Where can I found, if exist, a list of all items name that I can use in a subscribe request to a EMA service (eg: DIRECT_FEED, ELEKTRON_DD)?
DIRECT_FEED is a dummy feed name used by our example Provider applications - this allows you to connect a Consumer Example to a Provider example and request dummy data. So, you can request a dummy RIC code (instrument name) and the provider will create a dummy record with a few sample fields using that RIC code.
ELEKTRON_DD is typically the service name used by most organisations for data from our Elektron Realtime feed - and also the default service name if you are connecting to our Elektron Realtime in Cloud service.
In terms of RIC codes of instruments available on ELEKTRON - there are over 5 million instruments carried on Elektron - so it is not practical to get a list of all 5 million+ item names.
In order to get a list of RIC codes that you may be interested in - you have a few of choices