DSML V2 was designed to be used with a request/response protocol such as HTTP. For a given request document, a DSML V2 server/gateway is expected to produce a corresponding response document. No state is carried between one request to another request, so each request is completely independent of the other.
One of the benefits of this approach is to free the server from maintaining states, which promotes scalability. This design is also aligned with one of the goals of of DSML V2: transport independence. Since most transport protocols include session support, DSML V2 can still be implemented on the top of these protocols, and take advantage of their session support.
However, the design also introduces several challenges for LDAP operations that require session support. DSML Services for Windows implements session support in the SOAP transport layer.