Server Architecture Essay Example

Networking Client/Server Architecture Essay Example Networking Client/Server Architecture Paper Networking Client/Server Architecture Paper Networking Client/Server Architecture Introduction to 2-Tier Architecture 2-tier architecture is used to describe client/server systems where the client requests resources and the server responds directly to the request, using its own resources. This means that the server does not call on another application in order to provide part of the service. Introduction to 3-Tier Architecture In 3-tier architecture, there is an intermediary level, meaning the architecture is generally split up between: 1. A client, i. e. he computer, which requests the resources, equipped with a user interface (usually a web browser) for presentation purposes 2. The application server (also called middleware), whose task it is to provide the requested resources, but by calling on another server 3. The data server, which provides the application server with the data it requires | The widespread use of the term 3-tier architecture also denotes the following architectures: * Application sharing between a client , middleware and enterprise server * Application sharing between a client, application server and enterprise database server. Comparing both types of architecture 2-tier architecture is therefore a client-server architecture where the server is versatile, i. e. it is capable of directly responding to all of the clients resource requests. In 3-tier architecture however, the server-level applications are remote from one another, i. e. each server is specialised with a certain task (for example: web server/database server). 3-tier architecture provides: * A greater degree of flexibility Increased security, as security can be defined for each service, and at each level * Increased performance, as tasks are shared between servers Multi-Tiered Architecture In 3-tier architecture, each server (tier 2 and 3) performs a specialised task (a service). A server can therefore use services from other servers in order to provide its own service. As a result, 3-tier architecture is potentially an n -tiered architecture The Differences Between Thick ; Thin Client HardwareIn the world of client/server architecture, you need to determine if it will be the client or the server that handles the bulk of the workload. By client, we mean the application that runs on a personal computer or workstation and relies on a server to perform some operations. Thick or thin client architecture is actually quite similar. In both cases, you can consider it as being the client application running on a PC whose function is to send and receive data over the network to the server program. The server would normally communicate that information to the middle-tier software (the backend), which retrieves and stores that information from a database. While they share similarities, there are many differences between thick and thin clients. Thick and thin are the terms used to refer to the hardware (e. g. , how a PC communicates with the server), but the terms are also used to describe applications. While this article deals specifically with hardware issues, be sure to check back as we will continue our Thick and Thin discussion as related to applications. Thin ClientsA thin client is designed to be especially small so that the bulk of the data processing occurs on the server. Although the term thin client often refers to software, it is increasingly used for the computers, such as network computers and Net PCs, that are designed to serve as the clients for client/server architectures. A thin client is a network computer without a hard disk drive. They act as a simple terminal to the server and require constant communication with the server as well. | Thin clients provide a desktop experience in environments where the end user has a well-defined and regular number of tasks for which the system is used. Thin clients can be found in medical offices, airline ticketing, schools, governments, manufacturing plants and even call centers. Along with being easy to install, thin clients also offer a lower total cost of ownership over thick clients. Thick Clients In contrast, a thick client (also called a fat client) is one that will perform the bulk of the processing   in client/server applications. With thick clients, there is no need for continuous server communications as it is mainly communicating archival storage information to the server. As in he case of a thin client, the term is often used to refer to software, but again is also used to describe the networked computer itself. If your applications require multimedia components or that are bandwidth intensive, youll also want to consider going with thick clients. One of the biggest advantages of thick clients rests in the nature of some operating systems and software being unable to run on thin clients. Thick clients can handle thes e as it has its own resources. Thick vs. Thin A Quick Comparison Thin Clients| Thick Clients| Easy to deploy as they require no extra or specialized software installation Needs to validate with the server after data capture- If the server goes down, data collection is halted as the client needs constant communication with the server- Cannot be interfaced with other equipment (in plants or factory settings for example)- Clients run only and exactly as specified by the server- More downtime-Portability in that all applications are on the server so any workstation can access- Opportunity to use older, outdated PCs as clients- Reduced security threat| Data verified by client not server (immediate validation)- Robust technology provides better uptime Only needs intermittent communication with server More expensive to deploy and more work for IT to deploy- Require more resources but less servers- Can store local files and applications- Reduced server demands- Increased security issues   | Key Terms To Understanding Storage Servers: client The client part of a client-server architecture. Typically, a client is an application that runs on a personal computer or workstation and relies on a server to perform some operations. server A computer or device on a network that manages network resources. Servers are often dedicated, meaning that they perform no other tasks besides their server tasks. client/server architecture A network architecture in which each computer or process on the network is either a client or a server. |

Olfactory System - Sense of Smell

Olfactory System - Sense of Smell The olfactory system is responsible for our sense of smell. This sense, also known as olfaction, is one of our five main senses and involves the detection and identification of molecules in the air. Once detected by sensory organs, nerve signals are sent to the brain where the signals are processed. Our sense of smell is closely linked our sense of taste as both rely on the perception of molecules. It is our sense of smell that allows us to detect the flavors in the foods we eat. Olfaction is one of our most powerful senses. Our sense of smell can ignite memories as well as influence our mood and behavior. Olfactory System Structures   Patrick J. Lynch, medical illustrator / Creative Commons / Wikimedia Commons Our sense of smell is a complex process that depends on sensory organs, nerves, and the brain. Structures of the olfactory system include: Nose - opening containing nasal passages that allows outside air to flow into the nasal cavity. Also a component of the respiratory system, it humidifies, filters, and warms the air inside the nose.Nasal cavity - cavity divided by the nasal septum into left and right passages. It is lined with mucosa.Olfactory epithelium - specialized type of epithelial tissue in nasal cavities that contains olfactory nerve cells and receptor nerve cells. These cells send impulses to the olfactory bulb.Cribriform plate - a porous extension of the ethmoid bone, which separates the nasal cavity from the brain. Olfactory nerve fibers extend through the holes in the cribriform to reach the olfactory bulbs.Olfactory nerve - nerve (first cranial nerve) involved in olfaction. Olfactory nerve fibers extend from the mucous membrane, through the cribriform plate, to the olfactory bulbs.Olfactory bulbs - bulb-shaped structures in the forebrain where olfactory nerves end and the olfactory tract begins.Olfactory tract - band of nerve fibers that extend from each olfactory bulb to the olfactory cortex of the brain. Olfactory cortex - area of the cerebral cortex that processes information about odors and receives nerve signals from the olfactory bulbs. Our Sense of Smell Our sense of smell works by the detection of odors. Olfactory epithelium located in the nose contains millions of chemical receptors that detect odors. When we sniff, chemicals in the air are dissolved in mucus. Odor receptor neurons in olfactory epithelium detect these odors and send the signals on to the olfactory bulbs. These signals are then sent along olfactory tracts to the olfactory cortex of the brain. The olfactory cortex is vital for the processing and perception of odor. It is located in the temporal lobe of the brain, which is involved in organizing sensory input. The olfactory cortex is also a component of the limbic system. This system is involved in the processing of our emotions, survival instincts, and memory formation. The olfactory cortex has connections with other limbic system structures such as the amygdala, hippocampus, and hypothalamus. The amygdala is involved in forming emotional responses (particularly fear responses) and memories, the hippocampus indexes and stores memories, and the hypothalamus regulates emotional responses. It is the limbic system that connects senses, such as odors, to our memories and emotions. Sense of Smell and Emotions The connection between our sense of smell and emotions is unlike that of the other senses because olfactory system nerves connect directly to brain structures of the limbic system. Odors can trigger both positive and negative emotions as aromas are associated with specific memories. Additionally, studies have demonstrated that the emotional expressions of others can influence our olfactory sense. This is due to activity of an area of the brain known as the piriform cortex which is activated prior to odor sensation. The piriform cortex processes visual information and creates an expectation that a particular fragrance will smell pleasant or unpleasant. Therefore, when we see a person with a disgusted facial expression before sensing an odor, there is an expectation that the odor is unpleasant. This expectation influences how we perceive the odor. Odor Pathways Odors are detected through two pathways. The first is the orthonasal pathway which involves odors that are sniffed in through the nose. The second is the retronasal pathway which is a pathway that connects the top of the throat to the nasal cavity. In the orthonasal pathway, odors that enter the nasal passages and are detected by chemical receptors in the nose. The retronasal pathway involves aromas that are contained within the foods we eat. As we chew food, odors are released that travel through the retronasal pathway connecting the throat to the nasal cavity. Once in the nasal cavity, these chemicals are detected by olfactory receptor cells in the nose. Should the retronasal pathway become blocked, the aromas in foods we eat can not reach odor detecting cells in the nose. As such, the flavors in the food can not be detected. This often happens when a person has a cold or sinus infection. Smell Disorders Individuals with smell disorders have difficulty detecting or perceiving odors. These difficulties may result from factors such as smoking, aging, upper respiratory infection, head injury, and exposure to chemicals or radiation. Anosmia is a condition defined by the inability to detect odors. Other types of smell defects include parosmia (a distorted perception of odors) and phantosmia (odors are hallucinated). Hyposmia, the diminished sense of smell, is also linked to the development of neurodegenerative diseases such as Parkinsons and Alzheimers disease. Sources: Merkelt, Judith. How the Emotions of Others Influence Our Olfactory Sense. Neuroscience News, 24 Aug. 2017, neurosciencenews.com/olfaction-emotion-7368/. Sarafoleanu, C, et al. The Importance of the Olfactory Sense in the Human Behavior and Evolution. J Med Life, U.S. National Library of Medicine, 15 Apr. 2009, www.ncbi.nlm.nih.gov/pmc/articles/PMC3018978/. Smell Disorders. National Institute of Deafness and Other Communication Disorders, U.S. Department of Health and Human Services, 16 Jan. 2018, www.nidcd.nih.gov/health/smell-disorders.