README.md

NIOHttp

Reading and writing HTTP request and response objects from and to java.nio.channels .

⚠️ This project has exploratory character and is in a very early stage of development.

Goals

• Create a library/toolkit to write and read HTTP requests to and from java.nio.channels (Java's non-blocking IO)
• Explore java.util.concurrentjava.util.concurrent API
• Do not use external frameworks, integrate HTTP protocol and java.nio.channels using JDK 1.8+.

Boundary Conditions

• zero external dependencies beside standard JDK except for unit & integration testing and build automation

Idea

First one need to connect a SocketStream to a URL such as http://www.raumzeitfalle.de/.

 
 URL url = new URL("http://www.raumzeitfalle.de/");
 InetSocketAddress address = new InetSocketAddress(url.getHost(), url.getDefaultPort());
 SocketChannel socketChannel = SocketChannel.open(address);

The server won't respond unless a request is sent (for example a GET request).

  writeGetRequestTo(socketChannel);
  

Even with bad requests server will respond, however, this may take time and response time is different. Here the static HttpResponseReader.fromChannel(...) method provides a FutureTask< Void > which can be executed by an ExecutorService. To collect the result, a Consumer< HttpResponse > must be provided. (https://github.com/Oliver-Loeffler/NIOHttp/blob/master/src/main/java/net/raumzeitfalle/niohttp/playground/FutureDemo.java)

 FutureTask<Void> futureTask = HttpResponseReader
 				.fromChannel(socketChannel,r -> System.out.println(r.responseHeader());
 		
 ExecutorService executor = Executors.newFixedThreadPool(1);
 executor.submit(futureTask);

Furthermore HttpResponseReader.fromChannel(...) returns a Stream of HttpResponse objects (https://github.com/Oliver-Loeffler/NIOHttp/blob/master/src/main/java/net/raumzeitfalle/niohttp/playground/StreamDemo.java)

Stream<HttpResponse> responseStream = HttpResponseReader.fromChannel(socketChannel); 
responseStream.findFirst().ifPresent(consumer);

This would enable (given appropriate HttpResponse capabilities), interesting ways of working with HttpResponses.

HttpResponseReader.fromChannel(socketChannel)
	    .filter( r -> r.isNotBadRequest() )
	    .findFirst().ifPresent(consumer);
	    

The current implementation is not yet fully functional here, as the HttpResponseReader only reads exactly one message from a channel. The response reading process has to be extended for continuous reading so that HttpResponse streaming will work.

Resources

• HTTP Working Group: http://httpwg.org

The HTTP/1.1 Protocol

• Introduction for RFC7230: http://httpwg.org/specs/rfc7230.html#introduction
• Uniform Resource Identifier (URI) in HTTP: http://httpwg.org/specs/rfc7230.html#uri
• Message format: http://httpwg.org/specs/rfc7230.html#http.message
• Semantics and Content: http://httpwg.org/specs/rfc7231.html#top
• Request Methods http://httpwg.org/specs/rfc7231.html#methods
• Request Header fields: http://httpwg.org/specs/rfc7231.html#request.header.fields
• Response Status Codes: http://httpwg.org/specs/rfc7231.html#status.codes
• Response Header Fields: http://httpwg.org/specs/rfc7231.html#response.header.fields
• IANA Status code assignments: http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml

HTTP/2 Protocol

• Starting a HTTP/2 connection: http://httpwg.org/specs/rfc7540.html#starting
• The protocol: http://httpwg.org/specs/rfc7540.html
• HTTP/2 Message Exchanging: http://httpwg.org/specs/rfc7540.html#HTTPLayer

HTTP over TLS (transport layer security)

• https://tools.ietf.org/html/rfc2818#section-2

Java non-blocking IO (NIO and NIO2) and Networking

• Java API

• https://docs.oracle.com/javase/tutorial/

• Java NIO channels: http://docs.oracle.com/javase/8/docs/api/java/nio/channels/package-summary.html

• Guides & Tutorials, Inspiration

• NIO2: http://www.ibm.com/developerworks/java/library/j-nio2-1/index.html

• NIO2 Async FileChannel: http://www.baeldung.com/java-nio2-async-file-channel

• Jenkov: http://tutorials.jenkov.com/java-nio/index.html

• NIO Selectors: http://www.baeldung.com/java-nio-selector

• Apache HttpClient: http://www.baeldung.com/httpasyncclient-tutorial

• Javaworld on NIO/NIO2: http://www.javaworld.com/article/2078654/core-java/java-se-five-ways-to-maximize-java-nio-and-nio-2.html

• Java2s on non-blocking async IO: http://www.java2s.com/Tutorials/Java/Java_Network/0080__Java_Network_Asynchronous_Socket_Channels.htm

Other helpful references

• As RFC7230 uses the term ABNF, here the explanation: https://en.wikipedia.org/wiki/Augmented_Backus–Naur_form