XML to LINQ Question/s

Question

Hello,

Just before I begin heres a small overview of what I'm trying to achieve and then we'll get down to the gory details. At present I'm developing an application which will monitor a users registry for changes to specific keys which relate to user preferences. Were currently using mandatory profiles (not my choice), anyway the whole idea is to record the changes to a location where they can be writen back to a users registry next time they log on.

At the moment I have the system monitoring registry changes and firing events returning the key, value name and value that have changed. I was entering these into a list to create a single string containing all the data, then writing that list to a text file every so often. Now this has all been fine but I need to change the way data's held as breaking the strings down into key, value name and value again for the write back to registry requires too much overhead and theres also problems breaking the strings up in a uniquely identifiable fashion.

So it was suggested to me to look at XML, which I haven't used before and I've begun investigating it and it all looks simple enough, I've also used LINQ before to connect to embedded databases. What I'm currently struggling to get my head around is how LINQ is able to retrieve and manipulate the data in memory from XML, as I don't want to be constantly accessing the XML file due to a need to keep the application as quick as possible. At present all changes in the registry are cached into a List(String) then written to a text file every minute or so.

At the moment what I have is the system returning the key, value name and value in different strings, converging these into a single List(String) value, where as what I'm going to need is table or equivalent representing a key, which contains multiple value names with each value name containing a single value and finally a type (this wil be a number representing what kind of registry value this is, REG SZ, REG BINARY etc). Both in the XML file and the program it self.

Also what I don't quite get is unlike a database the tables and there schemas won't exist until the program first runs as it will create a new XML file rather than it already existing. This is due to the information being writen back to the users personal drive, so it has to be created when it first runs on the users machine.

I've tried a few links and tutorials etc but nothing has clicked just yet, so if you have an example or could maybe explain it to me a little better it would be appreciated.

Just one final bit I want to add is that my current idea for storing the data in program is to create a List of values, embedded in a List of value names and a list of value names embedded in a list of keys. Does that sound ok?

Now I know this is long, and kind of all over the place, so if someone could help it would be appreciated or if you require further information of clarification please let me know and I'll try my best.

Thanks

Answer 1

From what you describe it does seem like a good idea to use XML here.

As for accessing the XML dta in memory, I found the MSDN documentation quite helpful:
http://msdn.microsoft.com/en-us/library/bb387098.aspx

The basic idea is, LINQ-to-XML is just LINQ-to-Objects, working with objects that represent the XML elements.

I'm afraid I don't quite get your second question.

Answer 2

From what I understand, you are just thinking in the wrong direction. Your application does not want to manipulate XML in memory. You just want to work with some data structure in memory and would like to have an easy way to store it to disc and to read it back? If I understand that right:

Don't care about LINQ for XML. Just have a look at the build in XML serialization infrastructure. Then build an internal data structure which fits your applications needs and use an XmlSerializer to write it to disc and to read it back. No need to touch any XML by hand!