This module packages frozen versions of both the client and server for the Primus websockets library, the plugins it uses and the transport it uses, namely SockJS.
The rationale behind this module is that Primus does not ship with its client, the client has to be built by the server and it will depend on the settings provided to the server. This could become problematic as any dependency update could cause a discrepancy between the client and the server, who communicate with each other. Therefore, by ensuring both the client(s) and the server(s) always use the same version of this module, any problem due to a dependency mismatch should be mitigated.