Is there a quick way to modify environment variables, or configurations (that is accessible) for a module in IoT Edge?
Once a deployment is created, the environment variables become read only.
What would be the best practice of maintaining a modifiable set of configurations, so I can rather easily change them on the fly, and have the module be able to access them?
On Azure Cloud Services, for example, there are web configurations that are editable and would restart the service so they would kick in (since they are accessible to the service). I am looking for the same kind of behavior.
You can modify the module's device twin in the portal and deploy it. The module should be informed of the update. Alternatively you could send your module a direct message.
Screen shots on how to update the IOT Edge Module's Environment Variables.
Note, I am using the VisionAI Kit camera in this example.
Screen shots on how to update the IOT Edge Module's Environment Variables.
Note, I am using the VisionAI Kit camera in this example.
Your scenario is Cloud To Device (C2D)communication. Refer here for details.
Out of all, the best match is Module Twin Desired Property update.
You can easily create handlers for desired property updates in your edge module implementation and run custom logic based on the changes in desired properties.
For C#, the handler code would go like -
await ioTHubModuleClient.SetDesiredPropertyUpdateCallbackAsync(OnDesiredPropertiesUpdate, null);
This would be a great read on it.
P.S : Environment Variables are designed to be read-only after deployment. It should only have configurations that are deployment specific and do not change post deployment.
Related
I'm working on a UWP app (C++/WinRT) that must communicate extensively with a background process. Unfortunately, the background process must remain a full trust "Win32" process. Both are packaged in an MSIX.
For performance and programmability reasons, my first choice would be to turn the background process into an out-of-process WinRT component. App Services is a possibility but not ideal.
I've found numerous code samples for creating an OOP WinRT component via WRL. However, activation is performed via CoreApplication::RunWithActivationFactories(), which (as far as I know) requires an AppContainer.
I know I can consume a WinRT component in a Win32 process. Can I create one? If so, what would activation look like in C++/WinRT?
Yes, from the Windows 10 Version 1903, May 2019 Update, the windows have added support for non-packaged desktop apps to make use of user-defined (3rd party) Windows Runtime (WinRT) Components, which means that we can consume a Winrt component from the Win32 process directly. To successfully reference a C++ Windows Runtime component from a Win32 app, you need to use C++/WinRT to generate projection header files of your component. You can then include these header files in your app code to call your component.
For the detailed information, please refer to this article:
https://blogs.windows.com/windowsdeveloper/2019/04/30/enhancing-non-packaged-desktop-apps-using-windows-runtime-components/.
For the detailed sample, please refer to here:
https://github.com/microsoft/RegFree_WinRT/tree/master/Cpp.
Thanks.
Time and again I am faced with the issue of having multiple environments that must be configured individually for an application that would run in all of them (e.g. QA, regional production env's, dev, staging, etc.) and I am wondering what would be the best way to organize different configurations?
Would it be in the database? Different configuration files per environment? Or maybe the same file with different sections/xml tags? How would these be then deployed? Embedded within the app? Or put manually in after installation to be modified in-place?
This question is not technology-specific - I've worked with .net and Java, web-apps and desktop apps and this issue comes up time and again. I'm looking to learn different approaches to maybe adapt a hybrid to address this.
EDIT: There's one caveat that I must point out - when configuration is part of the deployed solution, it is generally installed under root user on the host. In large organizations developers usually don't have a root access to production hosts so any changes to the configuration require a new build and deployment. Needless to say this isn't the nicest approach - especially at organizations that have a very strict release process involving multiple teams and approval levels... (sigh I know!)
Borrowed from Jez Humble and David Farley's book "Continuous Delivery (page 41)", you can:
Your build scripts can pull configuration in and incorporate it into your binaries at build time.
Your packaging software can inject configuration at packaging time, such as when creating assemblies, ears, or gems.
Your deployment scripts or installers can fetch the necessary information or ask the user for it and pass it to your application at
deployment time as part of the installation process.
Your application itself can fetch configuration at startup time or run time.
It is considered bad practice by them to inject configuration files in build and compile times, because you should be able to deploy the same binary file to every environments.
My experience was that you could bake all configuration files for every environments (except sensitive information) to your deployment file (war, jar, zip, etc). And you design your application to take in an extra parameter when starts, to pickup the right sets of configuration files (from your extracted deployment file, or from local/remote file system if they are sensitive, or from a database) during application's startup time.
The question is difficult to answer because it's somewhat vague. There is no technology-agnostic approach to configuration as far as I know. Exactly how configuration is set up will depend on the language/technology in question.
I'm not familiar with .net but with java a popular approach is to have a maven build set up with different profiles. Each profile is specific to an environment. You can then define different properties files that have environment-specific values, an example from the above link is:
environment.properties - This is the default configuration and will be packaged in the artifact by default.
environment.test.properties - This is the variant for the test environment.
environment.prod.properties - This is basically the same as the test variant and will be used in the production environment.
You can then build your project as follows:
mvn -Pprod package
I have good news and bad news.
The good news is that Config4* (of which I am the maintainer) neatly addresses this issue with its support for adaptive configuration. Basically, this is the ability for a configuration file to adapt itself to the environment (including hostname, username, environment variables, and command-line options) in which it is running. Read Chapter 2 of the "Getting Started" manual for details. Don't worry: it is a short chapter.
The bad news is that, currently, Config4* implementations exist only for C++ and Java, so your .Net applications are out of luck. And even with C++ and Java applications, it won't make pragmatic sense to retrofit Config4* into an existing application. Because of this, I'd advise trying to use Config4* only in new applications.
Despite the bad news, I think it is worth your while to read the above-mentioned chapter of the Config4* documentation, because doing so may provide you with ideas that you can adapt to fit your needs.
I want to how know how to set about writing a monitoring app such as Windows task manager using Java Swing. The main feature I am concerned with is the grid with a graph which get drawn with time. What are the features that I need to accomplish this? (e.g.: Java2D etc).
JFreeChart can handle the graphing, as shown in the demo, but you'll have to use ProcessBuilder to query the host operating system for its notion of task.
Addendum: For an example, see the Memory Usage tab of the demo.
I am trying to write some simple Java web services so we can call Java code from .NET. So far, I got a proof-of-concept working under Glassfish. Pretty straightforward when the IDE does all the work.
Now I'm really bogging down on stuff in Java that should be really simple. For example, I want to externalize my configuration so I can change stuff like connection strings/usernames/application variables/etc without recompiling.
In .NET, you would just stick some strings in the web.config file in the root of the web site and use: ConfigurationManager.AppSettings["whateverIwant"];
I can get java.util.Properties to do what I want (from a standalone client), but I can't figure out where to put the .properties file and how to get the path to it from within the web service.
I need my approach to work within WebSphere Application Server as well. Thanks!
As others have mentioned, it greatly depends on the container, but almost always dynamic configurations are stored in a database instead of XML or .properties files.
As I see that this is just like a proof of concept, here's a quick and dirty solution: (don't do this for production code) use System Properties.
Disadvantage: with every change you need to reboot the container, but you don't need to recompile the app.
To use system properties in Glassfish you can go to the section "Configuration -> System Properties" and add properties there. Then from inside your application just call
String myValue = System.getProperty("myProperty");
To get the value. All java applications support these properties, but I don't know how to configure them in Websphere.
Alas, Java EE has a giant hole in the head when it comes to application configuration.
Your best bet is to either:
use JNDI to store config in the application server environment. This is hard to do portably, painful, and an absolute nightmare for the user to do any configuration. Configuration UI depends on which app server and version is in use and may be a command-line-only utility specific to that app server.
Use the Preferences API to store your configuration, and produce your own UI to edit it. This is OK ... except that you can't control when your settings are flushed and re-inited. Some app servers will do this when your app is re-deployed, which you probably don't want.
All in all, the situation absolutely stinks. There's no clean, sensible way for an app server to provide an app with a simple properties map and UI to edit it using the app server's admin tools.
I tried to work around this using web context parameters, but found that they too were buggy. Glassfish was ignoring more than the first web context parameter that was being set, and they were hard to access without having a servlet context so you couldn't really get to them easily across the whole app.
If anyone has a better answer I'd love to hear it, because the situation as it stands seems downright amazing for a spec that's been through several major iterations.
see also: Storing and editing configuration for Java EE applications
Application configuration is unfortunately container dependent. In general you access your configuration through JNDI. The approach I've recently used was the following:
Make a database available to your app (through JNDI, use the Glassfish database "wizard"). This is part is container dependent.
Create an entity bean that deserializes your settings from the database. The simple solution here is to have something like this:
#Entity
public class Setting {
#Id
private String name;
private String value;
...
}
Then it's a question of doing em.find(Setting.class, "whateveriwant").getValue(). Alternatively, you could create a single entity bean with all the settings as attributes.
Either way, this approach reduces the container dependency to a minimum.
The best solution I've found so far is "EAC4J (External Application Configuration For Java)". I've used successfully in many projects.
Put the following code in the contextInitialized method of a ServletContextListener:
ServletContext sc = sce.getServletContext();
Properties systemProps = System.getProperties();
String path = sc.getRealPath("WEB-INF/application.properties");
systemProps.load(new FileInputStream(path));
This reads from application.properties from the the WEB-INF folder of your web app when it starts. This will require a restart every time the configs change, but in my opinion, that is as it should be.
I am currently trying to use NAnt and CruiseControl.NET to manage various aspects of my software development. Currently, NAnt handles just about everything, including replacing environment specific settings (e.g., database connection strings) based on an input target that I specify on the command line.
CruiseControl.NET is used to build the application for the default environment (dev) anytime new code is committed. I also want CruiseControl.NET to invoke a build for my additional environments test and stage, but I do not want these to be automatically invoked every time that a dev build invoked (daily) as test and stage deployments happen far less frequently. Test and stage deployments only occur when the application is ready for QA.
I can easily do this by specifying multiple projects, one for each environment. However, I already have many projects configured, one for each milestone in within my application. If I have to setup 3 projects for each milestone the CruiseControl.NET configuration can get out of hand quickly.
Here is my question:
Can I parameterize a CruiseControl.NET project configuration such that the parameters are exposed by the web interface?
Preferably (I think), I could have checkboxes for each environment (e.g., dev, test, stage) exposed in the web interface. A build would be made for each environment that is checked, whether the build was forced or automatic. It would be even better if I could default the checked state.
This feature (Dynamic Build Parameters) is currently being worked on for 1.5, and you can try it out in the nightlies. Here's a post describing the feature.
As Scott has mentioned, this isn't available, but it wouldn't take too much just to write a little template and then auto-generate the ccnet.config file given that template and a list of environments in a mail-merge type way.
Unfortunately, you can't do anything like that with CruiseControl.NET. It's a good idea, so you might want to submit it as a feature request.
This is fully supported now starting with cruisecontrol 1.5: http://cruisecontrolnet.org/projects/ccnet/wiki/Parameters