Just read an interesting post on Steven Vinoski’s middleware matters about the lack of multiple-port support in the End-Point Reference EPR currently under review by the WS-Addresing working group and augmenting WSDL 1.1 by allowing for more dynamic usage patterns. Currently the EPR doesn’t suport multiple ports. Ports, for those that remember the original WSDL spec, enable a webservice to be accesible through multiple protocol/transport/format alternatives. Steve Vinoski proposes a useful “business card” analogy to explain the practicality of multiple ports, covered by one EPR. Personal addressing on the internet has arguably evolved this way anyway. Here are some examples of ports associated with the person Shane Dempsey (of Geesan Tech, for SPAM avoidance purposes) with basic URI: sdempsey@geesan.com
- EMAIL:
mailto:sdempsey@geesan.com(TCP, port 25) - MULTIMEDIA SESSIONS:
sip:sdempsey@geesan.com(UDP/TCP, port 5060) - SIP INSTANT MESSAGING:
im:sdempsey@geesan.com(UDP, port 5060) - JABBER INSTANT MESSAGING:
sdempsey@geesan.com(TCP, port 5222)
In some cases the URL scheme is provided, indicating a particular port (e.g. mailto: implies SMTP). The use of schemes is far from uniform however, meaning that there is not a direct port-scheme correlation. In the service domain, this is better. For example a SOAP service where information is transferred over an alternative application layer protocol such as SOAP, SIP or SMTP is possible. A hyperlink to such a SOAP service would take a form similiar to mailto:soap@mydomain.com