Network Protocol Design: The E-PostOffice

Outline of Problem The postal mail service allows customers to send items of physical mail (letters, postcards, parcels etc.) to a destination address (house, office, etc.). The basic operation involves the following steps: • The customer prepares the mail for posting. Each mail must have: o A destination address clearly visible o A stamp indicating payment and class (in UK, 1st or 2nd Class) • The customer deposits the mail in a post box • A postal service employee collects the contents of the post box on a regular basis and takes them to a sorting office • Sorting office employees group the mail according to destination and class o Mail without a stamp, or the wrong amount, are marked as ‘to pay’ • Each group of mail is transported to the sorting office local to the destination via the appropriate transport network (road, train, plane…). o In the case where the destination is within the same local area then the ‘transport’ is within the same office. • Sorting office employees at the destination sorting office sort the mail further into more fine-grained local groups (neighbourhoods, streets…) • ‘Postmen’ take the groups of mail and visit each destination to deliver mail at the physical address indicated on the outside of the mail. Note that the postal addresses in the UK are given a postal code consisting of an area code and a local code. The postcode for Byrom St is ‘L3 3AF’, which tells us that the building is in the Liverpool #3 postal district. Liverpool has about 25 postal districts. One postal district has exactly one associated sorting office, but each sorting office covers several districts. Detail of Questions In this coursework we consider an electronic version of the post mail service, where customers could send documents (letters, postcards, etc.) to a physical destination address (house, office, etc.) via the Internet. Unlike the regular post mail service, in this E-PostOffice service, the customers will submit electronic documents rather than physical documents. Before the document can be delivered to the physical destination address, it will be printed by the postal service, i.e. converted to piece of physical mail. Your task for this coursework is to design an application layer protocol that will support the E-PostOffice service operations starting from the interaction with the customer and the acceptance of his electronic item until the item reaches the printing stage where the item is converted into a physical mail. Your application protocol will work within a client-server architecture. The user has a client process to interact with the postal system while the server side handles the delivery of the mail (note – the delivery of the physical mail is outside of the client-server system, and therefore not your concern). You are required to define the different messages and associated processing that can be exchanged between the client and various server processes to achieve the functionality. see the file attached