API Tips from the Frontline

Transcript

1. foolab.ca | @foolabca API Tips From the Frontline IPC, Berlin - June 9, 2015
2. Anna Filina • Developer • Problem solver • Teacher • Advisor • FooLab + ConFoo 2
3. What you will learn • Don't repeat my mistakes • Overcome common obstacles • Build elegant & pragmatic APIs 4
4. Endpoints What URL to call when
5. Lists • /products • /products?category=games,movies&lang=fr • /products?include=platforms • /products?sort=-date • /products?page[number]=2&page[size]=100 • /products?lang=fr 6
6. Request/Response How to format stuff
7. Request • Bad: Content-Type: application/x-www-form-urlencoded • Content-Type: application/json • Send content (POST) in body, not headers 8
8. Request example: add POST /products HTTP/1.1 Host: api.example.org Content-Type: application/json; charset=UTF-8 { "data": { "name": "Skyrim", "price": 19.99 } } 9
9. Response example: list { "data": [ {"name": "Skyrim"}, {"name": "Civilization V"} ], "page": { "number": 1, "size": 2, "pages": 50, "total": 100 } } 10
10. 3 queries • Count query with same filters but no pagination • Query with filters, pagination & sorting, but only select DISTINCT IDs ◦ Because JOIN + LIMIT = wrong number of root records • Query all the data (with joins) by IDs and apply sorting 11
11. LIMIT SELECT * FROM game LEFT JOIN rating ON rating.game_id = game.id WHERE game.price < 20 LIMIT 2; 12 id name price game_id score 1 Skyrim 19.99 1 9.1 1 Skyrim 19.99 1 8.9 2 Diablo 3 17.89 2 8.5
12. Upload • Use tools, don't DIY (do it yourself). • Client-side: Symfony • Client-side (more dynamic): Plupload • Step 1: upload temp file. • Step 2: give file path to next API request. • Server-side: Guzzle. 13
13. Plupload var uploader = new plupload.Uploader({ runtimes: 'html5,html4', max_file_size: '5mb', url: '/api/upload', filters: [{extensions: 'jpg,png,jpeg'}] }); uploader.init(); 14
14. Guzzle <? $url = 'http://example.org/profiles/1/edit'; $request = $client->createRequest('PATCH', $url); $reqBody = $request->getBody(); $reqBody->setField('data', ['first_name':'Anna']); $file = new PostFile('i.jpg', fopen('/path', 'r')); $reqBody->addFile($file); $response = $client->send($request); 15
15. Status codes • Don't confuse API & HTTP codes • 2xx success • 3xx redirect • 4xx client error • 5xx server error • Send API-specific code in body 16
16. Example of error Status: 400 Content-Type: application/json; charset=UTF-8 { "error": { "code": 1001, "message": "Price must be greater than 0." } } 17
17. Testing Simpler than you think
18. HTTP • Use Guzzle or built-in framework tool • Generate HTTP request , compare output 19
19. Guzzle test // tests/ApiProductTest.php public function testGetOneProduct() { $client = new Client(); $response = $client->get('http://example.org/products/1', [ 'exceptions' => false, 'headers' => ['Accept' => 'application/json'] ]); $this->assertEquals(200, $response->getStatusCode()); // ... } 20
20. Guzzle test // ... $body = $response->getBody()->getContents(); $this->assertJsonStringEqualsJsonString('{ "data": { "id": "1", "name": "Skyrim", "price": 19.99 } }', $body); 21
21. Testing tips • Create separate database for tests • Write tests before you code: • TDD • Contract between you and client dev 22
22. Authentication Nooo, I hate that part! Someone else code it plz.
23. Multiple methods • Don't send username/password in each request ◦ Especially with untrusted 3rd parties ◦ Especially if no SSL • You can have multiple auth methods for one API • Sessions similar to tokens 24
24. OAuth2 • SSL required (can be risky) • Advanced features like access scope • Can be overkill if you need basic features • Private credentials 25
25. OAuth2 - conceptual diagram 26 User Client app
 (php/js/mobile) API Request Forward Validate Create token Store token Login form Login token user/pass
26. Digest • Its own encryption • Easy to implement • No replay (nonce) • Comes out-of-the-box with some frameworks 27
27. Digest - conceptual diagram 28 Request User/client app API Unauthorized Validate digest (nonce,pass) Request nonce
28. Refactoring to API Don't rewrite all the legacy at once
29. Progressive rewrite • Rewrite one component at a time • Start with whatever has fewer dependencies (or critical) • Delete dead code • Copy production data for dev environment 30
30. Services vs libraries • Services: GET /products?id=1,5 • Libraries: • Bypass HTTP • $db->getList( ["id" => "1,5"] ); • Can fetch without pagination • Can hydrate to models 31
31. Implementation tips Is this a good way to code it?
32. Libraries • I use Symfony & Doctrine • Aside from frameworks, I prefer small tools that don't do too much magic 33
33. Reuse & standardize • Goal: streamline endpoint creation • Base controller for common request processing • Base repository for querying with filters • Keep things fully customizable 34
34. Performance Make things faster. Much faster.
35. Benchmark • Give Tideways or Blackfire a spin • Make performance part of your test suite • In dev/test mode, use a meta block 36
36. Example { "meta": { "perf": { "db_time": 0.00367, "total_time": 0.3120, "memory": 19661 } } } 37
37. Performance tips • Don't use lazy loading. Example: $product->getPhotos(). • Craft your own joins and carefully select fields. • Avoid ORM built-in hydration for read operations. • Use API keys even for public endpoints (DDoS mitigation). • Put stuff in Memcached/Redis (especially blocked keys). • HTTP server can check headers 38
38. Useful links • Standard API format
 http://jsonapi.org/format/ • Digest implementation
 http://php.net/manual/en/features.http-auth.php • Symfony components
 http://symfony.com/doc/current/components/index.html • Book "Build APIs You Won't Hate"
 https://leanpub.com/build-apis-you-wont-hate 39
39. Anna Filina • Development: PHP, JS, etc. • Fix problems: bugs, performance, etc. • Workshops: testing, Symfony, AngularJS, API, etc. • Advisor: testing strategy, legacy code, etc. 40
40. @afilina afilina.com