Ahh! I would suggest you think about the flow of your application this way
which might clear things up:
- User on website loads a page, something like
/changeImage.html?newImage=picture1.jpg
- nodejs server receives request for /changeImage.html and parses the GET
string to find the var newImage = "picture1.jpg"
- Before returning to the user (rendering the HTML response for
changeImage.html), your server (not your html) runs a method to pass the
TCP command to your sign ( sendSignMessage({image = picture1.jpg},
callback) ). sendSignMessage would connect to the digital sign (or make
use of a previously initialized connection) per [[
http://nodejs.org/api/net.html#net_net_connect_arguments ]]
- sendSignMessage() waits until it receives a response from the sign and
passes that message on to the callback passed to it, which in turn should
finally render out (with that response included) to the user on the website.
There are a few reasons for this type of architecture:
- While I haven't done much work with digital signs, I have interfaced with
a lot of lighting control hardware, and those devices have trouble dealing
with lots of connections. Having your server maintain one connection which
is a proxy for all of your web users is useful
- It's really hard (and often times impossible) to get javascript in the
browser to connect to arbitrary ports
- It's also really hard (even with websocckets) to have javascript in the
browser act as a raw TCP connection to send arbitrary messages to a server
that isn't the same as the webserver (cross domain problems)
On Thursday, March 8, 2012 1:16:07 AM UTC-8, tomfish wrote:
>
> Yes I thought that Socket.IO would be a little overkill. I now know I
> need to use regular sockets. But I can't seem to get this working.
> I believe I need to make an html file that sends commands to my tcp
> server? There is now way I can make my index.html interact with my
> server.
>
> Kind regards,
> Tom
>
>
> On 8 mrt, 08:11, Evan <[email protected]> wrote:
> > Socket.io while awesome, might be a little overkill here. It sounds
> like
> > you just need to connect to a port on a remote machine and sent some
> > commands. You can start up your connection like this
> > [[http://nodejs.org/api/net.html#net_net_connect_arguments]] and then
> use
> > the client.write() method to send your string to the remote server.
> >
> >
> >
> >
> >
> >
> >
> > On Wednesday, March 7, 2012 5:54:43 AM UTC-8, tomfish wrote:
> >
> > > Hello,
> >
> > > I would like to send a command from a (local) website to a computer in
> the
> > > same network on a specific port. This port is in use by digital
> signage
> > > software. When the software receives this command, it changes the
> image.
> > > Can anyone help me with this? node.js and socket.IO are already
> installed,
> > > but I can't seem to find the right coding.
> >
> > > Thanks in advance,
> >
> > > Tom
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