ASP.NET Web Service - how to handle special characters in strings?

Question

To show this fundamental issue in .NET and the reason for this question, I have written a simple test web service with one method (EditString), and a consumer console app that calls it.

They are both standard web service/console applications created via File/New Project, etc., so I won't list the whole code - just the methods in question:

Web method:

    [WebMethod]
    public string EditString(string s, bool useSpecial)
    {
        return s + (useSpecial ? ((char)19).ToString() : "");
    }

[You can see it simply returns the string s if useSpecial is false. If useSpecial is true, it returns s + char 19.]

Console app:

        TestService.Service1 service = new SCTestConsumer.TestService.Service1();

        string response1 = service.EditString("hello", false);
        Console.WriteLine(response1);

        string response2 = service.EditString("hello", true); // fails!
        Console.WriteLine(response2);

[The second response fails, because the method returns hello + a special character (ascii code 19 for argument's sake).]

The error is:

• There is an error in XML document (1, 287)

• Inner exception: "'', hexadecimal value 0x13, is an invalid character. Line 1, position 287."

A few points worth mentioning:

• The web method itself WORKS FINE when browsing directly to the ASMX file (e.g. http://localhost:2065/service1.asmx), and running the method through this (with the same parameters as in the console application) - i.e. displays XML with the string hello + char 19.

• Checking the serialized XML in other ways shows the special character is being encoded properly (the SERVER SIDE seems to be ok which is GOOD)

• So it seems the CLIENT SIDE has the issue - i.e. the .NET generated proxy class code doesn't handle special characters

• This is part of a bigger project where objects are passed in and out of the web methods - that contain string attributes - these are what need to work properly. i.e. we're de/serializing classes.

Any suggestions for a workaround and how to implement it?

Or have I completely missed something really obvious!!?

Thanks in advance...

PS. I've not had much luck with getting it to use CDATA tags (does .NET support these out of the box?).

Answer 1

You will need to use byte[] instead of strings.

Answer 2

I am thinking of some options that may help you. You can take the route using html entities instead of char(19). or as you said you may want to use CDATA.

To come up with a clean solution, you may not want to put the whole thing in CDATA. I am not sure why you think it may not be supported in .NET. Are you saying this in the context of serialization?