a0d929ca_WSRP_v2_0_Specification__Statement_text
[#] CS004 [Section] 2.12 [Statement text] 
The Consumer MUST NOT invoke operations on any Portlets within the context of the initiating request from the client of the Consumer until either the receipt of a response or the invocation of performBlockingInteraction fails (e.g. times out).
WSRP v2.0 Specification
Statement text