[lwip-users] question about event API vs callback API

[Shawn_He]

Hi, I just started to work on TCP part of the stack, and as I mentioned in an earlier email, I was trying to use sequential API (which is similar to socket calls I assume), and it appeared that the connect() call (or more precisely lwip_connect() won't check on the socket option non-blocking or not).  I dig into the rawapi.txt file, and in the second paragraph it says that the stack is event based, and I did find there are two flags (one is called LWIP_EVENT_API, the other LWIP_CALLBACK_API), which made me a little bit confused. Here are my questions:
1. When I use the sequential API, do I need to set LWIP_EVENT_API to 1? Or the two are different concepts? If so, what are they referring to individually?
2. When I turn on the LWIP_EVENT_API, I got compile errors, a few functions used in api_msg.c file (such as tcp_accept, tcp_recv) currently would only be compiled when the LWIP_CALLBACK_API flag is set to 1, and since the two flags can't be set to 1 at the same time, I can't compile the code for EVENT API. Does this mean the flag condition for these functions should be removed so both API can access them?

Thanks.

Shawn