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What does this mean " Processes running on the application layer use sockets as an interface to take services from the transport layer to establish communication."?

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#1

This course is beautifully written. I couldn’t understand this one line though

#2

Hi Amit_L_Wadhwani!

It’s my pleasure to help you with this question. Let me build the context behind this line to make things clearer.
“Processes running on the application layer use sockets as an interface to take services from the transport layer to establish communication.”
You can notice that I have bolded and italicized some words in the above sentence. let me first explain what these words are and then we will come back to the whole sentence.
The bolded words represent different layers of the network models that you might have learn about in the “The Narrow Waist of the Internet” lesson. In this context, we know that:

  • The application layer is the highest layer of the OSI (Open Systems Interconnection) model or the TCP/IP (Transmission Control Protocol/Internet Protocol) model. It provides network services for applications or processes running on different devices.
  • The transport layer is the second highest layer of the TCP/IP, which is responsible for managing the actual transmission of data (of course, using services provided by other layers of the network stack).
  • The italicized word indicates the role played by the network socket.
    To summarize our discussion, what this sentence means is that the process or application at the application layer relies on the network socket to interact with the underlying layers (especially the transport layer) through the API calls provided by the socket interface, such as bind(), connect(), accept(), send(), etc., to send and receive data over a network.

Hope this makes sense now, if you have any other questions please feel free to ask. I would be more than happy to help.
Thanks!

#3

Thank you Hunain_Tahir for breaking it down for me. I got it now. Appreciate the thoughtful, comprehensive breakdown reasponse!

Course: Grokking the API Design Interview - Learn Interactively
Lesson: Hypertext Transfer Protocol (HTTP) - Grokking the API Design Interview