W3c web services architecture w3cwo rkinggro upno te

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Unformatted text preview: u type a Web site’s address into the lo catio n f ield o f yo ur bro wser, yo u’re telling the client to “go f ind the Web server so f tware at the address pro vided, and tell the server to return the Web site requested.” It is po ssible to link simple scripting languages to a Web server f o r perf o rming calculatio ns, accessing databases, o r custo mizing Web sites. But mo re advanced distributed enviro nments may use a catego ry o f so f tware called an applicat ion server. The applicatio n server (o r app server) ho uses business lo gic f o r a distributed system. Individual Web services served up by the app server are pro grammed to perf o rm dif f erent tasks: returning a calculatio n (“sales tax f o r yo ur o rder will be $ 11.58”), accessing a database pro gram (“here are the results yo u searched f o r”), o r even making a request to ano ther server in ano ther o rganizatio n (“Visa, please verif y this custo mer’s credit card number f o r me”). Figure 9. 6 In t his mult it iered dis t ribut ed s ys t em, client brows ers on various machines (des kt op , lap t op , mobile) acces s t he s ys t em t hrough t he Web s erver. The cas h regis t er does n’ t us e a Web brows er, s o ins t ead t he cas h regis t er logic is p rogrammed t o direct ly acces s t he s ervices it needs from t he ap p s erver. Web s ervices acces s ed from t he ap p s erver may be as ked t o do a variet y of funct ions , including p erform calculat ions , acces s corp orat e dat abas es , or even make reques t s from s ervers at ot her firms (for ex amp le, t o verify a cus t omer’ s credit card). Tho se little chunks o f co de that are accessed via the applicatio n server are so metimes ref erred to as Web services. The Wo rld Wide Web co nso rtium def ines Web serv ices as so f tware systems designed to suppo rt intero perable machine-to -machine interactio n o ver a netwo rk.W3C, “Web Services Architecture,” W3C Wo rking Gro up No te, February 11, 2004. And when co mputers can talk to gether (instead o f peo ple), this o f ten results in f ewer erro rs, time savings, co st reductio ns, and can even create who le new ways o f do ing business! Each Web service def ines the standard metho d f o r o ther pro grams to request it to perf o rm a task and def ines the kind o f respo nse the calling client can expect back. These standards are ref erred to as applicat ion programming int erf aces (APIs). Lo o k at the advantages that Web services bring a f irm like Amazo n. Using Web services, the f irm can allo w the same o rder entry lo gic to be used by Web bro wsers, mo bile pho ne applicatio ns, o r even by third parties who want to access Amazo n pro duct inf o rmatio n and place o rders with the f irm (there’s an incentive to f unnel sales to Amazo n—the f irm will give yo u a cut o f any sales that yo u send Amazo n’s way). Go o gle o f f ers many AP Is, including ho o ks that o ther develo pers use to leverage Go o gle Maps. And Facebo o k and Twitter have AP Is that, amo ng o ther things, allo w pro grammers to write apps that can po st status updates and tweets. Organizatio ns that have created a ro bust set o f Web services aro und their pro cesses and pro cedures are said to have a service­orient ed arch it ect ure (SOA). Organizing systems like this, with separate applicatio ns in charge o f client presentatio n, business lo gic, and database, makes systems mo re f lexible. Co de can be reused, and each layer can be separately maintained, upgraded, o r migrated to new hardware—all with little impact o n the o thers. Web services so und geeky, but here’s a co ncrete example illustrating their po wer. So uthwest Airlines had a Web site where custo mers co uld bo o k f lights, but many custo mers also wanted to rent a car o r bo o k a ho tel, to o . To keep custo mers o n So uthwest.co m, the f irm and its ho tel and rental car partners created a set o f Web services and shared the AP Is. No w custo mers visiting So uthwest.co m can bo o k a ho tel stay and rental car o n the same page where they make their f light reservatio n. This pro cess transf o rms So uthwest.co m into a f ull service travel destinatio n and allo ws the site to co mpete head-to -head with the likes o f Expedia, Travelo city, and Orbitz.J. McCarthy, “The Standards Bo dy P o litic,” Info Wo rld, May 17, 2002. Think abo ut why Web services are impo rtant f ro m a strategic perspective. By adding ho tel and rental car services, So uthwest is no w able to eliminate the travel agent, alo ng with any f ees they might share with the agent. This sho rtcut allo ws the f irm to capture mo re pro f its o r pass o n savings to custo mers, securing its po sitio n as the f irst place custo mers go f o r lo w-co st travel. And perhaps mo st impo rtantly, So uthwest can capture key data f ro m visito r travel searches and bo o kings (so mething it likely co uldn’t do if custo mers went to a site like Expedia o r Travelo city). Data is a hugely valuable asset, and this kind o f custo mer data can be...
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