We Keep Coding

ConfigurationSection various names and schema validation

I have custom System.Configuration.ConfigurationSection derived class which represents configuration section in my app.config file. I also have xsd schema document for that XML document. Configuration file has the following (simplified) structure:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="sectionOne" type="/*...*/" />
<section name="sectionTwo" type="/*...*/" />
<section name="sectionThree" type="/*...*/" />
</configSections>
<sectionOne xmlns="http://tempuri.org/MySchema.xsd">
<Container>
/*...*/
</Container>
</sectionOne >
<sectionTwo xmlns="http://tempuri.org/MySchema.xsd">
<Container>
/*...*/
</Container>
</sectionTwo >
<sectionThree xmlns="http://tempuri.org/MySchema.xsd">
<Container>
/*...*/
</Container>
</sectionThree >
</configuration>
As we can see, I have a several sections of that type, for various purposes, and I retrieve configuration data using ConfigurationManager class:
ConfigurationManager.GetSection(sectionName);
Because section name is not constant string value, xsd schema validate only elements that are children of the root element (starting from Container tag). Therefore in VS2012, in Error list toolbar, I get a following messages:
Could not find schema information for the element 'http://tempuri.org/MySchema.xsd:SectionOne'.
Could not find schema information for the element 'http://tempuri.org/MySchema.xsd:SectionTwo'.
Could not find schema information for the element 'http://tempuri.org/MySchema.xsd:SectionThree'.
How to fix that validation mechanism.

There is no solution that does not involve changing a XSD: it is not possible to write a schema matching elements with arbitrary names. All the possible valid element names must be specified explicitly, so to validate correctly the names of the section elements must be added either to the http://tempuri.org/MySchema.xsd schema or to DotNetConfig.xsd.

Variables in XML configuration

I'm trying to use xml configuration file in my project. Now it looks like:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="replication" type="Project.Replication.ReplicationConfigSection, Project.Replication" />
<section name="processing" type="Project.Processing.ProcessingConfigSection, Project.Processing" />
</configSections>
<replication>
<streams>
<stream name="STREAM_DATA_14360" />
</streams>
</replication>
<processing dataStream="STREAM_DATA_14360" />
</configuration>
It works OK, but I'm confused with duplicates in it ("STREAM_DATA_14360").
Can you remind me, how to create variables in XML or something for data reusing to be acceptable in application configuration?
UPDATE:
In real life my configuration has much more sections. There is a value, which apeears in many of this sections: STREAM_DATA_14360. So I want to be able to change this value only in one place of config file, and in other places to use reference to it.
Speed of changing configuration - is the first reason for it.
Size of a file is a second, because values can be huge: STREAM_INFO_FUTURE_SESSION_CONTENTS_12421 (that is third-party names)

You can simply add this value in <appSettings> and access it as you are saying.
You can do this as below:
<appSettings>
<add key="StreamName" value="STREAM_DATA_14360"/>
</appSettings>
In the code, you can access it as below:
string streamName = ConfigurationManager.AppSettings["StreamName"];
Make sure to add reference to System.Configuration assembly before using this.

XML doesn't have any native expansion macros or templating - any scenario would require that you do a preprocess step or have the code that reads the config involved in substituting the value.
If those aren't redacted names though, it seems a simple search/replace would solve the problem without much of a concern on false positives.
You could put something together with T4 templates as a preprocessor, whether that's worth it really depends on how often you expect to modify this file.
It should also be possible to shoehorn the web.config transformation engine into doing the replacements, but you may have to write some hosting code for the XDT engine depending on how your config file is setup.

Apart from using external code that might (or might not) facilitate your life, you can define your own classes that inherit from ConfigurationSection, wherein you define and encapsulate your key/value pairs and use the ConfigurationProperty attribute.
Have look at http://msdn.microsoft.com/en-us/library/2tw134k3.aspx for more info on How to: Create Custom Configuration Sections Using ConfigurationSection.
EDIT: you can make references in xsd (check here)

Thanks for your answers. I agree with Mark, there's no support of variables or references in XML. But, in my case there's much simpler solution. I feel stupid now, but hope that it will help another slowpoke too.
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="global" type="Project.GlobalConfigSection, Project" />
<section name="replication" type="Project.Replication.ReplicationConfigSection, Project.Replication" />
<section name="processing" type="Project.Processing.ProcessingConfigSection, Project.Processing" />
</configSections>
<global>
<streamNames>
<streamName name="STREAM_DATA_14360" id="1"/>
</streamNames>
</global>
<replication>
<streams>
<stream nameId="1" />
</streams>
</replication>
<processing dataStreamId="1" />
</configuration>
Consequence: need to edit code to use global section as a source of all long names
Advantage: fast renaming, reusability of values

Edit App.Config name-value pairs from a separate tool

I am trying to create a simple tool for a service person to update a few entries in the App.Config of a different program. The App.Config file contains custom parameters used upon initialization of our program.
Since the App.Config contains many sensitive items a tool is needed to ensure only certain parameters are changed. Thus, the reason not to allow them to edit the App.Config directly.
My questions:
How can I access the name-value pairs from the config sections of an App.config from a separate program?
Which is better suited for the UI: Winforms or WPF? Are their controls that make it easy to add more entries in the future?
The tool should allow the user to set either a String, int, double or Boolean.
Here is the structure of the App.Config:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<sectionGroup name="Settings">
<section name="Section1" type="System.Configuration.NameValueSectionHandler"/>
<section name="Section2" type="System.Configuration.NameValueSectionHandler"/>
<section name="Section3" type="System.Configuration.NameValueSectionHandler"/>
<section name="Section4" type="System.Configuration.NameValueSectionHandler"/>
</sectionGroup>
</configSections>
<Settings>
<Section1>
<add key="NAME_STRING" value="Some String"/>
</Section1>
<Section2>
<add key="NAME_INTEGER" value="10"/>
</Section2>
<Section3>
<add key="NAME_DOUBLE" value="10.5"/>
</Section3>
<Section4>
<add key="NAME_BOOLEAN" value="true"/>
</Section4>
</Settings>
... Omitted ...
</configuration>
In the program which uses the App.Config itself, I can easily change the values like so:
NameValueCollection nvc = (NameValueCollection)ConfigurationManager.GetSection("Settings/Section1");
Is there a similar way to do this from a separate program after loading the App.Config?

An answer to Question 1: An app.config file is an XML file. It might be easiest to load it as an XML document and modify that programmatically, followed by a save, than to use System.Configuration classes.
ETA: I believe it can be done with ConfigurationManager. Look at the OpenMappedExeConfiguration method. There's a good example there.

You could treat the app.config file as a normal XML file. Use either XDocument or XmlDocument to load the file.
Then use XPath or Linq to XML to find the name-value pairs.
As for Windows.Forms vs. WPF, its a design decision. Both have good and bad points.
[Update]
If you still want to use System.Configuration, you can use the ConfigurationManager.OpenExeConfiguration to get access to the other program's app.config file. This returns a Configuration object, which has a GetSection method.

Add custom configuration Element at runtime

Is it possible to add an custom configuration element at runtime.
Here is my app.config file
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="NodeList"
type="Configuration.NodeListSection, NodeListConfiguration"
requirePermission="false" />
</configSections>
<NodeList>
<nodes>
<add name="Dev1" isdefault="false" description ="Dev server" />
<add name="QA1" isdefault="true" description="QA server"/>
<add name="Prod1" isdefault="false" description="Production" />
</nodes>
</NodeList>
</configuration>
Can we add more nodes at runtime using C# code.

This doesn't appear to be from a built-in configuration section. You will find that "NodesList" is an section/element that is custom written. To determine where in your codebase it is coming from look for "NodesList" at the top of your config file in the configSections element. That will point you at the class to look into.
After that, you need the class to support write operations properly.
To learn a lot more about customising configuration files there is a great series at CodeProject on the topic. In particular, the section on Saving Configuration Changes should be helpful to you.
Edit (after more info added to question):
Try something like (of course it all depends on what's in NodeListSection codebase):
using Configuration;
var nodeListSection = ConfigurationManager.GetSection("NodeList") as Configuration.NodeListSection;
var newNode = new NodeElement() { Name = "xyz", IsDefault = false, Description = "New Guy" };
nodeListSection.Nodes.Add(newNode);
Configuration.Save(ConfigurationSaveMode.Modified);

The file you have posted does not look like a normal .NET config file, but a custom XML file.
In either case - .config files are just XML files - you can open, manipulate and save them using any of the XML libraries within the BCL, such as XDocument.
However, if you want to make changes to configuration during runtime, you will need to decide whether the application should apply these changes at runtime as well and code for this, as normally a configuration file will only be read at startup.

private void AddNewKey_Config(string key, string value, string fileName)
{
var configFile = ConfigurationManager.OpenExeConfiguration(fileName);
configFile.AppSettings.Settings.Add(key, value);
configFile.Save();
}

Unity Configuration and Same Assembly

I'm currently getting an error trying to resolve my IDataAccess class.
The value of the property 'type' cannot be parsed. The error is: Could not load file or assembly 'TestProject' or one of its dependencies. The system cannot find the file specified.
(C:\Source\TestIoC\src\TestIoC\TestProject\bin\Debug\TestProject.vshost.exe.config line 14)
This is inside a WPF Application project.
What is the correct syntax to refer to the Assembly you are currently in? is there a way to do this? I know in a larger solution I would be pulling Types from seperate assemblies so this might not be an issue. But what is the right way to do this for a small self-contained test project. Note: I'm only interested in doing the XML config at this time, not the C# (in code) config.
UPDATE: see all comments
My XML config:
<configuration>
<configSections>
<section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Microsoft.Practices.Unity.Configuration" />
</configSections>
<unity>
<typeAliases>
<!-- Lifetime manager types -->
<typeAlias alias="singleton" type="Microsoft.Practices.Unity.ContainerControlledLifetimeManager, Microsoft.Practices.Unity" />
<typeAlias alias="external" type="Microsoft.Practices.Unity.ExternallyControlledLifetimeManager, Microsoft.Practices.Unity" />
<typeAlias alias="IDataAccess" type="TestProject.IDataAccess, TestProject" />
<typeAlias alias="DataAccess" type="TestProject.DataAccess, TestProject" />
</typeAliases>
<containers>
<container name="Services">
<types>
<type type="IDataAccess" mapTo="DataAccess" />
</types>
</container>
</containers>
</unity>
</configuration>

In unity 5.7
The section line should be like this
<section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,Unity.Configuration" />

This looks fine. Are you sure your assembly name is correct? Check the project preferences to make sure the name of your assembly is correct:
Right click your project and click Properties
Click on the Application tab on the left
Look at the value of the "Assembly Name" field.
Sometimes if you've renamed your project, this field will still be the old value.
It's possible that this is not the issue at all, but it is the simplest thing to check. If you find that this is not the issue, reply to this and I'll post any other ideas I have.
Also, you might consider posting your sample as a .zip file so we can take a look at it.

I just had the same issue. this works for me :
Turn "Copy local" to true in the properties of Microsoft.Practices.Unity.
You should also add a reference to Microsoft.Practices.ObjectBuilder2 (Microsoft.Practices.Unity depends of it)