ʶһѵ¡ͧ Multitier Client Server

ͧ

֧кͧ͹/ѡѡк͹/ҹѴáѺҧҧçҧҹ͹͹/к öҹкҴ˭ͧҡӡѴҹͧ
кҡöк͹§ͧҧ ֧Ѻاк͹/ԷҾҡдǡҴͧкѭ ѡɳçҧ֧Ѻкѹ? :-Two Tier Three Tier???
ҡʶԵͧ˹ǨҴͧ Standish Group International, Inc. ѵ͹/Ẻ Three Tier ѵҡѺ17% 1996 ҴԺ͹Ҥ
çҧͧкѴٻҧ˹ͧ͡Ϳ젡͡ѡɳçҧͧкѺѺ͹ͧءдѺͧͧǹԴ͡Ѻͧ Ҿͧء͹ѴԹ͡Դͧçҧ
͡çҧͧͧҹͺʹͧͧ͹/͡çҧҡþ?ѡء͡Ѻк֧Դҹͧç͹/젤ӡѴͧçҧTwo Tier Three Tier ֧ª젢ӡѴͧçҧͧººҧѲ״

ӡѴ

͡ǡѺ͹кͧ͹Ѻʹԧͧ͹/àԧ͹Ϳػó?ͧٻҹͧ͹/ͧѺͧ(request)͹͡Ѻͧ?鹵ͺѺͧͺѺ(response)ҡٻ1 ֧͡кǹš¹ҧ͹Ѻ젡кǹͧ͹젨ͧѧͧҨͧѺҹŠäǺػóͧ͡ѧѡɳçҧ͹˹öͧѧÿ˹öԡ͹ѹ


ٻ 1 Client/ServerTransactions

ҹͧ͹͹ͧԴѹͺѺöԴ͹ ͿԴкǹͧ͹ҡкǹͧҹա˹ ѹԧ͹ͧѲҨ͡͹ʴҹͧ PC ѹ͹ö¡к˭Ѻͺ͹ҧԵѳѧҡѲçҧءҴ˭ó
͹öԴͧѹ͡éѺ֧çҧҧdistributed application ͹ػó¡͡ҡѹ
Bever (et al.) distributed application Сͺǹ¡͡ҡѹҹͧҧͧѹѹҹѧ
͹캹çҧ͹/ͧGUI (Graphic User Interface) ԧáԨǹ˭ǹͧ GUI дǡͧҧк͹ͧǹ print spooling (network print queues) ǹʴ (蹠 X-Window)

Դͧçҧ

ǹ˭شͧءend user Сͺ3 ǹ˭ ǹʴǹǹͧçҧ͹͸ԺǹСͺ͡¡

Two-tier Architecture

ǹСͺ 3 ǹ ͧѹ ǹʴǹǹͧŠö͡2 Ӿǡ ǹͧͧ͹ǹͧҹͧ
ͧ͹ѺѲͧѡҹҧͧͧͧ͹ѧͧѭҡѺҧçҧtwo tier
ǹͧʴ١Ǻ͹젠ǹҧ͹ǹͧ١ Ѵҹ
ͧٻͧSQL SQLҡ͹֧ͧ͹ҧ͹ҧͧ͹֧ͧҡѹͧŧٻҹ API (Application Program Interface) ѹͧ١ѴҧŶ١˹ҧͧ١ͧٹͧҹ١ͧͧǺѡʹͧ١׹ѧ͹ ١ѴдѺͧ͹ʴ͡



ٻ 2 DataAccess Topology for two-tier architecture
Majority of functional logic exists at the client level

ͧ two tier Ѳҡ к two tier öѲǹ ѡҡѹººѹ ѹк͹ҧ״
ͧͧ two tier öѡɳçҧ ҧë ѧٻẺ աѧͧѹ Դҡ Ѵ˹ ͧ෤Ԥ¡ ෤Ԥ rapid application develpment(RAD) ͧͧöҧǴ ó
IS organizations öԴǹ ͧ ҹͧѺѲк two tier ͹/ ѲҧǴ ŧٻҡ
çҧẺ two tier öҹǴ¹ŧ çҧ ǴШ ҧѺ¹ŧҧǴ Ҵ˭ͧ͹PC çҧẺ two tier ֧͡ѺѭͧǺ ѭͧ re-distribution ¹ͧ¹͹ ء ¹ŧ͹ҹҹҡ ͧҡҴǺѺاͧͧ ѧ Ѻ¹ Ѻا֧ͧӡѺ͹ءͧ
кѡʹк two tier Ѻ͹ҡ ͧҹҧѹ Ѻ SQL ͹/ѺѲ ǹҡ͡ҡ ԷҾʹҡ ͡ҹѹ ҧ͹ Š Ҩ¹ŧ ٭

Three-tier Architecture

çҧẺ Three tier (ٻ 3) ӨѴӡѴͧçҧẺ two tier ǹʴ ҹ͡ҡѹ 3 ǹ ͧ͹ѹ öʴ͹ѹѺкͧ two tier ҧͧѺǺʴ ӹdz ١ ˹ʴͧ͹ ¡١ҧ ҧ öӹdz ҧͧ͹͹ ѧ頠 ҧö ѹ C ѧҧҨ Multi-threaded öѺ͹ ѹ ءҧѹ
к Three tier ҡ ¡͹ ֧ к¡ ¡ RPC öҹẺ two tier к˭ ͧѺ SQL к Three tier öªҡ RPC
RPC ١¡ҡ˹ʴ ֧ ҧ RPC ״ SQL ¡ҡ ͹֧çҧ Two tier
RPC Դҡͧͧ͹ ͹ҹ Ѻͧ к֧çҧ ѺѺ ʴͧ Three tier ͹ ͧͧ SQL ա ҹ״ҡ

ٻ 3 Three Tier Architecture. Most of the logic processing is handled by functionality servers.
Middle-tier code can be accessed and utilized by multiple clients.

͡ҡªաҧ˹ ʴçҧ öҹҹ ɠ ա çҧͧ Three tier ѧ״ҹѾҡ ¹ŧͧ ö ҧ§ ͡ҡѧѴͧŴŧ

ººöҧ Two Tier Three Tier

ٻҿ 4 ֧ ٻҿ 6 ʴ֧ŧ Ѻ two tier three tier ŧ ͧкԴ ͧ ˹ c/s


ٻ4 Initial Development Effort

ٻ 4 ʴ֧ ººк ءẺ Three Tier Ѳҹ дѺҧ ͧдѺ 3 (Third Generation Language) C ҡԴ Ϳŷѹ platform ҧѹ
ҧç çҧẺ Two tier ͹حҵ дѺ٧ͧҧǹԴ͡Ѻ


ٻ 5 Subsequent Development Efforts

ҡٻǹͧ ҧҡ ö ªҡ ͧҧ ͧء͹ѹ ¡͹ѹ͡٧ ͧա


ٻ 6 Client Tool Migration

ٻ 6 ºº ¹ͧ к Two Tier ͧءͧк к Three Tier § ҧ ͧ Ѳͧҧʴ RPC


͡ҧԧ The Critical Choice of Client Server Architecture: A comparison of Two and Three Tier Systems