Server-send events polling vs. WebSockets vs. Server-sent Events

Here is a very detail article about Server-send events.

there are code examples and awesome descriptions on the mechanism and logics behind server-send event polling.

https://www.html5rocks.com/en/tutorials/eventsource/basics/

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Creating a file-based SWAP on your Beagleboard

On the Beagleboard you should expect to require a swap file given the limitation of how little RAM is available (between 256 MB and 512 MB). Some system programs like apt-get will only run properly when some swap space is present (due to 256 MB not being enough RAM). Some images (such as those from Linaro.org) do not come with a swap partition or any swap space allocated. Under Linux, swap space can be either a dedicated partition or a swap file. Both can be mounted as swap which the OS can access. Creating a Swapfile The following commands will create a 512MB file, limit access only to root, format it as swap and then make it available to the OS: sudo mkdir -p /var/cache/swap/ sudo dd if=/dev/zero of=/var/cache/swap/swapfile bs=1M count=512 sudo chmod 0600 /var/cache/swap/swapfile sudo mkswap /var/cache/swap/swapfile sudo swapon /var/cache/swap/swapfile To tell the OS to load this swapfile on each start up, edit the /etc/fstab file to include the ...

hreflang? what is it? where does it come from?

Hreflang tags are a technical solution for sites that have similar content in multiple languages. The owner of a multilingual site wants search engines to send people to the content in their own language. Say a user is Dutch and the page that ranks is English, but there’s also a Dutch version. You would want Google to show the Dutch page in the search results for that Dutch user. This is the kind of problem hreflang was designed to solve. And for the Webmasters who serve several versions of their content in different languages or for users in different countries should use hreflang annotations to help Google show the right version in the search results for each user. In this article, " How to implement hreflang tags... ", the author has lay out the steps from begin to finish on the right ways of implementing hreflang tags for your multilingual and multinational web sites. In another article, " hreflang: the ultimate guide ", the author has outlined the...

Tcpdump Tutorial With Examples

Tcpdump is a common packet analyzer that runs under the command line. It allows the user to display TCP/IP and other packets being transmitted or received over a network to which the computer is attached.[3] Distributed under the BSD license,[4] tcpdump is free software. Tcpdump works on most Unix-like operating systems: Linux, Solaris, FreeBSD, DragonFly BSD, NetBSD, OpenBSD, OpenWrt, macOS, HP-UX 11i, and AIX. In those systems, tcpdump uses the libpcap library to capture packets. The port of tcpdump for Windows is called WinDump; it uses WinPcap, the Windows port of libpcap. I've read through a lot of how-to articles in the past. and this article "TCPDUMP Tutorial with Examples" is the most thorough, most intuitive articles that I've read.

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