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This protocol is out of scope of this proposal.

Proposed changes

Cluster version

Server nodes stores ClusterVersion - set of Ignite versions in cluster (server and clients nodes). The joining node version must be checked versus the version (see OnDiscoveryNodeValidationProcessor

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):

• If ClusterVersion contains only one version (all nodes are run same version), then the joining node can be greater/less than this version by up to 1 minor version
• If ClusterVersion contains two versions, then joining node version must be one of the ClusterVersions.

Message DTO

There should be one serialization framework for communication and discovery protocol. 

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