Thursday, March 26, 2020
Renewing my CompTIA A+ certification
CompTIA is an organization that administers certification exams for IT professionals. I took and passed their entry-level exam, CompTIA A+, three years ago. The exam tests your knowledge of broad IT-related topics, such as internal hardware, cabling, troubleshooting, operating systems, and much much (MUCH) more.
I wrote a handful of blog posts about some of these topics while I was studying for the exam if you want to get a feel for what they test you on. You can also get the exam objects from their website (the form asks your for your email, but you don't have to give a real one).
Having to pay over $400 to take a test (actually, it's two separate tests) that I might fail was stressful to me, so I'm glad that I passed it! The exam expires after three years, so since I took it three years ago, I needed to renew it. There are several ways they allow you to renew your certification. I chose to enroll in their CertMaster CE training course, which renews your certification instantly upon completion. It's all done online and costs $129.
The way it works is you read through the content it gives you, which is organized based on the exam objectives of the exam you are renewing. At the end of each section, it gives you a 20-30 question multiple choice quiz. When you complete the quiz, it shows you which questions you got wrong, but doesn't tell you the right answer. You can "reset the assessment", which resets the quiz and lets you take it again.
You can give it a date for when you want to complete the training by, and it will recommend to you how much content ("knowledge points") you have to study each day in order to finish by that date. As you progress through each section, you earn knowledge points. It tells you how many knowledge points are in each section so you can get a feel for how long a section is.
It also has various "achievements" that you can earn to help motivate you. For example, there's one for getting 100% on a quiz and one for getting twenty consecutive questions correct. My left-brain found some of them to be a little patronizing (for example, resetting a quiz gives you an achievement), but it was nice to have that extra bit of encouragement.
I found the user interface of this web app to be very clean and intuitive. It is also very responsive, which leads me to believe that it's heavily JavaScript-based and doing a lot of caching in the background. For example, going back and forth between the pages in a lesson is instantaneous, as is flipping through the questions in a quiz.
I also loved the graphics they provided for showing what the different cable connectors look like (VGA, DisplayPort, USB, etc). They all have a consistent aesthetic to them, which made the learning process that much easier. I would post one here as an example, but I don't want to violate any copyrights.
In order to renew your certification, you have to get a 100% on each quiz. Once you do that, your certification is automatically renewed. You literally don't have to do anything else. I got an email no more than a day or two after I completed all the quizzes saying that my certification was renewed. My new expiration date was based upon my current expiration date, not the date I completed the CertMaster training. I appreciate that because I completed the training several months early!
Tuesday, March 24, 2020
Workaround implemented for file timestamp issue
A few months ago, I wrote a blog post about a problem related to the date modified timestamp on a database file not updating immediately after the file was modified. This was causing a problem with an application I wrote that relied on this timestamp to update the data it displayed on the screen to the end user. It would take around ten seconds for the timestamp to update, which meant that the user had to wait that amount of time before the most recent information was displayed to them.
While I did discover a clue as to why this was happening to some files and not others, I wasn't able to fix the core issue itself--the delayed updating of the date modified timestamp. However, I implemented a workaround that not only solved the problem of the end user getting delayed updates, but also improved the integrity of the file (an Access database file).
The workaround involved creating a lock file whenever a user writes to the database. When the user is done writing to the database, the application deletes the lock file. The application monitors for this file deletion event and refreshes itself whenever a deletion is detected. There are no delays in the file system reporting when a file is deleted, which means the user's screen updates instantaneously whenever the database is updated.
I also use the lock file to improve the integrity of the database file. If the user tries to write to the database, but the application detects the presence of the lock file, it means another user is currently writing to the database. If this happens, the application waits until the lock file is deleted before creating its own lock file and executing its own writes. This prevents multiple users from writing to the database simultaneously and potentially corrupting the database.
There is a second kind of lock file which the application also makes use of. If the file is opened in Microsoft Access, Access creates its own lock file. My application monitors for the presence of this lock file. If the user tries to write to the database while the Access lock file exists, the application cancels the write operation and displays an error message. The error message informs the user that the database is open in Access and that it cannot write to the database while Access is open. This also helps to prevent file corruption.
Similarly to the lock file that the application creates when the user writes to the database, the application uses the Access lock file to detect changes to the database. When the Access lock file is deleted, it not only means that Access has been closed, but that changes could have been made to the database while it was open. So, when this lock file is deleted, the application refreshes itself and updates the on-screen information for the end user.
This workaround has been in production for 1-2 months and has been working quite well.
While I did discover a clue as to why this was happening to some files and not others, I wasn't able to fix the core issue itself--the delayed updating of the date modified timestamp. However, I implemented a workaround that not only solved the problem of the end user getting delayed updates, but also improved the integrity of the file (an Access database file).
The workaround involved creating a lock file whenever a user writes to the database. When the user is done writing to the database, the application deletes the lock file. The application monitors for this file deletion event and refreshes itself whenever a deletion is detected. There are no delays in the file system reporting when a file is deleted, which means the user's screen updates instantaneously whenever the database is updated.
I also use the lock file to improve the integrity of the database file. If the user tries to write to the database, but the application detects the presence of the lock file, it means another user is currently writing to the database. If this happens, the application waits until the lock file is deleted before creating its own lock file and executing its own writes. This prevents multiple users from writing to the database simultaneously and potentially corrupting the database.
There is a second kind of lock file which the application also makes use of. If the file is opened in Microsoft Access, Access creates its own lock file. My application monitors for the presence of this lock file. If the user tries to write to the database while the Access lock file exists, the application cancels the write operation and displays an error message. The error message informs the user that the database is open in Access and that it cannot write to the database while Access is open. This also helps to prevent file corruption.
Similarly to the lock file that the application creates when the user writes to the database, the application uses the Access lock file to detect changes to the database. When the Access lock file is deleted, it not only means that Access has been closed, but that changes could have been made to the database while it was open. So, when this lock file is deleted, the application refreshes itself and updates the on-screen information for the end user.
This workaround has been in production for 1-2 months and has been working quite well.
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