• Purpose
• A Problem
• Obvious Solutions (Which Are Not Good)
• Ask To Republish
• Personal Ask For The Current Value
• Solution With Retained Message Mbox
• More Details About Retained Message Mbox
• Working Principle
• Creation Of A retained_msg Mbox
• Delivery Filters And Retained Messages
• Limitations
• Mutable Messages Are Not Supported
• Underwater Rocks
• Subscription In so_define_agent
• Possibility Of Cyclic References And Memory Leaks