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  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

  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

  Python FTP Server and Client

Distributed Log File Automated Archive System This week, we will introduce the automated compute cluster nodes' log automated archive system project and FTP Communication utility library module. Program Design Purpose: This project aims to create an FTP server & client lib program for file transfer and a files management system for log data synchronization. We will develop an automated log file archive system that regularly collects newly generated log files from multiple nodes in a compute...

       2024-09-29 04:07:50

  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

  bash network interface

Some of us may have seen /dev/tcp/<host>/<port> before, is this a special file system implemented in some BSD kernel? Because there is no /dev/tcp in Linux. Actually, this one is implemented in bash. We no need to rely on wget,nc to do network connection. It's very easy to use this interface: bash-4.2$ cat </dev/tcp/time.nist.gov/13 56188 12-09-18 15:34:26 50 0 0 733.5 UTC(NIST) * bash-4.2$ exec 3<>/dev/tcp/www.w3.org/80 bash-4.2$ echo -e "GET / HTTP/1.0\n\n" >&3 b...

   Bash,Network interface,/dev/tcp     2013-07-20 00:57:52

  Convert time to Unix time

Unix time is defined as the number of seconds that have elapsed since midnight Coordinated Universal Time (UTC), 1 January 1970,not counting leap seconds. It is used widely in Unix-like and many other operating systems and file formats. It is neither a linear representation of time nor a true representation of UTC. Unix time may be checked on some Unix systems by typing date +%s on the command line. Sometimes it's a bit difficult to compare times stored in different applications or systems with ...

   UNIX time, Oracle DATE, conversion, timestamp     2013-01-19 09:04:17

  What can .htaccess file do?

A .htaccess file is a directory-level configuration file supported by several web servers, that allows for decentralized management of web server configuration. What can a .htaccess file do? We summarized some of them here.  Hope it may help you. 1. Timezone settingSometimes when you use date() or mktime() functions in PHP, , it may display some weird information because of the timezone difference. For example, one possible warning is :Warning: date(): It is not safe to rely on the syste...

   .htaccess,setting,tip     2012-06-15 06:39:39

  Common usage of ls command in Linux

In Linux, ls might be one of the most frequently used commands. It is used to list files in a specific directory. In most cases, we may just use ls -l to list the files under a directory. But have you explored other usages of this command. In this post, we will summarise some other common usages of ls command Assuming we have below directory structure in our system, let's see them using tree command. List details of the files If we want to list the details of the files in /home/alvin/test_...

   LINUX,SHELL,LS     2018-12-16 03:00:42

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