A Logo is a graphical element that, together with its logotype (a uniquely set and arranged typeface) form a trademark or commercial brand. Typically, a logo’s design is for immediate recognition. The logo is one aspect of a company’s commercial brand, or economic or academic entity, and its shapes, colors, fonts, and images usually are different from others in a similar market. Logos are also used to identify organizations and other non-commercial entities.
These types of corporate identities are often developed by large firms who specialize in this type of work. However, if you want to save some bucks and want to design your logo then there are many sources to get logo design inspiration. Infect, we might able to help you by presenting this showcase of Highly beautiful, original and creative logo designs for your design inspiration. Read more…
Recently, we encountered an incident in a production system where empty strings (”) are passed in as arguments to a SQL statement.
The statement is expecting a valid user id or IC number.
Please note that Oracle will treat empty strings as null values and null values cannot be compared using = or <>.
The statement is also performing an outer join between two tables, and has a WHERE condition on a column in the outer (optional) table.
In such a case, the outer table’s column needs to be checked for nullability as well, which the statement did not.
The incident caused was that Oracle generated and cached a lousy query plan which performs full table scans on the tables and causes the database instance to slow down as the statement was called by multiple clients at the same time.
We have updated the SQL Coding Guidelines to highlight these aspects in detail.
Hibernate, a power ORM tool. From an object-oriented perspective, persistence actually can be considered an extension of an object’s lifecycle. a minor part of the software, as compared with the whole domain. Thus, a programmer who relies on a DBMS should not focus mainly on persistence, because DBMSs are complex entities with their own constraints, rules and protocols that the programmer needs to follow. In order to follow DBMS constraints, rules and protocols, programmers, even object-oriented programmers are tempted to put their main focus on the database technology and persistence and start performing data processing. Read more…
Something about the topic Friends wanted.
A good idea right? This idea came from one of my best friends. And she said since you have this blog, why do not do something useful for us? Read more…
Q: Explain the life cycle methods of a Servlet.
A: The javax.servlet.Servlet interface defines the tree methods known as life-cycle method.
public void init(ServletConfig config) throws ServletException
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException
public void destroy()
First the servlet is constructed, then initialized with the init()method.
Any request from client are handled initially by the service() method before delegating to the doXxx() methods in the case of HttpServlet.
The servlet is removed from service, destroyed with the destroy() method, then garbaged collected and finalized.
HashTable is widely used, HashMap is the class used to take the place of HashMap in the new framework, this means sun suggests to use HashMap instead of HashTable. Maybe you think HashTable works well, why not?
I’d like to talk something about the difference between HashTable and HashMap.
Read more…
OpenDNS offers quicker and more reliable Web browsing, but when you sign up for a free OpenDNS account, you can also get other features such as content/domain blocking and access to your DNS usage statistics. With then OpenDNS Domain Tagging tools, OpenDNS issued the following lists of the most-often blocked domains by parents, schools, and small businesses.
Read more…
Some programs benefit from having a language to describe
operations they can perform. The Interpreter pattern generally describes
defining a grammar for that language and using that grammar to interpret
statements in that language.
Motivation
When a program presents a number of different, but somewhat
similar cases it can deal with, it can be advantageous to use a simple language
to describe these cases and then have the program interpret that language.
Such cases can be as simple as the sort of Macro language recording facilities
a number of office suite programs provide, or as complex as Visual Basic for
Applications (VBA). VBA is not only included in Microsoft Office products,
but can be embedded in any number of third party products quite simply.
One of the problems we must deal with is how to recognize when a
language can be helpful. The Macro language recorder simply records menu
and keystroke operations for later playback and just barely qualifies as a
language; it may not actually have a written form or grammar. Languages
such as VBA, on the other hand, are quite complex, but are far beyond the
capabilities of the individual application developer. Further, embedding
commercial languages such as VBA, Java or SmallTalk usually require
substantial licensing fees, which make them less attractive to all but the
largest developers.
Read more…
The Chain of Responsibility forwards requests along a chain of
classes, but the Command pattern forwards a request only to a specific
module. It encloses a request for a specific action inside an object and gives it
a known public interface. It lets you give the client the ability to make
requests without knowing anything about the actual action that will be
performed, and allows you to change that action without affecting the client
program in any way.
Motivation
When you build a Java user interface, you provide menu items,
buttons, and checkboxes and so forth to allow the user to tell the program
what to do. When a user selects one of these controls, the program receives an
ActionEvent, which it must trap by subclassing, the actionPerformed event.
Let’s suppose we build a very simple program that allows you to select the
menu items File | Open and File | Exit, and click on a button marked Red
which turns the background of the window red. This program is shown
below.
Read more…
The Chain of Responsibility pattern allows a number of classes to
attempt to handle a request, without any of them knowing about the
capabilities of the other classes. It provides a loose coupling between these
classes; the only common link is the request that is passed between them. The
request is passed along until one of the classes can handle it.
One example of such a chain pattern is a Help system, where every
screen region of an application invites you to seek help, but in which there are
window background areas where more generic help is the only suitable result.
When you select an area for help, that visual control forwards its ID or name
to the chain. Suppose you selected the “New” button. If the first module can
handle the New button, it displays the help message. If not, it forwards the
request to the next module. Eventually, the message is forwarded to an “All
buttons” class that can display a general message about how buttons work. If
there is no general button help, the message is forwarded to the general help
module that tells you how the system works in general. If that doesn’t exist,
the message is lost and no information is displayed. This is illustrated below.
Read more…
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