There are three types of mobile applications: native app, hybrid app and web app. The applications with an icon on mobile phone screen are native app, which are programmed by language requested by a certain system. Applications on iOS system are constructed by Objective-C or Swift language. Although the native apps on phones use different language with that of websites, both use same protocols to communicate with servers, including HTTP, IP and TCP. In this article, I will deblackbox YouTube native application in iOS system.
Media function is the major function of YouTube app. People around the world, with the assistance of internet and phone, can watch or upload videos with this app. When a user wants to watch a specific video, the first step is to search it. The user can use keywords to search for this video by the search engine of YouTube. The search engine will match the keywords separately in different videos’ titles and return the videos at an order- from more matches to less matches. Other secret algorithm also decides this order, considering the popularities of a video and other elements that the users don’t know- the secrets for better search results. In this process, different servers are involved: YouTube server, its index servers and its video servers. After getting these results, the user can choose one to watch by “touching” the thumbnail image or the title of that video. When the user touches the top glass layer of a capacitive screen, the capacitance of that area increases so that the grids of wires and eletrodes can detect this change and translate this location to a certain request to servers. No matter the user touches the area of the image or the title, he will send a request to YouTube video server and it sends a signal to a computer acting as a multicast server, and then this server sends the video signal to the user by UDP. After watching this video, the user can log out the app or just close it.
The next time the user log in YouTube, he will find that the videos in recommendation pages are those related to what he watched these days. This is because the cookie stores the information every time the user searches and watches a video and use this information to recommend videos. The information in cookie can be shared by other applications and websites, which provides users with convenience because these applications can also use them to recommend the products or services users prefer. However, it also causes some security and privacy issue. The YouTube server itself also stores user information, including email address, password, payment method and some other personal information. In this way, the user can log in and make a purchase with convenience, although it also brings about privacy and security problems. In order to deal with these issue, Hypertext Transfer Protocol Secure (HTTPS) comes. In HTTPS, the communication protocol is encrypted using Transport Layer Security (TLS) or Secure Sockets Layer (SSL). The Apple company also has a range of APIs on its platforms to enable apps to employ secure network connections and to benefit from OS-level security policies.
Martin Irvine, Intro to the Web: Extensible Design Principles and “Appification”
Ron White, “How the World Wide Web Works.” From: How Computers Work. 9th ed. Que Publishing, 2007.
“What are the popular types and categories of apps,” https://thinkmobiles.com/blog/popular-types-of-apps/