Sunday, August 12, 2012

To Internet and Beyond...and Back

Shopping for a laptop, filing for tax returns, paying your school fees, using a GPS….

Click, click, click…

Ever wondered where your click “goes”?

In the traditional sense, in an offline database system, your "click" comes in contact with application programs such as Windows folders to reach out for  data, retrieve it and present it back to you.

However, on the internet, when you go online shopping at your favourite online shop, you are in fact reaching out for the shop’s database. Your click, which is a user generated input, traverses a predefined path that comprises of hardware and software, towards the shop’s information system, which is the database. Of course the façade, that is the webpage browser, is aesthetically designed, and it completely conceals the underlying world of codes and computer systems.


(Idaho Department of Commerce)(InformedBuying.com)(Lamb)(Reynolds)


Starting from the Internet and working inwards towards the company’s information system, where the database resides, are optimally normalized tables, which enable easy browsing and easy retrieval of data.

In the DBMS is where the actual data resides, and data, that is the image of a dress on a mannequin, the size , color and the other details are stored  in an efficient way.  The good housekeeping ideology of  ‘A place for everything and everything in its place’ in databases enables us to have a smooth shopping experience, be it  updating the quantity of the pair of shoes, or editing the contents of the virtual shopping cart when we change our mind.

As internet browsers the only thing we come across is the website which has been enhanced with user experience, user interface and information architecture and marketing concepts however backstage there are layers of software, hardware, programming modules and normalized tables of database.

Internet or non-internet environment, the DBMS which handles volumes of data is an organized system that we never come across directly.

Just as the very concept of the medium for database evolved so did the concept of PC interaction with internet and DB evolve.

Since there are different types of mediums involved here software, hardware, different programming languages, different types of data,  a specialized software called middleware is implemented.

In order for the application software running in the Web server to connect with software outside the Web server, there must be agreed upon interfaces, and indeed there are. The original such interface is called the Common Gateway Interface (CGI). Later, another such interface with certain performance advantages was developed, known as the Application Program Interface (API). These interfaces have associated software "scripts" that let them exchange data between the application in the server and the databases controlled by the database server. The connection to the databases could be made directly at this point, but again, with the prospect of different database management systems and different kinds of data involved, it made sense to create another level of standards to smooth out the differences and have one standard way of accessing the data. The most common set of such standards is called Open Database Connectivity (ODBC), which is designed as an interface to relational databases. (Gillenson)

The ODBC connects to the database server which finally  connects to the database which is the hub of information.

Everyone talks about the internet and how living without it would be unimaginable. Internet has progressed from luxury to a necessity. But the internet wouldn’t be an enjoyable experience without an effective database management system.

 In the back alleys of the internet lies an optimally normalized database table and your “clicks” travels up to it and back.



Reference

Gillenson, Mark L. "7." Fundamentals of Database Management Systems. Hoboken, NJ: Wiley, 2005.                                   
        N.pag. Print.

"Internet Shopping -Is Your Credit Card Information Safe!" Internet Shopping.                      
      InformedBuying.com, n.d. Web. 13 Aug. 2012.
      <http://www.informedbuying.net/shopping/smart_shopping.htm>.
"Internet Marketing-Your Community's Gateway to the World." Internet Marketing: Idaho
      Department of Commerce. Idaho Department of Commerce, n.d. Web.
     <http://commerce.idaho.gov/communities/internet-marketing/>.
Lamb, Eric. "Setting Up A Linux Web Server." Made of Everything You're Not. Eric Lamb, n.d.      
    Web. <http://blog.ericlamb.net/2009/05/setting-up-a-linux-web-server/>.
Reynolds, Warren. "How You Can Avoid Closing Delays and Save Your Home Sale."02038.      
    Waren Reynolds, n.d. Web. <http://www.02038.com/wp-ontent/uploads/2009/06/middleman.jpg>.


Sunday, August 5, 2012

Distributed Database Housekeeping Rules

Christopher. J. Date is known for his prominent work with relational database theory  and for formulating  the 12  basic principles of distributed databases. Date like Edgar. F. Codd was involved with IBM and wrote extensively about relational databases .

It appears, inspired by his colleague's "Codd’s 12 commandments" of relational database management system (RDBMS), Date formulated twelve basic principles of distributed databases. Although no current Distributed Database Management System conforms to all of them, they serve as a reference line for optimized allocation of databases and to keep the extent of  double duplicity of databases in check.


C. J. Date's Twelve Commandments For Distributed Databases 

1.     Local site independence. Each local site can act as an independent, autonomous, 
       centralized DBMS. Each site is responsible for security, concurrency control,  
       backup, and recovery.  
2.    Central site independence, No site in the network relies on a central site or any  
       other site. 
3.     Failure independence The system is not affected by node failures. The system 
        is in continuous operation even in the case of a node failure or an expansion of   
        the network. 
4.     Location transparency. The user does not need to know the location of data in 
        order to retrieve those data. 
5.     Fragmentation transparency. Data fragmentation is transparent to the user, 
        who sees only one logical database. The user does not need to know the name of  
        the database fragments in order to retrieve them. 
6.     Replication transparency .The user sees only one logical database. The  
        DDBMS transparently selects the database fragment to access. To the user, the 
        DDBMS manages all fragments transparently. 
7.     Distributed query processing. A distributed query may be executed at several  
        different DP sites. Query optimization is performed transparently by the  
        DDBMS. 
8.     Distributed transaction processing. A transaction may update data at several  
        different sites, and the transaction is executed transparently. 
9.     Hardware independence. The system must run on any hardware platform. 
10.   operating system independence. The system must run on any operating system  
        platform. 
11.   Network independence. The system must run on any network platform. 
12.   Database independence. The system must support any vendor's database  
        product.
(C. J. Date's twelve commandments for distributed databases)

These requirements are not limited to RDBMS's but extent to  the multi-media friendly ODBMS as well.  The rules have become a measure for evaluating distributed databases and they enable the database modeller to make better modelling decisions. (C. J. Date Rules)


Reference

"C. J. Date Rules." Scribd. N.p., n.d. Web. 6 Aug. 2012.
    <http://www.scribd.com/doc/26882380/C-J-Date-Rules>.
"C. J. Date's twelve commandments for distributed databases ." C. J. Date's twelve
    commandments for distributed databases . N.p., n.d. Web. 6 Aug. 2012.
    <www.uobabylon.edu.iq/uobColeges/ad