Quote:Original post by TFS_Waldo
What is the purpose of JSP?

Sun jumping on the bandwagon of Microsoft's ASP, realising that web developers seemed to want a way of mixing code and HTML

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Why use JSP?

Conventionally, because you're too much of a wuss to write a Java Servlet.

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What types of web sites is JSP aimed for?

Things maintained by people who don't have the ability, tools or inclination to write Java Servlets.

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What does XML do?

Absolutely nothing, it's just a general purpose extensible file format.

Quote:Why use XML?

Many reasons
- XML is a WELL DEFINED format for storing text (well, usually text) data in a structured format
- XML is extensible, i.e. if you have a schema you want to add something to, you can add it, and applications which don't understand that part should ignore it. This would be more tricky with (for example) a delimited or fixed-record file.
- XML takes care of some of the messier issues around, notably character encoding and escaping that would otherwise annoy you making your own text file format. You might even overlook them if making your own.
- XML is in most cases, HUMAN READABLE, so that it's possible to verify that the data appear correct manually.
- XML insists that its files are WELL FORMED, thus stopping applications from breaking the rules which govern character encoding, escaping etc (NOTE: there are some widely used XML applications which ignore this in the standard and accept badly formed files anyway)

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When should one use XML?

ONLY if you need to interchange data with other people or other peoples' applications. Generally speaking, if your data only needs to be read by your own code, there is little benefit. Some other format will probably be easier to work with.

Of course if you've already got tools which either emit or accept XML, it might be useful for your code to do so too.

Contrary to popular belief, using XML does not automatically make applications able to talk to each other. They still have to agree on a schema.

Also, I've found when doing integration, a lot of developers don't seem to understand XML very well, and produce and/or accept badly-formed (or invalid) XML.

When should you NOT use XML:

- If you need to store a large amount of data efficiently - XML adds a great deal of size to your files.
- If you need to read/write data efficiently - depending on the API and the schema, XML can be very inefficient to read/write compared to some other format.
- If you need to store (a significant amount of) binary data - XML has no standard way of doing this.
- For the sake of it.

Mark