XmlDataSource: The process cannot access the file because it is being used by another process

Question

User1196439756 posted

Ok so a little bit of background information before I ask my question. I have a desktop application that runs on my web server which writes xml files to an IIS directory every 5 seconds (The files are very small). So every 5 seconds each xml file is overwritten with new, fresh data. I use these xml files to bind 2 gridviews and a datalist on an asp.net webpage via XmlDatasource controls. This page is kind of like a "live feed" for my users so I have placed a Timer control inside an AJAX UpdatePanel that refreshes the gridviews and datalist every 5 seconds...I should also mention that I am setting the XMLDataSource.DataFile property on Page_Load according to the user's session value:

For example: FeedXDS.DataFile = "~/xml/" & Session("XmlGUID").ToString() & ".xml"

 

The problem is that I perodically get the following error:

The process cannot access the file 'C:\Webs\MySite\xml\7b7c972f-9545-4738-b5dc-b5ea00d21901.xml' because it is being used by another process.

I assume what is happening is the desktop application is trying to write the file while IIS is trying to read the file at the exact same time. How can I wrap the automatic databinding in a try catch statement?

 

Answer 1

User-821857111 posted

I think what I would do is the following in code behind (in pseudo-code):

try
    see if a file exists
    read XML file content
    deserilaise it using LINQ to XML
    cache it
    delete the file
catch
    don't do anything

GridView.DataSource = cached data 

Answer 2

User1196439756 posted

So get rid of the XMLDataSources completely? Will this cause a performance hit and be slower using LINQ to query the xml as opposed to a XmlDataSource and XSLT to bind controls?

Answer 3

User-821857111 posted

So get rid of the XMLDataSources completely?

Yes. Define an entity to represent the XML and bind a collection of that to the GridView.

Will this cause a performance hit and be slower using LINQ to query the xml as opposed to a XmlDataSource and XSLT to bind controls?

Either way the XML structure is traversed and converted into a form that can be bound to the GridView. Linq might be slower or quicker. I don't know. It's not something that would worry me unduly.

Answer 4

User1196439756 posted

Thank you for the suggestion. This seems to be working quite well so far!