The Horizon Messaging component provides the messaging router for communication between Horizon Connection Server components and between Horizon Agent and Connection Server.

This component supports the Java Message Service (JMS) API, which is used for messaging in Horizon 7.

Intercomponent message validation uses DSA keys. The key size is 512 bits by default, except in FIPS mode, where the key size is 2048 bits.

Note: When the message security mode is set to Enhanced, SSL/TLS is used to secure JMS connections rather than using per-message encryption. In enhanced message security mode, validation applies to only one message type. For enhanced message mode, VMware recommends increasing the key size to 2048 bits. If you are not using enhanced message security mode, VMware recommends not changing the default from 512 bits because increasing the key size affects performance and scalability.

If you want all keys to be 1024 bits, the RSA key size must be changed immediately after the first Connection Server instance is installed and before additional servers and desktops are created. See VMware Knowledge Base (KB) article 1024431 for more information.