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How to make select in WinSock exceed the 64-socket limit
When doing cross-platform network programming, the only API available on Windows that corresponds to the epoll/kevent style reactor event model is select. However, it has a limitation: the number of sockets passed into select cannot exceed FD_SETSIZE, which is set to 64. Therefore, select in Java’s NIO on Windows also has the same limit. Many services ported to Windows that use the reactor model face this constraint, which often gives the impression that server programs on Windows hav...
Three ways to define class in JavaScript
In object oriented programming, class is the template of object, it defines the properties and methods of a group of objects. Unfortunately, JavaScript doesn't support class, but we can have some workarounds to simulate class.1. Constructor functionThis is the classical approach, it is also the approach mentioned in many text books. It uses the constructor function to simulate class and it uses the keyword this to represent the object internally.function Cat() {  this.name = "Kelly...
JavaScript,Class,Method,Private,Inheritance 2012-07-09 11:59:51
Interesting Hello World
Hello world is the beginning of everything. When you first learn a new programming language, the first program you write is to print the "Hello world" string on the console with that language. For example: So who invented "Hello world"? It's Brian Kernighan, a canadian computer scientist and author of The C Programming Language and The Unix Programming Environment. In his books, he used to write "Hello world" which changed the whole world. Also programmers like to use foo and bar as variable n...
Programming,History 2013-08-29 11:31:00
One thought about JavaScript exception handle
Due to network, browser and cache issues, the JS executed in production may produce different results from the testing environments. Sometimes they may produce exceptions. Front-end developers may encounter this kind of exceptions frequently. But how to log and use them is seldomly considered by them. Actually, exception handling includes two steps : log and use. 1. Log Regarding to log error, this is relatively convenient, since in each browser, there is one interface called window.onerror. win...
JaavScript,Log,Exception,Email 2013-03-18 12:50:21
Set Real-Time Clock Unit for OT/IoT Device
Configure DS1307 RTC on BeagleBone-Black Arduino or Raspberry-PI Figure-00: Project Overview Diagram , version v0.1.2 (2024) Program Design Purpose: Real-Time Clock (RTC) modules are essential for maintaining accurate timekeeping in various applications, including system clocks, data logging, and alarm systems. In scenarios where devices operate offline, such as a ship's NMEA 0183 data recorder that logs engine and rudder data, or an RTU (Remote Terminal Unit) with real time state change config...
The war with spam comment
Spam comments are annoying and notorious. They are either malicious data from hackers to exploit the loopholes of the site or advertisements posted by robots. These kinds of comments have their own features and patterns, if we are careful enough, we can find ways to block most of them although it's not so easy. To block the comment with malicious executable codes such as JavaScript, we should remember one rule : never trust user input. So wherever there are user inputs, we need to check the vali...
Spam comment,Block,Filter 2013-11-29 20:29:43
this in JavaScript
this is a keyword in JavaScript. It refers to an internal object created automatically when a function executes, it can only be used in a function. For example: function test(){     this.x = 1;   }The this keyword will change when a function is called in different situations. However, the general rule is : this refers to the object which calls the function.Next we discuss the use of this in 4 different situatio...
this,keyword,use,JavaScript 2012-05-05 12:47:37
What does session_destroy() do in PHP?
In PHP manual, the description for session_destroy() function is : session_destroy() destroys all of the data associated with the current session. It does not unset any of the global variables associated with the session, or unset the session cookie. To use the session variables again, session_start() has to be called. I am confused about this description. If this function destroys all session data, then why the global variables associated with the session are not unset? Why can we u...
session_destroy,session_start 2013-08-31 09:59:05
Three images to understand immutability of String in Java
String is immutable in Java. This means once a String object is created and instantiated, that object cannot be changed. Any operation on the String object will create a new Object instead of operating on the original content. Below are three images to help you understand String immutability in Java. Declare a String String s = "abcd"; s stores the reference to the string content created in the heap. Assign the String reference to another String variable String s2 = s; s2 stores the same ...
Apache Tomcat Installation and Configuration
When you want to install Apache Tomcat on Windows System. You may find that there are some tricky parts. Next I will elaborate the steps to install and configure Tomcat. If you want to install Tomcat as a service without GUI. You need to download the 32-bit Windows.zip from http://tomcat.apache.org/download-70.cgi. After downloading this zip file. You need to unzip this file to the directory which you want to put this software to. After unzipping, you can go to the bin directory and find t...
TOMCAT 7,WINDOWS,APACHE,INSTALL,CONFIGUR 2011-04-10 14:17:21
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