People are indulging in an illusion whenever they find themselves explaining at a cocktail (鸡尾酒) party, say, that they are "in computers," or "in telecommunications," or "in electronic funds transfer". The implication is that they are part of the high-tech world. Just between US, they usually aren’t. The researchers who made fundamental breakthroughs in those areas are in a high-tech business. The rest of us are (71) of their work. We use computers and other new technology components to develop our products or to organize our affairs. Because we go about this work in teams and projects and other tightly knit working groups(紧密联系在一起的工作小组), we are mostly in the human communication business. Our successes stem from good human interactions by all participants in the effort, and our failures stem from poor human interactions.
B.
The main reason we tend to focus on the (72) rather than the human side of the work is not because it’s more (73) , but because it’s easier to do. Getting the new disk drive installed is positively trivial compared to figuring out why Horace is in a blue funk (恐惧) or why Susan is dissatisfied with the company after only a few months. Human interactions are complicated and never very crisp (干脆的, 干净利落的) and clean in their effects, but they matter more than any other aspect of the work.
C.
If you find yourself concentrating on the (74) rather than the (75) , you’re like the vaudeville character (杂耍人物) who loses his keys on a dark street and looks for them on the adjacent street because, as he explains, "The light is better there!".
For nearly ten years, the Unified Modeling Language (UML) has been the industry standard for visualizing, specifying, constructing, and documenting the (71) of a software-intensive system. As the (72) standard modeling language, the UML facilitates communication and reduces confusion among project (73) . The recent standardization of UML 2.0 has further extended the language's scope and viability. Its inherent expressiveness allows users to (74) everything from enterprise information systems and distributed Web-based applications to real-time embedded systems.
B.
The UML is not limited to modeling software. In fact, it is expressive enough to model (75) systems, such as workflow in the legal system, the structure and behavior of a patient healthcare system, software engineering in aircraft combat systems, and the design of hardware.
C.
To understand the UML, you need to form a conceptual model of the language, and this requires learning three major elements: the UML's basic building blocks, the rules that dictate how those building blocks may be put together, and some common mechanisms that apply throughout the UML.
Each machine supporting TCP has a TCP transport entity, either a library procedure, a user process, or part of the kernel. In all case, it manages TCP streams and()to the IP layer. A TCP()accepts user data streams from local process, breaks them into pieces not exceeding 64KB, and sends each piece as a separate IP(). When datagrams containing TCP data arrive at a machine, they are given to the TCP entity, which reconstructs the original byte streams.
B.
The IP layer gives no guarantee that datagrams will be delivered properly, so it is up to TCP to time out and()them as need be. Datagmms do arrive may well do so in the wrong order, it is also up to TCP to()them into messages in the proper sequence.