public static void ExecuteCommandWriter(IWriterService proxy, int op, X509Certificate2 signCert)
        {
            string name = "";

            if (op != 0)
            {
                name = HelperFunctions.ReadDatabaseName();
            }
            switch (op)
            {
            case 1:
                CheckIfExecuted(proxy.CreateDB(name, DigitalSignature.Create(name, "SHA1", signCert)));
                break;

            case 2:
                CheckIfExecuted(proxy.DeleteDB(name, DigitalSignature.Create(name, "SHA1", signCert)));
                break;

            case 3:
                Element tmpElem = Element.LoadFromConsole();
                CheckIfExecuted(proxy.WriteDB(name, tmpElem, DigitalSignature.Create(name, "SHA1", signCert)));
                break;

            case 4:
                List <Element> elems = proxy.ReadDB(name, DigitalSignature.Create(name, "SHA1", signCert));
                Console.WriteLine("Ids of all elements:");
                DisplayAllElements(elems, true);

                Element toEdit = GetElementToEdit(elems);

                Element newElem = Element.LoadFromConsole();
                newElem.Id = toEdit.Id;
                CheckIfExecuted(proxy.EditDB(name, newElem, DigitalSignature.Create(name, "SHA1", signCert)));
                break;

            case 5:
                DisplayAllElements(proxy.ReadDB(name, DigitalSignature.Create(name, "SHA1", signCert)));
                break;

            case 6:
                string city = HelperFunctions.ReadCity();
                Console.Write("Prosecna plata za grad " + city + ": ");
                Console.WriteLine(proxy.MedianMonthlyIncomeByCity(name, city, DigitalSignature.Create(name, "SHA1", signCert)));
                break;

            case 7:
                string country = HelperFunctions.ReadCountry();
                Console.WriteLine("Unesi godinu:");
                int   year = int.Parse(Console.ReadLine());
                float medianMonthlyIncome = proxy.MedianMonthlyIncome(name, country, year, DigitalSignature.Create(name, "SHA1", signCert));
                Console.WriteLine("Prosecna plata za " + country + " u " + year + " god.:" + medianMonthlyIncome);
                break;

            case 8:
                var tmpDict = proxy.MaxIncomeByCountry(name, DigitalSignature.Create(name, "SHA1", signCert));
                Console.WriteLine("Najveca plata za svaku drzavu:");
                foreach (KeyValuePair <string, Element> kvp in tmpDict)
                {
                    Console.WriteLine(kvp.Key + " : id:" + kvp.Value.Id + " plata:" + kvp.Value.Income);
                }
                break;

            case 0:
                Console.WriteLine("Cao poz");
                break;
            }
        }