From my point of view, the main issue is ObjectScript. Any new developer, would not see it as something that may help him in the future. Developers should not work at the same company and with the same technology for a lifetime. Every developer, should check the potential to change the job, and get a promotion. In comparison to more popular programming languages, ObjectScript can offer nothing at all. Python developers for instance can change work and get a better salary, much easier.

Even though, InterSystems products are supported by other programming languages, such as Java, .Net, and NodeJS. It's real pain, to make that work, even with the last trending Python, quite tricky to start. 

I'm sure, that to gain more people on our IRIS side, we have to look at the popular tools, frameworks, and libraries used by developers, and make them work with IRIS as well. Many libraries support a huge amount of databases, including some proprietary, but no IRIS at all. So, developers who know well Java, have a lot of possibilities to start a project very quickly which would work with any database, but IRIS.

I'm personally, trying to help with these issues. Even for ObjectScript, I managed to upgrade the developer's experience with modern IDE VSCode (So, the young developers who know what a modern development process should look like, would not be so shocked by so outdated Studio). Help with using Docker in the development process, package managers, and continuous integration, all with ObjectScript, and even static syntax analyzer. But I want that all the new projects would not use ObjectScript at all, to help with it, I have built Django driver to IRIS. I want to see IRIS support in as many programming languages as possible, and as many libraries and frameworks as possible. So, the developers would not have any issues in switching jobs, they have to use their knowledge which could be applicable anywhere. Want to build an application that uses SQL, that's ok, here is the driver, connect it and use it, as you would do it with another relational database.  NoSQL, ORM, or something else, is not an issue as well. But it's still too far to this point. 

Protocol and its implementation

I've looked at the realization in IRIS, and it does not support any streams, So, any call of Write, is like a complete message and it accepts only string.

Did you try with --format docker? I have no podman, just see, that it said on the error