This will be a series of multiple posts to answer the question. I’ll review both commercial as well as Open Source SOA/ESB’s to answer the question.
I’ll cover a simple typical scenario – yes the done to death PO approval 🙂

SOA Suites –
1) Oracle SOA Suite 12c
2) MuleESB
3) JBOSS SOA
4) WSO2 SOA
5) Apache (Camel, Drools, ActiveMQ)
6) OpenESB

Scenario –
1) Read PO XML from file(CSV)
2) Transform & Call WS with Canonical Interface
3) Run Business Rules to check if Approval requried
4) Send by FTP

Features –
1) Development effort & IDE
2) Deployment
3) Monitoring & Alerts
4) SOA Governance