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Partial Read From URL

Elliot Temple

11/6/2008 11:25:00 PM

Can anyone see a problem with this code to read only 20k from a URL? The
http connection will get closed, right?

Is there a better way to do this? My goal is to download the start of
mp3 files and then estimate their duration without downloading the
entire file.

def partial_uri_read(uri)
u = URI.parse(uri)
s = ""
Net::HTTP.start(u.host, u.port) do |http|
http.request_get(u.path) do |response|
response.read_body do |chunk|
s << chunk
return s if s.size > 20000
end
end
end
s
end

Thanks
Elliot Temple
--
Posted via http://www.ruby-....
3 Answers

ara.t.howard

11/6/2008 11:32:00 PM

0


On Nov 6, 2008, at 4:24 PM, Elliot Temple wrote:

> Can anyone see a problem with this code to read only 20k from a URL?
> The
> http connection will get closed, right?
>
> Is there a better way to do this? My goal is to download the start of
> mp3 files and then estimate their duration without downloading the
> entire file.
>
> def partial_uri_read(uri)
> u = URI.parse(uri)
> s = ""
> Net::HTTP.start(u.host, u.port) do |http|
> http.request_get(u.path) do |response|
> response.read_body do |chunk|
> s << chunk
> return s if s.size > 20000
> end
> end
> end
> s
> end
>
> Thanks
> Elliot Temple
> --
> Posted via http://www.....


maybe try


require 'open-uri'

uri = ......

open(uri){|fd| fd.read 20000}




a @ http://codeforp...
--
we can deny everything, except that we have the possibility of being
better. simply reflect on that.
h.h. the 14th dalai lama

Elliot Temple

11/6/2008 11:34:00 PM

0

Ara Howard wrote:
> On Nov 6, 2008, at 4:24 PM, Elliot Temple wrote:
>
>> s = ""
>>
>> Thanks
>> Elliot Temple
>> --
>> Posted via http://www.....
>
>
> maybe try
>
>
> require 'open-uri'
>
> uri = ......
>
> open(uri){|fd| fd.read 20000}

I did try that, but it downloads the entire file in my tests. I tried it
on a large file and it takes minutes to return, whereas my code returns
in a couple seconds. Am I missing something?

> ruby -v
ruby 1.8.6 (2008-03-03 patchlevel 114) [universal-darwin9.0]

Elliot
--
Posted via http://www.....com/.

Michael Morin

11/7/2008 3:32:00 AM

0

Elliot Temple wrote:
> Can anyone see a problem with this code to read only 20k from a URL? The
> http connection will get closed, right?
>
> Is there a better way to do this? My goal is to download the start of
> mp3 files and then estimate their duration without downloading the
> entire file.
>
> def partial_uri_read(uri)
> u = URI.parse(uri)
> s = ""
> Net::HTTP.start(u.host, u.port) do |http|
> http.request_get(u.path) do |response|
> response.read_body do |chunk|
> s << chunk
> return s if s.size > 20000
> end
> end
> end
> s
> end
>
> Thanks
> Elliot Temple

You can try using the Range header in HTTP. Not all servers have it
enabled I think (or that's what 3 minutes playing with telnet tells me).
Using range you can define which bytes of the file you want to
download, so the whole file is not downloaded. You can use this to
download the header and use the length of the file to estimate its length.