Question
When is SML used?
Answer
In addition to the Service Metadata Publisher (SMP), the Service Metadata Locator (SML) is the other key component that enables dynamic discovery of participants in message exchange infrastructures.
The SML is used to create or update the resource records in the Domain Name System (DNS) so that the Access Points can discover the SMP of the receiving participant.
As a result, these infrastructures can scale up without being affected by the management of an increasing number of participants. Instead of having to centrally manage a list of Access Points (known as 'static discovery') which all of them must be able to access and download, the discovery of participants becomes dynamic and possibly fully distributed and consequently much more scalable.
The current eDelivery SML service implements both the eDelivery SML specifications and the PEPPOL Transport Infrastructure SML specifications. The eDelivery SML Service uses a sample implementation of the SML software maintained by the European Commission.
For more details, please check the relevant SOD.