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dgiardini / rtl-ais

A simple AIS tuner and generic dual-frequency FM demodulator
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TCP server stops streaming; bug or intentional? #33

Closed mik3y closed 1 year ago

mik3y commented 3 years ago

Hi there! I have what may be a silly question about the intended usage of the TCP listener (./rtl_ais -T)

When I run rtl_ais in this mode, and connect a new client to the host and port (eg telnet localhost 10110), the client receives a burst of buffered messages, then nothing further. Sending a character from the client causes the connection to be closed.

What I'd expect: The client receives buffered messages, and continues to receive all newly-parsed messages, until either side terminates the connection.

Taking a look at docs and code, I can't quite see anything I'm doing wrong, so I'm thinking this is either intentional or perhaps just disused. Before I prep a PR, can you share any insight? Thanks for maintaining this!

dgiardini commented 3 years ago

Hi Mike This way works fine together with OpenCPN that open a connection, receive the messages and then close the connection. Would not be difficult to make it work the way you expect (that is very reasonable way), but I don't know if would worth to do it. Best regards, David

On Mon, Jan 25, 2021 at 10:59 PM mike w notifications@github.com wrote:

Hi there! I have what may be a silly question about the intended usage of the TCP listener (./rtl_ais -T)

When I run rtl_ais in this mode, and connect a new client to the host and port (eg telnet localhost 10110), the client receives a burst of buffered messages, then nothing further. Sending a character from the client causes the connection to be closed.

What I'd expect: The client receives buffered messages, and continues to receive all newly-parsed messages, until either side terminates the connection.

Taking a look at docs and code, I can't quite see anything I'm doing wrong, so I'm thinking this is either intentional or perhaps just disused. Before I prep a PR, can you share any insight? Thanks for maintaining this!

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mik3y commented 3 years ago

Hey David - Thanks very much for the fast reply! That makes sense now; OpenCPN is the main client, and it sounds like it is perfectly functional repeatedly connecting.

I'm going to prepare a patch that can keep the connection open, and will send it your way. I'll do so in a way which avoids breaking existing applications like this; perhaps a command line flag for "keep TCP connection open".

FYI: This mode of operation would make rtl_ais work like similar applications that exist in the ADS-B (plane tracking) world: dump1090 and readsb/readsb-proto being the most popular. I am building a web application that can visualize data from both (airdash), so it will be great to support ais similarly. Cheers!

mik3y commented 3 years ago

Just a short update: I've got this feature implemented now, in my branch here: https://github.com/mik3y/rtl-ais/commit/8507fbc6d45d36d6f2c2788352889d1d49ec4d3e . It is implemented as an opt-in feature (-k) so that if anything depends on the old behavior, it shouldn't break.

I'll be giving it some time testing, then will PR here. Cheers!