Message passing is both time- and space-coupled – that is, messages are both directed towards a particular entity and require the receiver to be present at the time of the message send. Consider the case, though, where messages are directed towards a name rather than an address and this name is resolved using DNS. Does such a system exhibit the same level of indirection?
What will be an ideal response?
, in DNS, a name may map on to more than one IP address, for example to share load across a number of computers. Given this, a name server provides an additional level of indirection in that a sender may not be bound to a given receiver but rather refer to a logical name which is then bound to one of a number of possible receivers. This provides a similar effect to space uncoupling although the implementation details are different when compared to communicating through a more explicit intermediary such as a group, publish-subscribe system, message queue or shared memory abstraction.
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Harvard researchers are experimenting with robot swarms which are groups of robots that ________
A) work together to perform a task without human intervention B) provide large scale commercial kiosks C) sweep minefields for unexploded ordinance D) storm buildings
Define intangible costs and benefits. Give an example of each one.
What will be an ideal response?
The __________________________ authorizes access to the database.
What will be an ideal response?
Which of the following is the port number used by HTTP?
A) 3389 B) 80 C) 443 D) 21