Tài liệu Công Nghệ Thông Tin

Application system reuse The whole of an application system may be reused either by incorporating it without change into other systems (COTS reuse) or by developing application families. Component reuse Components of an application from sub-systems to single objects may be reused. Covered in Chapter 17. Object and function reuse Software compo...

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Program state can be modeled as a list of pairs. E.g., [[x,1], [y,5]] Function to retrieve the value of a variable from the state: get(Var, [[Var, Val] | _], Val). get(Var, [_ | Rest], Val) :- get(Var, Rest, Val). E.g., ?- get(y, [[x, 5], [y, 3], [z, 1]], V). V = 3

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Prolog programs are made from terms, which can be: Variables Constants Structures Variables begin with a capital letter, like Bob. Constants are either integers, like 24, or atoms, like the, zebra, ‘Bob’, and ‘.’. Structures are predicates with arguments, like: n(zebra), speaks(Y, English), and np(X, Y) The arity of a structure is its numb...

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A file can be treated as an input or output stream. In reality file streams are buffered for efficiency: it is not practical to read or write one character at a time from or to mass storage. It is common to treat text files as streams.

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Testing software for reliability rather than fault detection. Measuring the number of errors allows the reliability of the software to be predicted. Note that, for statistical reasons, more errors than are allowed for in the reliability specification must be induced. An acceptable level of reliability should be specified and the software tested ...

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They emerged in the 1960’s with Lisp Functional programming mirrors mathematical functions: domain = input, range = output Variables are mathematical symbols: not associated with memory locations. Pure functional programming is state-free: no assignment Referential transparency: a function’s result depends only upon the values of its parameters...

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Risk management is concerned with assessing the possible losses that might ensue from attacks on the system and balancing these losses against the costs of security procedures that may reduce these losses. Risk management should be driven by an organisational security policy. Risk management involves Preliminary risk assessment Life cycle risk ...

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Conversion is the technical process by which a new system replaces an old system Three major steps to a conversion plan Acquire and install needed hardware Install software Convert data Three dimensions to a conversion plan Conversion style Conversion location Conversion modules

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Benchmarks uses the java.util.Random class — a more controlled way to generate random numbers. Constructors: If we set the same seed, we get the same “random” sequence.

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Imperative programming paradigm Algorithms + Data Structures = Programs [Wirth] Produce a program by functional decomposition Start with function to be computed Systematically decompose function into more primitive functions Stop when all functions map to program statements

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