This document discusses using Perl to access web APIs. It provides examples of popular web APIs like Twitter, Google, and Flickr. It explains that web APIs use HTTP, URIs, and return formats like JSON and XML. The document then demonstrates how to use Perl modules like LWP, URI, and JSON to make requests to the Twitter Search API, handle UTF-8 encoding, and parse the JSON response. Finally, it mentions more advanced modules for web services in Perl like WebService::Simple.

1. Perl Web API
Web API Perl
yusukebe
2010/07/23
Yokohama.pm#6 x PerlCasual#3

2. • Perl
• Web API &&Perl
• /
– LWP::*
•
– 20 : Web API ←
– 30 : sugyan
• ( )

3. Web API
• API = Application Programming Interface
– /
• Web API
API

4. Web API
• Twitter API
• Google Ajax API
• YouTube API
• Flickr API
• mixi API
• API
• etc…

5. /
• Web
– HTTP
– URI
– GET/POST
– JSON/XML etc.

6. 3 (GET )
1. URI
2. GET
3.

7. • Twitter perl
– http://search.twitter.com/search.json?q=perl
• GET
• JSON
•

8. Twitter Search API
• Twitter
• http://dev.twitter.com/doc/get/search
•

9. API
• URI
– http://search.twitter.com/search.json
•
– JSON/atom
•
– GET
•
– q=perl

10. Web

11. URI
• ASCII
• URI
• http://search.twitter.com/search.json?q=
%E3%81%8A%E3%81%AF
%E3%82%88%E3%81%86

12. URI
use URI;
use utf8;
my $query = ' ';
my $uri =
URI‐>new('http://search.twitter.com/search.json');
my $params = {
q => $query,
result_type => 'popular',
};
$uri‐>query_form(%$params);
print "$urin";
http://search.twitter.com/search.json?
result_type=popular&q=%E3%81%8A%E3%81%AF
%E3%82%88%E3%81%86

13. Web API
• LWP::UserAgent
– Others: LWP::Simple, URI::Fetch
• HTTP::Request
•
– GET/POST/PUT/DELETE/HEAD
• HTTP::Response

14. LWP::UserAgent
use URI;
use LWP::UserAgent;
my $uri = URI‐>new('http://search.twitter.com/
search.json?q=perl');
my $ua = LWP::UserAgent‐>new();
my $res = $ua‐>get( $uri );
die $res‐>status_line if $res‐>is_error;
print $res‐>content . "n";

15. • cpanm JSON -> JSON::XS or JSON::PP
• JSON
– uXXXX Unicode ascii
–
– u304au306fu3088u3046

16. JSON
use JSON qw( decode_json );
use Encode qw( encode_utf8 );
my $json_text =
'{"user":"yusukebe","message":"u304au306fu3088u3046"}';
my $ref = decode_json($json_text);
print encode_utf8("$ref‐>{user} : $ref‐>{message}n");
yusukebe :

17. • URI URI
• LWP::UserAgent URI
/
• JSON

18. • #yokohamapm
use LWP::UserAgent;
use URI;
use JSON qw(decode_json);
use Encode qw(encode_utf8);
my $query = '#yokohamapm';
my $uri = URI‐>new('http://search.twitter.com/search.json');

19. my $params = {
q => $query,
result_type => 'recent',
};
$uri‐>query_form(%$params);
my $ua = LWP::UserAgent‐>new;
my $res = $ua‐>get($uri);
die "Error: ". $res‐>status_line if $res‐>is_error;
my $json = $res‐>content;
my $ref = decode_json($json);
for my $tweet ( @{ $ref‐>{results} } ) {
print encode_utf8("@$tweet‐>{from_user}: $tweet‐>{text}n");
}

20. $ perl twitter_search.pl
@mazkeng: ust #yokohamapm
@hokke_mirin: 2 #perlcasual
#yokohamapm
@yusukebe: #yokohamapm

21. WebService::Simple
use WebService::Simple;
use Data::Dumper;
my $query = '#yokohamapm';
my $service = WebService::Simple‐>new(
base_url => 'http://search.twitter.com/search.json',
response_parser => 'JSON',
);
my $res = $service‐>get( { q => $query });
my $ref = $res‐>parse_response();
print Dumper $ref;

22. • Web API =
• Standing on the shoulders of giants -
-

23. ?
WEB+DB PRESS vol.58
2010 8
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