However, it must be noted that there is no one type of architecture that may be considered the correct choice. Such choice relies on the consideration of several factors as well as on weighing such factors. Network architecture selection, according to Palley, should take into consideration the following factors:
Frequency of use of global data entails considering whether the use or sharing of data is localized. Basically, if data is to be shared by elements on a wider geographical area, much consideration must be given to the choice of architecture (i.e. ring/hierarchical). However, if the use of data is primarily localized, then such factor should not be much of an issue. Secondly, if global data is dynamic or heavily updated, considerations need to be made since the redundancy of data may lead to combinatorial update problems and data integrity problems. However, if data is static, redundancy of data would not be a problem; and "replicated" global data would be appropriate. Also, one needs to consider whether quick responses are needed when exchange of data occurs. In cases when response times are significant, the discussion of network efficiency becomes vital to the development and planning of the network. Undoubtedly, the size of the network should also be considered together with the other factors cited. Also, the budget given for the planning of the network is likewise vital since certain types of network architectures are more expensive than others. Lastly, one must anticipate future changes to the network as there are updates that need to be made every so often.
The case of Blue Skies Inc. is to be discussed in this paper. Blue Skies Inc. is an organization that is currently considering expanding its services throughout the United States. Based in Des Moines, the company plans to open at least two reservation counters in every U.S. city with a population over 800,000, and create a Web site where customers can make reservations online. In such an environment, Blue Skies expects that they will handle 200,000 transactions on a daily basis. As such, the company requires the setting up of a network that can efficiently handle the aforementioned volume of transactions. Specifically, the appropriate choice of network architecture that will meet the needs of the organization must be determined. The choice of network architecture entails choosing either a terminal services or a mainframe based network.
Before selecting the appropriate network architecture, the distinction between the two options must first be identified. Also, the known advantages of each of the two types of architectures must likewise be stated.
According to Software Diversified Services (SDS), "Mainframes used to be defined by their size, and they can still fill a room, cost millions, and support thousands of users. But now a mainframe can also run on a laptop and support two users. So today's mainframes are best defined by their operating systems: Unix and Linux, and IBM's z/OS, OS/390, MVS, VM, and VSE." Also, John Campbell identifies three features that a mainframe based