Letting several assemblies access the same text file - c#

I've got many assemblies/projects in the same c#/.net solution. A setting needs to be saved by people using the web application gui, and then a console app and some test projects need to access the same file. Where should I put the file and how to access it?
I've tried using "AppDomain.CurrentDomain.BaseDirectory" but that ends up being different for my assemblies. Also the "System.Reflection.Assembly.Get*Assembly.Location" fail to give me what I need.
Maybe this isn't something I should but in a file, but rather the database? But it feels so complicated doing that for a few lines of configuration.

Put the file in
Path.Combine(
Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData),
"[Company Name]\[Application Suite]");

Personally, I would be leveraging the database because the alternative is either a configuration headache or is more trouble than it's worth.
You could configure each application to point to the same file, but that becomes problematic if you want to move the file. Or you could write a service to manage the file and expose that to clients, but at this point you may as well just use the DB.

Thought about storing it in the registry or in Isolated Storage? Not sure if multiple applications can share Isolated Storage or not, though.

projects can have build events -- why not add a post-build event to copy the file to all required locations?

Related

How to get access to the files stored on another repository in code

I want to get the access (read) files with text which located on another repository. Is it possible to do at all?
We faced the problem of preserving the history of big files if we place them in the same repo. For every commit it saves another copy of these files in History, which leads to very understandable issues. So we decided to create another repo and store them there. But I have noe exp how can I access it from the code inside the current solution.
I'd be nice to get the filePath of this files in currect solution, so can read them and process.
If you want to reference something, it either needs to be placed alongside your project, or you need a build step that retrieves it and places it somewhere your project can reference.
If these are actual text files you're wanting to read at runtime, those text files need to be discoverable by some means... The fact they're in another repository doesn't help, because that's just another file path that you aren't aware of.
I'd recommend building/publishing your other repository to some discoverable location that your main project can reference at build time or run time.
You can use git clone operation, and just download files to your project. In your main project add rules to .gitingnore to skip those big files from main repo.
You should take a step back and revisit the original problem - large files bogging down the repo. As I noted in comments, what you say (that each such file is copied in every commit) is not accurate; but it is true that large files - especially large binary files - can cause problems in git repos.
And the standard tool to solve those problems is LFS. This creates a separate "LFS repo" and manages its relationship to the base repo automatically, which means questions about how to manually read files from a different repo can be avoided entirely.

Create global configuration file for .net app

I have a big application that has lots of app.config and web.config files.
I also have 4 environments so for each environment i need to change specific config values to match the working env.
I feel it is a waste of time doing it manually each time and leaves a lot of room for mistakes when changing values.
Do you know a way to make it easier working with all those config files?
I also need a way to deploy them to other servers (each config to its own server and folder).
Thanks,
Chen.
The steroid approach is the :
http://social.msdn.microsoft.com/Forums/vstudio/en-US/1bec3733-0d42-4d06-af61-5225bddbdb54/how-to-implement-configuration-service-50-of-the-stocktrader-50-sample-application
Configuration Service the StockTrader Application.
EDIT.............
The poor man's way is to zip up your config files SEPARATE from your binaries.
And zip up the config files in their own zip file. That way, you "have them" if you need them, but you don't accidentally overwrite them on fresh deploys.
And if you add values to the config files, put them in your release notes.
Also, throwing good ArgumentNullExceptions (or similar) in your app when something from the configuration file(s) is not there........is a best practice.

how to change .NET user settings location

By default settings are stored at: C:\Documents and Settings\\Local Settings\Application Data\<Project Name>
How can I change this path to application directory. I also don't want to have different files for different users. How make the settings global?
I tried to change the scope of the settings to "application" but then I cannot change them at runtime.
Using the default built-in behavior you can't!
Q: Why is the path so obscure? Is there any way to change/customize
it?
A: The path construction algorithm has to meet certain rigorous
requirements in terms of security,
isolation and robustness. While we
tried to make the path as easily
discoverable as possible by making use
of friendly, application supplied
strings, it is not possible to keep
the path totally simple without
running into issues like collisions
with other apps, spoofing etc.
The LocalFileSettingsProvider does not
provide a way to change the files in
which settings are stored. Note that
the provider itself doesn't determine
the config file locations in the first
place - it is the configuration
system. If you need to store the
settings in a different location for
some reason, the recommended way is to
write your own SettingsProvider. This
is fairly simple to implement and you
can find samples in the .NET 2.0 SDK
that show how to do this. Keep in mind
however that you may run into the same
isolation issues mentioned above .
I agree with Robert Harvey's answer do it yourself, or write a custom settings provider.
You can always read and write your own XML configuration files.
There are difficulties with programmatically changing settings for all users (since they come from the exe.config file, which is usually in Program Files and thus protected from write access in modern OSes). You can try making the settings application-wide but then use the ConfigurationManager to mess with the config file, similarly to the solution to this question.

Using the database to hold application settings

I am looking at ways to make our application more extensible and easier to manipulate without having to alter the web.config (or, in our case, application.config files, which contain the appsettings node).
One way I have thought about is keeping the app settings in the database table that has a sqlcachedependancy. This means that:
Any time a setting is changed in the database, the cache is invalidated, and the settings are retrieved again, thus updating the application in realtime without having to alter files and restart the entire app.
We can create a custom tool which allows us to alter the settings.
The cons as I see it are that this may cause serious logic problems in that, if you have something that checks an appsetting at the start of a process, and it then changes halfway through, you could end up unintentionally altering the process flow, as the requirement for a complete application restart is negated.
Is there a way round this?
Is there a better way to manage appsettings, so that you can alter them on the fly remotely for one, several, or all servers in one go?
I think you've nailed the two major players:
either you have access to the file system and you put all your settings in a plethora of *.config files there
OR:
you don't have access (or only very limited access) to the server's file system and thus you're probably better off putting config settings and user preferences in a database, basically leaving nothing but the connection string to the config file on disk
Both approaches have their pros and cons. I've been trying for a long time to find a way to "materialize" a config section from a database field, so that I could basically just use the config XML, but stored in a database field. Unfortunately, the entire .NET 2.0 config system is very much "locked down" and just only assumes data will come from files - there's no way to plug in e.g. a database provider to allow the config system to read its contents from a database field :-( Really too bad!
The only other approach I've seen is a "ConfigurationService" in the StockTrader 2.0 sample app provided by Microsoft, but for my needs, it felt like overkill and like a really complex, really heavy-weight subsystem.
You could use SQLite, which will be a self-contained DB in a single file. Two birds with one stone?
If you reference an external config file that contains appsettings (leaving everything else in the normal app.config) then I believe editing it only reloads those settings, it doesn't force the whole app to restart.
There's a similar question on the subject here:
Nested app.config (web.config) files
WRT the problem of values changing in the middle of program execution, I guess you could locally cache the values, and raise an event when they change, allowing routines to reach a suitable point before using the updated values.
I think in asp.net we sort of get this for free because each page lifecyle is distinct, so the value is simply applied to new page requests only, not in the middle of an execution.
Edit: A little extra info:
Configuration Changes Cause a Restart of the Application Domain
From MSDN:
Changes to configuration settings in Web.config files indirectly cause the application domain to restart. This behavior occurs by design. You can optionally use the configSource attribute to reference external configuration files that do not cause a restart when a change is made. For more information, see configSource in General Attributes Inherited by Section Elements.
More information on the ConfigurationManager class in the System.Configuration namespace which could be used to modify the config files programatically (ie in a custom tool, if relevant disk read permissions can be provided). If you stick to using the built in configuration classes, I think changing the external configs, would not cause application restart, but would raise events (such as property changed) which you could handle, to ensure your code is not caught out by changing settings.

Is switching app.config at runtime possible?

Is there a way at runtime to switch out an applications app.config (current.config to new.config, file for file). I have a backup/restore process which needs to replace its own application.exe.config file. I have seen this post but it does not answer how to do this at runtime.
Turns out I can swap the .config file for the new one and do a ConfigurationManager.RefreshSection(...) for each section. It will update from the new .config file.
Microsoft .NET's app.config is not designed for your scenario, as well as many others. I often encounter a similar need, so I have spent a lot of effort designing a solution.
Redesign to use app.config only as a configuration bootstrap: specify where to find the rest of the real configuration data. This information should almost never change, so there is no need to handle file watching or application restarts.
Pick an alternate location for the real configuration data: a file, a database, perhaps even a web service. I prefer a database most of the time, so I create a configuration table with a simple structure that allows me to store my data.
Implement a simple library to wrap your configuration access so that you have a simple API for the rest of your application (via dependency injection). Hide the usage of app.config as well as your real configuration storage location(s). Since .NET is strongly-typed, make the configuration settings so--convert each string retrieved into the most-specific type available (URL, Int32, FileInfo, etc.).
Determine which configuration settings can be safely changed at runtime versus those that can't. Typically, some settings need to change along with others, or it simply makes no sense to allow them to change at all. If all your configuration data can safely change at runtime, then that makes things easy, but I HIGHLY doubt such a scenario. Hide the changeability and interdependencies of the configuration settings to the extent possible.
Design the response to the unavailability of your real configuration data. I prefer to treat the absence of any configuration setting as a fatal error that aborts the application, unless I can identify a usable default. Likewise, I abort in the absence of the configuration storage container (file, database table, etc.).
Enjoy, and best wishes.
Are you able to restart the application when you detect that you need to switch files? If so, it's just a matter of switching the files and restarting. Now, the tricky bit is if .NET keeps the app.config file open while the program is running. I suspect it doesn't, but if the most obviously approach fails, I suggest you have a second application (cfgswitcher.exe) which waits for the process with a PID specified on the command line to terminate, then switches config files and relaunches the original process. Then your app would just need to launch cfgswitcher.exe (passing in its own PID as a command line argument) and terminate.
As I say though, it's worth trying the more obvious approach first.
EDIT: If you can't restart the application (or even part of it in a new AppDomain) then various aspects of app.config (assembly bindings etc) can't be changed. If you're only interested in your own configuration sections changing, then I suggest you store them in a separate config file and reload them whenever you want to.
Look at the events available to you on the ApplicationSettingsBase class. There are PropertyChanged & SettingChanging that may give you what you need.
You could also watch the file and if it has changed call the reload method to get the new settings.
I don't think it is possible at all to switch the configuration at runtime without restarting, so if you can't apply Jon's approach, you should try to come up with an other approach.
Anyway, maybe it's just me not having enough information about your scenario, but this kind of feels fishy.
Are you sure that swapping the configuration file is the best way to achieve whatever requirement you need to meet? I mean, this is quite an uncommon thing. If I were you, I would try to come up with some other approach.

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