REACTING TO CHANGE ! KYLE FULLER 

BUILDING better API CLIENTS 

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DOZENS of APPS 

HTTP / APIS 

THERE’S AN API 

COMPONENTS OF AN API CLIENT 

perform(.RetrieveArticles) { result in switch result { case .Success(let representor): /* We've got some articles */ case .Error(let error): /* We hit an error */ } } 

FOUNDATION 

NSURLSession OR NSURLConnection 

NSURLRequest 

NSURLHTTPResponse 

SIMPLE... 

HTTP SEMANTICS 

SERIALISATION (JSON) 

CONVERT to VALUE-MODELS 

struct Article { let title:String let body:String let author:Author let image:[NSURL] } struct Author { let name:String let twitter:String } 

articles[0]["author"]["name"] 

"/articles" 

"name" 

"nme" 

- age + birthday 

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MAPPING 

HTTP JSON MODEL MAPPING TESTS (STUBS & FIXTURES) DOMAIN LOGIC? 

$ cloc **Model**.{h,m} **API**.{h,m} 95 text files. 83 unique files. 0 files ignored. ------------------------------------------------------------------------------- Language files blank comment code ------------------------------------------------------------------------------- Objective C 51 1420 499 5598 C/C++ Header 32 258 480 479 ------------------------------------------------------------------------------- SUM: 83 1678 979 6077 ------------------------------------------------------------------------------- 

6077 LINES OF CODE 

ANDROID 

15,000 LINES OF CODE 

WINDOWS PHONE 

20,000 LINES OF CODE 

... 

30,000 LINES OF CODE 

BUILDING an API CLIENT 

DOMAIN-SPECIFIC 

INTEGRATED 

MIXING PROTOCOL SEMANTICS 

WHAT DOES THE API LOOK LIKE? 

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GETTING STARTED 

TESTS 

MOCK 

[OHHTTPStubs stubRequestsPassingTest:^BOOL(NSURLRequest *request) { return ([request.URL.host isEqualToString:@"trunk.cocoapods.org"] && [request.URL.path isEqualToString:@"/api/v1/sessions"]); } withStubResponse:^ OHHTTPStubsResponse *(NSURLRequest *request) { NSString *fixture = OHPathForFileInBundle(@"sessions.json", nil); NSDictionary *headers = @{ @"Content-Type": @"application/json" }; return [OHHTTPStubsResponse responseWithFileAtPath:fixture statusCode:200 headers:headers]; }]; 

{ "created_at": "2014-04-21 23:08:00 +0200", "email": "[email protected]", "name": "Kyle Fuller", "sessions": [ { "created_at": "2014-05-04 15:20:19 +0200", "valid_until": "2014-09-09 15:20:19 +0200", "verified": false }, { "created_at": "2014-05-04 15:20:20 +0200", "valid_until": "2014-09-09 15:20:20 +0200", "verified": true } ] } 

AND REPEAT 

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CAN’T WE USE THIS? 

UNDERSTANDABLE by machines 

POWERING YOUR TESTS with API BLUEPRINT 

pod `CCLRequestReplay` 

[OHHTTPStubs stubRequestsPassingTest:^BOOL(NSURLRequest *request) { return ([request.URL.host isEqualToString:@"trunk.cocoapods.org"] && [request.URL.path isEqualToString:@"/api/v1/sessions"]); } withStubResponse:^ OHHTTPStubsResponse *(NSURLRequest *request) { NSString *fixture = OHPathForFileInBundle(@"sessions.json", nil); NSDictionary *headers = @{ @"Content-Type": @"application/json" }; return [OHHTTPStubsResponse responseWithFileAtPath:fixture statusCode:200 headers:headers]; }]; [OHHTTPStubs stubRequestsPassingTest:^BOOL(NSURLRequest *request) { return ([request.URL.host isEqualToString:@"trunk.cocoapods.org"] && [request.URL.path isEqualToString:@"/api/v1/pods"]); } withStubResponse:^ OHHTTPStubsResponse *(NSURLRequest *request) { NSString *fixture = OHPathForFileInBundle(@"pods.json", nil); NSDictionary *headers = @{ @"Content-Type": @"application/json" }; return [OHHTTPStubsResponse responseWithFileAtPath:fixture statusCode:200 headers:headers]; }]; [OHHTTPStubs stubRequestsPassingTest:^BOOL(NSURLRequest *request) { return ([request.URL.host isEqualToString:@"trunk.cocoapods.org"] && [request.URL.path isEqualToString:@"/api/v1/pod/../owners"]); } withStubResponse:^ OHHTTPStubsResponse *(NSURLRequest *request) { NSString *fixture = OHPathForFileInBundle(@"pod-querykit-owners.json", nil); NSDictionary *headers = @{ @"Content-Type": @"application/json" }; return [OHHTTPStubsResponse responseWithFileAtPath:fixture statusCode:200 headers:headers]; }]; ... 

{ "created_at": "2014-04-21 23:08:00 +0200", "email": "[email protected]", "name": "Kyle Fuller", "sessions": [ { "created_at": "2014-05-04 15:20:19 +0200", "valid_until": "2014-09-09 15:20:19 +0200", "verified": false }, { "created_at": "2014-05-04 15:20:20 +0200", "valid_until": "2014-09-09 15:20:20 +0200", "verified": true } ] } { "name": "QueryKit", "version": "0.8.3", "authors": { "Kyle Fuller": "[email protected]" }, "social_media_url": "http://twitter.com/kylefuller", "source": { "git": "https://github.com/QueryKit/QueryKit.git", "tag": "0.8.3" }, "source_files": [ "QueryKit/*.{h}", "QueryKit/ObjectiveC/*.{h,m}" ], "requires_arc": true } ... 

let URL = NSBundle.mainBundle().URIForResource("palaver", withExtension:"apib.json") requestReplayManager.addRecordings(fromBlueprintURL:URL, error:nil) 

GET /sessions 

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EMBRACE CHANGE 

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WE MADE A MISTAKE. 

WE WANT TO CHANGE... ENDPOINT URI. 

NEGOTIATE AT RUN-TIME 

WE WANT TO CHANGE... PAGINATION LOGIC. 

FOLLOWING LINKS 

TRANSITION BETWEEN STATES 

"Paging is achieved with the published_before parameter." 

published_before 

[ { "published_date": "2013-04-30T16:05:45+00:00", ... } ] 

GET /articles?published_before=2013-04-30T16:05:45+00:00 

SERVER LOGIC 

Next Page = 

Prevent BREAKING CHANGES 

BUILDING BETTER CLIENTS from THE API 

FLEXIBILITY 

CASCADED REQUESTS 

GET /categories GET /authors GET /articles 

BANDWIDTH 

LARGE DATA 

$ curl -I http://api.something.com/articles HTTP/1.1 200 OK Content-Type: application/json Content-Length: 12524998 

BREAK IT UP 

PAGINATION 

/list VS /list/detail 

USE Last-Modified 

USE Cache-Control 

USE STANDARDS 

LET’S BUILD BETTER APIS TOGETHER 

KYLE FULLER