Listing Up HTTP Header Fields

Posted on February 7, 2011 by Chris Allo

Whenever I write the code for HTTP request, I feel dumbed that I don’t memorize the header fields. So it would be nice to list up the fields with description in some place like blog. Some useful header fields are here. (More headers are in Wikipedia)

Header Fields for HTTP Request

Field Name Field Description Example
Accept Content-Types that are acceptable. text/plain
Accept-Charset Character sets that are acceptable. utf-8
Accept-Encoding Acceptable encodings. gzip
Accept-Language Acceptable languages for response. en-US
Cache-Control Used to specify directives that MUST be obeyed by all caching mechanisms along the request/response chain. no-cache
Content-Type The mime type of the body of the request. application/x-www-form-urlencoded
User-Agent The user agent string of the user agent. Mozilla/5.0 (Linux; X11)
Posted in DEVELOPMENT | Tagged | Leave a comment

Uncertainty

Posted on December 30, 2010 by Chris Allo

Why do people do their business? It is a trivial question for most entrepreneurs. And how about uncertainty? That is, I can convert the question into “Are you sure that your business is cool enough?”

[ Dice gives us fun because it shows uncertainty. But dicey. ]

Success in business requires the satisfaction in myriads of views. But few thinks about the uncertainty, which motivates and accelerates the one. If you are not sure that the business works, you cannot affirm the employees to go on the way. And that would stuck in there. Never go further.

However, that kind of conviction is differ from the recklessness. I hope to share my opinion on how to distinguish the actual conviction from the brute courage. Please checkout the points below and reponse me for correction if needed.

  • It should be sustainable. If it temporarily survives, it’s going with the temporary feeling. Intuition is quite different with the feeling that intuition is sustainable. Sustainability involves the financial
  • It should be programmable. Without the programmability, the belief is just a pipe dream. It is the most difficult to figure out before kicking off the business so it needs the help from experts.
  • It should require more opinions. The idea need to be shared so that you could know how other people are thinking about the issue. Maybe more possible options are not weighed just because you thought it alone.
  • It should be scalable. The need in market can change. The scalability makes more flexible when the market changes. For example, people designing TV business like Google-TV should consider the usability of any other devices as well in case the future technology evolves and expands into other platforms.

Well.. lots of more things to consider. But here I suggested is the core values for business I think. And they are what I consider whenever thinking about new business. You’d rather trust your business with those equipped.

Posted in BUSINESS | Tagged | Leave a comment

The Introduction of RDMS Optimization

Posted on December 16, 2010 by Chris Allo

Almost all online services are using database. However, not-optimized database scheme causes disaster. The service would be slow down and sometimes get down with data requests overflown. Here I give a brief guideline on how to optimize database scheme.

Most database management system enacted on RDBMS(Relational Database Management System) base. The keyword is “Relational.” The way how to make relations mostly determines the whole performance.

There are 3 types of relation – 1:1, 1:n and n:m. Let’s take a look for each.

One-to-One(1:1) relation
Although it is rarely used as all 1:1 relations can be expressed as one composite dataset, understanding the concept would help to see the connections more clear. A student and his student ID match is an example. One student has one ID and one ID is possessed by one student.

One-to-Many(1:n) relation
It is the most common relation that most hierarchical structure can be represented with it. For example, suppose that 16 full-time employees are working in a company. Then the company has 16 employees, and each employee belong to one company.

Many-to-Many(n:m) relation
This relation is the most complicated structure among relations so it requires the performance overhead. It traverses N*M times to search for data while One-to-Many relation does it N times. One of good examples is the relation between class and student. Students take many classes and each class has many students.

The key is that, avoid Many-to-Many relation to maximize performance. If it is inevitable, count the number of data records and control it with discussion. The performance is not to be ignored in web service.

Posted in DEVELOPMENT | Tagged , | Leave a comment