Calling a service with parameters in a YAML file, passed as parameter in a launch file

Hi. Here is my problem : - I have two nodes A and B, where A launches a service which needs some parameters. - Both are launched via a launch file where a YAML file is passed as a parameter to B with the 'rosparam' tag. - The data represented in the YAML file correpond precisely to what the service in A needs as parameters. Is there a way to call A from B with the content of the YAML without having to manually parse individually each values contained in the file (it's only composed of strings but the structure itself is pretty complex) ? Thanks!