• Email SMS Message in .NET

    sending SMS message using .NET SmtpClient and mobile carrier email-to-text service
    - posted on March 19, 2015 by Vsevolod Geraskin in tutorials about code4 .net6 smtp1 email2 sms1 c#1

    Our app needs to send notifications to customers' mobiles, but we don't have much time. Fortunately, each mobile carrier provides email-to-SMS service for clients having a data package. Thus, the easiest way to send an SMS message to a cell phone with a data plan would be to compose an email message and send it to the provided address. read more...


  • Bitmaps in Android ListView

    loading bitmaps to display pictures while maintaining smooth Android ListView performance
    - posted on October 24, 2014 by Vsevolod Geraskin in tutorials about android3 java4 code4

    A simple task such as displaying your gallery photos in a ListView component can lead to a significant loss of performance in your Android application, to the point where it would render the application unusable. Worse yet, the application might run out of memory and crash while loading bitmaps. Just think about user quickly scrolling through a list of hundreds of photos each the size of 3-10 megabytes. Thus, to display pictures in ListView is not straightforward and requires several performance considerations. read more...


  • .NET POST Request

    crafting .NET POST request using HTTPWebRequest object
    - posted on July 11, 2014 by Vsevolod Geraskin in tutorials about .net6 http6 code4

    Oftentimes, such as when hacking demos, we want our client side app talking to some form backend without spending too much time on it. One way to do it in a Microsoft environment is to do a quick POST request using `HTTPWebRequest` object. `HTTPWebRequest` does exactly what the name suggests and saves us a lot of time from having to write our own HTTP calls. read more...


  • MIME Email with Attachment

    creating MIME messages with attachment using Linux Shell
    - posted on May 25, 2014 by Vsevolod Geraskin in tutorials about linux3 shell2 email2

    Sometimes, we may want to have our own MIMEs (as in Mail Extensions messages, although bossing around an entourage of stripy shirt artists may be fun) for use with such programs as sendmail. While creating a simple text email using MIME is simple, adding attachments requires a bit of work and can be tricky. Thankfully, Linux Bash Shell gives us the right tools to get the job done. read more...


  • OpenSSL and select()

    reading OpenSSL records correctly within C select() statement
    - posted on February 21, 2014 by Vsevolod Geraskin in tutorials about c5 tls/ssl6 security7 openssl2 select1 code4

    In recent years, many event-driven server-side technologies, such as Node.js javascript library and lighttpd web server, enabled programmers to easily build applications which scale much better than traditional span new process or thread for each new connection servers, such as Apache. Both node.js javascript engine and lighttpd are written in C/C++ language using I/O multiplexors which have been in existence for many years. One of such multiplexors is C `select()` statement which has been around forever. Securing software communication channels is one of the major issues in today's world, and, in this tutorial, we will examine how to read OpenSSL records using `select()` multiplexor, should we decide to create our own secure event-driven library or the hot new web server from ground up. read more...


  • Simple Two Factor Authentication Scheme

    implementing multi-factor server-side authentication the easy way
    - posted on January 14, 2014 by Vsevolod Geraskin in tutorials about tls/ssl6 security7 openssl2 http6 oauth2 shell2

    In a perfect world, we would not need any authentication. In a real world, we often feel protected enough by our `Password1` universal password. Maintaining sufficient security is often a major pain for internet organizations, as security and usability are almost always in either or relationship. read more...