m个进程(P_i，0≤i≤m-1)通过k个等长的缓冲区(B_i，0≤i≤k-1)向n个进程(Q_i，0≤i≤m-1)发送消息。每个进程P_i发送消息的顺序与数量不受限制，每个进程Q_i接收消息的顺序与数量也不受限制，但发送进程与接收进程作为两个分别的整体，要求消息发送与接收的整体次序相同。为保证消息发送与接收的充分并行，需要设置(24)。

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The　relational　database　model　requires　the　data　be(71)through　programs　that　don't　rely　on　the　position　of　the　data　in　the　database.　This　is　in　direct(72)to　the　other　database　mode,　where　the　program　has　to　follow　a　series　of　pointers　to　the　data　it　seeks.　A　program(73)a　relational　database　simply　asks　for　the　data　it　seeks;　the　DBMS　performs　the　necessary　searches　and(74)the　information.　　The(75)on　how　the　search　is　done　are　specific　to　the　DBMS　and　vary　from　product　to　product.

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The　kernel　is　the(66)of　an　operating　system　such　as　Windows98,　Windows　NT,　Mac　OS　or　Unix.　The　kernel　provides　basic　services　for　the　other　parts　of　the　operating　system,(67)it　possible　for　it　to　run　several　programs　at　once(multitasking),　read　and　write　files　and　connect　to　networks　and　peripherals.　Applications　and　utility　programs　use　the　services　provided　by　the　kernel　to　provide　practical　business　functionality.

In　operating　systems　such　as　Windows　or　most　versions　of　Unix,　the　kernel(68)everything　except　application　and　utility　programs.

In　microkernel　operating　systems　such　as　Digital　Unix　and　Apples　forthcoming　Mac　OS　Server,　the　kernel(69)supports　only　multitasking　and　memory　management.　Other　services　such　as　applications,　utilities　and　the　user　interface　support　device　drivers,　API　and　graphics　which　all(70)outside　the　microkernel.