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Perl in the Internet of Things

This document provides an agenda and overview for a workshop on using Perl for Internet of Things applications. The workshop will cover using Perl and HTTP for device communication, creating web clients and APIs with HTTP::Tiny and Dancer, and developing REST APIs in Perl. Attendees will learn how any language can be used for IoT by treating devices as HTTP clients that trigger actions by making requests to server responses. Practical examples will include reading sensor data and communicating with Arduino devices from Perl programs.

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PPeerrll iinn tthhee IInntteerrnneett ooff TThhiinnggss Dave Cross Magnum Solutions Ltd dave@mag-sol.com
 9:10 (ish) – Part 1  11:00 – Coffee  11:30 – Part 2  11:50 – End LPW Schedule  Possibly cupcakes 8th November 2014 2
 Perl and the IoT  Web Client Primer  Web APIs with Dancer  Introduction to REST  REST APIs in Perl LPW What We Will Cover 8th November 2014 3
PPeerrll aanndd tthhee IInntteerrnneett ooff TThhiinnggss
 Things  On the Internet  Providing useful services LPW The Internet of Things 8th November 2014 5
LPW The Internet of Things 8th November 2014 6
 Cutting edge interactions  Latest technologies  Modern languages LPW The Hype  Scala  Erlang 8th November 2014 7
 It's just HTTP  Some event triggers action  Thing makes an HTTP request  Server sends response  Thing does something LPW The Reality  Usually 8th November 2014 8
 Any language works  Perl just as effective as other languages  Perl has a long history of writing HTTP servers  And HTTP clients  Many useful modules LPW The Reality  Of course 8th November 2014 9
 Your “thing” is an HTTP client  But its interface will be unusual  Limited input/output channels  Hardware sensors  Device::SerialPort  Device::BCM2835  Arduino workshop LPW Hardware 8th November 2014 10
 Your “thing” won't be displaying web pages  So returning HTML is probably unhelpful  Data-rich representation LPW HTTP Response  JSON 8th November 2014 11
WWeebb CClliieenntt PPrriimmeerr
 We're used to writing web server applications in Perl  But we can write web clients too  Programs that act like a browser  Make an HTTP request  Parse the HTTP reponse  Take some action LPW Web Clients  And we'll cover more about that later 8th November 2014 13
 Most people would reach for LWP  LWP is “libwww-perl”  Library for writing web clients in Perl  Powerful and flexible HTTP client  Install from CPAN LPW LWP 8th November 2014 14
 Small web client library for Perl  Part of standard Perl installation  Tiny is good for IoT LPW HTTP::Tiny  Since Perl 5.14 8th November 2014 15
 use HTTP::Tiny; LPW Using HTTP::Tiny my $response = HTTP::Tiny->new->get('http://example.com/'); die "Failed!n" unless $response->{success}; print "$response->{status} $response->{reason}n"; while (my ($k, $v) = each %{$response->{headers}}) { for (ref $v eq 'ARRAY' ? @$v : $v) { print "$k: $_n"; } } print $response->{content} if length $response->{content}; 8th November 2014 16
 Create a new user agent object (“browser”) with new()  Various configuration options  my $ua = HTTP::Tiny->new(%options); LPW HTTP::Tiny->new 8th November 2014 17
 agent – user agent string  cookie_jar – HTTP::CookieJar object  default_headers – hashref LPW Options  Or equivalent 8th November 2014 18
 local_address  keep_alive  max_redirect  max_size  timeout LPW Low-Level Options  Of response 8th November 2014 19
 http_proxy  https_proxy  proxy  no_proxy  Environment variables LPW Proxy Options 8th November 2014 20
 verify_SSL – default is false  SSL_options – passed to IO::Socket::SSL LPW SSL Options 8th November 2014 21
 Use the request() method  $resp = $ua->request(  Useful options LPW Making Requests $method, $url, %options );  headers  content 8th November 2014 22
 Response is a hash  success – true if status is 2xx  url – URL that returned response  status  reason  content  headers LPW Responses  Not an object 8th November 2014 23
 Higher level functions for HTTP requests  get  head  post  put  delete LPW Easier Requests 8th November 2014 24
 Each is a shorthand way to call request()  $resp = $ua->get($url, %options)  $resp = $ua->request(  Same options  Same response hash LPW Easier Requests 'get', $url, %options ) 8th November 2014 25
 $ua->request('post', $url,  $ua->post($url, %options)  Where do post parameters go?  In %options LPW POSTing Data %options)  content key  Build it yourself  www_form_urlencode() 8th November 2014 26
 $ua->post_form($url, $form_data)  $form_data can be hash ref  Or array ref  Sort order LPW POSTing Data  { key1 => 'value1', key2 => 'value2' }  [ key1 => 'value1', key2 => 'value2' ] 8th November 2014 27
 HTTP::Tiny::UA  HTTP::Thin  HTTP::Tiny::Mech LPW See Also  Higher level UA features  Wrapper adds HTTP::Request/HTTP::Response compatibility  WWW::Mechanize wrapper for HTTP::Tiny 8th November 2014 28
WWeebb AAPPIIss WWiitthh DDaanncceerr
LPW 8th November 2014 Dancer  Dancer is a simple route-based web framework for Perl  Easy to get web application up and running  See Andrew Solomon's class at 12:00  We're actually going to be using Dancer2
LPW 8th November 2014 Simple API  Return information about MP3s  GET /mp3  List MP3s  GET /mp3/1  Info about a single MP3
LPW 8th November 2014 Database  CREATE TABLE mp3 ( id integer primary key, title varchar(200), artist varchar(200), filename varchar(200) );
LPW 8th November 2014 DBIx::Class  $ dbicdump -o dump_directory=./lib MP3::Schema dbi:SQLite:mp3.db Dumping manual schema for MP3::Schema to directory ./lib ... Schema dump completed.  $ find lib/ lib/ lib/MP3 lib/MP3/Schema.pm lib/MP3/Schema lib/MP3/Schema/Result lib/MP3/Schema/Result/Mp3.pm
LPW 8th November 2014 Data  Insert some sample data  sqlite> select * from mp3; 1|Royals|Lorde|music/lorde/pure-heroine/ royals.mp3 2|The Mother We Share|Chvrches| music/chvrches/the-bones-of-what-we-believe/the-mother- we-share.mp3 3|Falling|Haim|music/haim/days-are-gone/ falling.mp3
LPW 8th November 2014 Create Application  $ dancer2 gen -a MP3  + MP3 [ ... ] + MP3/config.yml [ ... ] + MP3/lib + MP3/lib/MP3.pm + MP3/bin + MP3/bin/app.pl
LPW 8th November 2014 Run Application  $ MP3/bin/app.pl  >> Dancer2 v0.153002 server 6219 listening on http://0.0.0.0:3000
LPW 8th November 2014 Run Application
LPW 8th November 2014 Implement Routes  Our application doesn't do anything  Need to implement routes  Routes are defined in MP3/lib/MP3.pm  get '/' => sub { template 'index'; };
LPW 8th November 2014 Implement Routes  Our application doesn't do anything  Need to implement routes  Routes are defined in MP3/lib/MP3.pm  get '/' => sub { template 'index'; };
LPW 8th November 2014 Implement Routes  Our application doesn't do anything  Need to implement routes  Routes are defined in MP3/lib/MP3.pm  get '/' => sub { template 'index'; };
LPW 8th November 2014 Implement Routes  Our application doesn't do anything  Need to implement routes  Routes are defined in MP3/lib/MP3.pm  get '/' => sub { template 'index'; };
LPW 8th November 2014 /mp3 Route  Display a list of MP3s  Get them from the database  Use Dancer2::Plugin::DBIC  In config.yml  Plugins: DBIC: default: dsn: dbi:SQLite:dbname=mp3.db
LPW 8th November 2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
LPW 8th November 2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
LPW 8th November 2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
LPW 8th November 2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
LPW 8th November 2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
LPW 8th November 2014 /mp3 Route
LPW 8th November 2014 /mp3 Route
LPW 8th November 2014 /mp3/:id Route  Display details of one MP3  Dancer gives us parameters from path  $value = param($name)
LPW 8th November 2014 /mp3/:id Route  get '/mp3/:id' => sub { my $mp3 = schema->resultset('Mp3') ->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } content_type 'text/plain'; return $mp3->title . "n" . $mp3->artist . "n" . $mp3->filename; };
LPW 8th November 2014 /mp3/:id Route  get '/mp3/:id' => sub { my $mp3 = schema->resultset('Mp3') ->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } content_type 'text/plain'; return $mp3->title . "n" . $mp3->artist . "n" . $mp3->filename; };
LPW 8th November 2014 /mp3/:id Route  get '/mp3/:id' => sub { my $mp3 = schema->resultset('Mp3') ->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } content_type 'text/plain'; return $mp3->title . "n" . $mp3->artist . "n" . $mp3->filename; };
LPW 8th November 2014 /mp3/:id Route  get '/mp3/:id' => sub { my $mp3 = schema->resultset('Mp3') ->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } content_type 'text/plain'; return $mp3->title . "n" . $mp3->artist . "n" . $mp3->filename; };
LPW 8th November 2014 /mp3/:id Route
LPW 8th November 2014 /mp3/:id Route
LPW 8th November 2014 Plain Text?  Yes, plain text is bad  Easy fix  Serializer: JSON  In config.yml  Rewrite routes to return data structures  Dancer serialises them as JSON
LPW 8th November 2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
LPW 8th November 2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
LPW 8th November 2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
LPW 8th November 2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
LPW 8th November 2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
LPW 8th November 2014 Return Data  get '/mp3/:id' => sub { my $mp3 = schema-> resultset('Mp3')->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } return { title => $mp3->title, artist => $mp3->artist, filename => $mp3->filename, }; };
LPW 8th November 2014 Return Data  get '/mp3/:id' => sub { my $mp3 = schema-> resultset('Mp3')->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } return { $mp3->get_columns }; };
LPW 8th November 2014 JSON
LPW 8th November 2014 JSON
LPW 8th November 2014 JSON
LPW 8th November 2014 JSON
LPW 8th November 2014 URLs  It's good practice to return URLs when you can  Easier for clients to browse our data  We can do that for our list
LPW 8th November 2014 URLs  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; my $url = uri_for('/mp3') . '/'; return { mp3s => [ map { { title => $_->title, artist => $_->artist, url => $url . $_->id, } } @mp3s ] }; };
LPW 8th November 2014 URLs  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; my $url = uri_for('/mp3') . '/'; return { mp3s => [ map { { title => $_->title, artist => $_->artist, url => $url . $_->id, } } @mp3s ] }; };
LPW 8th November 2014 URLs  $ GET http://localhost:3000/mp3  {"mp3s":[ { "url":"http://localhost:3000/mp3/1", "title":"Royals","artist":"Lorde" }, { "url":"http://localhost:3000/mp3/2", "artist":"Chvrches","title":"The Mother We Share" }, { "url":"http://localhost:3000/mp3/3", "artist":"Haim","title":"Falling" } ]}
LPW 8th November 2014 More on URLs  Currently our system has only one resource  mp3  It's usual to have links to other resources  MP3s have artists  Link to other resources using URLs  Make it easier for clients to walk our data model
LPW 8th November 2014 More on URLs  In our MP3 JSON we have this  “artist”:”Lorde”  It would be better to have  “artist_name”:”Lorde” “artist_url”:”http://localhost:3000/artist/1”  Perhaps add a url() method to all of our objects
LPW 8th November 2014 Other GET Actions  Getting lists of objects is easy  Other things to consider  Searching  Sorting  Paging  Filtering  CGI Parameters to DBIC to SQL to JSON
LPW 8th November 2014 Other Actions  We will want to to other things to our data  Add objects  Update objects  Delete objects  CRUD operations
LPW 8th November 2014 Other Actions  Use HTTP methods  POST /mp3  Create  GET /mp3/:id  Read  PUT /mp3/:id  Update  DELETE /mp3/:id  Delete
LPW 8th November 2014 Other Actions  Use HTTP methods  POST /mp3  Create  GET /mp3/:id  Read  PUT /mp3/:id  Update  DELETE /mp3/:id  Delete
LPW 8th November 2014 Other Actions  Easy to write Dancer handlers for these  delete '/mp3/:id' => sub { schema->resultset('Mp3')-> find(param('id'))-> delete; }  But it can be hard to get right  What should we return here?  Is there a better way?
RREESSTT
 Representational State Transfer  Abstraction of web architecture  Dissertation by Roy Fielding, 2000  Particularly applicable to web services LPW REST 8th November 2014 81
 Base URI for service  Defined media type  HTTP methods for interaction  Hypertext links for resources  Hypertext links for related resources LPW RESTful Web Services 8th November 2014 82
RESTful vs Non-RESTful  Good test  Which HTTP methods does it use?  Web services often use only GET and POST  GET /delete/mp3/1  GET /mp3/1/delete  Not RESTful  DELETE /mp3/1  Might be RESTful LPW 8th November 2014 83
 Dancer has a REST plugin  Dancer2::Plugin::REST  Makes our live much easier LPW RESTful Dancer 8th November 2014 84
 Does three things for us  Creates routes  Utility functions for return values  Returns data in different formats LPW Dancer2::Plugin::REST 8th November 2014 85
 resource mp3 => LPW Creates Routes get => sub { ... }, create => sub { ... }, delete => sub { ... }, update => sub { ... }; 8th November 2014 86
 resource mp3 => LPW Creates Routes get => sub { ... }, create => sub { ... }, delete => sub { ... }, update => sub { ... }; 8th November 2014 87
 post '/mp3'  get '/mp3/:id'  put '/mp3/:id'  delete '/mp3/:id' LPW CRUD Routes  Create  Read  Update  Delete 8th November 2014 88
 post '/mp3'  get '/mp3/:id'  put '/mp3/:id'  delete '/mp3/:id' LPW CRUD Routes  Create  Read  Update  Delete 8th November 2014 89
 resource mp3 => LPW Creates Routes get => sub { my $mp3 = schema->resultset('Mp3')-> find(params->{id}); if ($mp3) { status_ok( { $mp3->get_columns } ); } else { status_not_found('MP3 Not Found'); } }; 8th November 2014 90
 Note: Still have to create main listing route  /mp3 LPW Creates Routes 8th November 2014 91
 Simple status_* functions for return values  status_ok(%resource)  status_not_found($message)  status_created(%new_resource) LPW Utility Functions 8th November 2014 92
 Allow user to choose data format  By changing the URL  get '/mp3/:id'  get '/mp3:id.:format'  YAML, JSON, Data::Dumper support built-in LPW Format Options 8th November 2014 93
Format Options - JSON  $ GET http://localhost:3000/mp3/1.json  {"id":1,"filename":"music/lorde/pure-heroine/ LPW royals.mp3","title":"Royals","ar tist":"Lorde"} 8th November 2014 94
 $ GET http://localhost:3000/mp3/1.yml  --- artist: Lorde filename: music/lorde/pure-heroine/ LPW Format Options -YAML royals.mp3 id: 1 title: Royals 8th November 2014 95
 $ GET http://localhost:3000/mp3/1.dump  $VAR1 = { LPW Format Options -YAML 'filename' => 'music/lorde/pure-heroine/ royals.mp3', 'title' => 'Royals', 'artist' => 'Lorde', 'id' => 1 }; 8th November 2014 96
 Dancer and Dancer2::Plugin::REST make simple REST easy  But full REST support is more complex  Here's a REST state machine LPW More Complex REST  Other frameworks do the same 8th November 2014 97
LPW 8th November 2014 98
LPW 8th November 2014 99
LPW 8th November 2014 100
LPW Read a Good Book 8th November 2014 101
 There's a lot to think about when getting REST right  Can CPAN help?  Web::Machine  WebAPI::DBIC LPW CPAN to the Rescue 8th November 2014 102
 Perl port of Erlang webmachine  You write subclasses of Web::Machine::Resource  Override methods where necessary  See Stevan Little's YAPC::NA 2012 talk LPW Web::Machine  With bits stolen from Ruby and Javascript versions too 8th November 2014 103
 use Web::Machine; LPW Example { package WasteOfTime::Resource; use parent 'Web::Machine::Resource'; use JSON::XS qw(encode_json); sub content_types_provided { [{ 'application/json' => 'to_json' }] } sub to_json { encode_json({ time => scalar localtime }) } } Web::Machine->new( resource => 'WasteOfTime::Resource' )->to_app; 8th November 2014 104
 $ plackup time.psgi  $ curl -v http://0:5000 LPW Example HTTP::Server::PSGI: Accepting connections at http://0:5000/ [ ... ] < HTTP/1.0 200 OK < Date: Sat, 08 Nov 2014 11:34:02 GMT < Server: HTTP::Server::PSGI < Content-Length: 35 < Content-Type: application/json < * Closing connection #0 {"time":"Sat Nov 8 11:34:02 2014"} 8th November 2014 105
 $ curl -v http://0:5000 -H'Accept: text/html' LPW Example [ ... ] < HTTP/1.0 406 Not Acceptable < Date: Sat, 08 Nov 2014 11:34:02 GMT < Server: HTTP::Server::PSGI < Content-Length: 14 < * Closing connection #0 Not Acceptable 8th November 2014 106
 sub content_types_provided { [ LPW Example { 'application/json' => 'to_json' }, { 'text/html' => 'to_html' }, ] } 8th November 2014 107
 sub content_types_provided { [ LPW Example { 'application/json' => 'to_json' }, { 'text/html' => 'to_html' }, ] } 8th November 2014 108
 sub content_types_provided { [  sub to_html { LPW Example { 'application/json' => 'to_json' }, { 'text/html' => 'to_html' }, ] } my $time = localtime; return “<html> <head><title>The Time Now Is:</title></head> <body> <h1>$time</h1> </body> </html>”; } 8th November 2014 109
 $ curl -v http://0:5000 -H'Accept: text/html' LPW Example [ ... ] < HTTP/1.0 200 OK < Date: Sun, 09 Dec 2012 02:26:39 GMT < Server: HTTP::Server::PSGI < Vary: Accept < Content-Length: 103 < Content-Type: text/html < * Closing connection #0 <html><head><title>The Time Now Is:</title></head><body><h1>Sat Nov 8 11:34:02 2014</h1></body></html> 8th November 2014 110
 “WebAPI::DBIC provides the parts you need to build a feature-rich RESTful JSON web service API backed by DBIx::Class schemas.”  REST API in a box LPW WebAPI::DBIC 8th November 2014 111
 Built on top of Web::Machine  And Path::Router  And Plack  Uses JSON+HAL LPW WebAPI::DBIC  Hypertext Application Language 8th November 2014 112
 $ git clone https://github.com/timbunce/WebAPI-DBIC.  $ cd WebAPI-DBIC  $ cpanm Module::CPANfile  $ cpanm --installdeps . # wait ...  $ export WEBAPI_DBIC_SCHEMA=DummyLoadedSchema  $ plackup -Ilib -It/lib webapi-dbic-any.psgi  ... open a web browser on port 5000 to browse the API LPW Try It Out git 8th November 2014 113
Try It Out (Your Schema)  $ export WEBAPI_DBIC_SCHEMA=Foo::Bar  $ export WEBAPI_DBIC_HTTP_AUTH_TYPE=none  $ export DBI_DSN=dbi:Driver:...  $ export DBI_USER=...  $ export DBI_PASS=...  $ plackup -Ilib webapi-dbic-any.psgi  ... open a web browser on port 5000 to browse the API LPW 8th November 2014 114
CCoonncclluussiioonn
 Perl is great for the Internet of Things  Perl is great for text processing  Perl is great for network processing  IoT apps are often mainly HTTP transactions LPW Conclusion  And Perl is good at those 8th November 2014 116
 Perl Training  Central London  Next week  Intermediate Perl  Advanced Perl  See advert in brochure LPW Sponsor's Message  11/12 Nov  13/14 Nov 8th November 2014 117
 Perl Training  Central London  Next week  Intermediate Perl  Advanced Perl  See advert in brochure LPW Sponsor's Message  11/12 Nov  13/14 Nov 8th November 2014 118
TThhaatt''ss AAllll FFoollkkss • Any Questions?

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Perl in the Internet of Things

  • 1.
    PPeerrll iinn tthhee IInntteerrnneett ooff TThhiinnggss Dave Cross Magnum Solutions Ltd dave@mag-sol.com
  • 2.
     9:10 (ish)– Part 1  11:00 – Coffee  11:30 – Part 2  11:50 – End LPW Schedule  Possibly cupcakes 8th November 2014 2
  • 3.
     Perl andthe IoT  Web Client Primer  Web APIs with Dancer  Introduction to REST  REST APIs in Perl LPW What We Will Cover 8th November 2014 3
  • 4.
    PPeerrll aanndd tthhee IInntteerrnneett ooff TThhiinnggss
  • 5.
     Things On the Internet  Providing useful services LPW The Internet of Things 8th November 2014 5
  • 6.
    LPW The Internetof Things 8th November 2014 6
  • 7.
     Cutting edgeinteractions  Latest technologies  Modern languages LPW The Hype  Scala  Erlang 8th November 2014 7
  • 8.
     It's justHTTP  Some event triggers action  Thing makes an HTTP request  Server sends response  Thing does something LPW The Reality  Usually 8th November 2014 8
  • 9.
     Any languageworks  Perl just as effective as other languages  Perl has a long history of writing HTTP servers  And HTTP clients  Many useful modules LPW The Reality  Of course 8th November 2014 9
  • 10.
     Your “thing”is an HTTP client  But its interface will be unusual  Limited input/output channels  Hardware sensors  Device::SerialPort  Device::BCM2835  Arduino workshop LPW Hardware 8th November 2014 10
  • 11.
     Your “thing”won't be displaying web pages  So returning HTML is probably unhelpful  Data-rich representation LPW HTTP Response  JSON 8th November 2014 11
  • 12.
  • 13.
     We're usedto writing web server applications in Perl  But we can write web clients too  Programs that act like a browser  Make an HTTP request  Parse the HTTP reponse  Take some action LPW Web Clients  And we'll cover more about that later 8th November 2014 13
  • 14.
     Most peoplewould reach for LWP  LWP is “libwww-perl”  Library for writing web clients in Perl  Powerful and flexible HTTP client  Install from CPAN LPW LWP 8th November 2014 14
  • 15.
     Small webclient library for Perl  Part of standard Perl installation  Tiny is good for IoT LPW HTTP::Tiny  Since Perl 5.14 8th November 2014 15
  • 16.
     use HTTP::Tiny; LPW Using HTTP::Tiny my $response = HTTP::Tiny->new->get('http://example.com/'); die "Failed!n" unless $response->{success}; print "$response->{status} $response->{reason}n"; while (my ($k, $v) = each %{$response->{headers}}) { for (ref $v eq 'ARRAY' ? @$v : $v) { print "$k: $_n"; } } print $response->{content} if length $response->{content}; 8th November 2014 16
  • 17.
     Create anew user agent object (“browser”) with new()  Various configuration options  my $ua = HTTP::Tiny->new(%options); LPW HTTP::Tiny->new 8th November 2014 17
  • 18.
     agent –user agent string  cookie_jar – HTTP::CookieJar object  default_headers – hashref LPW Options  Or equivalent 8th November 2014 18
  • 19.
     local_address keep_alive  max_redirect  max_size  timeout LPW Low-Level Options  Of response 8th November 2014 19
  • 20.
     http_proxy https_proxy  proxy  no_proxy  Environment variables LPW Proxy Options 8th November 2014 20
  • 21.
     verify_SSL –default is false  SSL_options – passed to IO::Socket::SSL LPW SSL Options 8th November 2014 21
  • 22.
     Use therequest() method  $resp = $ua->request(  Useful options LPW Making Requests $method, $url, %options );  headers  content 8th November 2014 22
  • 23.
     Response isa hash  success – true if status is 2xx  url – URL that returned response  status  reason  content  headers LPW Responses  Not an object 8th November 2014 23
  • 24.
     Higher levelfunctions for HTTP requests  get  head  post  put  delete LPW Easier Requests 8th November 2014 24
  • 25.
     Each isa shorthand way to call request()  $resp = $ua->get($url, %options)  $resp = $ua->request(  Same options  Same response hash LPW Easier Requests 'get', $url, %options ) 8th November 2014 25
  • 26.
     $ua->request('post', $url,  $ua->post($url, %options)  Where do post parameters go?  In %options LPW POSTing Data %options)  content key  Build it yourself  www_form_urlencode() 8th November 2014 26
  • 27.
     $ua->post_form($url, $form_data)  $form_data can be hash ref  Or array ref  Sort order LPW POSTing Data  { key1 => 'value1', key2 => 'value2' }  [ key1 => 'value1', key2 => 'value2' ] 8th November 2014 27
  • 28.
     HTTP::Tiny::UA HTTP::Thin  HTTP::Tiny::Mech LPW See Also  Higher level UA features  Wrapper adds HTTP::Request/HTTP::Response compatibility  WWW::Mechanize wrapper for HTTP::Tiny 8th November 2014 28
  • 29.
  • 30.
    LPW 8th November2014 Dancer  Dancer is a simple route-based web framework for Perl  Easy to get web application up and running  See Andrew Solomon's class at 12:00  We're actually going to be using Dancer2
  • 31.
    LPW 8th November2014 Simple API  Return information about MP3s  GET /mp3  List MP3s  GET /mp3/1  Info about a single MP3
  • 32.
    LPW 8th November2014 Database  CREATE TABLE mp3 ( id integer primary key, title varchar(200), artist varchar(200), filename varchar(200) );
  • 33.
    LPW 8th November2014 DBIx::Class  $ dbicdump -o dump_directory=./lib MP3::Schema dbi:SQLite:mp3.db Dumping manual schema for MP3::Schema to directory ./lib ... Schema dump completed.  $ find lib/ lib/ lib/MP3 lib/MP3/Schema.pm lib/MP3/Schema lib/MP3/Schema/Result lib/MP3/Schema/Result/Mp3.pm
  • 34.
    LPW 8th November2014 Data  Insert some sample data  sqlite> select * from mp3; 1|Royals|Lorde|music/lorde/pure-heroine/ royals.mp3 2|The Mother We Share|Chvrches| music/chvrches/the-bones-of-what-we-believe/the-mother- we-share.mp3 3|Falling|Haim|music/haim/days-are-gone/ falling.mp3
  • 35.
    LPW 8th November2014 Create Application  $ dancer2 gen -a MP3  + MP3 [ ... ] + MP3/config.yml [ ... ] + MP3/lib + MP3/lib/MP3.pm + MP3/bin + MP3/bin/app.pl
  • 36.
    LPW 8th November2014 Run Application  $ MP3/bin/app.pl  >> Dancer2 v0.153002 server 6219 listening on http://0.0.0.0:3000
  • 37.
    LPW 8th November2014 Run Application
  • 38.
    LPW 8th November2014 Implement Routes  Our application doesn't do anything  Need to implement routes  Routes are defined in MP3/lib/MP3.pm  get '/' => sub { template 'index'; };
  • 39.
    LPW 8th November2014 Implement Routes  Our application doesn't do anything  Need to implement routes  Routes are defined in MP3/lib/MP3.pm  get '/' => sub { template 'index'; };
  • 40.
    LPW 8th November2014 Implement Routes  Our application doesn't do anything  Need to implement routes  Routes are defined in MP3/lib/MP3.pm  get '/' => sub { template 'index'; };
  • 41.
    LPW 8th November2014 Implement Routes  Our application doesn't do anything  Need to implement routes  Routes are defined in MP3/lib/MP3.pm  get '/' => sub { template 'index'; };
  • 42.
    LPW 8th November2014 /mp3 Route  Display a list of MP3s  Get them from the database  Use Dancer2::Plugin::DBIC  In config.yml  Plugins: DBIC: default: dsn: dbi:SQLite:dbname=mp3.db
  • 43.
    LPW 8th November2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
  • 44.
    LPW 8th November2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
  • 45.
    LPW 8th November2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
  • 46.
    LPW 8th November2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
  • 47.
    LPW 8th November2014 /mp3 Route  In MP3/lib/MP3.pm  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; content_type 'text/plain'; return join "n", map { $_->title . ' / ' . $_->artist } @mp3s; };
  • 48.
    LPW 8th November2014 /mp3 Route
  • 49.
    LPW 8th November2014 /mp3 Route
  • 50.
    LPW 8th November2014 /mp3/:id Route  Display details of one MP3  Dancer gives us parameters from path  $value = param($name)
  • 51.
    LPW 8th November2014 /mp3/:id Route  get '/mp3/:id' => sub { my $mp3 = schema->resultset('Mp3') ->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } content_type 'text/plain'; return $mp3->title . "n" . $mp3->artist . "n" . $mp3->filename; };
  • 52.
    LPW 8th November2014 /mp3/:id Route  get '/mp3/:id' => sub { my $mp3 = schema->resultset('Mp3') ->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } content_type 'text/plain'; return $mp3->title . "n" . $mp3->artist . "n" . $mp3->filename; };
  • 53.
    LPW 8th November2014 /mp3/:id Route  get '/mp3/:id' => sub { my $mp3 = schema->resultset('Mp3') ->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } content_type 'text/plain'; return $mp3->title . "n" . $mp3->artist . "n" . $mp3->filename; };
  • 54.
    LPW 8th November2014 /mp3/:id Route  get '/mp3/:id' => sub { my $mp3 = schema->resultset('Mp3') ->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } content_type 'text/plain'; return $mp3->title . "n" . $mp3->artist . "n" . $mp3->filename; };
  • 55.
    LPW 8th November2014 /mp3/:id Route
  • 56.
    LPW 8th November2014 /mp3/:id Route
  • 57.
    LPW 8th November2014 Plain Text?  Yes, plain text is bad  Easy fix  Serializer: JSON  In config.yml  Rewrite routes to return data structures  Dancer serialises them as JSON
  • 58.
    LPW 8th November2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
  • 59.
    LPW 8th November2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
  • 60.
    LPW 8th November2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
  • 61.
    LPW 8th November2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
  • 62.
    LPW 8th November2014 Return Data  get '/mp3' => sub { my @mp3s = schema-> resultset('Mp3')->all; return { mp3s => [ map { { title => $_->title, artist => $_->artist } } @mp3s ] }; };
  • 63.
    LPW 8th November2014 Return Data  get '/mp3/:id' => sub { my $mp3 = schema-> resultset('Mp3')->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } return { title => $mp3->title, artist => $mp3->artist, filename => $mp3->filename, }; };
  • 64.
    LPW 8th November2014 Return Data  get '/mp3/:id' => sub { my $mp3 = schema-> resultset('Mp3')->find(param('id')); unless ($mp3) { status 404; return 'Not found'; } return { $mp3->get_columns }; };
  • 65.
  • 66.
  • 67.
  • 68.
  • 69.
    LPW 8th November2014 URLs  It's good practice to return URLs when you can  Easier for clients to browse our data  We can do that for our list
  • 70.
    LPW 8th November2014 URLs  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; my $url = uri_for('/mp3') . '/'; return { mp3s => [ map { { title => $_->title, artist => $_->artist, url => $url . $_->id, } } @mp3s ] }; };
  • 71.
    LPW 8th November2014 URLs  get '/mp3' => sub { my @mp3s = schema->resultset('Mp3')->all; my $url = uri_for('/mp3') . '/'; return { mp3s => [ map { { title => $_->title, artist => $_->artist, url => $url . $_->id, } } @mp3s ] }; };
  • 72.
    LPW 8th November2014 URLs  $ GET http://localhost:3000/mp3  {"mp3s":[ { "url":"http://localhost:3000/mp3/1", "title":"Royals","artist":"Lorde" }, { "url":"http://localhost:3000/mp3/2", "artist":"Chvrches","title":"The Mother We Share" }, { "url":"http://localhost:3000/mp3/3", "artist":"Haim","title":"Falling" } ]}
  • 73.
    LPW 8th November2014 More on URLs  Currently our system has only one resource  mp3  It's usual to have links to other resources  MP3s have artists  Link to other resources using URLs  Make it easier for clients to walk our data model
  • 74.
    LPW 8th November2014 More on URLs  In our MP3 JSON we have this  “artist”:”Lorde”  It would be better to have  “artist_name”:”Lorde” “artist_url”:”http://localhost:3000/artist/1”  Perhaps add a url() method to all of our objects
  • 75.
    LPW 8th November2014 Other GET Actions  Getting lists of objects is easy  Other things to consider  Searching  Sorting  Paging  Filtering  CGI Parameters to DBIC to SQL to JSON
  • 76.
    LPW 8th November2014 Other Actions  We will want to to other things to our data  Add objects  Update objects  Delete objects  CRUD operations
  • 77.
    LPW 8th November2014 Other Actions  Use HTTP methods  POST /mp3  Create  GET /mp3/:id  Read  PUT /mp3/:id  Update  DELETE /mp3/:id  Delete
  • 78.
    LPW 8th November2014 Other Actions  Use HTTP methods  POST /mp3  Create  GET /mp3/:id  Read  PUT /mp3/:id  Update  DELETE /mp3/:id  Delete
  • 79.
    LPW 8th November2014 Other Actions  Easy to write Dancer handlers for these  delete '/mp3/:id' => sub { schema->resultset('Mp3')-> find(param('id'))-> delete; }  But it can be hard to get right  What should we return here?  Is there a better way?
  • 80.
  • 81.
     Representational StateTransfer  Abstraction of web architecture  Dissertation by Roy Fielding, 2000  Particularly applicable to web services LPW REST 8th November 2014 81
  • 82.
     Base URIfor service  Defined media type  HTTP methods for interaction  Hypertext links for resources  Hypertext links for related resources LPW RESTful Web Services 8th November 2014 82
  • 83.
    RESTful vs Non-RESTful  Good test  Which HTTP methods does it use?  Web services often use only GET and POST  GET /delete/mp3/1  GET /mp3/1/delete  Not RESTful  DELETE /mp3/1  Might be RESTful LPW 8th November 2014 83
  • 84.
     Dancer hasa REST plugin  Dancer2::Plugin::REST  Makes our live much easier LPW RESTful Dancer 8th November 2014 84
  • 85.
     Does threethings for us  Creates routes  Utility functions for return values  Returns data in different formats LPW Dancer2::Plugin::REST 8th November 2014 85
  • 86.
     resource mp3=> LPW Creates Routes get => sub { ... }, create => sub { ... }, delete => sub { ... }, update => sub { ... }; 8th November 2014 86
  • 87.
     resource mp3=> LPW Creates Routes get => sub { ... }, create => sub { ... }, delete => sub { ... }, update => sub { ... }; 8th November 2014 87
  • 88.
     post '/mp3'  get '/mp3/:id'  put '/mp3/:id'  delete '/mp3/:id' LPW CRUD Routes  Create  Read  Update  Delete 8th November 2014 88
  • 89.
     post '/mp3'  get '/mp3/:id'  put '/mp3/:id'  delete '/mp3/:id' LPW CRUD Routes  Create  Read  Update  Delete 8th November 2014 89
  • 90.
     resource mp3=> LPW Creates Routes get => sub { my $mp3 = schema->resultset('Mp3')-> find(params->{id}); if ($mp3) { status_ok( { $mp3->get_columns } ); } else { status_not_found('MP3 Not Found'); } }; 8th November 2014 90
  • 91.
     Note: Stillhave to create main listing route  /mp3 LPW Creates Routes 8th November 2014 91
  • 92.
     Simple status_*functions for return values  status_ok(%resource)  status_not_found($message)  status_created(%new_resource) LPW Utility Functions 8th November 2014 92
  • 93.
     Allow userto choose data format  By changing the URL  get '/mp3/:id'  get '/mp3:id.:format'  YAML, JSON, Data::Dumper support built-in LPW Format Options 8th November 2014 93
  • 94.
    Format Options -JSON  $ GET http://localhost:3000/mp3/1.json  {"id":1,"filename":"music/lorde/pure-heroine/ LPW royals.mp3","title":"Royals","ar tist":"Lorde"} 8th November 2014 94
  • 95.
     $ GEThttp://localhost:3000/mp3/1.yml  --- artist: Lorde filename: music/lorde/pure-heroine/ LPW Format Options -YAML royals.mp3 id: 1 title: Royals 8th November 2014 95
  • 96.
     $ GEThttp://localhost:3000/mp3/1.dump  $VAR1 = { LPW Format Options -YAML 'filename' => 'music/lorde/pure-heroine/ royals.mp3', 'title' => 'Royals', 'artist' => 'Lorde', 'id' => 1 }; 8th November 2014 96
  • 97.
     Dancer andDancer2::Plugin::REST make simple REST easy  But full REST support is more complex  Here's a REST state machine LPW More Complex REST  Other frameworks do the same 8th November 2014 97
  • 98.
  • 99.
  • 100.
  • 101.
    LPW Read aGood Book 8th November 2014 101
  • 102.
     There's alot to think about when getting REST right  Can CPAN help?  Web::Machine  WebAPI::DBIC LPW CPAN to the Rescue 8th November 2014 102
  • 103.
     Perl portof Erlang webmachine  You write subclasses of Web::Machine::Resource  Override methods where necessary  See Stevan Little's YAPC::NA 2012 talk LPW Web::Machine  With bits stolen from Ruby and Javascript versions too 8th November 2014 103
  • 104.
     use Web::Machine; LPW Example { package WasteOfTime::Resource; use parent 'Web::Machine::Resource'; use JSON::XS qw(encode_json); sub content_types_provided { [{ 'application/json' => 'to_json' }] } sub to_json { encode_json({ time => scalar localtime }) } } Web::Machine->new( resource => 'WasteOfTime::Resource' )->to_app; 8th November 2014 104
  • 105.
     $ plackuptime.psgi  $ curl -v http://0:5000 LPW Example HTTP::Server::PSGI: Accepting connections at http://0:5000/ [ ... ] < HTTP/1.0 200 OK < Date: Sat, 08 Nov 2014 11:34:02 GMT < Server: HTTP::Server::PSGI < Content-Length: 35 < Content-Type: application/json < * Closing connection #0 {"time":"Sat Nov 8 11:34:02 2014"} 8th November 2014 105
  • 106.
     $ curl-v http://0:5000 -H'Accept: text/html' LPW Example [ ... ] < HTTP/1.0 406 Not Acceptable < Date: Sat, 08 Nov 2014 11:34:02 GMT < Server: HTTP::Server::PSGI < Content-Length: 14 < * Closing connection #0 Not Acceptable 8th November 2014 106
  • 107.
     sub content_types_provided{ [ LPW Example { 'application/json' => 'to_json' }, { 'text/html' => 'to_html' }, ] } 8th November 2014 107
  • 108.
     sub content_types_provided{ [ LPW Example { 'application/json' => 'to_json' }, { 'text/html' => 'to_html' }, ] } 8th November 2014 108
  • 109.
     sub content_types_provided{ [  sub to_html { LPW Example { 'application/json' => 'to_json' }, { 'text/html' => 'to_html' }, ] } my $time = localtime; return “<html> <head><title>The Time Now Is:</title></head> <body> <h1>$time</h1> </body> </html>”; } 8th November 2014 109
  • 110.
     $ curl-v http://0:5000 -H'Accept: text/html' LPW Example [ ... ] < HTTP/1.0 200 OK < Date: Sun, 09 Dec 2012 02:26:39 GMT < Server: HTTP::Server::PSGI < Vary: Accept < Content-Length: 103 < Content-Type: text/html < * Closing connection #0 <html><head><title>The Time Now Is:</title></head><body><h1>Sat Nov 8 11:34:02 2014</h1></body></html> 8th November 2014 110
  • 111.
     “WebAPI::DBIC providesthe parts you need to build a feature-rich RESTful JSON web service API backed by DBIx::Class schemas.”  REST API in a box LPW WebAPI::DBIC 8th November 2014 111
  • 112.
     Built ontop of Web::Machine  And Path::Router  And Plack  Uses JSON+HAL LPW WebAPI::DBIC  Hypertext Application Language 8th November 2014 112
  • 113.
     $ gitclone https://github.com/timbunce/WebAPI-DBIC.  $ cd WebAPI-DBIC  $ cpanm Module::CPANfile  $ cpanm --installdeps . # wait ...  $ export WEBAPI_DBIC_SCHEMA=DummyLoadedSchema  $ plackup -Ilib -It/lib webapi-dbic-any.psgi  ... open a web browser on port 5000 to browse the API LPW Try It Out git 8th November 2014 113
  • 114.
    Try It Out(Your Schema)  $ export WEBAPI_DBIC_SCHEMA=Foo::Bar  $ export WEBAPI_DBIC_HTTP_AUTH_TYPE=none  $ export DBI_DSN=dbi:Driver:...  $ export DBI_USER=...  $ export DBI_PASS=...  $ plackup -Ilib webapi-dbic-any.psgi  ... open a web browser on port 5000 to browse the API LPW 8th November 2014 114
  • 115.
  • 116.
     Perl isgreat for the Internet of Things  Perl is great for text processing  Perl is great for network processing  IoT apps are often mainly HTTP transactions LPW Conclusion  And Perl is good at those 8th November 2014 116
  • 117.
     Perl Training  Central London  Next week  Intermediate Perl  Advanced Perl  See advert in brochure LPW Sponsor's Message  11/12 Nov  13/14 Nov 8th November 2014 117
  • 118.
     Perl Training  Central London  Next week  Intermediate Perl  Advanced Perl  See advert in brochure LPW Sponsor's Message  11/12 Nov  13/14 Nov 8th November 2014 118
  • 119.
    TThhaatt''ss AAllll FFoollkkss • Any Questions?