This week, things were a tad bit different from the previous days. The expressive internet architecture, or XIA, for short, is not trying to change the narrow based hourglass model, but instead is trying to make it evolvable. This is  a huge difference compared to other project funded by the Nation Science Fund. In today’s internet, everything revolves around IP. For example, if the client requests something online, the client has to retrieve the information from a server somewhere using packets that hold the client’s IP address as well as the servers IP address. On top of having all these IP’s, the client also receives specific information about the server from which it received its contents. XIA is basically trying to change this. XIA states that the client doesn’t need to know anything about the server. It just needs to know how to get the information in a timely and precise manner. In order to do this, they have to change how the client and server communicate. Instead of using IP’s to figure out the source and destinations, XIA wants to use ID’s. Instead of having to go directly to a server to retrieve content, they want to go directly to the source of the content and retrieve it using the client and content ID instead of using today’s model of client and server IP’s; however using this model raised serious security issues because there was no way to find out if the content was secure. To attack this problem, XIA decided to use hashes. By using content hashes,  the content can be easily checked to see if it’s malicious by comparing the hash to the ID. The hash can be a function which receives the content as a parameter and returns a unique string of numbers, which is then used to compare to the ID. If the string matches the id, then the content is secure. An example of a hash function can be MD5, which is the most popular hash function designed by Ron Rivest. After finding a solution to this issue, another problem arose: what if the router does’t know where the content is, or maybe what if it doesn’t know show to reach it? The solution to this problem is fallbacks. If your trying to reach a CID(content ID), SID(service ID), HID(Host ID), or even UID(User ID) and using the original primary path isn’t an option, then it will simply “fallback” and use different hosts to reach the original destination. The theory and concept behind this seemed so interesting that I had to check out the source code, but it was so complicated that it made me realize something: If the code is really that complicated and the project is still under research, then that means that the code is just going to get more complex, isn’t it? The fact that the internet is so large, and yet people are trying to change the way it works, to me, is just so amazing!