Question

I’m creating an iOS app which uses django as my backend. I need to have a chat functionality between users.

I heard that XMPP is good for real time communication, and I have successfully set up ejabberd as the XMPP server. But still I’m having hard time to deal with the details:

I created the app first and then the chat feature, so before I setup ejabberd, there are already users in my django DB. I need ejabberd to authenticate users against my existing DB and I have almost solved this by using external authentication. There is only one small problem, as ejabberd seems to require the jabber ID like [e-mail], and here abc means the virtual host of ejabberd. I don’t know maybe I could only use one virtual host on my server(which is the domain name)? But then at the beginning I asked the user to register using emails which are from different domains of course, e.g. gmail.com, yahoo.com, but [e-mail]@abc.com is not a valid jabber ID, so maybe one small trick I can do here is to convert first @ to # and handle it properly in the python script in the backend. But maybe I did it totally wrong?

Another issue is about user profile. I stored the user information as well in my django DB, e.g. display name, avatar url, etc. I learnt that I could use the vCard module if I want to get those information from XMPP server. So maybe I need to have duplicated information in two places? And still I haven’t figured out how to synchronize the user information from DB to ejabberd. Or maybe I just need to have only one source, which is my DB, and the iOS client could then query the information from the backend whenever needed?

I feel that XMPP is not easy to setup, is it really popular to use it in your Apps? Especially if chatting is not the main functionality of your App and you are not expecting to have huge messages from big number of users?

Answer 1

You wrote:

but [e-mail]@abc.com is not a valid jabber ID

You are supposed to escape the user id (i.e “username@gmail”).

XEP 106 explains how you should escape the node part of a JID.

In python, it would look something like this:

def escape_node(node):
    """ """
    node.strip()
    node = node.replace('\\', "\\5c")
    node = node.replace(' ',  "\\20")
    node = node.replace('\"', "\\22")
    node = node.replace('\&', "\\26")
    node = node.replace('\'', "\\27")
    node = node.replace('\/', "\\2f")
    node = node.replace(':',  "\\3a")
    node = node.replace('<',  "\\3c")
    node = node.replace('>',  "\\3e")
    node = node.replace('@',  "\\40")
    return node

With regards to storing your users’ details in Django. When you register your Django users in XMPP, just make sure that you also register valid vCards for them.

When a Django user changes his details, update the vCard as well.