读取C＃编写的XML文件

Question

I have a program that logs it's progress and other data to an XML file. I want to be able to open this XML file without blocking out the writer program (not a .NET program, and I have no control over it), and to read the XML as it comes, waiting for more when it is all processed, until the EOF is received.

How can this be achieved in C#?

Note that there are 2 problems:

1. Keeping a reading stream open without blocking the other process.
2. Knowing when there is more input and waiting when there isn't.

Answer 1

If I needed to do this I would do something like the following:

Use a FileSystemWatcher to get notified when the file changes. Then just read the file and parse the XML as you require.

I would go down this route as it will be difficult to read the stream as and when the external application writes to the file.

Answer 2

I did soemthing similar in past yielding in an OS program called Tailf . Just check the code if you want to do it yourself, or grab all from it, it should almost work for you as well, a part the fact I just care about text files.

Answer 3

You can open a file stream without locking it by passing in the following flags:

new FileStream(logFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

As far as waiting for the "EOF", if the other program is only writing data intermittently, you may have to put some sort of heuristics into your progress (ie. stop peeking for new data only if there's nothing new for X minutes).