SEARCH KEYWORD -- file transfer


  How does PHP session work?

This article is about how PHP session works internally. Below are the steps : 1. Session in PHP is loaded into PHP core as an extension, we can understand it as an extension. When session extension is loaded, PHP will call core functions to get the session save_handler, i.e interface or functions for reading and writing session data. By default, PHP will handle session data by writing and reading files on the server. But PHP also supplies custom methods for handling session data, we can use sess...

   PHP, session, mechanism     2012-12-28 13:36:49

  How long does the heuristic cache of the browser actually cache?

Heuristic cache Heuristic caching is the default behavior of browser caching (i.e., for responses without Cache-Control), which is not simply "not caching", but implicitly caching based on the so-called "heuristic cache". HTTP is designed to cache as much as possible, so even if Cache-Control is not specified, the response will be stored and reused if certain conditions are met. This is called heuristic caching. HTTP/1.1 200 OK Content-Type: text/html Content-Length: 1024 Date: Tue, 22 Feb 2022 ...

   HEURISTIC CACHE,WEB DESIGN     2023-05-26 08:40:13

  Why accessing Java HashMap may cause infinite loop in concurrent environment

HashMap in Java is frequently used to handle key/value pairs. But it is not a good candidate to be used in concurrent environment where ConcurrentHashMap should be used instead. If used in concurrent environment, it may cause lots of unexpected behavior even including make the program getting into an infinite loop situation. To understand how this can happen, let's first discuss how HaspMap works internally. In this post we will use implementation of HashMap before Java 8 as example, Java 8 prov...

   JAVA,HASHMAP,INFINITE LOOP     2020-03-29 01:47:00

  How does Base64 work

Base64 is a data encoding scheme used in safe data transfer such as HTTP and its extensions. Base64 encoding can conver arbitrary group of bytes into a sequence of readable ASCII characters. These converted characters can safely put in a HTTP header without causing any problem while the peers process the HTTP header. Base64 encoding was invented as part of the MIME content transfer encoding. It is similar to other encoding schemes such as Uuencode and BinHex but with higher efficiency....

   ALGORITHM,BASE64     2016-03-09 23:47:40

  JSON in JavaScript

When sending an AJAX request to the server, the response can have two formats : XMLHttpRequest.responseXML to access data with XML format and XMLHttpRequest.responseText to access data with string format. XML is the standard data transfer format, but one weakness is it's troublesome to parse and retrieve the data. JSON(JavaScript Object Notation) is a light weight data interchange format, we call it the JavaScript object representation. The advantage of using JSON as the data format is itself is...

   JSON,JavaScript     2013-05-04 23:25:57

  How Kafka achieves high throughput low latency

Kafka is a message streaming system with high throughput and low latency. It is widely adopted in lots of big companies. A well configured Kafka cluster can achieve super high throughput with millions of concurrent writes. How Kafka can achieve this? This post will try to explain some technologies used by Kafka. Page cache + Disk sequential write Every time when Kafka receives a record, it will write it to disk file eventually. But if it writes to disk every time it receives a record, it would ...

   BIG DATA,KAFKA     2019-03-08 09:42:57

  About JavaScript source map

Last week jQuery 1.9 was released. This is the last release before jQuery 2.0. It adds many new functions, one of them is the source map. By accessing http://ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js , you can scroll to the last line and you will see below line : 　//@ sourceMappingURL=jquery.min.map This is source map, it is a separate file and it is put at the same directory as the source file. You can click here and see what it looks like. It's an very useful functio...

   Source map, JavaScript, jQuery     2013-02-01 07:06:44

  Generate certificate from cert file in Java

A certificate is often used to prove the identity of a server. The certificate will contain information such as the subject and issuer of the certificate. It will also contain the validation date of the certificate. A certificate is often exported to an external cert file which is transferred over the internet. We will often see its use in SSL communication which provides secure communication between two entities. In this post, we will show how to read the data from an external certificate file ...

   PKCS12,CertificateFactory,Example,Java,X509     2015-06-08 06:47:05

  Run JavaScript in GoLang

In some cases, there might be some JavaScript code needs to be ran in a GoLang project. Fortunately, there are a few libraries which support running JavaScript in GoLang. The most famous one would be v8. This is a Go API for the famous v8 JavaScript engine originally developed for the Chrominum project and the foundation of NodeJS. In this post, we will show some simple steps to get v8 working in a GoLang program on MacOS. First you need to install the package so that you can import it. Run...

   GOLANG,JAVASCRIPT,V8     2019-05-16 07:40:38

  10 modern technologies we will still use in 2030

Although there is rapid revolution for new technology, some technologies can survive with the passage of time. Here are 10 modern technologies which may continue to exist in 2030. 1. QWERTY keyboard Speech recognition, handwriting recognition and gesture control input will become the trend for the next two decades. Nonetheless QWERTY keyboard input is still one of the most accurate way - although not necessarily the most convenient. Although physical keyboard disappear on phones and tablet PCs, ...

   New technology,Trend     2012-11-12 11:02:02

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