Ultimate Guide to Supply Chain Management

Ultimate Guide to Supply Chain Management The supply chain is probably one of the more complex systems that all managers have to be knowledgeable about. Its broad coverage, which includes entire organizations, people, information, various activities and all other resources that play a role in the flow of products or services from producers to suppliers to customers to end users. This complexity, coupled with its dynamic nature, calls for a way to keep that flow going in such a way that facilitates and does not, in any way, hinder the operations of the business. This discipline is called supply chain management. © Shutterstock.com | TrueffelpixIn this article, well show 1) what supply chain management is all about, 2) which elements play an important role in supply chain management, 3) what activity levels SCM entails, 4) the major components of a supply chain management, as well as 5) some challenges in SCM.SUPPLY CHAIN MANAGEMENTThe simplest definition of supply chain management, or SCM, as it is popularly known, is the “management of the flow of goods and services through interconnected or linked networks or channels, operating as if in a chain”. These goods may also refer not only to finished goods or final products, but also raw materials and work-in-process inventory. If we are going to be more technical about it, however, the definition of SCM would be the“design, planning, execution, control and monitoring of supply chain activities, with the objective of creating value, building a competitive infrastructure, leveraging worldwide logistics, synchronizing supply with demand, an d measuring performance on a global scale.”The application of SCM is also seen to be as complex as the network or chain that it manages, since it does not draw from one or two disciplines alone. It takes on an integrated approach that takes its cues from various areas or disciplines, such as procurement, operations management and logistics. Recent decades have also seen information technology figuring more and more into SCM.Ultimately, managing the supply chain will improve the visibility of inventory, and the velocity of its movement. To break it down, SCM is concerned with the management of:The flow of raw materials (from suppliers) into the organization, to be used in its operations;The process undergone by materials within the organization to turn it into finished goods;The flow of the resulting finished goods from the organization, through distribution channels, to arrive into the hands of the end user, customer or consumer.Businesses can benefit from SCM because, when done r ight, it can make supply chain more cost-effective and efficient. It will:Improve the supply chain networkMinimize delaysReduce costs and inefficienciesIncrease productivityPromote collaboration and enhance relationshipsBoost customer satisfactionAside from the above, SCM has also become an important business tool in the sense that it improves the relationship between the organization and its partners along the supply chain, which may include suppliers, distributors, and logistics operators.ELEMENTS OF SUPPLY CHAIN MANAGEMENTBusiness experts have narrowed down the elements of SCM into four: demand management, effective communication, process integration, and collaboration.Demand managementThese involve activities that are used in predicting or forecasting the future demand for an organization’s products or services, so it could plan the flow of its manufacturing processes better.Just as supply and demand go together, so do supply management and demand management. The focus is not on the supply or even the production process, because the main concern is the customers: their needs and their preferences, as these will dictate the demand. Activities will be carried out in order to find out what the customers want or need and, in the process, make decisions that will put the company in a competitive advantage in the industry.Effective CommunicationBusinesses benefit a lot from effective communication, and the supply chain is no different. An organization has identified sources of demand and operational information, and it should ensure that the same information will be disseminated to all its members, especially those who are directly involved in the supply chain.By keeping the members of the organization apprised with the latest and correct information, they will also be reminded of their duties and responsibilities in the supply chain or network, so they can deliver what is expected of them. It also enables them to make the necessary adjustments, should there b e a need to do so.Business Process IntegrationBefore SCM, businesses were focused on managing the individual functions of workers and departments within the company. SCM changed that approach as it involves the integration of business processes, particularly the processes along the supply chain, in order to facilitate a continuous flow or movement of resources.In other words, SCM entailed collaboration and partnership between and among the players of business processes. It covers the relationship between the suppliers and the buyers, the product developers and end users, the systems in use that are common to the parties, and the information being shared or exchanged among them.Some of the identified processes in the supply chain that may be integrated include the following:Customer management: These processes involve customer relationship management and customer service management. The organization has to pay attention to its relationship with its customers or end users and, at the same time, become a reliable source of customer information, providing real-time information about its products and services, such as availability, logistics and other information that customers may be interested in.Manufacturing flow management: The predictive value of the demand management processes will enable the organization to produce and supply products and services more reliably and in a more flexible manner. Depending on the demand, the organization can make better decisions on matters related to its manufacturing processes, such as scheduling, batches or lot sizes, and work intervals.Procurement: Procurement is more than just the simple act of purchasing. There are a lot of details to pay attention to when obtaining raw materials and products from suppliers outside of the organization. These include actually sourcing for supplies by looking for suppliers, resource planning, assessing the need of supplies of the organization, placement of order, as well as the transport, ha ndling, storage and warehousing of the purchased supplies.Product development: One of the concerns of organizations is to shorten product life cycles, and one way of achieving that is to decrease the time to market these products. Thus, product development should also be integrated with customer service and customer relationship management.Inventory management: Businesses also have to maintain an inventory of their supplies or raw materials. After all, not all businesses adopt the Just-in-Time method of procuring inventory, where they will purchase supplies and receive them just as they are about to be placed in production. In most cases, companies maintain inventory or stock of these materials until such time that they will be needed in the manufacturing process. This is also part of SCM. Of course, inventory management processes also cover keeping track of their inventory of the finished goods that came out of the production process, awaiting delivery to the customers. Inventory m anagement will be conducted in order to keep the amount of wastage low, as well as the cost of storing inventory.Supplier relationship management: This is closely related to the procurement processes, because a huge part of being able to conduct procurement processes smoothly and more efficiently relies on the relationship of the organization with the suppliers or the providers of the materials that are being procured.Order management: There are separate processes for tracking orders from customers, assigning products to these orders, and scheduling the delivery of the orders to the customers.Distribution: This could also be termed as physical distribution, as it involves physically delivering a service or moving a product to the customer, with the use of an appropriate marketing channel.Relationship management through outsourcing: Reducing life cycles can also be accomplished by outsourcing key activities that used to be performed in-house. Examples of partners through outsourcing that an organization will closely be working with in the supply chain include transport and delivery service providers, and warehousing or storage agents.CollaborationThis is another key term in supply chain management, because much of the activities involve relationships: the relationship between top management and its people, between members of the organization particularly those who work in teams, and between the organization and its partners in the supply chain.Maintaining good relationships with suppliers, for instance, will increase the likelihood of reducing costs as well as provide a guarantee that the quality of the materials or products that they supply will be high. You may have seen companies remaining partners with certain suppliers for years â€" decades, even. There is a great probability that this is because they have excellent SCM, with focus on collaboration and partnerships.SCM LEVELS OF ACTIVITIESSCM involves a lot of activities that are all geared towards improvi ng the flow of materials through the supply chain. To make things easier, these activities have been grouped into three:1. StrategicThis involves decisions made by top management, and they encompass the issues that will affect the entire organization, not just a single department or unit. Examples are decisions on what sales market to penetrate, which suppliers or partners to collaborate with, and where to set up a major manufacturing plant or warehouse.Often, these decisions are made by top management.2. TacticalDecisions that are more focused on the financial side of things will fall under this category. The main concern will be in minimizing costs. For example, the company can enter into agreements with its distributors to conduct their activities in a more cost-efficient manner. It can also strike a deal with their warehousing partners to find ways to lower their cost of inventory storage.3. OperationalThese involve decisions that are made on a daily basis within the organizatio n, such as arranging and rearranging production schedules, taking orders from customers, transporting raw materials from storage to the production site, and moving finished goods from the production site to the warehouse.There are three main flows that are tackled in SCM.Product Flow: This was the simple definition of supply chain management, since it involves the movement of products or goods from a supplier to a customer. But it also includes the movement of products or goods from a customer that is returning them.Information Flow: This pertains to the flow of data or information â€" in real-time â€" on orders, availability of products, and the status of orders and the delivery thereof.Finances Flow: This covers all matters related to the financial side of the transactions, such as the pricing, the applicable credit terms, the payment schedules and terms. If there are consignment arrangements entered into, they will also belong to the finances flow.COMPONENTS OF SUPPLY CHAIN MANAG EMENTSCM has the following basic components:Planning and ControlAs in every other process, the first stage involves coming up with a plan or strategy on how the company’s product or service will meet the needs of its target customers or end users, while allowing the business to earn a profit. This involves taking into consideration all the resources that will be used in the manufacture and delivery of these products to the customers.It does not end there, either. Once a strategy has been developed, there is a need to monitor the supply chain and see to it that the plan is being followed.DevelopmentWe have reiterated how collaboration and partnerships play very important roles in SCM, and that is especially apparent in this stage. The organization has to build and maintain strong relationships with its raw materials suppliers and service providers.This covers identifying the suppliers that the organization feels most comfortable working with, and coming up with plans and agreements on pricing, shipping, delivery, and payment.ManufacturingThis is where the raw materials are placed into production to come up with the finished product, which will then undergo testing and packaging. The activities involved in this component include scheduling, resources allocation, finished goods inventory management, and quality control measures.DeliveryWe now come to the logistics. At this point, all the finished products that were packaged will now be brought along the distribution channels so they can reach the customers. It covers order receipt and fulfillment, warehousing, shipping and payment collection.Building strong relationships with carriers or transport companies that will handle the shipping and delivery processes will also fall under this component.ReturnPart of supply chain management is how the organization will handle when customers return defective products to the company, and find ways to deal with any potential negative effect of such returns.One of the strat egies in SCM to address returns-related issues is to set up a network that will be dedicated to receiving the defective products and providing assistance to customers who are returning these products, as well as responding to customers’ questions, if any.We can never take out the organization structure as one of the components of SCM, because they will have an effect on how SCM is carried out. We can further break that down into the following.The power and leadership structure. At the end of the day, it is the decision of top management that will prevail. They have the final decision on the conduct of SCM.The management methods or styles used. How the management runs or supervises the company will also affect how SCM is carried out.The overall organizational culture or attitude. Much of the corporate culture or attitude toward SCM will be dictated by those in power. It is a sad reality that, although the concept of the supply chain has been around for a very long time, there are s till many business that do not pay much attention to it.With the advancement of technology, SCM has become automated, thanks in large part to the many software applications or programs developed specifically for the management of supply chains. Of course, before choosing which program will work for your specific business, you still have to do your research.CHALLENGES TO SCMIf we are to name a disadvantage of SCM, it would be the huge amount of investment it requires, both in money, time, manpower, and other resources to plan, implement and monitor it. This is further aggravated by the fluctuating costs in the global market today.Today, businesses also have greater chances of bringing their operations global. The internet has certainly made it possible for companies to have a wider reach in terms of their target market. But this has also posed a challenge to the logistics because, when they used to think about their supply chain only within their state or country, now they have to ex pand it on an international or even global scale, too.Competition has also risen to a global scale, which means companies now have to pour more resources into ensuring that their supply chain or supply network can compete with that of their rivals. Again, this will go back to the issue of whether the company has enough resources to meet the required investment. Clearly, SCM does not come cheap. But with proper implementation, it can bring greater benefits.

Character Analysis Of Bartleby And The Wolf Of Wall Street

In the movie, the Wolf of Wall Street wall street is depicted as a lively work environment filled with promising work and big profit. The movie follows a man named Jordan through the exciting ups and downs of his career on Wall Street. Herman Melville paints an entirely different picture of wall street in his short story Bartleby, The Scrivener: A story of Wall Street. In Melville’s story, we follow Bartleby through a depressing career on wall street that eventually ends in his death. Herman Melville expresses his loathing of wall street in Bartleby, The Scrivener: A story of Wall Street as well as arguing that working on Wall Street is an awful job. Bartleby losing his vision represents a wall street worker becoming discontent with†¦show more content†¦From the way the narrator describes his own environment in a similar way, describing it as an upstairs chamber with two windows that show nothing. Colt’s environment seems equally as depressing as the Lawyer’s. Still, the lawyer is not driven to violence, when Bartleby is finally kicked out of the dim building he starts starving himself, presumably to kill himself. Melville is articulating that Wall Streets offices are places of death. Whether it is an employer exploiting another worker or an employee is drawn absolutely mad, the lifeless environment of Wall Street is a huge component of worker’s sadism against themselves or others. Melville is calling out of all wall street in this piece, not just certain offices, by generalizing his characters. Melville does not give the the lawyer a name and keeps all of the names of the Lawyer’s employees as nicknames like, â€Å"Nippers† and â€Å"Turkey†. The employees nicknames do not have anything to do with the work that they provide either. They are based on physical appearance or a specific behavior of each worker. Gingernut, another worker gets his nickname because Nippers and Turkey send him to get ginger nut cakes. The nicknames are based on insignificant things about the character so the nicknames must be significant too. Melville did not want to use real names because all names have some sort of meaning. So, to keep the employees

Poems After the Attack †A September 11th Anthology

In the years since the September 11, 2001 terrorist attack on America, poets and readers continue to turn to poetry in an effort to make sense of the devastation and the horror of that day. As Don Delillo wrote in Falling Man: A Novel: People read poems. People I know, they read poetry to ease the shock and pain, give them a kind of space, something beautiful in language . . . to bring comfort or composure. This collection comes to you accompanied by our hope that in your grief, anger, fear, confusion, or resolve  these poems offer you grace. Daniel Moore (Abd al-Hayy), â€Å"A Little Ramshackle Shack†Matthew Abuelo, â€Å"Upon 9/11†Adam, â€Å"If Only†Ken Adams aka Dudley Appleton, â€Å"911†Joe Aimone, â€Å"The W After†Cristin OKeefe Aptowicz, â€Å"WTC 9/11†Paula Bardell, â€Å"Silence (over Manhattan)†Tony Beyer, â€Å"In the Wake of America†Michael Brett, â€Å"Tomorrow†Tony Brown, â€Å"Dispatch from the Home Front: Halloween 2001†Penny Cagan, â€Å"September Eleventh†Lorna Dee Cervantes, â€Å"Palestine†David Cochrane, â€Å"Firefighters Prayer†Jim Cohn, â€Å"Ghost Dance†Julie Craig, â€Å"Before and After†Peter Desmond, â€Å"Good Morning, Uzbekistan!†Jesse Glass, â€Å"down†JD Goetz, â€Å"9/11/02†jj goss, â€Å"Aftermath of 9-11†Dorothea Grossman, â€Å"Ruins†Marj Hahne, â€Å"Remembrance† and â€Å"A New York Winter†Mary Hamrick, â€Å"An American Soldierâ € Elizabeth Harrington, â€Å"Normally†Judyth Hill, â€Å"Wage Peace†Michael Hillmer, â€Å"The Lights That Have Vanished†Bob Holman, â€Å"Cement Cloud†Larry Jaffe, â€Å"Will It Be Heard† and â€Å"5000 Souls Leaving†Karen Karpowich, â€Å"In Central Park†Eliot Katz, â€Å"When the Skyline Crumbles†John Kissingford, â€Å"September 12† and â€Å"Image†Doug McClellan, â€Å"Day One†Poet Laureate Billy Collins’ commemorative poem â€Å"The Names† in The New York TimesFormer Poet Laureate Robert Pinsky’s poem â€Å"9/11† in The Washington Postâ€Å"Poetry and Sept. 11: A Guided Anthology† by Robert Pinsky in Slateâ€Å"The Language of War and Peace,† special issue of Big Bridgeâ€Å"Words To Comfort,† a selection of poems and photographs from the NYC benefit readings October 17, 2001 in Jacket 15â€Å"Poems for the Time,† anthology collected by Alici a Ostriker in Moby Livesâ€Å"Poetry and Tragedy,† reactions and poems from the recent Laureates in USA Today

Accounting. How to prepare income statements Free Essays

There are different ways in how two income statements are prepared. For example: the income statement (also known as PL) of a merchandising company consists of Revenue, Expenses (related to the sales volume through the Cost of Goods Sold (COGS) and General Administrative Expense (GSA), which all result in Net Income. The income statement of a Service company consists of Service Revenue minus any Expenses related to that service, which results in Net Income. We will write a custom essay sample on Accounting. How to prepare income statements or any similar topic only for you Order Now Another way to look at it is that inventory never leaves the balance sheet until it is physically sold to a customer, which transfers it to Cost of Goods Sold. The basic differences between the financial statements of a merchandising business and a service business include reporting cost of merchandise sold on the income statement and the : A. owner’s equity section of the balance sheet B. other income section of the income statement C. inclusion of merchandise inventory on the balance sheet as a current asset D. inclusion of an owner’s equity statement The primary difference in handling inventory, accounts payable and accounts receivable. In a merchandising company you will probably have inventory that needs to be valued. This can be done FIFO or LIFO (first in first out, or last in first out) basis. The asset that your inventory represents can be offset by your accounts payable if you purchased inventory on account. At the end of the year for tax purposes you have to account for the change in your inventory value. In addition in a mechanizing company you may have to handle local sales taxes and such. In a service company there is no inventory and normally no local taxes on services sold. Distinguish the activities of a service business from those of a merchandising business. The primary differences between a service business and a merchandising business relate to revenue activities. Merchandising businesses purchase merchandise for selling to customers. On a merchandising business’s income statement, revenue from selling merchandise is reported as sales. The cost of the merchandise sold is subtracted from sales to arrive at gross profit. The operating expenses are subtracted from gross profit to arrive at net income. Merchandise inventory, which is merchandise not sold, is reported as a current asset on the balance sheet. How to cite Accounting. How to prepare income statements, Papers

Osmometric Thirst free essay sample

Thirst  is the craving for liquids, resulting in the basic  instinct  of humans or animals to  drink. It is an essential mechanism involved in  fluid balance. It arises from a lack of fluids and/or an increase in the concentration of certain osmolites  such as  salt. If the water volume of the body falls below a certain threshold, or the osmolite concentration becomes too high, the  brain  signals thirst. Continuous  dehydration  can cause a myriad of problems, but is most often associated with neurological problems such as seizures, and renal problems. Excessive thirst, known as  polydipsia, along with excessive urination, known as  polyuria, may be an indication ofdiabetes. Thirst produced by an increase in the osmotic pressure of the interstitial fluid relative to the intracellular fluid thus producing cellular dehydration fluid, Intracellular fluid, fluid contained within cells. Osmometric thirst occurs when the osmotic balance between the amount of water in the cells amp; the water outside the cells becomes disturbed means when the concentration of salts in the interstitial fluid is greater than that inside the cells, resulting in the movement of intracellular water outside of the cell by osmosis. This is what happens when we eat salty pretzels. The Na is absorbed into the blood plasma, which disrupts the osmotic balance between the blood plasma amp; the interstitial fluid. This draws water out of the interstitial fluid and into the plasma, now upsetting the balance between the cells and the interstitial fluid. The result is water leaving the cells to restore the balance. The disruption in the interstitial solution is recognized by neurons called osmoreceptors. These osmoreceptors are located in the region of the anterior hypothalamus. These osmoreceptors send a signal that causes us to drink more water, in order to restore the osmotic balance between the cells and surrounding fluid. In the case of pretzel eating, if we do not drink more water, eventually the excess Na is simply excreted by the kidneys. The body must have water to excrete in order to rid itself of nitrogenous wastes, so the reduction in water excretion causes fluid-seeking behavior. OSMOMETRIC THIRST  is stimulated by cellular dehydration. It occurs when the tonicity of the interstitial fluid increases, which draws water out of the cells (think of water seeking to be balanced), cells then shrink in volume. The word osmosis means movement of water, through semi permeable membrane, from low solute concentration to high solute concentration. There are receptors and other systems in the body that detect a decreased volume or an increased osmolite concentration. They signal to the  central nervous system, where central processing succeeds. There are some RECEPTORS FOR OSMOMETRIC THIRST (already in the central nervous system more specifically in hypothalamus notably in two circumventrivular organs that lack an effective brain-barrier the organumvasculosum of the lamina terminalis (OVLT) and the  subfornical organ  (SFO). However, although located in the same parts of the brain, these osmoreceptors that evoke thirst are distinct from the neighboring osmoreceptors in the OVLT and SFO that evoke arginine vasopressin  release to decrease  fluid output. In addition, there are  visceral osmoreceptors. These project to the  area postrema and  nucleus tractussolitarius  in the brain), the neurons that respond to changes in the solute concentration of the interstitial fluid start firing when water is drawn out of them due to hyper tonicity; most likely located in the anteroventral tip of the third ventricle (AV3V); if activated, they send signals to neurons that control rate of vasopressin secretion So, the question will be raised such as do we want more or less vasopressin? We want more vasopressin; remember high levels of vasopressin cause kidneys to retain water, sweating causes loss of water through skin, which increases tonicity of interstitial fluid, which then draws water out of the capillaries and cells. We can lose water only from the cells, but not intravascular, by eating a salty meal in which salt is absorbed from the digestive tract into the blood, this makes the blood hypertonic (high concentration of salt), this draws water into the cell from the interstitial fluid, the loss of water from the interstitial fluid makes  it  hypertonic, now water is drawn out of the cells, as blood plasma increases in volume, kidneys excrete more water and sodium, eventually, excess sodium is excreted, along with the water that was taken from the interstitial fluid and intercellular fluid, this results in an overall loss of water from the cells, however, blood plasma volume never decreased. The damage to AV3V area can cause diabetes and lack of thirst (excessive urination, so must force self to drink) subfornical organ  (SFO) circumventricular organ whose AII receptors are the site where angiotensin acts to produce thirst; it has few neural inputs, as its job is to sense the presence of a hormone in the blood; it has many  outputs  to various parts of the brain:   endocrine   SFO axons project to neurons in the supraoptic and paraventricular nuclei that are responsible for production and secretion of the posterior pituitary hormone vasopressin   Autonomic   axons project to cells of the paraventricular nucleus and other parts of the hypothalamus, which the send axons to brain stem nuclei which control the sympathetic and parasympathetic nervous system; this system controls angiontensin’s effect on blood pressure. behavioral   axons sent to  median preoptic nucleus, an area which controls drinking and secretion of vasopressin median preoptic nuc leus   receives information from: 1. OVLT regarding osmoreceptors 2. SFO regarding angiotensin. Baroreceptors via the nucleus of the solitary tract Lateral Hypothalamus and Zona Incerta esions of the hypothalamus disrupt osmometric and volumetric thirst, but not meal-associated drinking lesions of the zona incerta disrupt hormonal stimulus for volumetric thirst, but not the neural ones that originate in the atrial baroreceptors zona incerta sends axons to brain structures involved in movement influences drinking behavior Central processing The  area postrema  and  nucleus tractussolitarius  signal, by  5-HT, to  lateral parabrachial nucleus, which in turn signal to median preoptic nucleus. In addition, the area postrema and nucleus tractussolitarius also signal directly to subfornical organ. Thus, the median preoptic nucleus and subfornical organ receive signals of both decreased volume and increased osmolite concentration. They signal to higher integrative centers, where ultimately the conscious craving arises. However, the true  neuroscience  of this consciou s craving is not fully clear. In addition to thirst, the  organumvasculosum of the lamina terminalis  and the  subfornical organ  contribute to  fluid balance  by  vasopressin  release. Studies done†¦. Some research and study presents a theoretical model for osmotic (cellular dehydration) thirst, and evaluates several of the implications of the model. Ss were 11 male Sprague-Dawley rats. The model for osmotic thirst asserts that when a load consisting of n millimols of effective osmotic solute dissolved in v ml. of water is introduced into the extracellular compartment, the S will drink a volume of water, D (in ml. ), which is proportional to the volume of water, Diso (in ml. ), required to dilute the hypertonic load to isotonicity (ALPHA). Thus, D = k (Diso) = k-n/a-v=, where k is the constant of proportionately representing the contribution of the kidney to osmotic regulation. The experimental data show that under conditions of osmotic thirst this model accurately predicts the rats drinking behavior. Osmoregulatory thirst associated with deficits of intracellular fluid volume. Small increases of 1–2% in the effective osmotic pressure of plasma result in stimulation of thirst in mammals. It has been shown in both human subjects and other mammals that when the plasma osmolality (usually in the range of 280–295 mosmol/kgH2O) is increased experimentally as a result of increasing the concentration of solutes such as NaCl or sucrose that do not readily pass across cell membranes, thirst is stimulated. By contrast, increasing plasma osmolality by systemic infusion of concentrated solutes such as urea or  D-glucose that more readily cross nerve cell membranes is relatively ineffective at stimulating thirst (8,12,  18). In the former case, a transmembrane osmotic gradient is established and cellular dehydration results from movement of water out of cells by osmosis. Cellular dehydration does not occur with the permeating solutes in the latter case, and it is considered that specific sensor cells in the brain, termed osmoreceptors (initially in relation to vasopressin secretion), respond to cellular dehydration to initiate neural mechanisms that result in the generation of thirst (8,  18). Although there is evidence that some osmoreceptors may be situated in the liver, much evidence has accrued that localizes an important population of osmoreceptive neurons to the preoptic/hypothalamic region of the brain. The hypothalamus was implicated in the generation of thirst in the early 1950s when Bengt Andersson was able to stimulate water drinking in goats by electrical or chemical stimulation of the hypothalamus. Although he observed that drinking was induced by injection of hypertonic saline into the hypothalamus in a region between the columns of the fornix and the mamillothalamic tract, the solutions injected were grossly hypertonic, making it difficult to come to a firm conclusion that physiologically relevant osmoreceptors for thirst existed in this region. Andersson and colleagues later found evidence that more rostral tissue in the anterior wall of the third ventricle was more likely to be the site of sensors mediating osmotic thirst and proposed a role for the ambient Na+  concentration in this region of the brain in the initiation of thirst. Neural mechanisms sub serving osmotically stimulated thirst†¦ More than 25 years ago, clues emerged as to the crucial role of a region in the anterior wall of the third ventricle in thirst mechanisms when it was shown that ablation of tissue in the anteroventral third ventricle wall (AV3V region) of goats and rats caused either temporary or permanent adipsia (1,  10). In those animals with lesions that did recover spontaneous water drinking, loss of dipsogenic responsiveness to osmotic and ANG stimuli was evident. Another clue to the location of cerebral osmoreceptors sub serving thirst came from studies in sheep suggesting that the cerebral osmoreceptors sub serving thirst and vasopressin secretion were, at least in part, located in brain regions lacking a blood-brain barrier. In subsequent years, evidence (reviewed in Ref. 14) from the study of lesions, electrophysiological recordings, and the expression of the immediate early gene c-fos  in rats have confirmed that neurons in both the organum vasculosum of the lamina terminalis (OVLT) and the subfornical organ (SFO) are most likely the sites of very sensitive osmoreceptors (Fig. 1? ). The SFO and OVLT are two circumventricular organs that lack a blood-brain barrier and that are situated in the anterior wall of the third ventricle (the lamina terminalis). In particular, the dorsal part of the OVLT and the periphery of the SFO are osmosensitive in the rat. However, the median preoptic nucleus (MnPO), which is situated in the lamina terminalis longitudinally between the two circumventricular organs and is an integral part of the AV3V region, is also strongly activated by osmotic stimuli. Lesion studies in rats have shown that the MnPO may play a crucial role in the generation of thirst in response to both osmotic and hormonal signals being relayed to this nucleus by neural inputs from the SFO and possibly the OVLT (10). Another aspect of osmoregulatory drinking is that it may be blocked pharmacologically by intracerebroventricularly injected ANG antagonists, suggesting that a central angiotensinergic pathway is involved in most mammals. The MnPO, which is rich in ANG type 1 receptors but is not amenable to circulating ANG II, is a likely site of this angiotensinergic synapse. The MnPO receives afferent neural input from neurons in both the SFO and the OVLT and may integrate neural signals coming from osmoreceptive neurons in these circumventricular organs with visceral sensory inflow from the hindbrain However, combined ablation of both the SFO and OVLT leaving a considerable part of the MnPO intact reduces but does not totally abolish osmotically induced drinking. This suggests that neurons within the MnPO may be osmoreceptive also or that they receive osmotically related input from other parts of the brain [e. g. , the area postrema (AP)] or body (e. g. , hepatic portal system). It is clear that the lamina terminalis is a region of the brain where stimuli from the circulation, such as plasma hypertonicity or hormones (e. g. , ANG II, relaxin), exert their dipsogenic action. In regard to the subsequent efferent neural pathways that may project from the lamina terminalis to other brain regions (including the cerebral cortex) to generate thirst, little is known at present. The lateral hypothalamic area, the hypothalamic paraventricular nucleus, and the periaqueductal gray are all regions that receive a strong neural input from the lamina terminalis and have been proposed as regions that may participate in the generation of thirst. However, evidence in support of such proposals is scarce. Recent studies using positron emission tomography in human volunteers identified several brain regions that became activated during an intravenous infusion of hypertonic saline that produced a strong thirst sensation in these subjects. In particular, the anterior and posterior parts of the cingulate cortex were activated, and on satiation of the thirst, these areas rapidly declined in activity. This cingulate region has been implicated in other goal-directed behaviors and probably plays a yet-to-be-specified role in the generation of human thirst. Angiotensin and thirst Classic studies by Fitzsimons and associates (see Ref. 8  for review) were the first to clearly demonstrate that renin and its effector peptide, ANG II, were highly effective as dipsogenic stimuli in the rat. Systemically administered renin or ANG II generates water intake in sated rats. As is true for osmotically stimulated drinking, ANG-induced thirst requires the structures of the lamina terminalis (i. e. SFO, MnPO, and OVLT) for sensing circulating peptides (particularly the SFO) and for initial central nervous system processing and integration of this peripherally derived information (10). The dipsogenic action of ANG is even more impressive when it is injected directly into the brain, and this has been demonstrated in several mammals (rat, goat, dog, sheep) and also in birds (duck, pigeon). This route of administration is believed to mimic the action of this peptide at one or more periventricular brain sites. The presence of a brain renin-angiotensin system with all the components of the metabolic cascade as well as receptors being synthesized de novo in the brain has been demonstrated. It has been hypothesized that circulating ANG II acts on forebrain circumventricular organs (SFO, OVLT) in the mode of a hormone and that, either directly or indirectly, it activates angiotensinergic pathways projecting to central integrative sites when the peptide acts as a neurotransmitter (11). The systemic (renal/circulating) and the brain renin-angiotensin systems, although distinct, are functionally coupled with one another and play complementary roles in the maintenance of body fluid homeostasis. Inhibition and facilitation of thirst through hindbrain actions In addition to humoral factors acting through forebrain targets and networks to facilitate drinking, there is evidence of both stimulatory and inhibitory signals acting on or through the hindbrain. When the hypertension induced by intravenous ANG II in rats is reduced or normalized by coadministration of a systemically acting hypotensive drug, drinking responses to infusions of ANG II are enhanced (7). In rats with actions of the systemic renin-angiotensin system blocked, reducing blood pressure to below normal resting levels enhances the drinking response to intracerebroventricular ANG II infusions (11). Inhibition of thirst arises not only from arterial baroreceptors but also from volume receptors on the low-pressure side of the circulation. Distention of the region of the junction of the right atrium and vena cava or of the pulmonary vein at the entry to the left atrium by inflating balloons inhibits experimentally induced drinking. In contrast, when, in ogs, both low-pressure cardiopulmonary and high-pressure arterial baroreceptors are unloaded by reducing venous return to the heart, drinking is stimulated (9,  17). Under such conditions, Quillen and colleagues (15) found that denervation of either the cardiopulmonary or sinoaortic baroreceptors significantly attenuated thirst in the dog and that denervation of both sets of receptors completely abolished drinking even though circulating levels of ANG were high. Afferent input from the cardiopulmonary and arterial baroreceptors is carried to the brain by the IXth and Xth cranial nerves, with most of these nerves terminating in the nucleus of the solitary tract (NTS). Lesions centered on the AP, but also encroaching on the medial portions of the medial NTS (i. e. , an AP/mNTS lesion), as well as bilateral lesions centering on the medial subnucleus of the NTS proper, produce rats that overrespond to thirst-inducing treatments associated with hypovolemia (5). These effects are likely to be due to removal of inhibitory baroreceptor-derived input. However, it is possible that the AP also plays a role in the inhibitory control of thirst derived from systemic blood volume expansion or acute hypertension. As demonstrated by Antunes-Rodrigues and colleagues (2), a peptide made and released from the cardiac atria, ANP, inhibits drinking. Release of ANP in response to hypervolemia and hypertension may inhibit drinking. Its action is discussed below. Interestingly, the AP/NTS region contains cells with axons that project to the lateral parabrachial nucleus (LPBN). Electrolytic, anesthetic, and neurotoxic lesions of the LPBN produce overdrinking to mediators of extracellular dehydration in the rat (11). This is similar to the effects of AP/mNTS lesions. A significant portion of the cells that project from the AP/mNTS to the LPBN contain serotonin (5-HT), and bilateral injections of the nonselective 5-HT receptor antagonist methysergide enhance drinking as well as NaCl solution intake in response to several dipsogenic stimuli in rats (see Ref. 11  for review). The model that has been proposed is that there is a hindbrain inhibitory circuit involving the AP, NTS, and LPBN that receives and processes neural and humoral input derived from activation of cardiopulmonary and arterial baroreceptors. Ascending pathways from this inhibitory complex project to many forebrain structures, such as the structures along the lamina terminalis, the central nucleus of the amygdala, and various hypothalamic nuclei that have been implicated in thirst. In turn, many of these forebrain structures have reciprocal connections with the LPBN and NTS. It is within this visceral neural network where the input from both excitatory and inhibitory humoral and visceral afferent nerves is likely to be processed to give rise to drinking behaviors or the perception of thirst.

Smart socket Essay Example

Smart socket Essay Although ad-hoc solutions exist for some of these problems, it is usually up to the applications user to discover the cause of the connectivity problems and find a solution. In this paper we describe Smokestacks, a communication library that lifts this burden by automatically discovering the connectivity problems and solving them with as little support from the user as possible. Categories and Subject Descriptors: C. 2. 4 [Distributed Systems]: Distributed applications General Terms: Algorithms, Design, Reliability Keywords: Connectivity Problems, Grids, Networking, Parallel Applications 1 . Parallel applications are increasingly run in Grid environments. Unfortunately, on many Grid sites the ability of machines to create or accept network connections is severely limited by network address translation (NAT) [14, 26] or firewalls [15]. There are even sites that completely disallow any direct communication between the compute nodes and the rest of the world (e. G. , the French Grinding system [3]). In addition, multi homing (machines with multiple network addresses) can further complicate connection setup. We will write a custom essay sample on Smart socket specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Smart socket specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Smart socket specifically for you FOR ONLY $16.38 $13.9/page Hire Writer For parallel applications that require direct communication between their components, these limitations have hampered the transition from traditional multi receptors or cluster systems to Grids. When a combination of Grid sites is used, serious connectivity problems are often encountered. Smokestacks is part of the Ibis project, and can be found at http://www. CSS. Vi. Ml/ibis Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or the full citation on the first page. Many problems, however, can only be solved by adapting the application or the communication library it uses. To make matters worse, as soon as the set of Grid systems being used changes, large part of this process needs to be repeated. As a result, running a parallel application on multiple Grid sites can be a strenuous task [34]. In this paper we will describe a solution to this problem: the Smokestacks communication library. The primary focus of Smokestacks is on ease of use. It automatically discovers a wide range of connectivity problems and attempts to solve them with little or no support from the user. Smokestacks combines many known solutions, such as port forwarding, TCP splicing and SSH tunneling, and introduces several new ones that resolve problems with multi homing and machine identification. In 30 connection setup experiments, using 6 different sites worldwide, Smokestacks was always able to establish a connection, while conventional sockets only worked in 6 experiments. Using heuristics and caching, Smokestacks is able to significantly improve the connection setup performance. Smokestacks offers a single integrated solution that hides the complexity of connection setup in Grids behind a simple interface that closely resembles sockets. We will show that it is relatively straightforward to port an existing application to Smokestacks, provided that certain programming guidelines are followed. Smokestacks is not specifically intended for use in parallel applications or Grids. It can also be applied to other distributed applications, such as visualization, cooperative environments, or even consumer applications such as instant messaging, file sharing, or online gaming. However, many of these applications only require a very limited degree of connectivity. Often, clients simply connect to a server in a well-known location, making it relatively easy to apply an ad-hoc solution when a connectivity problem occurs. Parallel applications, however, can be much more challenging. They often require a large number of connections between the participating machines, and each machine must such applications in a Grid environment with limited connectivity is difficult. Therefore, this paper will focus on this domain. N Section 2 we describe the connectivity related problems encountered while running applications on multiple Grid sites. Section 3 describes how these problems are solved in Smokestacks and briefly looks at the programming interface. Section 4 evaluates the performance of Smokestacks, Section 5 describes related work, and Section 6 concludes. 2. CONNECTIVITY PROBLEMS In this section we will give a description of the network related problems that can occur when running a single parallel or distributed application on multiple Grid sites. . 1 Firewalls As described in [1 5], A firewall is an agent which screens network traffic in some way, blocking traffic it believes to be inappropriate, dangerous, or both. . Many sites use firewalls to protect their network from unauthorized access. Firewalls usually allow outbound connections, but block incoming connections, often with the exception of a few welkin ports (e. G. , port 22 for SSH). It is obvious that this inactivity restriction can cause severe problems when running a parallel application on multiple sites. When only a single participating site uses firewall, the connectivity problems can sometimes be solved by ensuring that the connections setups are in the right direction, I. E. , that all required connections between open and firewall machines are initiated at the firewall site. This solution may require changes to the applications or communication libraries, however. Also, if both sites use a firewall, this approach can no longer be used. In this case, a firewall will always be encountered regardless of he connection setup direction. One way to solve the problems is to request an open port range in the firewall. Connectivity can then be restored by adapting the application to only use ports in this range. Besides requiring reconfiguration of the firewall, open ports are also seen as a threat to site security. When both machines are behind a firewall it may still be possible to establish a direct connection using a mechanism called TCP splicing [6, 10, 13, 20]. Simply put, this mechanism works by simultaneously performing a connection setup from both sides. Since this approach requires explicit cooperation teens the machines, some alternative communication channel must be available. . 2 Network Address Translation As described in [21], Network Address Translation is a method by which IP addresses are mapped from one address realm to another, providing transparent routing to end hosts. . NAT was introduced in [12] as a temporary solution to the problem of IPPP address depletion. Although the intended solution for this problem, IPPP, has been available for some time, NAT is still widely used to day. Frequently used [21, 29]. This type of NAT allows outbound connections from sites using riveter addresses, but does not allow incoming connections. Both the IP address (and related fields) and the transport identifier (e. G. , TCP and JODI port numbers) of packets are translated, thereby preventing port number collisions when a set of hosts share a single external address. As mentioned above, NAT only allows outbound network connections. Incoming connections are rejected, since the connection request does not contain enough information to find the destination machine (I. E. , only the external IP address is provided, but that may be shared by many machines). This restriction leads to connectivity problems hat are very similar to those caused by firewalls. Therefore, the solution described in Section 2. 1 (connecting in the right direction) also applies too NAT setup, and fails in a similar way when multiple NAT sites try to interconnect. Although the TCP splicing mechanism can also be used to connect two NAT sites, a more complex algorithm is required to compensate for the port translation performed by NAT [6, 20]. Some NAT implementations have support for port forwarding, where all incoming connections on a certain port can be automatically forwarded to a certain host inside the NAT site. Using mechanisms such as Upon [5], DIF [28], or MEDICO [30], applications can contact the NAT implementation and change the port forwarding rules on demand. Port forwarding lifts many of the restrictions on incoming connections. Unfortunately, Upon is mostly found in consumer devices, MEDICO is still under development, and DIF only supports NAT (and firewall) implementations based on Interfile [1]. As a result, these mechanisms are not (yet) generally usable in Grid applications. Currently, Smokestacks only supports Upon. In addition to causing connection setup problems, NAT also complicates machine identification. Machines in a NAT tit generally use IP addresses in the private range [26]. These addresses are only usable within a local network and are not globally unique. Unfortunately, parallel applications often use a machines IP address to create a unique identifier for that machine. When multiple NAT sites participate in a single parallel run, however, this approach can not be used, since the machine addresses are no longer guaranteed to be unique. 2. 3 Non-routed networks On some sites no direct communication between the compute nodes and the outside world is possible due to a strict separation between the internal and external networks. No aching is accessible, and the connectivity of this machine may be limited by a firewall or NAT. Two of the sites used in Section 4 use such a setup. It is clear that this is a major limitation when the site is used in a parallel application. The only possibility for the compute nodes to communicate with other sites is to use front-end machine as a bridge to the outside world, using, for example, an SSH tunnel or a SOCKS [24] proxy. These are non-trivial to set up, however. 2. 4 Multi Homing When multi-homed machines (I. E. , machines with multiple network addresses) participate in a parallel application, another interesting problem occurs. When creating a connection to such a machine, a choice must be made on which of the possible target addresses to use. The outcome of this choice may depend on the location of the machine that initiates the connection. For example, the front-end machine of a site has two addresses, a public one, reachable over the internet, and a private one used to communicate with the sites compute nodes. As a result, a different address must be used to reach teachings depending on whether the connection originates inside or outside of the site. In [34] we called this the Reverse Routing Problem. Normally, when a multi-homed machine is trying to connect to a single IP address, a routing table on the machine decides which network is used for the outgoing connection. In the example described above the reverse problem is encountered. Instead of having to decide how to exit a multi-homed machine, we must decide on how to enter it. This problem is non-trivial, since the source machine generally does not have enough information available to select the correct target address. As a result, several connection attempts to different addresses of the target may be necessary before a connection can be established. In Section 3. 2 we will describe heuristics that can be used to speed up this process. Multi homing can have a major effect on the implementation of parallel programming libraries. The example above shows that it is not sufficient to use a single address to represent a multi-homed machine. Instead, all addresses must be made available to the other participants of the parallel application. In addition, some of the addresses may be in a private range and refer to a different machine when used in a different site. Therefore, it is also essential to check if a connection was established to the correct machine. 3. SMOKESTACKS In this section we will give an overview of the design, implementation and programming interface of the Smokestacks library, and describe how it solves the problems described in the previous section. 3. 1 Overview Currently, Smokestacks offers four different connection setup mechanisms, Direct, Reverse, Splicing, and Routed. An overview of how these mechanisms solve the connectivity problems described in Section 2. As the table shows, each problem is solved by at least one mechanism. Table 1 : Overview of connectivity problems and their solutions. Connection Setup Mechanism Problems Direct Reverse Splicing Routed Identification X Multi Homing X Single FEW/NAT pox xx Dual MINOT (X) XX No Routing X The machine identification and multi-homing problems are solved by the direct connection setup. As will be explained below, this approach also has limited firewall traversal capabilities (using SSH tunneling), so in certain situations it may succeed in establishing a connection in a single or even a dual firewall setting. In the table these entries are shown between brackets. A reverse connection setup is only capable of creating a connection when a single firewall or NAT limits the connectivity. Splicing is capable of middling both single and dual firewall/NAT configurations. However, this approach is significantly more complex than a reverse connection setup (especially with dual NAT) and may not always succeed. Therefore, reverse connection setup is preferred for single firewall/NAT configurations. A routed connection setup can be used in any situation where the connectivity is limited. Unlike the previous two approaches it does not result in a direct connection. Instead all network traffic is routed via external processes called hubs (explained in Section 3. 3), which may degrade both latency and throughput of the connection. Therefore, the previous mechanisms are preferred. When connecting to or from a machine on a non-routed network, however, a routed connection is the only choice. The Smokestacks implementation is divided into two layers, a low-level Direct Connection Layer, responsible for all actions that can be initiated on a single machine, and a high-level Virtual Connection Layer that uses side-channel communication to implement actions that require cooperation of multiple machines. The direct connection layer is implemented using the standard socket library. The virtual connection layer is implemented using the direct connection layer. Both layers will be explained in more detail below. Currently, Smokestacks is implemented using Java [2]. 3. 2 Direct Connection Layer do not require explicit cooperation between machines, such as determining the local addresses or creating a direct connection. It also supports a limited form of SSH tunneling. 3. 2. 1 Machine Identification During initialization, the direct connection layer starts by scanning all available network interfaces to determine which IP addresses are available to the machine. It then generates a unique machine identifier that contains these addresses, and that can be used to contact the machine. This identifier will automatically be unique if it contains at least one public address. If all addresses are private, however, additional work must be done. A machine that only has private addresses is either in a NAT site or uses a non-routed network. In the first case, a unique identifier can still be generated for the machine by acquiring the external address of the NAT. Provided that this address is public, the combination of external and machine addresses should also be unique, since other machines in the same NAT site should have a different set of private addresses, and all other NAT sites should have different external address. The Smokestacks library will use Upon to discover the external address of the NAT site. If this discovery fails, or if the returned address is not public, a Universally Unique Identifier (JUDI) [23], will be generated and included in the machine identifier, thereby making it unique. 3. 2. 2 Connection Setup Once initialized, the direct connection layer can be used to set up connections to other machines. The identifier of the target machine may contain multiple network addresses, some of which may not be reachable from the current location. The private dresses in the identifier may even refer to a completely different machine, so it is important that the identity of the machine is checked during connection setup. As a result, several connection attempts may be necessary before the correct connection can be established. When multiple target addresses are available, a choice must be made in which order the connection attempts will be performed. Although simply using the addresses in an arbitrary order should always result in a connection (pro-vided that a direct connection is possible), this may not be the most efficient approach. Many Grid sites offer historiographer networks such as Merriment [7] or Infinite [4] in addition to a regular Ethernet network. Using such a network for inter-site communication may significantly improve the applications performance. In general, these fast networks are not routed and use addresses in the private range, while the regular Ethernet networks (often) use public addresses. Therefore, by sorting the target addresses and trying all private ones first, the fast local networks will automatically be selected in sites with such a setup. The drawback of if the connection originates on a different site. This may cause a significant overhead. Therefore, Smokestacks uses a heuristic that sorts the target addresses in relation to the addresses that are available locally. For example, if only a public address is available on the local machine, it is unlikely that it will be able to create a direct connection to a private address of a target. As a result, the connection order public before private is used. This order is also used if both machines have public and private addresses, but the private addresses refer to a different network (e. G. , 10. 0. 0. 10 vs 192. 168. 1. 20). The order private before public is only used if both machines have private addresses in the same range. Section 4 will illustrate the performance benefits of this heuristic. Unfortunately, it is impossible to make a distinction between addresses of the same class. For example, if a target has multiple private addresses, we can not automatically determine which address is best. Therefore, if a certain network is preferred, the user must specify this explicitly. Without this explicit configuration, Smokestacks will still create a direct connection (if possible), and the parallel application will run, but its performance may be suboptimal. When a connection has been established, an identity check s performed to ensure that the correct machine has been reached. This would be a simple comparison if the complete identifier of the target is available, but unfortunately this is not always the case. User provided addresses are often used to bootstrap a parallel application. These addresses are often limited to a single hosannas or IP address, which may only be part of the addresses available to the target machine. Therefore, the identity check used by Smokestacks also allows the use of partial identifiers. Whenever a connection is created, the target machine provides its complete identity o the machine initiating the connection. This machine then checks if both the public and private addresses in the partial identity are a subset of the ones in the complete identity. If so, the partial identity is accepted as a subset of the complete identity, and the connection is established. Note that although the connection is created to a machine that matches the address specified by the user, it is not necessarily the correct machine from the viewpoint of the parallel application. Unfortunately, in such cases it is up to the user to provide an address that contains enough information to reach the correct machine. . 2. 3 Open Port Ranges and Port Forwarding When a firewall has an open port range available, Smokestacks can ensure that all sockets used for incoming connections are bound to a port in this range. There is no way of discovering this range automatically, however, so it must be specified explicitly by the user. In addition, Smokestacks can use the Upon protocol to configure a NAT to do port forwarding, I. E. Automatically forward all incoming connections on a certain external port to a specified internal address. However, as explained before, this protocol is mainly used in consumer devices. In addition to regular network connections, the direct connection layer also has limited support for SSH tunneling. This feature is useful for connecting to machines behind a firewall that allows SSH connections to pass through. It does, however, require a suitabl e SSH setup (I. E. , public key authentication must be enabled). Creating an SSH tunnel is similar to a regular connection setup. The target addresses are sorted and tried consecutively. Instead of using the port specified in the connection setup, however, the default SSH port (I. E. , 22) is used. When a connection is established and the authentication is successful, the receiving SSH daemon is instructed to forward all traffic to the original destination port on the same machine. If this succeeds, the regular identity check will be performed to ensure that the right machine has been reached. Although this approach is useful, it can only be used to set up a tunnel to a different process on the target machine. Using this approach to forward traffic to different machines requires extra information. For example, setting up an SSH tunnel to a compute node of a site through the sites fronted, can only be done if it is clear that the fronted must be contacted in order to reach the target machine. Although this approach is used in some projects [8], the necessary information cannot be obtained automatically and must be provided by the user. Therefore, Smokestacks uses a different approach which will be described in detail in Section 3. 3. 3. 2. Limitations The direct connection layer offers several types of connection setup which have in common that they can be initiated by a single machine. No explicit cooperation between machines is necessary to establish the connection. There are many cases, however, where connectivity is too limited and the direct connection layer cannot be used. In general, direct connections to sites that use NAT or a firewall are not possible. Although SSH tunneling and o pen port ranges alleviate the firewall problems, they require a suitable SSH setup or extra information from the user. Port forwarding reduces the problems with NAT, but is rarely supported in Grid systems. Therefore, these features are of limited use. In the next section we will give a detailed description of the virtual connection layer, which solves these problems. 3. 3 Virtual Connection Layer Like the direct connection layer, the virtual connection layer implements several types of connection setup. It offers a simple, socket-like API and has a modular design, making it easy to extend. Besides a direct module that uses the direct connection layer described above, it contains several modules that offer more advanced types of connection setup. These modules have in common that they cooperation (and thus communication) between the source and target machines in order to establish a connection. As a result, side-channel communication is required to implement these modules. 3. 3. 1 Side-Channel Communication In Smokestacks, side-channel communication is implemented by creating a network f interconnected processes called hubs. These hubs are typically started on the fronted machines of each participating site, so their number is usually small. When a hub is started, the location of one or more other hubs must be provided. Each hub will attempt to setup a connection to the others using the direct connection layer. Although many of these connections may fail to be established, this is not a problem as long as a spanning tree is created that connects all hubs. The hubs use a gossiping protocol to exchange information about themselves and the hubs they know, with the hubs that they are connected to. This way information about each hub quickly spreads to all hubs in the network. Whenever a hub receives information about a hub it has not seen before, it will attempt to set up a connection to this hub. This way, new connections will be discovered automatically. All gossiped information contains a state number indicating the state of the originating machine when the information was sent. Since information from a hub may reach another hub through multiple paths, the state number allows the receiver to decide which information is most recent. By recording the length of the path traversed thus far in he gossiped information, hubs can determine the distance to the sites that they can not reach directly. Whenever a hub receives a piece of information about another hub containing a shorter distance than it has seen so far, it will remember both the distance and the hub from which the information was obtained. This way, we automatically create a distributed routing table with the shortest paths between each pair of hubs. This table is later used to forward application information (as will be described below). When an application is started, the virtual layer on each machine creates a single connection to the hub local to its tit. The location of this hub can either be explicitly species- fled or discovered automatically using JODI multicast. 3. 3. 2 Virtual Addresses The connection to the hub can now be used as a side channel to forward requests to otherwise unreachable machines. To ensure that the target machines can be found, addresses are used, consisting of the machine identifier (see Section 3. 2), a port number, and the identifier of the hub the machine is connected to. All requests for the target machine can then be sent to the local hub, which forwards it in the direction of the target

A profit margin Essays

A profit margin Essays A profit margin Essay A profit margin Essay Already highly competitive and overcrowded market; establishing a new name in this area would be very difficult and an expensive business.  As Giusti is a well established firm in this sector with a worldwide customer base it has already overcome these threats of entry. The company however is constantly looking to widen its product range; recently in the field of storage silos and homogenisers for cosmetic creams. In the new product range these barriers do exist and Giusti struggles in this area, as it does not have sufficient personnel to develop these new ranges. As a result we find that new products are evolutionary rather than revolutionary. The company tends to develop products on the job, and this is a practice common with small engineering companies. It is beneficial in that it keeps overheads low but when the newly developed product does not perform as anticipated then the rectification costs can escalate as generally the unit is on site at a customers factory.  Becomix, who are a German competitor of Giusti, have similar problems but a higher level of manning so development can be carried out along side production engineering. Threat Of Substitutes  Manufacturing in the United Kingdom has been on a general slow down for a number of years now and this is reflected in the customer base Giusti has in this country. Along with other process equipment suppliers Giusti has accepted that, especially in the food sector, the use of second hand vessels and pumps etc is becoming more and more common due to constraints on expansion budgets. As a result the company has formed close ties with second hand equipment stockists and, where appropriate, will offer the option of using new or pre-used equipment. Bargaining Power Of Suppliers  The price of stainless steel is elevated due to surcharges for nickel content, but this is fairly constant and common to competitors. Occasionally a customer may specify that a particular manufacturer of ancillary equipment be used in a project and in cases like these it is very difficult to negotiate significant discounts.  Giustis prices have been known to be at the upper end of the market scale in the past and great efforts have been made over the last nine years to reduce the cost of the equipment by increasing the efficiencies in the factory (purchasing seam-welding equipment, the increasing use of computer controlled laser cutting, economic batching of standard components, etc.), value-engineering the equipment to reduce materials used, required fabrication, machining, polishing, and fitting time on the shop floor. The efficiency increases have resulted in the company being able to use a nine year old pricing list for current, and much improved, equipment. The area that is still expensive is the control systems and bought out components.  The company has been aware for some time that many bought out components (valves, pumps, gear units, electrical equipment, etc.) are manufactured in India and the Far East, shipped to Europe and then distributed on to the customer. In setting up an office in India three years ago the company is endeavouring to cut out the European middle-man and gain the cost saving. Ironing out the reliability and quality issues with these suppliers is key to this initiatives long-term success. Bargaining Power Of Buyers  In recent years the customer base serviced by Giusti has seen a rationalization; with pharmaceutical companies merging, e.g. SmithKline Beecham and Glaxo Wellcome now knows as Glaxo SmithKline (GSK), and firms such as Avon Cosmetics relocating to save on production costs, i.e. moving production from Northampton to Poland. As a supplier to these companies Giusti now have fewer customers but the buyers that remain now have greater bargaining power. In a suppliers seminar held by GSK in the last year they stated that all suppliers were to reduce prices across the board by 21% if they were to remain on the recommended suppliers list. As stated earlier Giusti has made great efforts to reduce production costs in an attempt to maintain profitability but when customers such as H. J. Heinz hold tendering auctions on-line and award the contract to the lowest bidder then there is a point where a line is to be drawn between maintaining a busy factory and maintaining a profit margin.  Becomix do not enter into pricing or delivery time battles, relying on the quality of their products. The price on the box is the price that everyone pays and stated delivery may go back, but never be improved on. They have a perceived added value that is high and is sufficient to bear a price and delivery premium.