pass value from app.config from one console application to one class library

Question

In my console application I have this on app.config

 <appSettings>
    <add key="Microsoft.ServiceBus.ConnectionString" value="Endpoint=sb://xx.servicebus.windows.net/;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=xx/KrM="/>
  </appSettings>

The console application does the following:

 static void Main(string[] args)
        {
            try
            {
                Console.WriteLine("Press key to continue");
                Console.ReadKey();
                QueueHelper.ReceiveMessage("Empresa");
            }
            catch (Exception ex)
            {

                throw ex;
            }
        }

However I wanted to isolate the Queing methods in a different class library, so the actual implementation of ReceiveMessage is in another class library

 /// <summary>
        /// Receives a message
        /// </summary>
        /// <param name="queuName"></param>
        public static void ReceiveMessage(string queuName)
        {
            QueueClient Client = QueueClient.CreateFromConnectionString(connectionString, "Empresa");

            // Configure the callback options
            OnMessageOptions options = new OnMessageOptions();
            options.AutoComplete = false;
            options.AutoRenewTimeout = TimeSpan.FromMinutes(1);

            // Callback to handle received messages
            Client.OnMessage((message) =>
            {
                try
                {
                    Empresa empresa = GetBody<Empresa>(message);
                    // Process message from queue
                    //Console.WriteLine("Body: " + );
                    Console.WriteLine("MessageID: " + message.MessageId);

                    // Remove message from queue
                    message.Complete();
                }
                catch (Exception ex)
                {
                    // Indicates a problem, unlock message in queue
                    message.Abandon();
                }
            }, options);
        }

The problem is that its trying to get the connection string info from app.config which is local to that library and not to the caller.

So I get a null connection string.

Now, I dont want to duplicate app settings in my class library projects, how and what would be the best way to achieve this?

One of the reasons for this is that at the end this console app will be installed in Azure as a WebJob, and Azure has an interface to change AppSettings for webjobs, but not for class libraries.

Answer 1

Using reflection you might be able to get hold of the application configuration from the calling assembly.

Below is a sample code

public static void ReceiveMessage(string queuName)
    {
        var assembly = Assembly.GetCallingAssembly();

        string configPath = new Uri(assembly.CodeBase).LocalPath;
        var configManager = ConfigurationManager.OpenExeConfiguration(configPath);
        var connectionString = configManager.ConnectionStrings.CurrentConfiguration.AppSettings.Settings["Microsoft.ServiceBus.ConnectionString"];


        QueueClient Client = QueueClient.CreateFromConnectionString(connectionString, "Empresa");

        // Configure the callback options
        OnMessageOptions options = new OnMessageOptions();
        options.AutoComplete = false;
        options.AutoRenewTimeout = TimeSpan.FromMinutes(1);

        // Callback to handle received messages
        Client.OnMessage((message) =>
        {
            try
            {
                Empresa empresa = GetBody(message);
                // Process message from queue
                //Console.WriteLine("Body: " + );
                Console.WriteLine("MessageID: " + message.MessageId);

                // Remove message from queue
                message.Complete();
            }
            catch (Exception ex)
            {
                // Indicates a problem, unlock message in queue
                message.Abandon();
            }
        }, options);
    }

The ConfigurationManager is a part of System.Configuration Assembly.

If you have an even more complex scenario then please post the details and I will try to figure out the solution.