Thank you for the time you're spending answering my question.
What I meant is whether it is guaranteed that the stubs themselves are thread-safe. If they maintain some object-level state inside them, then this may cause problems.
The SLSBs are okay. The container takes care of that.
The stubs, however, live on the client, not necessarily in a managed environment. So, in a perfect world, they will be thread-safe but I was afraid that might be left to the discretion of each vendor.
Furthermore, I'm not sure how well they scale. If they maintain state and, therefore, serialize requests, they may quickly turn into bottlenecks.
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