这意味着此类文档的流通必须能够跟踪，而这又要求传输协议要十分可靠。

This means that the flow of such documents must be traceable, which requires a transport protocol that is reliable.

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此外，现在已经有许多重要的传输支持可靠的消息传递，并且在传输级别对必要的格式和协议进行了编码。

Furthermore, there are important existing transports that already support reliable messaging and encode the necessary formats and protocols at the transport level.

youdao

当然，其中之一是Web服务通常是使用不可靠的无状态传输协议(明确地说是HTTP)来实现的。

One, of course, is the fact that Web services are often implemented using unreliable, stateless transport protocols, specifically, HTTP.

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