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how to append a xml file in c# if exists, or make new if not?

i am adding tracing for audit purposes of a simple process i have built as an .exe and set in the scheduler to run every 10 minutes. i want to have the application output the results into an xml file.

if the file exists then open and append data to it, if it does not exist i want to create a new xml file that will be persisted and used on next run.

here is my code now, what do i need to add, how do i open the xml file (on c:/file.xml) and use it to append nodes to?

also i think my code is like a newbs, so some help in showing me the correct streamlined way would help me learn best practice with C#/ XML

string err = "";
        XmlDocument doc = new XmlDocument();// Create the XML Declaration, and append it to XML document

        XmlDeclaration dec = doc.CreateXmlDeclaration("1.0", null, null);
        doc.AppendChild(dec);// Create the root element

        XmlElement root = doc.CreateElement("STATS");
        doc.AppendChild(root);

        // Create URL's            
        XmlElement urlNode = doc.CreateElement("keepalive");
        urlNode.SetAttribute("runTime", DateTime.Now.ToString());

        try
        {
            WebProxy wp = new WebProxy("http://proxy.ml.com:8083/");
            WebClient w = new WebClient();
            w.Proxy = wp;

            if (w.DownloadString("http://wwww.idealcoding.com") != "")
                urlNode.SetAttribute("result", "UP");
            else
                urlNode.SetAttribute("result", "DOWN");
        }
        catch (Exception ex)
        {
            err = ex.Message;
            urlNode.SetAttribute("result", "DOWN");
        }
        finally {
            root.AppendChild(urlNode);
            doc.Save("c:/keepAlive.xml");
        }

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this is my XML file:

<STATS>
  <keepalive runTime="11/22/2010 9:40:43 AM" result="UP" /> 
 </STATS>

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Carl Tawn

What is it you want to add to the file, a new <STATS /> everytime it runs or a new <keepalive /> adding to STATS?

realcoding

ASKER

i want to just add keepalive nodes, such that each run of the app will log the time it ran and result.
if the file exists i want to load it into the xml object and add a keepalive node with the current runs info and so on... if the xml file does not exist then do as i do here and create a new one.

but as it stands every run of the app creates and over-writes the xml file leaving only one node , not very useful.

SOLUTION

Avodah

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ASKER CERTIFIED SOLUTION

Carl Tawn

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Avodah

Also to handle when this file gets very large I would write to a new write each hour / day. You could create folders for further organization. File would be suffixed with Date & Time. Folders would be suffixed with Date.

DaTribe

realcoding

ASKER

why would you use a serializable object? whats the gain?

Avodah

The gain for me would be simply manipulating this object easily with c# and then in the end simply turning it back to XML. Avoid the hassles with XML plus another huge bonus would be I could add or remove properties from the Audit class and deserialization would still be successful and as the file contents are over-written when saving then there would be no problem saving the new structure.

I save myself development time and hassles. More maintainable solution. In this instance as its every 10 minutes mission critical performance is not required - still some of the suggestions I provided work around that.

DaTribe