Sample service

service.swift

import Dispatch
import Foundation

public protocol Service {
    static func run()
}


class ServiceApplication {

    static private let queue = DispatchQueue.global(qos: .background)
    static private var services = [Service.Type]()
    static private var config : Dictionary<String,Any>?

    static func register(_ service: Service.Type) {
        services.append(service)
    }

    static private func load() {
        services.forEach { service in
            queue.async {
                service.run()
            }
        }
    }

    static private func loadConfigDictionary() {
        let currentDirectoryURL = URL(fileURLWithPath: FileManager.default.currentDirectoryPath)
        if #available(OSX 10.11, *) {
            let url = URL(fileURLWithPath: CommandLine.arguments[1], relativeTo: currentDirectoryURL)
            config = NSDictionary(contentsOf: url) as? Dictionary<String,Any>
        } else {
            // Fallback on earlier versions
        }

    }

    static func getConfig(_ key: String) -> Any? {
        return config?[key]
    }

    static func run() {
        if CommandLine.argc > 1 {
            loadConfigDictionary()
        }
        load()
        while true {

        }
    }
}

// *****************************************************************************
// SAMPLE
// *****************************************************************************


public class PrintService : Service {
   static public func run() {
       for i in 0..<10 {
           print("hello world  : \(i)")
       }
   }
}

public class Print2Service : Service {
   static public func run() {
       for i in 0..<10 {
           print("hello world2 : \(i*i)")
       }
   }
}

ServiceApplication.register(PrintService.self)
ServiceApplication.register(Print2Service.self)
ServiceApplication.run()