Review HTTP

Web API Implementation
	Javadocs for HttpServer
	Ticket to Ride example
	Server and Client
	File Handler (later)
	
JSON Generation/Parsing

	GSON
	
	import com.google.gson.*;
	
	SomeClass anObject = new SomeClass();
	
	Gson gson = new Gson();
	
	// Convert object to JSON string
	String jsonStr = gson.toJson(anObject);
	
	// Convert JSON string to object
	SomeClass anObjectCopy = gson.fromJson(jsonStr, SomeClass.class);
	
	
	Dealing with InputStream's and OutputStream's
		InputStream is a sequence of bytes that can be read (show Javadocs)
		OutputStream is a sequence of bytes that can be written (show Javadocs)

		Reader is a sequence of characters that can be read (show Javadocs)
		Writer is a sequence of characters that can be written (show Javadocs)
		
		HTTP request bodies are accessed through Input/OutputStream's
			1. OutputStream on client: HttpURLConnection.getOutputStream()			
			2. InputStream on server: HttpExchange.getRequestBody()
			
		HTTP response bodies are accessed through Input/OutputStream's
			1. OutputStream on server: HttpExchange.getResponseBody()
			2. InputStream on client: HttpURLConnection.getInputStream()
			
		GSON can convert objects to and from Strings
		It can also convert objects to and from Readers/Writer's
		
		Convert InputStream to Reader: InputStreamReader class
		Convert OutputStream to Writer: OutputStreamWriter class
	
	
	JSON Tasks
		1. Reading/Writing web API Request and Result objects
			a. How would you append a LoginRequest object to an HTTP request body?
			
			LoginRequest loginRequest = ...
			Writer writer = new OutputStreamWriter(httpConn.getOutputStream());
			gson.toJson(loginRequest, writer);
			
			
		2. Convert JSON string to web API Request or Result object
			a. How would you read a LoginRequest object from an HTTP request body?
			
			Reader reader = new InputStreamReader(httpExch.getRequestBody());
			LoginRequest loginRequest = gson.fromJson(reader, LoginRequest.class);	
			
			
		3. Load provided JSON files for data generation
			a. How would you parse the JSON data in the "locations.json" file?
			
			class Location {
				String latitude;
				String longitude;
				String city;
				String country;
			}
			
			class LocationData {
				Location[] data;
			}
			
			Reader reader = new FileReader("locations.json");
			LocationData locData = gson.fromJson(reader, LocationData.class);

File Handler
	Your server needs an HTTP handler that will serve up the HTML, CSS, and image
		files for the web API test page.
		
	This handler is different than the web API method handlers, because it 
		doesn't implement a web API.
	
	Rather, it simply returns files that are requested by a web browser.
	
	Your FileHandler should have a context of "/", which makes it the default
		handler when no other handler context matches the requres URL
	
	In your project's root folder, create a sub-folder to store the web API test
		files in the "web" folder in the project zip file
	
	When your FileHandler receives an HTTP request, it should do the following:
		1. Retrieve the request URL from the HttpExchange
		2. Translate the request URL path to a physical file path on your server
		3. Open the requested file, and return its contents in the HTTP 
			response body

		import java.nio.file.*;
		
		String filePathStr = "the/path/of/a/file";
		Path filePath = FileSystems.getDefault().getPath(filePathStr);
		Files.copy(filePath, httpExch.getResponseBody());
		
Request Flow
	HTTP Handler
		JSON -> Request
		Call Service
		Result -> JSON
		
	Service
		DoService(Request req): Result
			Database db = new Database();
			try {
				// Open database connection
				db.openConnection();
				
				// Use DAOs to do requested operation
				db.getDaoA().doWhatever(req.x, req.y);
				db.getDaoB().doWhatever(req.z);
				
				// Close database connection
				db.closeConnection(true);
				
				// Create and return Result object
				Result rslt = new Result(a, b, c);
				return rslt;
			}
			catch (DatabaseException ex) {
				db.closeConnection(false);
			}

Server File Structure
	db/
		fms.sqlite
	json/
		fnames.json
		locations.json
		...
	web/
		index.html
		fav.ico
		fav.jpg
		css/
			main.css
		...