Validating well-formed XML files

PDI offers different options for validating XML documents, including the validation of a well-formed document. The structure of an XML document is formed by tags that begin with the character < and end with the character >. In an XML document, you can find start-tags: <exampletag>, end-tags: </exampletag>, or empty-element tags: <exampletag/>, and these tags can be nested. An XML document is called well-formed when it follows the following set of rules:

• They must contain at least one element

• They must contain a unique root element – this means a single opening and closing tag for the whole document

• The tags are case sensitive

• All of the tags must be nested properly, without overlapping

In this recipe, you will learn to validate whether a document is well-formed, which is the simplest kind of XML validation. Assume that you want to extract data from several XML documents with museums information, but only want to process those files that...