1. Publishing and transporting Web Services over XMPP
Johannes Wagener

2. Web Services – State of the Art
UDDI:
Universal Description,
Discovery and Integration
WSDL:
Web Services Description Language
SOAP:
Simple Object Access Protocol
(from Wikipedia)

3. http is a pull protocol! Client Server doBLAST() (waiting) (working)
Firewall
http timeout

4. Workaround Client Server doBLAST() ID Client (loop) Server (working)
checkResult(ID)
“please wait”
(…)
Client
Server
(finished)
checkResult(ID)
RESULT

5. Next generation of Web Services
should ...
be a properly and strictly defined standard
allow stateful job management
allow asynchronous client notification
be discoverable
have big user community with a lot of software

6. About XMPP The Extended Messaging and Presence Protocol
Formerly known as Jabber
Invented by Jeremie Miller in 1998
Formalized by the Internet Engineering Task Force since 2004
RFC 3920 – 3923, 4622
XMPP Standards Foundation continues to define various XMPP Extensions
“…a protocol for streaming XML elements in order to exchange structured information in close to real time between any two network endpoints.
While XMPP provides a generalized, extensible framework for exchanging XML data, it is used mainly for the purpose of building instant messaging and presence applications.” (from RFC 3920)

7. (from Wikipedia)

8. XMPP Architecture similar to Email …
server1.com
server2.org
server3.net

9. XMPP Architecture one user can connect with different resources
server1.com
server2.org
server3.net
User ID
Server
Resource

10. XMPP Architecture Server Components
server3.net
service.server3.net

11. XMPP Architecture Use cases of Server Components
conference.server3.net
msn.server3.net
server3.net
userdirectory.server3.net

12. XMPP Architecture present
jabber.org

13. XMPP Architecture present
jabber.org
googl .com

14. XMPP Architecture present
jabber.org
gmx.net
googl .com

15. … but many unofficial servers, too.

16. Clients

17. Servers

18. Servers
Clusterable

19. Libraries 3 x .NET 3 x C 2 x C# 7 x C++ 3 x COM 2 x Delphi 1 x Flash
9 x Java
1 x Java Script
1 x Lisp
1 x Mono
5 x Perl
2 x PHP
4 x Python
2 x Ruby
1 x TCL
1 x XPCom

20. The Protocol An inbound and outbound “XML Stream”
Client connections are usually done with TCP. However there are no restrictions; i.e. many server allow polling over HTTP
Streams may be encrypted in various formats
Packets are sent as “stanzas”
There are three top level stanzas:
<message/> … to submit messages
<presence/> … to submit presence information
<iq/> … for everything else – and that’s a lot

21. Simplified Stream Example... with two <message/> stanzas
(from RFC 3920)

22. Information Query: <iq/>
C: <iq
to='server.org'
type='get'
id='request_1'>
<query xmlns='jabber:iq:version'/>
</iq>
S: <iq type='result'
from='server.org'
<query xmlns='jabber:iq:version'>
<name>ejabberd</name>
<version>1.1.2</version>
<os>win32/nt </os>
</query>

23. XMPP Extensions Protocol (XEPs)
(…)

24. (Web) Service Discovery
There are three kinds of information that need
to be discovered about an entity
its basic identity (type and/or category)
the features it offers and protocols it supports
any additional items associated with the entity, whether or not they are addressable as JIDs

25. Web Service related XEPs}
Asynchronous +
Stateful -
Discoverable -
Asynchronous +
Stateful +
Discoverable +

26. Ad-Hoc Commands C: <iq type='set' from='user@server.org'
to='service.server.org'
id='iq_127'>
<command xmlns='
node='function_name'
action='complete'/>
<THE RPC INPUT/OUTPUT DATA/>
</command>
</iq>
S: <iq type='result'
from='service.server.org'
sessionid='RPC-SESSION-1'
status='completed'>
<THE RPC OUTPUT/OUTPUT DATA/>

27. Use Case: Disco and Ad-Hoc Commands Rendering a GUI around a service with the XEP-0004 X-Data envelope
XEP-0004 X-Data Forms
optimized for GUI

28. Ad-Hoc Commands X-Data Forms (XEP-0004) GUI X-Data Forms (XEP-0004)
C: <iq type='set'
to='service.server.org'
id='iq_127'>
<command xmlns='
node='function_name'
action='complete'/>
<THE RPC INPUT DATA/>
</command>
</iq>
S: <iq type='result'
from='service.server.org'
sessionid='RPC-SESSION-1'
status='completed'>
<THE RPC OUTPUT DATA/>
X-Data Forms (XEP-0004)
GUI
X-Data Forms (XEP-0004)
GUI

29. Web Service related XEPs}
Asynchronous +
Stateful -
Discoverable -
Asynchronous +
Stateful +
Discoverable +
Yet another XEP?
SOAP ?
WSDL ?
something else?

30. Test Case: Web Service Server Component
WSDbfetch
SOAP
wsdbfetch.gandhi
gandhi

31. Test Case: Client GUI (chat-client), Scripting Environment (Bioclipse)
WSDbfetch
SOAP
wsdbfetch.gandhi
gandhi

32. XEP-0050 Ad-Hoc Commands Transporting EMBL-EBI’s WSDbfetch Web Service over XMPP

33. Summary:
XMPP is
a well established and widely used XML routing technology
a server-client oriented architecture
working with unique entity identifiers
offering a discoverable network
an asynchronous protocol (the server can push data to the client)
“result is available”
Client
Server
function(data)
“function started”

34. Andreas Heusler
Egon Willighagen
Ola Spjuth

36. XEP-0096: File Transfer Requirements
Enable seamless file transfer, including fall-back mechanisms as appropriate.
Ensure that the profile will work even when one or both parties are behind a firewall.
Define a full-featured set of metadata for file transfers, including the following:
description
size
name
date
hash
Optionally support ranged transfers.