EMA C++ RDM Usage Guide : 2 Domain Model Overview : 2.4 Consumer / Interactive Provider Initial Interaction
 
2.4 Consumer / Interactive Provider Initial Interaction
An Open Message Model consumer application can connects to Open Message Model interactive provider applications, including the LSEG Real-Time Distribution System, Data Feed Direct, and the Delivery Platform. This interaction first requires an exchange of login messages between the consumer and provider, where the provider can either accept or reject the consumer. If the consumer is allowed to log in, it may then request the list of services available from the provider. Optionally1, the consumer can request any dictionaries it needs to decode data from the provider. After this process successfully completes, the consumer application can begin requesting from non-administrative domains, which provide other content (e.g. Market Price, Market By Order).
Figure 1. Open Message Model Consumer and Interactive Provider Initial Interactions
 
Figure 2.  

1 Instead of downloading any needed dictionaries, the application can load them from a local file.