Application Layer and Applications - The Interface between the Networks - Literature review Example

Application Layer and Applications - The Interface between the Networks al Affiliation Application Layer and Applications -The Interface between the Networks The Open Systems Interconnection reference model (OSI) was created as a guideline for the network protocol design that has several layers and an abstract representation. The networking process in the OSI model is divided into 7 logical layers, all of which have different functionalities and are assigned specific services and protocols (Lammle, 2011). The layer under discussion in this paper is the application layer and applications. The application layer is the layer that provides the interface existing between the applications used in communication and the underlying network where messages are transmitted. This layer in the OSI model serves as the first step of ensuring that data is on the network. It ensures that a user can access the services that are provided by the other layers, and defines the protocols that applications use to exchange data. In this layer, there are many protocols that are already in existence and others are under development. The widely known TCP/IP Application layer ISO OSI protocols are comprised of those that enable the exchange of information. They define the format and control the information required, for instance, for common Internet communication uses (Karris, 2009). These protocols include the Domain Name Service Protocols (DNS), Hypertext Transfer Protocol (HTTP), Simple Mail Transfer Protocol (SMTP), Telnet, a terminal emulation protocol and File Transfer Protocol (FTP). The requests for comments define the above protocols. The functions done by the application layer protocols allow the underlying data network to interface with the human network. For example, when a person opens a web browser such as Mozilla, an application is automatically initiated and the program is placed in the device memory where the function is executed. Therefore, each executing program that is put in a device is a process. Here, only two forms of software processes that offer network access exist (Lammle, 2011). When referring to applications, they are software programs that people use in communication over the network. Some of these applications are aware of the network, which means that they execute the protocols of the layer under discussion and initiate communication with the lower layers in a direct manner. An example of these applications is the web browser. The application layer is useful in helping other programs to use network resources, such as transfer of files. Services, such as the transfer of files, are clear to the user but also interface with the network to enable the data to be transferred. There are different types of data that must be transferred. Despite this fact, these kinds of data all require different network services to prepare them for processing that happens at the lower levels of the OSI model. The applications or network services required here use protocols that outline the data formats and the standards that must be used in this process. The protocols are important because they help in ensuring that the data network has a single way to format and direct all the different kinds of data that are used and transferred. This fact makes it important to understand the function of the various network services that come into play but first, the protocols that dictate their operations have to be well understood (Karris, 2009). Just like other layers in the OSI model, the application layer requires the uses of the other layers below it to ensure that the communication process starts and ends successfully. Here, protocols also play a significant role in selecting the messages that are exchanged between the source and destination hosts, the type and format of the data, the methods used in error identification and recovery and also in making the syntax commands (Dye, McDonald, & Rufi, 2011). It is important to point out that the source and destination devices use the application protocols when the communication function is ongoing. This means that the application layer protocols must match during the communication function. This will ensure that rules applied in data exchange between services and applications must be consistent thereby ensuring that the communication process occurs successfully. The types of the messages and the structuring of those messages are done by the application layer protocols (Dye, McDonald, & Rufi, 2011). The messages vary in different ways ranging from data messages, error messages to request for services among other types of messages that are all determined by the application layer protocols. It is important that the message sent from the source to the destination receive the desired or expected feedback from the destination and that the required service is initiated when the data has been successfully transferred. The application layer protocols ensure that this happens by defining the message dialogues in specific data transfer processes. Therefore, the application layer services must ensure that there are multiple protocols working to ensure that all the above functions work in a communication experience for it to be successful (Karris, 2009). The application layer is layer 7, the top layer in the OSI and TCP/IP models. It provides the interface between the applications that a user requires in communication and the network through which messages are transmitted. Human beings create the communication then the software and hardware in place convert the communication from an abstract aspect to a digital format. From this, the services provided by the application layer initiate the transfer of data from humans to devices (client to server) and vice versa. In certain cases, one may want to access information put in a device connected to a network yet the information is not there physically. In this case, a user can use three ways to access the information. The three means include applications and application layer services and protocols, client/ server model and peer-to-peer networking (Dye, McDonald, & Rufi, 2011). In the client/ server model, the client is the person requesting for information while the device is the server. Here, the user requests the data from the device that responds by sending the data to the client. The application layer is important here because it describes the format with which the request from the client is taken and the one by which the server makes the response. The terms upload and download work in client/ server model as upload refers to the transfer from a client to the server whereas download refers to the data transfer from the server to the client. The application layer services and protocols represent a process where one application employs different application layer services that require multiple processes to be executed. Here, the servers control many clients that request for information all at the same time. This means that all requests must be handled uniquely so that the network can work without errors meaning that lower-layer functions must be included in the process. The peer-to-peer (P2P) networking and applications has two forms that include design and applications. Here, devices are connected together using a specific network thereby enabling the two devices to share data and files. Dedicated servers are not needed in P2P networks because one device could function as the server for the transaction of data while at the same time function as a client server. The roles played in P2P function are done on request basis (Dye, McDonald & Rufi, 2011). Despite the fact that there are different network applications, software is at the centre of them all, for instance, in host computers. For example, when operating the Web, there are two types software namely the Web server software and the browser software in the user’s device that are used in the process and communicate together. In understanding the operating systems, it is important to note that processes classified, as truth-processes are those that communicate rather than software pieces. A process refers to the program that runs within an end system. Therefore, when communication processes are in one end system, they communicate through inter-process communication dictated by the operating system in the end system. An application will involve two hosts that communicate over the same network (Karris, 2009). A network application has several pairs of processes that communicate messages to and from each other over the network. For instance, in the Web application a client browser process will communicate messages with a Web server process. Therefore, for the communication process to be successful, the sending process must identify the receiving process that requires the specification of the two pieces of information required including the host address of the machine and the identifier that points to the receiving process on the destination host. In Internet applications, for instance, the host address is specified by the IP address meaning that the IP addresses must be carefully managed because it must be unique. In the second piece of information, a receive-side port number helps to specify the information allowing the receiver to direct the message to the required process (Lammle, 2011). In conclusion, as stated above, the application layer, the interface between the networks provides a means through which a user can access information on the network by using an application by functioning as the main interface for the user to use in interacting with a specific application, significantly the network. The layer is the closest to the end user thus enabling the user and the application layer to interact directly with the software application that executes a communicating component. The application layer serves several functions including identification of communication partners, the synchronization of communication and the determination of resource availability. References Dye, M., McDonald, R., & Rufi, A. (2011). Network fundamentals: CCNA exploration companion guide (vol. 1). New York: Cisco Press. Karris, S. T. (2009). Networks: Design and management. New York: Orchard Publications. Lammle, T. (2011). CCNA Cisco Certified Network Associate Deluxe study guide. New York: John Wiley & Sons Outline (project summary) The networking process in the OSI model is divided into 7 logical layers, all of which have different functionalities and are assigned specific services and protocols. The application layer is layer 7, the top layer in the OSI and TCP/IP models. It provides the interface between the applications that a user requires in communication and the network through which messages are transmitted. It provides the interface existing between the applications used in communication and the underlying network where messages are transmitted. This layer in the OSI model serves as the first step of ensuring that data is on the network. It ensures that a user can access the services that are provided by the other layers, and defines the protocols that applications use to exchange data. These protocols include the Domain Name Service Protocols (DNS), Hypertext Transfer Protocol (HTTP), Simple Mail Transfer Protocol (SMTP), Telnet, a terminal emulation protocol and File Transfer Protocol (FTP). The requests for comments define the above protocols. The application layer is useful in helping other programs to use network resources, such as transfer of files. Services, such as the transfer of files, are clear to the user but also interface with the network to enable the data to be transferred. The application layer services and protocols represent a process where one application employs different application layer services that require multiple processes to be executed. Despite the fact that there are different network applications, software is at the centre of them all, for instance, in host computers. In summary, the application layer provides a means through which a user can access information on the network by using an application by functioning as the main interface for the user to use in interacting with a specific application, significantly the network. Read More