Using sockets

[Björnke von Gierke]

On 15.01.2014, at 01:14, Peter Haworth <pete at lcsql.com> wrote:

> The dictionary adds to the confusion when, in the write to socket entry, it
> says the socket id is an ip address followed by a port when it's actually
> followed by a socket.

I agree that there's some small inconsistencies in naming sockets vs. ports, but it's actually easy.

For example, if you think of IP's as houses, then ports are their (thousands of) doors. Sockets are the little roads between two of those doors (yes even for the same house). Unlike in the real world, those roads are only constructed and paved when you open a socket. The communication happens as so called packets, you can imagine those as very stupid pedestrians, whom always will follow a single road (Note that LC does a great job at obsfucating the packeted nature of IP communication).

So a socket is always a connection between two ports. One of them is always the server, and the other is always the client. As a test, try to open a port, and query the openSockets, it will list the open ports. You'll see an outgoing port on the server, and an incoming port on the client. They exist because there's a socket opened.

> However it only mentions the socketTimeoutInterval.

I found the socketTimeout message to be useless. Here's some of it's properties (from memories of a few years back, I could be remembering wrong on some of these):

- It will fire if nothing is happening on the socket (no reads or writes pending), in regular intervals
- It will fire if a non-blocking read or write is pending or unhandled
- It will fire during long reads or writes, while they are happening
- It will not fire if there is no socket open

In other words, according to LC, everything is always timing out, making the message completely useless in my view (maybe it can be used to find out that the socket is unexpectedly closed, because there sure as hell is no other way to find that important info out in LC...).


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