessful. The only viable solution if this trend continues is the creation of “gated communities.”)

    And then there is software engineering. Many students, including myself, put off this course until their last semester. This is because of reports of how not useful the course is and that it is taught backwards from the actual process (testing is done first, while design and specification is taught last).

    My first assignment is read either a 30 or 50 page paper on software disasters  and report on it in 2-3 single spaced paper. More distressing is that the course is packed with students; this is not helping my anxiety.

    All three courses involve group work. So, that’s a definite shift from my previous coursework and I don’t know what to expect.

    … As an aside, for anyone that does a Powerpoint presentation, please don’t use a white background. It visibly color shifts and flashes on a projector. (It’s bad enough for my migraines to be around florescent lights; I don’t need the screen I’m reading to blink, too.)

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