Java™ Application Development on Linux - Dator

222Chapter 9Ant: An IntroductionSample XML tagged dataIf you have an empty element, one that that either does not or cannot havedata between its start tag and end tag, you may “combine” the start and endtag by putting the slash at the end of the tag:Obviously, there is more to it than this, but it is enough to begin with.XML’s uses range from publishing to networked interprocess communications.Our interest here is in using it to represent a model of a piece of softwareand the various ways that software might be built and deployed. So from hereon, we will be discussing not XML in general, but the ant document type. Actually,ant’s markup language uses unvalidated XML. In other words, thereisn’t officially a schema for ant. Thus, the only formal definition for an antXML file is what ant accepts and understands. This is more common than itshould be. Any XML markup vocabulary really should have a schema, but oftenXML use starts with “Oh, this is just a quick thing. No one will ever read orwrite this markup. Just these two programs of mine.” These famous last wordswill one day be right up there with “I only changed one line of code!” Asstrongly as we feel about this, ant really can never have a DTD, at least not acomplete one. The custom task feature makes this impossible.9.4.2 The Buildfile TagsThe buildfile (usually named build.xml) begins with a header announcingthat this is an XML document and specifying what version of XML is beingused in it:The delimiters mark up an XML statement (as opposed to anXML tag). 6 In this case, we are declaring that this is an XML document andthat it is using XML version 1.0.6. Note that these are the terms we are using to describe XML to a new user. They are not theformal terms for these document elements. For the proper names, consult an XML reference.