This is service code:

import rospy
from temizlik_robotu_pkg.srv import *
def servisCevapCB(istek):
    print(istek.sayi)
    istek.sonuc=1
    return istek

def servisSayma():
    rospy.init_node("servis_geri_say_nd")
    rospy.Service("geri_say", geriSay, servisCevapCB)
    rospy.spin()

servisSayma()

And this is client code:

import rospy
from temizlik_robotu_pkg.srv import *

def client():
    rospy.init_node("client_geri_say_nd")
    rospy.wait_for_service("geri_say")
    servis=rospy.ServiceProxy("geri_say", geriSay)

try:
    gelen_cevap=servis(5)

    print("sonuc: " +gelen_cevap.sonuc)
except rospy.ServiceException:
    print("servisde hata var")

client()

and this is .srv file:

int32 sayi
---

int32 sonuc