MATLAB Central Newsreader - urlread passing special characters

urlread passing special characters

Michele — Wed, 20 Feb 2008 22:08:02 -0500

Help! I need to do a urlread with a GET method and a
parameter that contains slashes, eg.

urlread ('http://192.168.0.253', 'GET',
{'/goform/getdevicestatus', ''})

The problem is that urlread translates the / (hex 2F) into
the 3 character string '%2F' in the actual TCP packet data
that gets sent out. This is similar to the problem I had
last year getting urlread to take base64 encoded passwords.
That one was solved by using
urlConnection.setRequestProperty. Unfortunately, I don't
know if I can do that in this case, or how to do it. I'm
not sure what "property" I might need to use.

So my question is, is there a way in Matlab to assemble a
TCP packet that includes special characters in the data?
Any and all help would be greatly appreciated. Thanks!

Re: urlread passing special characters

Matthew Simoneau — Wed, 20 Feb 2008 22:30:04 -0500

URLREAD is encoding these because the GET needs to be a
valid URL. Shouldn't whatever's on the other end be
decoding these?

Re: urlread passing special characters

Michele — Thu, 21 Feb 2008 01:35:03 -0500

"Matthew Simoneau" <matthew@mathworks.com> wrote in message
<fpi9lc$fkh$1@fred.mathworks.com>...
> URLREAD is encoding these because the GET needs to be a
> valid URL. Shouldn't whatever's on the other end be
> decoding these?

That's really an excellent question. To avoid any
embarrassment to the manufacturer of the device I'm trying
to talk to, I'll refer to it simply as a "Frobniz 43" -
that's not its real name. (Its real name is the HRGZ-01
Z-Wave Gateway by Hawking Technology).

All I can tell you is that when I send an HTTP "get device
status" command to the Frobniz using the web client provided
by Hawking, the packet comes out as
'/goform/getdevicestatus' on the wire. When I try to
emulate that in Matlab using urlread, it comes out as
'%2Fgoform%2Fgetdevicestatus' and I get back an error
message from Matlab "Error downloading URL.".

The URL itself is valid, because I do get an appropriate
response when I do a plain urlread on the server without a
getdevicestatus request.

Considering the overall quality of the rest of their
software, its unlikely the Frobniz Corp. is going to repair
their reader, so my only other hope is to somehow coerce
Matlab into feeding the Gateway some data it would find more
palatable.

I'm sure this would be handy for other peoples' problems
too. Is there any workaround for this? Thanks (and thanks
again for your help on the last go-around too).

Re: urlread passing special characters

Matthew Simoneau — Thu, 21 Feb 2008 02:29:02 -0500

Maybe you don't want to send this as a parameter after all,
but just as part of the URL. Does this work?

>> urlread('http://192.168.0.253/goform/getdevicestatus')

Re: urlread passing special characters

Michele — Thu, 21 Feb 2008 18:09:01 -0500

Re: urlread passing special characters

Michele — Thu, 21 Feb 2008 18:28:01 -0500

"Matthew Simoneau" <matthew@mathworks.com> wrote in message
<fpinle$e5l$1@fred.mathworks.com>...
> Maybe you don't want to send this as a parameter after all,
> but just as part of the URL. Does this work?
>
> >> urlread('http://192.168.0.253/goform/getdevicestatus')

Sigh... this is a perfect example of how sometimes you get
so hung up on complexities that you totally forget about the
obvious. (Putting on the Homer Simpson accent) "DOHHH!"

Yes, of course, that was it. That works fine. Thanks - I
owe you two now :-)