Roy's Technology Diary

Whilst developing web applications, more than often we are confronted with the need to validate user inputs. On the client-side (browsers) we generally do that with scripting languages; and for those users who have perhaps deliberately disabled their browser script support; we perform the same set validation on the server side, and this time we write some lines-of-code to extract the user input from the HTTP request and validate the same. Well, although ironic; yet it seems to be a de-facto that - we have to specify the validation rules separately on the client and server side, for eventually validating something that is semantically same. A technical analysis into the core reason reveals that – although the semantics of the herein discussed "thing" (i.e. the user input) are the same, yet the representations of the semantic on the client and server side are different; which enforces us to implement the extraction and validation logic differently. So going by that theory - if ...

Schematron is a rule-based validation language for making assertions about patterns found in XML documents. It is a simple language which is based very much on XML itself and uses standard XPath to specify the assertion statements. The Schematron definations (a.k.a Schema) can be processed with standard XSL templates; which makes Schematron applicable is a variety of scenarios. Although a Schematron defination is referred as a Schema, but one must understand that Schematron differs in the basic concept from other schema languages; i.e. it is not based on grammars but on finding tree patterns in the parsed document. This approach allows many kinds of structures to be represented which could be difficult with grammar-based schema languages. For instance - imagine how would a typical schema be, for the following XML document - <?xml version="1.0" encoding="UTF-8"?> <instance> #### <person> ######## <fname/> ######## <lname/> #### </pers...

Work in Progress The Scarlet project is currently under development. Please keep an eye on the sourceforge project site (sourceforge.net/projects/scarlets) or contact personally for updates. Introduction to Domain Specific Language (DSL) Domain-specific languages have lately become a hot topic and a lot is being spoken and written about them all over the internet; much of the buzz around functional languages is their applicability to (once again) put the power and control of an application in exactly the right place where it belongs, i.e. in the hands of its users. By defining a simple language that the application users can understand, feel comfortable to communicate and use, programmers can effectively reduce their involvement in the never-ending cycle of UI requests and enhancements and can let users create scripts and other tools that allow them to create newer behavior in the applications they use. A perfect example of a wildly successful DSL is the Microsoft® Office Excel ...

Its been quite a while since my last post here. I understand that my sudden disappearing act must have annoyed a many of my regular visitors; especially the ones who are expecting the second part of the XRX tutorial. Whilst you wait for the concluding part of the XRX article, I thought of sharing somethings that i found to be interesting - As Java Web application frameworks have become more powerful and flexible, they've also become more complex. John O'Hanley's WEB4J framework in many ways flies in the face of this trend: it offers few customization options, but is easy to learn and work with. Read on to learn about the unusual (and somewhat contrarian) development principles behind WEB4J. You'll also have the opportunity to test out the framework by building a feature for a sample Web application... [ more ]

During my tenure at Software AG, I was introduced to the power of XML. To my candor, i was very impressed to see the wide range of problems that XML promised to solve. Especially, to mention the performance power-punch that XML databases unleash when combined with XQuery and REST. A couple of years later, I moved into the consultancy world. Being back in the consultancy world and seeing business systems with my renewed XML-ized eyes (all credits to Software AG Tamino API and tools laboratory), I was highly dismayed to find that business oriented systems seldom use the real power of XML. The usage of XML herein has been more-so confined to defining application configurations and bare minimum transformation to either render interface elements or reports. I agree, there have been a few exceptions to this statement too. After spending quite some years revolting the general underutilization of XML; apparently I found my preferred architecture – i.e. XRX (XForms/REST/XQuery). What is so u...

Natural language processing (a.k.a. NLP) is a stream of artificial intelligence and computational linguistics. In theory, it is the most attractive method of human-computer interaction; but as natural language recognition seems to require extensive knowledge about the outside world and the ability to manipulate it, implementing Natural Language Processing has infact been one of the most sought after conundrums in the computing world. This article presents an abstract introduction to natural language processing and further discusses implementing the same to query databases. What is a Natural Language Processing (NLP)…? Natural language processing is the collection of techniques employed to enable the computers to understand the languages spoken by humans. The concept linguistic analysis and processing originated with efforts in the United States in the 1950s, wherein the intent was to use computers to automatically translate texts from foreign languages into English. Since compute...

I have been experimenting with virtualization since quite sometime now. My interest towards hypervisors or virtualization was sourced from the need to enhance the productivity my development and testing staff, by enabling them to switch between multiple operating systems on the very same box, without having to reboot the entire system. Although virtualization has been around since many years now, but my search for better and cost-effective hypervisors recently seems to have been complimented with a plethora of them available at zero cost. VMware is finally giving away its Update 2 for VMware Infrastructure 3.5 along with a lightweight edition of its market leading hypervisor, ESX 3i, for free. Read more about this new here . Another competitive product is this segment is VirtualBox ; which is a powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers, it is also the ...

Scaling Database is one of the most common and important issue that every business confronts in order to accommodate the growing business and thus caused exponential data storage and availability demand. There two principle approaches to accomplish database scaling; v.i.z. vertical and horizontal. Regardless of which ever scaling strategy one decides to follow, we usual land-up buying ever bigger, faster, and more expensive machines; to either move the database on them for vertical scale-up or cluster them together to scale horizontally. While this arrangement is great if one has ample financial support, it doesn't work so well for the bank accounts of some of our heroic system builders who need to scale well past what they can afford. In this write-up, I intend to explain a revolutionary and fairly new database architecture; termed as Sharding, that some websites like Friendster and Flickr have been using since quite sometime now. The concept defines an affordable approach t...

Most product development starts with a good design in mind. The initial architecture is clear and elegant. But then something begins to happen. What really happens is that the programs, like people, get old. However, unlike (in most cases) people there is no guarantee that software will mature as it grows old. Even worse, if we aren’t taking care of standard Software Quality Assurance (SQA), our system is not only ageing, but infact it is rotting. A Software undesirably grows old for two major reasons – The product owners have failed to modify the software to meet changing needs. The changes are made that yield poor results. It is SQA that determines the way we can check and improve our software quality. SQA is a planned and systematic approach to evaluation of the quality and adherence to software product standards, processes, and procedures. It includes the process of assuring that standards and procedures are established and followed throughout the software acquisiti...

Recently whilst browsing through Geertjan’s blog, to keep myself abreast with the technological happenings of Netbeans; I stumbled upon an interesting write-up which discussed about a Java API for music, namely JFugue. Being inclined to music since my early days, the short write-up immediately caught-up my attention. I didn’t have enough time in hand to investigate it in detail; however, least I had a look at the API’s “programming” guide and was really astonished to find that now one can define musical scores, notes etc. and program an entire virtual orchestra to play and record the same in standard MIDI format. Following are some more musical Java APIs - JFugue Drum++ JMusic Now that’s definitely music to ears for all the programmers out there who have a musical predilection.

If you've been thinking of web services and feeling scared of that XML mess in the web service description (wsdl) files. Well, rest aside that scare now. And, by rest I mean, Re presentational S tate T ransfer (REST). Representational state transfer (REST) is a style of software architecture for distributed hypermedia systems such as the World Wide Web. And thus invariably it could be also implemented in the world of web services as another revolutionary way of communication with web services. In REST, resources have URIs and are manipulated simply through HTTP header operations. Therefore, now one can imagine having a web service without all that WSDL clutter. REST works around a very simple principle, i.e. HTTP methods POST, GET, PUT and DELETE can be compared with the CREATE, READ, UPDATE, DELETE (CRUD) operations associated with database technologies or any application model objects. The following table associates several common HTTP verbs with similar database operations, howe...

Lately, I've been playing around a bit with facial pattern recognition algorithms and their open source implementations. I came across many reference implementation but a very few were implemented in Java, and the Eigenfaces algorithm by far happens to be the best amongst them all. During my research around the said topic i happened to stumble-upon an implementation called FAINT (The Face Annotation Interface - http://faint.sourceforge.net). Faint by far the best facial pattern recognition API and as you must have already guessed, it implements the Eigenfaces algorithm. Now enough of theory talks, how about implementing an example with faint...? Here is one for all you face-recognition enthusiasts. The following example simply searches for faces in a given photograph and thumbnails them. Now, I know thats not face recognition; but be a little creative here. Once you have the facial thumbnails extracted, its never a big deal to look further in the Faint API and find methods which ca...