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Efficient HTTP Apis

Adrian Cole
Adrian Cole

The document discusses the implementation and advantages of using HTTP/2 with OkHttp in Java for building efficient HTTP APIs. It covers the features of OkHttp, including support for HTTP/2, websocket, and capabilities for handling request/response efficiently through compression and caching. The text also highlights performance improvements and best practices for using the OkHttp library in client-server communication.

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Efficient HTTP Apis A walk through http/2 via okhttp @adrianfcole
introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
* Can be blamed for the http/2 defects in okhttp! @adrianfcole • engineer at Pivotal on Spring Cloud • lots of open source work • focus on cloud computing
okhttp • HttpURLConnection Apache HttpClient compatible • designed for java and android • BDFL: Jesse Wilson from square https://github.com/square/okhttp
introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
$ curl https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ [ { "id": 1, "owner_id": 0, "name": "Able" }, ... { "id": 26, "owner_id": 0, $ curl https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ { "id": 2, "owner_id": 0, "name": "Beatific" } $ curl -X POST https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Content-Type: application/json’ -d ’{ "name": "Open-minded" }’ $ curl -X DELETE https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ json apis are so simple
$ curl https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ [ { "id": 1, "owner_id": 0, "name": "Able" }, ... { "id": 26, "owner_id": 0, "name": "Zest" } $ curl https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ { "id": 2, "owner_id": 0, "name": "Beatific" } $ curl -X POST https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Content-Type: application/json’ -d ’{ "name": "Open-minded" }’ $ curl -X DELETE https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ so many bytes?! 1642!
$ curl --compress https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ -H ‘Accept-encoding: gzip, deflate’ [ { "id": 1, "owner_id": 0, "name": "Able" }, ... { "id": 26, "owner_id": 0, "name": "Zest" $ curl https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ { "id": 2, "owner_id": 0, "name": "Beatific" } $ curl -X POST https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Content-Type: application/json’ -d ’{ "name": "Open-minded" }’ $ curl -X DELETE https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ now with gzip 318
java + gson url = new URL(“https://apihost/things”); connection = (HttpURLConnection) url.openConnection(); connection.setRequestProperty(“SecurityToken”, “b08c85073c1a2d02”); connection.setRequestProperty(“Accept”, “application/json”); connection.setRequestProperty(“Accept-Encoding”, "gzip, deflate"); is = connection.getInputStream(); isr = new InputStreamReader(new GZIPInputStream(is)); things = new Gson().fromJson(isr, new TypeToken<List<Thing>>(){});
okhttp + gson client = new OkHttpClient(); url = new URL(“https://apihost/things”); connection = new OkUrlFactory(client).open(url); connection.setRequestProperty(“SecurityToken”, “b08c85073c1a2d02”); connection.setRequestProperty(“Accept”, “application/json”); connection.setRequestProperty(“Accept-Encoding”, "gzip, deflate"); is = connection.getInputStream(); isr = new InputStreamReader(is); // automatic gunzip things = new Gson().fromJson(isr, new TypeToken<List<Thing>>(){}); is.close();
We won! • List body reduced from 1642 to 318 bytes! • We saved some lines using OkHttp • Concession: cpu for compression, curl is a little verbose.
introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
okhttp • v2.5 has lots of stuff since v1 • buffer, call, cache, interceptor, url • http/2 and WebSocket support • Apache adapter https://github.com/square/okhttp
okhttp client = new OkHttpClient(); request = new Request.Builder() .url(“https://apihost/things”) .header(“SecurityToken”, “b08c85073c1a2d02”) .header(“Accept”, “application/json”) .header(“Accept-Encoding”, "gzip, deflate”).build(); // ^^ look, ma.. I’m immutable! reader = client.newCall(request).execute().body().charStream(); things = new Gson().fromJson(reader, new TypeToken<List<Thing>>(){}); • OkHttp has its own api, which has a concise way to get bytes or chars (via okio).
okhttp call client = new OkHttpClient(); request = new Request.Builder() .url(“https://apihost/things”) .header(“SecurityToken”, “b08c85073c1a2d02”) .header(“Accept”, “application/json”) .header(“Accept-Encoding”, "gzip, deflate").build(); call = client.newCall(request); call.enqueue(new ParseThingsCallback()); call.cancel(); // changed my mind • OkHttp also has an async api, which (also) supports cancel!
• # Explicity trust certs for your properties • new CertificatePinner.Builder() • .add(“my.biz”, publicKeySHA1) • .add(“*.my.biz”, publicKeySHA1) • .build() • # Respond to authentication challenges • new Authenticator() { • public Request authenticate(Proxy p, Response rsp) { • return rsp.request().newBuilder() • .header(“Authorization", “Bearer …”) • # Set your own floor for TLS • new ConnectionSpec.Builder(MODERN_TLS) okhttp security
okhttp interceptor client = new OkHttpClient(); client.interceptors().add((chain) ->
 chain.proceed(chain.request().newBuilder()
 .addHeader("SecurityToken", securityToken.get())
 .build())
 ); request = new Request.Builder() .url(“https://apihost/things”) .header(“Accept-Encoding”, "gzip, deflate").build(); call = client.newCall(request); call.enqueue(new ParseThingsCallback()); • Now you can change your security token!
okio • ByteString • Unbounded Buffer • Source/Sink abstraction https://github.com/square/okio
// Okio is (more than) a prettier DataInputStream BufferedSink sink = Okio.buffer(Okio.sink(file)); sink.writeUtf8("Hello, java.io file!”); sink.writeLong(1000000000000000L); sink.close(); // Streaming writes with no housekeeping new RequestBody() { @Override public void writeTo(BufferedSink sink) throws IOException { sink.writeUtf8("Numbersn"); sink.writeUtf8("-------n"); for (int i = 2; i <= 997; i++) { sink.writeUtf8(String.format(" * %s = %sn", i, factor(i))); } } —snip— // Lazy, composable bodies new MultipartBuilder("123") .addPart(RequestBody.create(MediaType.parse(“text/plain”, "Quick")) .addPart(new StreamingBody("Brown")) okio samples
samples • Starters like web crawler • How-to guide w/ recipes https://github.com/square/okhttp/tree/master/samples
introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
Hey.. List #1 is slow! 368!
Ask Ilya why! • TCP connections need 3- way handshake. • TLS requires up to 2 more round-trips. • Read High Performance Browser Networking http://chimera.labs.oreilly.com/books/1230000000545
HttpUrlConnection • http.keepAlive - should connections should be pooled at all? Default is true. • http.maxConnections - maximum number of idle connections to each host in the pool. Default is 5. • get[Input|Error]Stream().close() - recycles the connection, if fully read. • disconnect() - removes the connection.
Don’t forget to read! ... is = tryGetInputStream(connection); isr = new InputStreamReader(is); things = new Gson().fromJson(isr, new TypeToken<List<Thing>>(){}); ... InputStream tryGetInputStream(HttpUrlConnection connection) throws IOException { try { return connection.getInputStream(); } catch (IOException e) { InputStream err = connection.getErrorStream();   while (in.read() != -1); // skip err.close(); throw e; }
or just use okhttp try (ResponseBody body = client.newCall(request).execute().body()) { // connection will be cleaned on close. } client.newCall(request).enqueue(new Callback() { @Override public void onFailure(Request request, IOException e) { // body is implicitly closed on failure } @Override public void onResponse(Response response) { // make sure you call response.body().close() when done } });
We won! • Recycled socket requests are much faster and have less impact on the server. • Concessions: must read responses, concurrency is still bounded by sockets.
Let’s make List #2 free Cache-Control: private, max-age=60, s-maxage=0 Vary: SecurityToken Step 1: add a little magic to your server response Step 2: make sure you are using a cache! client.setCache(new Cache(dir, 10_MB)); Step 3: pray your developers don’t get clever // TODO: stupid server sends stale data without this new Request.Builder().url(”https://apihost/things?time=” + currentTimeMillis());
// Limit cache duration thisMessageWillSelfDestruct = new Request.Builder() .url(“https://foo.com/weather”) .cacheControl(new CacheControl.Builder().maxAge(12, HOURS).build()) .build(); // Opt-out of response caching notStored = new Request.Builder() .url(“https://foo.com/private”) .cacheControl(CacheControl.FORCE_NETWORK) .build(); // Offline mode offline = new Request.Builder() .url(“https://foo.com/image”) .cacheControl(CacheControl.FORCE_CACHE) .build(); okhttp cache recipes
We won again! • No time or bandwidth used for cached responses • No application-specific cache bugs code. • Concessions: only supports “safe methods”, caching needs to be tuned.
introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
http/1.1 • rfc2616 - June 1999 • text-based framing • defined semantics of the web http://www.w3.org/Protocols/rfc2616/rfc2616.html
FYI: RFC 2616 is dead! • RFC 7230-5 replaces RFC 2616. • Checkout details on www.mnot.net/blog
spdy/3.1 http://www.chromium.org/spdy/spdy-protocol/spdy-protocol-draft3-1 • google - Sep 2013 • binary framing • retains http/1.1 semantics • concurrent multiplexed streams
http/2 https://tools.ietf.org/html/rfc7540 • rfc7540 - May 2015 • binary framing • retains http/1.1 semantics • concurrent multiplexed streams
multiplexing header compression flow control priority server push http/2 headline features
multiplexing header compression server push http/2 headline features
Looking at the whole message Request: request line, headers, and body Response: status line, headers, and body
http/1.1 round-trip GZIPPED DATA Content-Length: 318 Cache-Control: private, max-age=60, s- maxage=0 Vary: SecurityToken Date: Sun, 02 Feb 2014 20:30:38 GMT Content-Type: application/json Content-Encoding: gzip Host: apihost SecurityToken: b08c85073c1a2d02 Accept: application/json Accept-encoding: gzip, deflate GET /things HTTP/1.1 HTTP/1.1 200 OK • http/1.1 sends requests and responses one at a time over a network connection
http/2 round-trip GZIPPED DATA :status: 200 content-length: 318 cache-control: private, max-age=60, s- maxage=0 vary: SecurityToken date: Sun, 02 Feb 2014 20:30:38 GMT content-type: application/json :method: GET :authority: apihost :path: /things securitytoken: b08c85073c1a2d02 accept: application/json accept-encoding: gzip, deflate HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM • http/2 breaks up messages into stream-scoped frames
Interleaving HEADERS Stream: 5 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 5 Flags: DATA Stream: 5 Flags: END_STREAM HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 5 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM • http/2 multiplexes a network connection by interleaving request/response frames
Canceling a Stream HEADERS Stream: 5 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 5 Flags: HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 5 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM RST_STREAM Stream: 5 ErrorCode: CANCEL • interrupts a response without affecting the connection
control frames HEADERS Stream: 5 HEADERS Stream: 3 DATA Stream: 5 DATA Stream: 3 HEADERS Stream: 3 HEADERS Stream: 5 SETTINGS Stream: 0 SETTINGS Stream: 0 DATA Stream: 5 • connection-scoped frames allow runtime updates, like flow-control
OkHttp/2 Architecture Frame Reader Thread Frame Writer Lock Control Frame Queue FramedConnection
multiplexing header compression server push http/2 headline features
http/1.1 headers GZIPPED DATA Content-Length: 318 Cache-Control: private, max-age=60, s- maxage=0 Vary: SecurityToken Date: Sun, 02 Feb 2014 20:30:38 GMT Content-Type: application/json Content-Encoding: gzip Host: apihost SecurityToken: b08c85073c1a2d02 Accept: application/json Accept-encoding: gzip, deflate GET /things HTTP/1.1 HTTP/1.1 200 OK 168! 195! 318 • You can gzip data, but not headers!
header compression GZIPPED DATA :status: 200 content-length: 318 cache-control: private, max-age=60, s-maxage=0 vary: SecurityToken date: Sun, 02 Feb 2014 20:30:38 GMT content-type: application/json content-encoding: gzip :method: GET :authority: apihost :path: /things securitytoken: b08c85073c1a2d02 accept: application/json accept-encoding: gzip, deflate HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM 8 bytes 52 bytes compressed 8 bytes 85 bytes compressed • 161 byte overhead instead of 363 8 bytes
indexed headers! GZIPPED DATA :status: 200 content-length: 318 cache-control: private, max-age=60, s-maxage=0 vary: SecurityToken date: Sun, 02 Feb 2014 20:30:39 GMT content-type: application/json content-encoding: gzip :method: GET :authority: apihost :path: /things securitytoken: b08c85073c1a2d02 accept: application/json accept-encoding: gzip, deflate HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM 8 bytes 28 bytes compressed 8 bytes 30 bytes compressed • 82 byte overhead instead of 363 8 bytes
hpack http://tools.ietf.org/html/rfc7541 • rfc7540 - May 2015 • static and dynamic table • huffman encoding
multiplexing header compression server push http/2 headline features
push promise :method: GET :path: /things ... HEADERS Stream: 3 HEADERS Stream: 3 DATA Stream: 4 :method: GET :path: /users/0 ... PUSH_PROMISE Stream: 3 Promised-Stream: 4 HEADERS Stream: 4 push response goes into cache DATA Stream: 3 Server guesses a future request or indicates a cache invalidation
okhttp + http/2 • OkHttp 2.3+ supports http/2 on TLS+ALPN connections. • Works out of the box on Android • Java needs hacks until JEP 244 For now, add jetty’s ALPN to your bootclasspath. * Verify version matches your JRE * $ java -Xbootclasspath/p:/path/to/alpn-boot-8.1.4.v20150727.jar
We won! • 1 socket for 100+ concurrent streams. • Advanced features like flow control, cancellation and cache push. • Dramatically less header overhead.
okhttp tools • There are tools that leverage OkHttp natively… • including its http/2 features.
MockWebServer SSLSocketFactory factory = SslContextBuilder.localhost().getSocketFactory(); OkHttpClient client = new OkHttpClient() .setSslSocketFactory(factory); @Rule public final MockWebServer server = new MockWebServer() .setSslSocketFactory(factory); @Test public void evenWithHttp2SlowResponsesKill() throws Exception { server.enqueue(new MockResponse().setBody(lotsOfThings) .throttleBody(1024, 1, SECONDS)); // slow connection 1KiB/second request = new Request.Builder() .url(server.getUrl(”/”) + ”things”) —snip— • MockWebServer uses http/2 by default when using TLS
Retrofit 2 @Headers("Accept-Encoding: gzip, deflate”) interface ThingService { @GET("things") Single<List<Things> list(); // RxJava support! } retrofit = new Retrofit.Builder() .client(client) .baseUrl(“https://apihost/“) .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) .addConverterFactory(GsonConverterFactory.create()) .build(); thingsService = retrofit.create(ThingService.class); subscription = thingsService.iist().subscribe(System.out::println) • Retrofit 2 extends OkHttp with api model binding
okcurl $ java -Xbootclasspath/p:alpn-boot.jar -jar okcurl.jar https://twitter.com -X HEAD --frames >> CONNECTION 505249202a20485454502f322e300d0a0d0a534d0d0a0d0a << 0x00000000 6 SETTINGS >> 0x00000000 6 SETTINGS >> 0x00000000 4 WINDOW_UPDATE >> 0x00000000 0 SETTINGS ACK >> 0x00000003 60 HEADERS END_STREAM|END_HEADERS << 0x00000000 0 SETTINGS ACK << 0x00000003 2097 HEADERS END_STREAM|END_HEADERS >> 0x00000000 8 GOAWAY
introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
Engage! • Consider http/2 or at least spdy! • Check-out okhttp and friends • Test http/2 load balancers like google cloud https://github.com/square/okhttp/tree/master/mockwebserver http://square.github.io/retrofit/ https://cloud.google.com/compute/docs/load-balancing/http/
Thank you! github square/okhttp @adrianfcole

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Efficient HTTP Apis

  • 1. Efficient HTTP Apis A walk through http/2 via okhttp @adrianfcole
  • 2. introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
  • 3. introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
  • 4. * Can be blamed for the http/2 defects in okhttp! @adrianfcole • engineer at Pivotal on Spring Cloud • lots of open source work • focus on cloud computing
  • 5. okhttp • HttpURLConnection Apache HttpClient compatible • designed for java and android • BDFL: Jesse Wilson from square https://github.com/square/okhttp
  • 6. introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
  • 7. $ curl https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ [ { "id": 1, "owner_id": 0, "name": "Able" }, ... { "id": 26, "owner_id": 0, $ curl https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ { "id": 2, "owner_id": 0, "name": "Beatific" } $ curl -X POST https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Content-Type: application/json’ -d ’{ "name": "Open-minded" }’ $ curl -X DELETE https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ json apis are so simple
  • 8. $ curl https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ [ { "id": 1, "owner_id": 0, "name": "Able" }, ... { "id": 26, "owner_id": 0, "name": "Zest" } $ curl https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ { "id": 2, "owner_id": 0, "name": "Beatific" } $ curl -X POST https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Content-Type: application/json’ -d ’{ "name": "Open-minded" }’ $ curl -X DELETE https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ so many bytes?! 1642!
  • 9. $ curl --compress https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ -H ‘Accept-encoding: gzip, deflate’ [ { "id": 1, "owner_id": 0, "name": "Able" }, ... { "id": 26, "owner_id": 0, "name": "Zest" $ curl https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Accept: application/json’ { "id": 2, "owner_id": 0, "name": "Beatific" } $ curl -X POST https://apihost/things -H ‘SecurityToken: b08c85073c1a2d02’ -H ‘Content-Type: application/json’ -d ’{ "name": "Open-minded" }’ $ curl -X DELETE https://apihost/things/2 -H ‘SecurityToken: b08c85073c1a2d02’ now with gzip 318
  • 10. java + gson url = new URL(“https://apihost/things”); connection = (HttpURLConnection) url.openConnection(); connection.setRequestProperty(“SecurityToken”, “b08c85073c1a2d02”); connection.setRequestProperty(“Accept”, “application/json”); connection.setRequestProperty(“Accept-Encoding”, "gzip, deflate"); is = connection.getInputStream(); isr = new InputStreamReader(new GZIPInputStream(is)); things = new Gson().fromJson(isr, new TypeToken<List<Thing>>(){});
  • 11. okhttp + gson client = new OkHttpClient(); url = new URL(“https://apihost/things”); connection = new OkUrlFactory(client).open(url); connection.setRequestProperty(“SecurityToken”, “b08c85073c1a2d02”); connection.setRequestProperty(“Accept”, “application/json”); connection.setRequestProperty(“Accept-Encoding”, "gzip, deflate"); is = connection.getInputStream(); isr = new InputStreamReader(is); // automatic gunzip things = new Gson().fromJson(isr, new TypeToken<List<Thing>>(){}); is.close();
  • 12. We won! • List body reduced from 1642 to 318 bytes! • We saved some lines using OkHttp • Concession: cpu for compression, curl is a little verbose.
  • 13. introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
  • 14. okhttp • v2.5 has lots of stuff since v1 • buffer, call, cache, interceptor, url • http/2 and WebSocket support • Apache adapter https://github.com/square/okhttp
  • 15. okhttp client = new OkHttpClient(); request = new Request.Builder() .url(“https://apihost/things”) .header(“SecurityToken”, “b08c85073c1a2d02”) .header(“Accept”, “application/json”) .header(“Accept-Encoding”, "gzip, deflate”).build(); // ^^ look, ma.. I’m immutable! reader = client.newCall(request).execute().body().charStream(); things = new Gson().fromJson(reader, new TypeToken<List<Thing>>(){}); • OkHttp has its own api, which has a concise way to get bytes or chars (via okio).
  • 16. okhttp call client = new OkHttpClient(); request = new Request.Builder() .url(“https://apihost/things”) .header(“SecurityToken”, “b08c85073c1a2d02”) .header(“Accept”, “application/json”) .header(“Accept-Encoding”, "gzip, deflate").build(); call = client.newCall(request); call.enqueue(new ParseThingsCallback()); call.cancel(); // changed my mind • OkHttp also has an async api, which (also) supports cancel!
  • 17. • # Explicity trust certs for your properties • new CertificatePinner.Builder() • .add(“my.biz”, publicKeySHA1) • .add(“*.my.biz”, publicKeySHA1) • .build() • # Respond to authentication challenges • new Authenticator() { • public Request authenticate(Proxy p, Response rsp) { • return rsp.request().newBuilder() • .header(“Authorization", “Bearer …”) • # Set your own floor for TLS • new ConnectionSpec.Builder(MODERN_TLS) okhttp security
  • 18. okhttp interceptor client = new OkHttpClient(); client.interceptors().add((chain) ->
 chain.proceed(chain.request().newBuilder()
 .addHeader("SecurityToken", securityToken.get())
 .build())
 ); request = new Request.Builder() .url(“https://apihost/things”) .header(“Accept-Encoding”, "gzip, deflate").build(); call = client.newCall(request); call.enqueue(new ParseThingsCallback()); • Now you can change your security token!
  • 19. okio • ByteString • Unbounded Buffer • Source/Sink abstraction https://github.com/square/okio
  • 20. // Okio is (more than) a prettier DataInputStream BufferedSink sink = Okio.buffer(Okio.sink(file)); sink.writeUtf8("Hello, java.io file!”); sink.writeLong(1000000000000000L); sink.close(); // Streaming writes with no housekeeping new RequestBody() { @Override public void writeTo(BufferedSink sink) throws IOException { sink.writeUtf8("Numbersn"); sink.writeUtf8("-------n"); for (int i = 2; i <= 997; i++) { sink.writeUtf8(String.format(" * %s = %sn", i, factor(i))); } } —snip— // Lazy, composable bodies new MultipartBuilder("123") .addPart(RequestBody.create(MediaType.parse(“text/plain”, "Quick")) .addPart(new StreamingBody("Brown")) okio samples
  • 21. samples • Starters like web crawler • How-to guide w/ recipes https://github.com/square/okhttp/tree/master/samples
  • 22. introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
  • 23. Hey.. List #1 is slow! 368!
  • 24. Ask Ilya why! • TCP connections need 3- way handshake. • TLS requires up to 2 more round-trips. • Read High Performance Browser Networking http://chimera.labs.oreilly.com/books/1230000000545
  • 25. HttpUrlConnection • http.keepAlive - should connections should be pooled at all? Default is true. • http.maxConnections - maximum number of idle connections to each host in the pool. Default is 5. • get[Input|Error]Stream().close() - recycles the connection, if fully read. • disconnect() - removes the connection.
  • 26. Don’t forget to read! ... is = tryGetInputStream(connection); isr = new InputStreamReader(is); things = new Gson().fromJson(isr, new TypeToken<List<Thing>>(){}); ... InputStream tryGetInputStream(HttpUrlConnection connection) throws IOException { try { return connection.getInputStream(); } catch (IOException e) { InputStream err = connection.getErrorStream();   while (in.read() != -1); // skip err.close(); throw e; }
  • 27. or just use okhttp try (ResponseBody body = client.newCall(request).execute().body()) { // connection will be cleaned on close. } client.newCall(request).enqueue(new Callback() { @Override public void onFailure(Request request, IOException e) { // body is implicitly closed on failure } @Override public void onResponse(Response response) { // make sure you call response.body().close() when done } });
  • 28. We won! • Recycled socket requests are much faster and have less impact on the server. • Concessions: must read responses, concurrency is still bounded by sockets.
  • 29. Let’s make List #2 free Cache-Control: private, max-age=60, s-maxage=0 Vary: SecurityToken Step 1: add a little magic to your server response Step 2: make sure you are using a cache! client.setCache(new Cache(dir, 10_MB)); Step 3: pray your developers don’t get clever // TODO: stupid server sends stale data without this new Request.Builder().url(”https://apihost/things?time=” + currentTimeMillis());
  • 30. // Limit cache duration thisMessageWillSelfDestruct = new Request.Builder() .url(“https://foo.com/weather”) .cacheControl(new CacheControl.Builder().maxAge(12, HOURS).build()) .build(); // Opt-out of response caching notStored = new Request.Builder() .url(“https://foo.com/private”) .cacheControl(CacheControl.FORCE_NETWORK) .build(); // Offline mode offline = new Request.Builder() .url(“https://foo.com/image”) .cacheControl(CacheControl.FORCE_CACHE) .build(); okhttp cache recipes
  • 31. We won again! • No time or bandwidth used for cached responses • No application-specific cache bugs code. • Concessions: only supports “safe methods”, caching needs to be tuned.
  • 32. introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
  • 33. http/1.1 • rfc2616 - June 1999 • text-based framing • defined semantics of the web http://www.w3.org/Protocols/rfc2616/rfc2616.html
  • 34. FYI: RFC 2616 is dead! • RFC 7230-5 replaces RFC 2616. • Checkout details on www.mnot.net/blog
  • 35. spdy/3.1 http://www.chromium.org/spdy/spdy-protocol/spdy-protocol-draft3-1 • google - Sep 2013 • binary framing • retains http/1.1 semantics • concurrent multiplexed streams
  • 36. http/2 https://tools.ietf.org/html/rfc7540 • rfc7540 - May 2015 • binary framing • retains http/1.1 semantics • concurrent multiplexed streams
  • 39. Looking at the whole message Request: request line, headers, and body Response: status line, headers, and body
  • 40. http/1.1 round-trip GZIPPED DATA Content-Length: 318 Cache-Control: private, max-age=60, s- maxage=0 Vary: SecurityToken Date: Sun, 02 Feb 2014 20:30:38 GMT Content-Type: application/json Content-Encoding: gzip Host: apihost SecurityToken: b08c85073c1a2d02 Accept: application/json Accept-encoding: gzip, deflate GET /things HTTP/1.1 HTTP/1.1 200 OK • http/1.1 sends requests and responses one at a time over a network connection
  • 41. http/2 round-trip GZIPPED DATA :status: 200 content-length: 318 cache-control: private, max-age=60, s- maxage=0 vary: SecurityToken date: Sun, 02 Feb 2014 20:30:38 GMT content-type: application/json :method: GET :authority: apihost :path: /things securitytoken: b08c85073c1a2d02 accept: application/json accept-encoding: gzip, deflate HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM • http/2 breaks up messages into stream-scoped frames
  • 42. Interleaving HEADERS Stream: 5 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 5 Flags: DATA Stream: 5 Flags: END_STREAM HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 5 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM • http/2 multiplexes a network connection by interleaving request/response frames
  • 43. Canceling a Stream HEADERS Stream: 5 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 5 Flags: HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 5 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM RST_STREAM Stream: 5 ErrorCode: CANCEL • interrupts a response without affecting the connection
  • 44. control frames HEADERS Stream: 5 HEADERS Stream: 3 DATA Stream: 5 DATA Stream: 3 HEADERS Stream: 3 HEADERS Stream: 5 SETTINGS Stream: 0 SETTINGS Stream: 0 DATA Stream: 5 • connection-scoped frames allow runtime updates, like flow-control
  • 47. http/1.1 headers GZIPPED DATA Content-Length: 318 Cache-Control: private, max-age=60, s- maxage=0 Vary: SecurityToken Date: Sun, 02 Feb 2014 20:30:38 GMT Content-Type: application/json Content-Encoding: gzip Host: apihost SecurityToken: b08c85073c1a2d02 Accept: application/json Accept-encoding: gzip, deflate GET /things HTTP/1.1 HTTP/1.1 200 OK 168! 195! 318 • You can gzip data, but not headers!
  • 48. header compression GZIPPED DATA :status: 200 content-length: 318 cache-control: private, max-age=60, s-maxage=0 vary: SecurityToken date: Sun, 02 Feb 2014 20:30:38 GMT content-type: application/json content-encoding: gzip :method: GET :authority: apihost :path: /things securitytoken: b08c85073c1a2d02 accept: application/json accept-encoding: gzip, deflate HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM 8 bytes 52 bytes compressed 8 bytes 85 bytes compressed • 161 byte overhead instead of 363 8 bytes
  • 49. indexed headers! GZIPPED DATA :status: 200 content-length: 318 cache-control: private, max-age=60, s-maxage=0 vary: SecurityToken date: Sun, 02 Feb 2014 20:30:39 GMT content-type: application/json content-encoding: gzip :method: GET :authority: apihost :path: /things securitytoken: b08c85073c1a2d02 accept: application/json accept-encoding: gzip, deflate HEADERS Stream: 3 Flags: END_HEADERS, END_STREAM HEADERS Stream: 3 Flags: END_HEADERS DATA Stream: 3 Flags: END_STREAM 8 bytes 28 bytes compressed 8 bytes 30 bytes compressed • 82 byte overhead instead of 363 8 bytes
  • 50. hpack http://tools.ietf.org/html/rfc7541 • rfc7540 - May 2015 • static and dynamic table • huffman encoding
  • 52. push promise :method: GET :path: /things ... HEADERS Stream: 3 HEADERS Stream: 3 DATA Stream: 4 :method: GET :path: /users/0 ... PUSH_PROMISE Stream: 3 Promised-Stream: 4 HEADERS Stream: 4 push response goes into cache DATA Stream: 3 Server guesses a future request or indicates a cache invalidation
  • 53. okhttp + http/2 • OkHttp 2.3+ supports http/2 on TLS+ALPN connections. • Works out of the box on Android • Java needs hacks until JEP 244 For now, add jetty’s ALPN to your bootclasspath. * Verify version matches your JRE * $ java -Xbootclasspath/p:/path/to/alpn-boot-8.1.4.v20150727.jar
  • 54. We won! • 1 socket for 100+ concurrent streams. • Advanced features like flow control, cancellation and cache push. • Dramatically less header overhead.
  • 55. okhttp tools • There are tools that leverage OkHttp natively… • including its http/2 features.
  • 56. MockWebServer SSLSocketFactory factory = SslContextBuilder.localhost().getSocketFactory(); OkHttpClient client = new OkHttpClient() .setSslSocketFactory(factory); @Rule public final MockWebServer server = new MockWebServer() .setSslSocketFactory(factory); @Test public void evenWithHttp2SlowResponsesKill() throws Exception { server.enqueue(new MockResponse().setBody(lotsOfThings) .throttleBody(1024, 1, SECONDS)); // slow connection 1KiB/second request = new Request.Builder() .url(server.getUrl(”/”) + ”things”) —snip— • MockWebServer uses http/2 by default when using TLS
  • 57. Retrofit 2 @Headers("Accept-Encoding: gzip, deflate”) interface ThingService { @GET("things") Single<List<Things> list(); // RxJava support! } retrofit = new Retrofit.Builder() .client(client) .baseUrl(“https://apihost/“) .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) .addConverterFactory(GsonConverterFactory.create()) .build(); thingsService = retrofit.create(ThingService.class); subscription = thingsService.iist().subscribe(System.out::println) • Retrofit 2 extends OkHttp with api model binding
  • 58. okcurl $ java -Xbootclasspath/p:alpn-boot.jar -jar okcurl.jar https://twitter.com -X HEAD --frames >> CONNECTION 505249202a20485454502f322e300d0a0d0a534d0d0a0d0a << 0x00000000 6 SETTINGS >> 0x00000000 6 SETTINGS >> 0x00000000 4 WINDOW_UPDATE >> 0x00000000 0 SETTINGS ACK >> 0x00000003 60 HEADERS END_STREAM|END_HEADERS << 0x00000000 0 SETTINGS ACK << 0x00000003 2097 HEADERS END_STREAM|END_HEADERS >> 0x00000000 8 GOAWAY
  • 59. introduction hello http api! hello okhttp! uh oh.. scale! hello http/2! wrapping up
  • 60. Engage! • Consider http/2 or at least spdy! • Check-out okhttp and friends • Test http/2 load balancers like google cloud https://github.com/square/okhttp/tree/master/mockwebserver http://square.github.io/retrofit/ https://cloud.google.com/compute/docs/load-balancing/http/