Example sync timeouts

Handler.cs

namespace Server
{
    public class Handler : IHandleMessages<SynchroniseSite>
    {
        public IProvideSites SiteProvider { get; set; }
        public async Task Handle(SynchroniseSite message, IMessageHandlerContext context)
        {
            try
            {
                List<Data> data = new List<Data>();
                // assuming connection is sync and long-running
                await Task.Run(() => {
                    var connection = SiteProvider.GetConnection(message.SiteId);
                    data.AddRange(connection.GetSomeData());
                })
                
                // awaiting the above will throw any exceptions happening in the task body
                // so if we reached here we know the connection is online
                await context.Publish("Connection is online");
                
                // just showing the LINQ way for education purposes, but be aware this might lead to more allocations
                var tasks = data.Select(item => context.Publish("Got some new info")).ToArray();

                await Task.WhenAll(tasks);
            }
            catch (Exception exception)
            {
                //This will be a specific connection exception
                await context.Publish("Connection is offline");
            }
        }
    }
}