OS:Concurrent and Distributed Software Design(3)

1.1.4 Database management and transaction processing systems

       这节主要讲了数据库管理与事务处理中的并发操作问题（感觉有点像操作系统中的临界资源的处理，也有点像并行机中Cache一致性问题）。有一些数据并不要求随时的写入，而更多情况下（比如银行系统），是需要数据能够安全地访问与更新的。主要的数据库应用中的并发问题还是由于多客户端同时请求操作相同或者相关的数据造成的。

 

Requirements

l       To support separate activities

l       To ensure that the separate activities access and update common data without interference

l       To ensure that the results of transactions are recorded permanently and securely before the user is told that an operation has been done

 

1.1.5 Middleware

The idea is to build a layer of software (middleware) above the heterogeneous operating systems to present a uniform platform above which distributed applications can run.

 

1.1.6 Distributed systems: The World Wide Web

       www的相关发展 ( WWW, HTML, URL, http)

       后台大规模数据库的支持

客户端应用程序的并发加快处理速度(动画等处理)

 

 

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