init_node need locating after Publisher?

edit

I create one simple to send msgs to other nodes, but others cannot get msgs, even if they have been connected. The code shows as following.

#!/usr/bin/env python
# license removed for brevity
import rospy
from std_msgs.msg import String

def talker():
    rospy.init_node('talker')
    pub = rospy.Publisher('chatter', String, queue_size=10)    
    hello_str = "hello world %s" % rospy.get_time()
    pub.publish(hello_str)
    rospy.loginfo(hello_str)

if __name__ == '__main__':
    talker()

But when I move the init_node after rospy.publisher, it works well. And like this.

#!/usr/bin/env python
# license removed for brevity
import rospy
from std_msgs.msg import String

def talker():
    pub = rospy.Publisher('chatter', String, queue_size=10)
    rospy.init_node('talker')
    hello_str = "hello world %s" % rospy.get_time()
    pub.publish(hello_str)
    rospy.loginfo(hello_str)

if __name__ == '__main__':
    talker()