The main task to meet virtually all popular (they have listed) with the relevant JAPANESE (there are also) web frameworks. Languages can be divided into two broad classes: compiled (albeit in a bytecode) with strict static typing — Java, C# and interpreted (albeit byte-code :) ) with nonstrict dynamic typing — Python, PHP, Ruby. If used to write in Pascal, the first you must to learn will be easier, and second, as a rule, is a more compact code (and, logically, less development time).
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Personally, I would choose between Java and Python. From learning C# would have abstained due to strong binding of the most popular framework for it to a specific OS family (Mono is not an analogue .Net — they support multiple overlapping APIs for cross-platform you will need to use only the crossing), from PHP in mind a large number of "legacy" features of the language itself and its standard libraries of Ruby — a rather small community, IMHO.
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You can still see server-side Javascript (not to study another language, but without JS you are unlikely to do), but then I really have nothing to say, except that there is node.js and it is focused on asynchronous processing model.
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>The problem is compounded by the fact that it is necessary to work with magnetic stripe readers and other tricks.
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Not experienced, but something tells me that the server platform there is practically nothing depends