How to Parse Missing XML Nodes

Search out the missing nodes.

XML coded files create interactive Web pages of information which the reader can use to search, manipulate or rearrange to suit a particular purpose such as a data query. Each line of code, called a node, contains a piece of data used by the server to relay that data to the reader. The server reads the entire document before accepting a command prompt or query. If a node is missing anywhere within the code, the server registers a "Fail" and no data is delivered. Several languages, Visual Basic, C#, C++, Java, Python and others, can be deployed to parse the document and find the missing nodes.

Instructions

1. The following is a typical section of XML code:

   <?xml version="1.0" encoding="UTF-8"?>

   <urlset

   <URL>

   <loc>http://knowyourtrade.com/</loc>

   <priority>1.00</priority>

   <lastmod>2009-05-25T20:49:54+00:00</lastmod>

   <changefreq>daily</changefreq>

   </URL>

   <URL>

   <loc>http://knowyourtrade.com/review.html</loc>

   <priority>0.80</priority>

   <lastmod>2009-05-25T20:49:54+00:00</lastmod>

   </URL>

   <URL>

   <loc>http://knowyourtrade.com/sort2.html</loc>

   <priority>0.80</priority>

   <lastmod>2009-05-25T20:49:54+00:00</lastmod>

   <changefreq>daily</changefreq>

   </URL>

   Notice in the second Document Object Model (line 13 DOM), the

   "<changefreq>daily</changefreq>"

   node is missing.

2. Formulate a search program first by counting the number of nodes in a typical DOM, four in this case, and give them a name: (Article 1) (Article 2) and so no.

3. Create a search parameter that addresses the missing nodes like: "return,(null;1), return,(null;2)," and so on. You will not necessarily need to include all four probe values in the search. If you know that there is only one area where a node might be missing, one will work.

4. Write a basic search program in the language of your choice and insert the search parameters you have written into the body of the program. Code protocol varies with the particular language you are using. Use the one you are most familiar with.

5. Run the search and examine the returned line results. Fill in the error lines with the appropriate nodes. Run the XML file. If the results are unsatisfactory, examine your search program for possible errors and run it again.

Tips & Warnings

• For the easiest way to find a solution if your search program fails, go to a forum that specializes in your code language, enter your code and an example of your XML file and ask for help. Node parsing is a common problem and most programmers are eager to volunteer a solution to your problem.

• Keep a separate file of your original XML document. A faulty search program can occasionally change embedded code. Always use a fresh file version when running a new search.

References

• W3 Schools: XML Parser
• W3 Schools: XML DOM Nodes
• Javs2: Read XML Node Using the XML Path
• Stack Overflow: XML Missing Element in Python