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Client Server - Select ‘B1’ model protocol from B1DB...

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Operate in a heterogeneous environment, which consists of multi vendor hardware & software Communications between client and server is message –based via a well-defined API . Goals: usability, flexibility, interoperability, and scalability Read SYSTEM OF SYSTEMS (will be on FINALS ) Client Server Request() (1) receives Process (2) Return (3) Do with answers (4) Side effect – Client does not use its resources properly because context is lost. Use rollback to resolve the issues 2-tier architecture is more expensive to maintain as time increases. N tier architecture is less expensive to maintain as time goes by. Time(x) vs Cost (y)
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0 5 10 15 20 25 30 35 n-tier 2-tier Select * from Buses, Disks where Buses.protocol = Disks.protocol; Global as view Mediator B1DB B2DB B3DB D1DB D2DB (model, protocol)-Local view
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Unformatted text preview: Select ‘B1’, model, protocol from B1DB UNION Select ‘B2’, model, protocol from B2DB UNION Select B3(or manf), model, protocol from B3DB PreparedStatement psmt1 = conn.prepareStatement(“SELECT ‘D1’, model, protocol from D1DB where protocol = ?”) While(rs.next()){ String prot = Rs.getString(“protocol”); Psmt1.setString(1,prot); ResultSet rs2 = psmt.executeQuery(); Ex1 V1(c,p) <- par(c,p) V2(c,g) <- par(c,p) AND par(p,g) Ex2 ggp(c,x) <- par(c,u) AND par(u,v) AND par(v,x) Sol1(c.x) V1(c,u) AND V1(u,v) AND V1(v,x) Sol2(c,x) V2(c,g) AND V1(g,x) Sol3(c,x) V1(c,u) AND V2(u,x) SELF JOIN Select R1.c, R3.p from V1 as R1, V1 as R2, V1 as R3 Where R1.p = R2.c and R2.p = R3.c;...
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