Agility not in name but in spirit
It appears that the whole software development industry is washed agog with this holy mantra of Agile, and everyone is jumping onto this massive bandwagon trying to proclaim themselves as purveyors of whatever is cool in software development. However, what started out with the best of intentions, has been productized and monetized to the point where it has lost its essence....read more
Migrating Spring MVC From JSP to AngularJS
This article is written for Spring developers who are familiar with JSP development and who would like to understand how to migrate to a frontend-based web application like AngularJS.
Introduction on AngularJS
The Emergence of DevOps and the Fall of the Old Order
Software Engineering has always been dependent on IT operations to take care of the deployment of software to a production environment. In the various roles that I have been in, the role of IT operations has come in various monikers from “Data Center” to “Web Services”. An organisation delivering software used to be able to separate these roles cleanly. Software Engineering and IT Operations were able to work in a somewhat isolated manner, with neither having the need to really know the knowledge that the other hold in their respective domains. Software Engineering would communicate with IT operations through “Deployment Requests”. This is usually done after ensuring that adequate tests have been conducted on their software.
However, the traditional way of organising departments in a software delivery organisation is starting to seem obsolete. The reason is that software infrastructure have moved towards the direction of being “agile”. The same buzzword that had gripped the software development world has started to exert its effect on IT infrastructure. The evidence of this seismic shift is seen in the fastest growing (and disruptive) companies today. Companies like Netflix, Whatsapp and many tech companies have gone into what we would call “cloud” infrastructure that is dominated by Amazon Web Services....read more
MySQL Transaction Isolation Levels and Locks
Recently, an application that my team was working on encountered problems with a MySQL deadlock situation and it took us some time to figure out the reasons behind it. This application that we deployed was running on a 2-node cluster and they both are connected to an AWS MySQL database. The MySQL db tables are mostly based on InnoDB which supports transaction (meaning all the usual commit and rollback semantics) as well as row-level locking that MyISAM engine does not provide. So the problem arose when our users, due to some poorly designed user interface, was able to execute the same long running operation twice on the database.
As it turned out, due to the fact that we have a dual node cluster, each of the user operation originated from a different web application (which in turn meant 2 different transaction running the same queries). The deadlock query happened to be a “INSERT INTO T… SELECT FROM S WHERE” query that introduced shared locks on the records that were used in the SELECT query. It didn’t help that both T and S in this case happened to be the same table. In effect, both the shared locks and exclusive locks were applied on the same table. An attempt to explain the possible cause of the deadlock on the queries could be explained by the following table. This is based on the assumption that we are using a default REPEATABLE_READ transaction isolation level (I will explain the concept of transaction isolation later)...read more
When it comes to Software Version/Configuration Management, there might be a whole lot of vendor or open source implementations to choose from but in recent years, there’s none that could parallel Git in terms of being the most development/hacking friendly.
I’ve used quite a few different forms of software management tools, from the CVS/SVN family to the Clearcase/Perforce family (which I personally feel is absolutely horrible) but it is with Git that I finally think that Software Versioning is no longer a necessary evil but something that actually helps in the software development process. Perhaps, I will need to corroborate my statement with some examples later but using Git can actually encourage developers to experiment and be creative in their code, knowing that they can always reset back any code changes without any penalty or overheads....read more