comparison between RFC posting and uc4 from webmethods to SAP??

can any1 list the advantages of posting data to SAP through RFC call compared to Uc4 job?

Regards,
RDS

Hi,
We are migrating the webMethods code from 4.6 versions to 6.5 versions.
In 4.6 we used the conversation script concept but there is no conversation concept in webMethods 6.5 version.
Please guide me the best suitable approach to overcome the conversation concept in 4.6 versions.
Thanks
Ashok kumar.G