Hello fellow igniters! I recently started reconnaissance before the implementation of IEP-23 [1] in Python thin client. I think it is an interesting and much promising feature. As I understand, the changes associated with this feature will result in a new version of the binary protocol.
What bothers me is not the changes required by the implementation itself, but the upcoming changes in the way that the fallback to the previous versions of the protocol is going to be handled. I have not found a open discussion on this topic neither on this mailing list, nor in Jira. If such a discussion took place, please inform me with a link. Based on what I have heard so far, I made the following conclusions: 1) the client is now expected to handle multiple binary protocol versions; 2) since the protocol is implemented the way the client first reports its version to the server on handshake, and not the other way, the client now must try to connect to the server using its preferred version of the protocol, and in case of an error, reconnect with another version. These changes are raised some concerns for me, for example: 1) the version negotiation mechanism implemented on client can not be made transparent to the end user. We must give the user an option, so that they could choose from the entire set of versions supported by the client, a subset of the versions their application is designed to work with. That will complicate the user API; 2) the complexity of the client will also be increased, especially considering unit testing. Certain tests will require a certain version of Ignite server, so they can no longer be implemented environment- agnostically, leading to a weird mix on unit and integration levels; 3) I do not see, or not aware of, the preconditions to such changes. I think the number of potential applications that can benefit from multi- protocol client is quite low. Usually all the hassle of version matching lie on the deployment level, above the app level. Please prove me wrong on this subject. Instead of supporting multiple binary protocols inside one client package, I would strongly prefer to support each version of the protocol separately, in the corresponding branch of the package repository. It would still be possible for the end user to use multiple protocols in one app, but with certain code-level and deployment-level efforts combined. Again, I most probably lack awareness on the subject, and therefore my conclusions may be premature, but anyway, let us discuss. I will appreciate any bit of knowledge from the community. [1] https://cwiki.apache.org/confluence/display/IGNITE/IEP- 23:+Best+Effort+Affinity+for+thin+clients
