Introduction to Webmachine

Webmachine is a toolkit to build REST APIs implemented in Erlang.

Transcript

1. Introduction to Webmachine! ! ! Mark Allen! mrallen1@yahoo.com! @bytemeorg! http://byte-me.org! https://github.com/mrallen1!
2. HTTP is complicated!
4. Abstraction!
5. Toolkit!
6. A gentle introduction! to Erlang!
7. Sincerely flattered!
8. dj-webmachine! (python)!
9. webmachine.rb! (ruby)!
10. webmachine.js! (node)!
11. liberator! (clojure)!
12. scalamachine! (scala)!
13. Framework!
14. Framework!
16. Hello World! Resource!
17. -module(hello_world_resource). -export([init/1, to_html/2]). -include_lib("webmachine/include/webmachine.hrl"). init([]) -> {ok, "Hello, world"}. to_html(Req, State) -> {io_lib:format("<html><head><title>~s</title></ head><body>~s</body></html>", [State, State]), Req, State}.
18. -module(hello_world_resource). -export([init/1, to_html/2]). -include_lib("webmachine/include/webmachine.hrl"). init([]) -> {ok, "Hello, world"}. to_html(Req, State) -> {io_lib:format("<html><head><title>~s</title></ head><body>~s</body></html>", [State, State]), Req, State}.
19. -module(hello_world_resource). -export([init/1, to_html/2]). -include_lib("webmachine/include/webmachine.hrl"). init([]) -> {ok, "Hello, world"}. to_html(Req, State) -> {io_lib:format("<html><head><title>~s</title></ head><body>~s</body></html>", [State, State]), Req, State}.
20. Conditional GET!
21. -module(hello_world_resource). -export([init/1, to_html/2, generate_etag/2]). -include_lib("webmachine/include/webmachine.hrl"). init([]) -> {ok, "Hello, world"}. to_html(Req, State) -> {io_lib:format("<html><head><title>~s</title></ head><body>~s</body></html>", [State, State]), Req, State}. generate_etag(Req, State) -> {mochihex:to_hex(crypto:md5(State)), Req, State}.
22. Encoding Support!
23. -module(hello_world_resource). -export([init/1, to_html/2, generate_etag/2]). -export([encodings_provided/2]). -include_lib("webmachine/include/webmachine.hrl"). init([]) -> {ok, "Hello, world"}. to_html(Req, State) -> {io_lib:format("<html><head><title>~s</title></ head><body>~s</body></html>", [State, State]), Req, State}. generate_etag(Req, State) -> {mochihex:to_hex(crypto:md5(State)), Req, State}. encodings_provided(Req, State) -> {[{"gzip", fun(X) -> zlib:gzip(X) end}], Req, State}.
25. Content Negotiation!
26. -module(hello_world_resource). -export([init/1, to_html/2, to_json/2, generate_etag/2]). -export([encodings_provided/2, content_types_provided/2]). -include_lib("webmachine/include/webmachine.hrl"). init([]) -> {ok, "Hello, world"}. content_types_provided(Req, State) -> {[{"text/html", to_html}, {"application/json", to_json}], Req, State}. to_json(Req, State) -> {mochijson2:encode({struct, [{greeting, list_to_binary(State)}]}), Req, State}. to_html(Req, State) -> {io_lib:format("<html><head><title>~s</title></ head><body>~s</body></html>", [State, State]), Req, State}. %% ...
28. Resource! Implementation! Pattern!
29. f(Req, State) -> {RetVal, Req, State}.
30. Manipulating! Requests or Responses!
31. wrq:get_req_header(HeaderName, Req) -> 'undefined' | HeaderValue
32. wrq:set_resp_header( HeaderName, HeaderValue, Req) -> NewReq.
33. to_json(Req, State) -> {mochijson2:encode({struct, [{greeting, list_to_binary(State)}]} ), wrq:set_resp_header( "Content-Type", "application/json", Req), State}.
35. Visual Debugging!
37. curl -v -Haccept:application/xml 127.0.0.1:8000
38. Basic URL Dispatch!
39. {["a"], some_resource, []}
40. {["a"], some_resource, []}
41. {["a"], some_resource, []}
42. Fancy URL Dispatch!
43. % The atom '*' is a wildcard {["a", '*'], some_resource, []} % matches /a/b/c or /a/b/c/d
44. % bind 2nd element to 'foo' {["a", foo], some_resource, []} % retrieve with % wrq:path_info(foo, Req) % URL of /a/b returns "b"
45. % bind 2nd element to 'foo' {["a", foo], some_resource, []} % /a/b/c/d => 404 Not Found
46. % dispatch /a/b/c/d {["a", foo, '*'], some_resource, []}
47. Handling POST!
48. •  allowed_methods/2 •  post_is_create/2 •  create_path/2 •  content_types_accepted/2 •  handler functions!
49. Other cool stuff:! •  Streaming requests/ responses! •  File uploads!
50. Resources:! •  https://github.com/basho/webmachine! •  https://github.com/mrallen1/wm_hello! •  https://speakerdeck.com/mrallen1/ intro_to_webmachine!
51. Thank you!! ! Questions?!