To write distributed applications, programmers must learn and use a large variety of lower-level libraries for cross-tier communication, data marshaling, synchronization, and security.

要编写分布式应用，程序员必须学习和使用针对跨层通信、数据编制、同步和安全等领域的底层类库。

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Data is organized in a number of categories - Sales, Security, Computer, Internet, Communication, Financial Management, Training, etc. -, each category being further organized in sub-categories.

同时还数据对进行了分门别类的管理，类别有销售、安全、计算机、因特网、通信、金融管理和培训等，每个分类又有进一步的子分类。

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In modern network and communication system, the security of data convey seems important day by day.

在现代的网络和通信系统中，数据传输的安全性日益显得重要。

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