Build Your Own ASP.NET 2.0 Web Site Using C# & VB, Second Edition

Path

contains methods for manipulating a file or directory

For the most part, we read from and write to text files by using the File class to

return a stream. If we want to write to a text file, we use the StreamWriter class;

conversely, we use the StreamReader class to read from a text file.

Setting Up Security

Before our ASP.NET page can read and write files on your hard disk, the ASP.NET

page must have permissions to access the file we’re trying to read or write. Setting

the permissions depends on our context. Here's a couple of possible scenarios:

❑

If you’re running the page using Cassini or Visual Web Developer’s integrated

web server, the code will run under the credentials of your user account, so

it will inherit all your permissions. For example, if you’re a computer admin-

istrator, then your page will be able to access any resource on your computer.

❑

If you’re running the page using IIS, the code will run under the credentials

of the ASPNET user account on your system. By default, this account has

access to any folder that is part of an IIS application.

Running Under IIS

The IIS scenario is particularly relevant because your web application will

run under IIS when hosted on a production server. Also of note is the fact

that, while you may fine-tune the permission rules on your development

machine, on a hosting server, you will probably not be allowed to access

folders outside your application’s virtual directory.

On your own machine, you’ll need to set special permissions only if you use IIS,

and you want to write in a folder that’s not part of an existing IIS application.

If you’re in this situation, read on. Otherwise, feel free to skip to the next section,

in which we’ll create within your application’s folder structure a file that will be

accessible under the default configuration of either IIS or Cassini.

1. Create a new folder called WritingTest somewhere on your disk. For the

purposes of this discussion, I’ll assume it’s at C:\WritingTest.

2. In Windows XP, simple file sharing is enabled by default. This hides the

Security tab you’ll need to select in Step 4, preventing you from granting web

applications write access to this directory. To disable simple file sharing,

open the Windows Control Panel and double-click the Folder Options icon.

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Setting Up Security

Figure 14.1. Disabling simple file sharing

In the View tab, uncheck Use simple file sharing (Recommended) (as Fig-

ure 14.1 indicates, this should be the last option on the list).

3. Open the C: drive with the Windows Explorer (not the IIS control panel),

right-click on the WritingText directory and select Properties.

4.

Select the Security tab.

5.

Add the ASPNET account to the Group or user names list by clicking Add…,

and typing it into the Select Users or Groups dialog as shown in Figure 14.2.

A new entry called ASP.NET Machine Account (machinename\ASPNET) will be

added to the list.

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Chapter 14: Working with Files and Email

Figure 14.2. Adding the ASPNET account

6.

Select the new user in the list, and click on the Write checkbox under Allow

in the permissions list, as shown in Figure 14.3.

7.

Click OK.

Figure 14.3. Giving write access to ASPNET

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Setting Up Security