Data communications in week to delved deeper into the Application Layer. Looking specifically at HTTP and SMTP and Application architectures.

The Application Layer can be further segmented into User Interface, Business Logic, Data Access and Data Storage. Clients and servers where defined and three basic architectures:

  • Host base architectures (server heavy)
  • Client-based architectures (client heavy)
  • Client-server architectures (shared)

Client Server architectures are the latest in the application architecture evolution and has give rise to the need for some middleware softwares. Middleware acts as a translator between different varieties of software. Some examples include:

  • Distributed Computing Environment (DCE)
  • Common Object Request Broker Architecture (CORBA)
  • Open Database Connectivity (ODBC)

The client server architecture is still evolving and segmentation of the application layer onto multiple tiers is now being enable by faster connection speeds. This allows for better load balancing and greater extendibility/scalability of services.

Wireshark open source network protocol analyzer

HTTP and SMTP were then covered in some detail, the key points are summarized in the diagrams below:

HTTP Request
Webmail + SMTP

 

The tutorial saw us utilizing Wireshark, an open source network protocol analyser. This was a very apt practical exercise as it enabled us to find and identify each of the 5 layers (Application layer -> Transport layer -> Network layer -> Data Link layer -> Physical Layer).