c# pattern for two applications sharing a configuration file - c#

I have two applications that have many common configuration properties. When a configuration property of one changes, I want the other to change as well. Does anyone have a sensible way to accomplish this before I start off down the wrong track?
EDIT: I'm using .NET 2.0

You can create and reference a common configSource for the configuration section(s) involved. For instance, if you wanted a common set of AppSettings, copy your current appSettings to a new file (say appSettings.shared.config) and replace them in both app configs with this:
<appSettings configSource="appSettings.shared.config"/>
Here's more documentation: http://sunali.com/2008/01/23/configsource-property-dividing-configuration-files-into-pieces/
Far as I know, this cannot be done for an entire file, only sections, and each section will need its own file (and the section must still be declared in the configurationsections element of the app.config). But, this has a number of really cool uses; for instance, you can separate your connection strings into files geared towards different environments (local, development, testing, staging, production) and by changing one filename in one place you've now pointed your app at the different environment.

One easy way to accomplish this is to use the configSource attribute in the app.config in both applications, and point this to a common file. Bingo, change one file, all apps are updated.
Check the MSDN documentation on it here.

there are a couple of different ways you could do this:
use the registry
use a config file in a common location
use a configuration table in a database

Related

How to use environment dependent app.config file

We are a group of C#/.NET 4.5 developers working on the same application.
The application has a set of configurations related to each developer machine, like the connection string to the DB, network related settings (proxies, IPs, credentials) and a LOT MORE.
Because the application has grown we are incurring in a lot of environment related configurations like for example:
If this is MyPC then load the connection string for my PC.
If this is the XDeveloperPC then specify proxy’s settings.
Also if new developers leaves or join the group, then the process to update the file becomes a total head ache. Maintaining the file has become very hard and is a possible source of bug and errors.
I was thinking in having specific app.config files related to each developer environment like:
app_MyPC.config
app_XDeveloperPC.config
And when the application builds or executes then specify which one to load as if it where the default app.config of the application. Then, when the application or any class or method refers to a given configuration (like the connection string) is access to this configuration file as if it where accessing to the app.config default file.
I would not want to create a Configuration class that builds immediately when the application starts because then I should have references from every place to this class and the application is quite large, with a bunch of projects and dlls.
I rather prefer to hear some opinions and what do you think should be the best way to achieve this.
Is it possible to achieve this?
How?
Do you know a better approach?
FYI, please note that .NET only loads one config file for the whole application. You could try multiple config files something as like specified here,
Multiple App.Config Files in .NET Class library project
Hope this helps...
You can specify sections of app.config to be loaded from another file. See this answer
However, you might have to customize the above solution, the app.config files and the way configs are organized.
Another approach is to use a custom settings file instead of app.config. This will need some code change to use the config file. This config can either be an XML or a JSON file (JSON is easy to deal with). You can use an inheritance model wherein generic settings come from one file, specific settings come from another file and so on. Also, you can load settings from such file at runtime and change application behavior on the fly.
If you decide to use custom config file, and if you already have lot of code written considering App.config file, you can abstract the app.config calls to a method and let that method deal with where to pull the settings value from. That way you can minimize the code change and keep everything tidy.
Maybe you can use the machine.config file (C:\Windows\Microsoft.NET\Framework\your Framework version\Config\machine.config)

Using .NET ConfigurationManager to read settings from a string instead of an app.config file

We are running multiple instances of our service (implemented as a .exe file) on different machines in our data center. However, we would like to store configuration parameters for this .exe file in a central location (as opposed to being in the .exe.config per machine).
To do this, we are planning to move the content of the .exe.config files to an attribute in a central repository (Active Directory or SQL) and make the .exe's running on all machines read from this repository.
I would like reuse all the existing classes used for reading/writing configuration information (using ConfigurationManager, ConfigurationProperty etc., basically using the entire .NET Configuration framework) - however, instead of loading it from the .exe.config file (which it does by default - I want it to load it from a string value of the XML blob that I will retrieve from that central repository.
I was trying to find ways to do it using the ConfigurationManager API but couldn't find anything that could load a Configuration Section from a string. Any pointers?
I suppose you could write your own ConfigurationSection that will then load the real config data from your central repository.
Alternatively, do you have some sort of centralized deployment system in place for installing software on your various servers? How does your service get deployed? Rather than adding complexity to your software you should look for existing tools that already solve your problem.
Although I doubt this is what it was intended for, we've done this in our project using ProtectedConfigurationProvider. Basically, this class is supposed to allow you to encrypt your configuration file but we simply have the Decrypt method connect to our database and return the configuration information. See this for notes on implementing. This felt a little hacky, but we couldn't find any other way without completely rewriting all of the configuration parsing logic.

How to use partial config files

I am involved in a project where development and testing is going on in different locations. There are a few entries in the app.config that are "local" to the different locations (hence, "config"). Therefore, everyone tends to keep his own app.config, which always makes it difficult for a new setting to be introduced.
I'm looking for an idea, something like partial classes, where the bulk of an app.config can be in one place, and a few items in another, and yet all wind up in the proper exe.config after a build.
First of all you can split up config file using the configSource attribute. For example, in web.config you could write:
<authentication configSource="ConfigFiles\authentication.config" />
.. and have your authentication config in another file. This may be of use to you, with local variations (eg. DB settings).
Secondly, and more importantly, you probably want to watch this video to learn about deploying to different environments (using web.debug.config and web.release.config)
http://www.hanselman.com/blog/WebDeploymentMadeAwesomeIfYoureUsingXCopyYoureDoingItWrong.aspx

web.config best practices when upgrading

I send out an app and I let customers make changes to connection strings and such in the web.config.
When I upgrade my app this causes an annoyance because I don't want to overwrite their values with mine.
This is especially bad when versions of .net are upgraded.
How do people typically handle this type of situation?
For example do they somehow split the web.config out so the customer data is no longer part of it?
I've never heard of anyone making web.config accessible and writable to customers or any other business folk. You're just asking for trouble.
It sounds like you may want to develop a small front-end (web) utility to allow them to submit values in a form and save to a database. Then have your application access the database for these values, and not the web.config.
This seems to be more of a content management issue.
Split your configuration file into two. One for you and the other for your customers.
All configurations that are customizable by your customers go into the customer config file and everything else goes into yours.
This will let you easily upgrade/modify your config file without overwriting your customers'.
You can use the SectionInformation.ConfigSource element to declare associated configuration files. This blog post shows you how you can do it.
I even used it in this project to detect changes to external configurations in ASP.NET.
There are a few ways to handle this. I'll mention two. One concerns your delivery process. The other actually involves the web.config.
1) Don't ship the web.config as "code". Consider it "configuration". This doesn't apply well to all scenarios (in fact, a customer based scenario is the bad scenario I was thinking of). If you are delivering to "production" you can agree to make them responsible for the contents of web.config (and a good practice there is to try and refactor as much as you can to machine.config). That way, things like the connection string become production concerns and not development concerns.
2) Use the configSource attribute. ASP.NET 2.0 supports externalizing attributes with the configSource attribute. It can be hard to turn over ALL of the web.config as a "production concern" (in a delivery to customer scenario, They may not be experts in all of this).
So you externalize it like this. Here is your current appSettings section, for example:
<appSettings>
<add key="EnableFrobbing" value="false" />
<add key="ExpectFooingFrom" value="fooingserver#domain.com " />
</appSettings>
If these are settings you want to externalize so your new shipments don't override customer settings, replace it with this:
<appSettings configSource="App_Data\WebConfigXML\appSettings.xml"/>
Relative paths only here as far as I know.
References:
(Shows the property is new in ASP.NET 2.0)
http://msdn.microsoft.com/en-us/library/system.configuration.sectioninformation.configsource%28v=VS.80%29.aspx
http://www.codeproject.com/KB/aspnet/Manage_Webconfig.aspx
http://trycatchfail.com/blog/post/2008/09/25/Webconfig-magic-configSource-and-file-attributes.aspx
You have a couple options. The best, IMO, would be to not publish web configs when you push the app to their environment. If a new configuration section/setting needs to be written, you can either encapsulate some logic to programmatically write the new config in a little helper app and run that as a post-deployment action, or you can just paste the new settings into an e-mail and send to someone you trust on the other end to put it in the configs. I would recommend against the second option in 99% of cases; there is a lot of potential for crossing wires or just being ignored, then it's your fault when the system goes down because the configs didn't make it in.

How do I create C# configuration files for each of my classes?

If I go to Project -> Myproject Properties -> Settings I can create a settings file for the entire project. However supposed each class requires its own configuration file. Is there a similar way to do this at the class level?
By way of example suppose I have a parent class Car with subclasses Ford and Honda. I want to have a single property YEAR and a single piece of code for reading the YEAR property. I could do this by having two configuration files with the same YEAR property. If I used Ford.YEAR and Honda.YEAR than I would need two separate pieces of code for parsing the data which could get messy for a large number of classes.
It's not really designed for that.
You can use the System.Configuration.ConfigurationSettings classes to open a file explicitly in code to read your settings from. THis will work however the designer will give you no assistance creating your settings files.
Do you have an issue with class wide settings?
Another way that might help you is to create a custom configuration section which you can put in the file. Then you can split each of your classes settings into it's own configuration section. That might suit your purposes?
Configuration data is stored for an executable in its config file (which is a single file, regardless of the number of "settings" files in your project) and is not class-specific. You can set naming conventions for your setting keys configuration options related to a class like ClassName.ConfigName.
You could to create specific sections for your subclasses: How to: Create Custom Configuration Sections Using ConfigurationSection
When you start a .net application, it takes your entry point assembly configuration file and load it up into memory. But just one.
So, if you have a MyApplication.exe which uses a MyLibrary.dll and both have configuration files, just MyApplication.exe.config will be loaded.
You'd have to do it manually, as the others have suggested. However, I'd strongly recommend against this, as I would think you'd have a configuration nightmare to deal with in the end.
As per the other answers, no configuration files are not class specific, you'd be best off creating a class which handles retrieving and setting configuration (a ConfigManager-style interface).
I'd have to ask you though, do you really want configuration per class?
That sounds like a configuration management nightmare scenario. You'd have to entertain scenarios where configuration is either missing or invalid on a per-class basis - and take appropriate steps accordingly.
If your design calls for per-class configuration, perhaps you would be better served storing it in a database or using another medium?
Many of the current IoC containers would allow you to do such a thing through its dependency injection (DI) possibilities. In fact, when XML configuration was all the rage in DI land, you would pretty much get all this out of the box. Today many IoC containers support a programmatic way of setting up dependencies, which you can quite easily hook to whatever XML file you want to provide. Check out this example with the IoC container StructureMap:
IContainer c = new Container();
c.Configure(ce=>
ce.For(typeof(A)).Use(typeof(A)).WithProperty("Test").EqualTo("Hello"));
var a = c.GetInstance<A>();
Debug.Assert(a.Test == "Hello");
By parsing an XML file containing information like targeted type, name of the property, its value, and then calling the above API, you can get what you want.

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