1. Sockets, Routing, Sessions, Handlers
Hand-Made Server
Sockets, Routing, Sessions, Handlers
HTTP Server
SoftUni Team
Technical Trainers
Software University
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2. Table of Contents Important Information Sockets Web Server
Http Classes
Request Handlers
Routing
Cookies and Sessions
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3. Have a Question?
sli.do #JavaWeb

4. Important Information
Readme.txt
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5. It should not be used in production environment
Guideline
This is a guideline for creating your own web server
It will cover basic concepts, but it will not be complete
The tutorial will be focused on the idea behind web servers, not the best practices for creating them.
You will be given Interfaces that you need to implement. You decide how to do it.
It should not be used in production environment

6. How to create connection with Java?
Sockets
How to create connection with Java?
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7. Server Socket Open a port and listen on it
Accept incoming connection from a client
Set a timeout for the socket
ServerSocket serverSocket = new ServerSocket(8080);
Socket clientSocket = serverSocket.accept();
serverSocket.setSoTimeout(10000);
10 seconds timeout

8. Web Server How to implement one?
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9. Server Structure Server Socket Open Socket Connection Handler Http
Request
Http Handler
Post Handler
Get Handler
Close
Socket
Socket
Output Stream
Http
Response

10. Server Interface interface Server {
void runServer() throws SocketException; }
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11. Server Implementation
The server should keep the ServerSocket
After the server is started it should set a timeout to the socket
Create a loop that will create connections
Each connection should be asynchronous (FutureTask<?>)
Create a new class that will handle the connection and implement the Runnable interface

12. Connection Handler It should keep the client Socket
It should keep BufferedReader and PrintWriter, which it will initialize using the socket input and output streams
This will be main point of our connection
We will implement the run() method later

13. HttpContext, HttpRequest, HttpResponse
Http Classes
HttpContext, HttpRequest, HttpResponse
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14. HttpRequestType Enumeration
GET,
POST }

15. HttpRequest Interface
interface HttpRequest { String getURL();
String getPath();
HttpRequestType getRequestType();
String getHeader(String name);
Map<String, String> getURLParameters();
Map<String, String> getFormData();
void addParameter(String name, String value); }

16. HttpContext Interface
interface HttpContext { HttpRequest getHttpRequest(); }

17. HttpResponse Interface
interface HttpResponse { String getResponse();
void addResponseHeader(String header,
String value); }

18. HttpRequest Implementation
The class should be able to parse any HTTP Request or throw BadRequestException in case it fails
The Request Line should hold 3 values
The Http version should be 1.1
Request method MUST be GET or POST
The URL should contain "/details?user=pesho"
The Path should contain "/details"
The headers MUST contain the "Host" header.

19. HttpRequest Implementation (2)
The parameters map is filled with the query string parameters
The form data map should be filled with the request body if the request method is POST

20. HttpContext Implementation
It should keep the HttpRequest
It should take the request string in the constructor and pass it to the HttpRequest class

21. HttpResponse Implementation
It should keep the response headers
It should keep the response status
It should keep the response body
There should be 2 types of response - View and Redirect
The response status can be an enum

22. HttpResponseCode Enumeration
enum HttpResponseCode { OK(200, "OK"), MovedPermanently(301, "Moved Permanently"), Created(201, "Created"), Found(302, "Found"), Unauthorized(401, "Unauthorized");
HttpResponseCode(int value, String text) {
this.value = value;
this.text = text; }

23. Request Handlers GET and POST handlers
Icon made by Freepik from
Request Handlers
GET and POST handlers
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24. RequestHandler Interface
interface RequestHandler {
void handle(HttpContext httpContext)
throws IOException;
void setWriter(Writer writer); }

25. RequestHandler Implementation
It must be abstract
It must implement RequestHandler
It should keep Function<HttpContext, HttpResponse> and Writer
The constructor must accept the function
It should only override the setWriter() method

26. GetHandler Implementation
It must extend the RequestHandler implementation
It should take a function in the constructor and send it to the super constructor
It should override the handle() method
The handle() method should add response headers and write the response

27. PostHandler Implementation
It must extend the RequestHandler implementation
It should take a function in the constructor and send it to the super constructor
It should override the handle() method
The handle() method should add response headers and write the response

28. Routing Catching URL calls
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29. AppRouteConfig Interface
interface AppRouteConfig {
AppRouteConfig addRoute(String path,
RequestHandlerImpl handler);
Iterable<Map.Entry<HttpRequestType,
Map<String, RequestHandlerImpl>>> getRoutes(); }

30. AppRouteConfig Implementation
It should keep a map with all of the request types as keys and other map as value
The inner map should keep string that is the route and RequestHandlerImpl, which will be the Get or Post handler
The addRoute() method should put the new route in the corresponding inner map
Example of a valid route
/users/{(?<id>[0-9]+)}/edit

31. RoutingContext Interface
interface RoutingContext {
RequestHandlerImpl getHandler();
Iterable<String> getParamNames(); }

32. RoutingContext Implementation
It will keep the info about a route
The handler that needs to handle the route
The parameter names that the route needs

33. ServerRouteConfig Interface
interface ServerRouteConfig {
Map<HttpRequestType,
Map<String, RoutingContext>> getRoutes(); }

34. ServerRouteConfig Implementation
It should keep a map with key request type and value map of string and RoutingContext
It should traverse all of the AppRouteConfig routes and parse them
For each route it should create a RoutingContext that will keep the info about the route
Example of a route after being parsed
/users/{(?<id>[0-9]+)}/edit
^/users/(?<id>[0-9]+)/edit$

35. HttpHandler Implementation
It should implement RequestHandler
It should keep the ServerRouteConfig
It should parse the route and call the corresponding handler from the ServerRouteConfig

36. Cookies and Sessions Saving user info
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37. HttpCookie Interface interface HttpCookie {
void addCookie(String key, String value);
void removeCookie(String key);
boolean contains(String key);
String getCookie(String name); }

38. HttpCookie Implementation
It should keep Map<String, String>
The add(), remove(), contains() and get() methods should use the map

39. HttpSession Interface
String getId();
void clear();
void add(String key, String value);
String get(String key);
boolean isAuthenticated(); }

40. HttpSession Implementation
The ID should be random generated
The clear() method should clear the session parameters collection
The isAuthenticated() method should check if there is any data in the session parameters collection
The other methods should do the corresponding operations over the collection

41. SessionCreator Singleton
private SecureRandom random;
//TODO: Initialize the random and make the class singleton
public String generateSessionId() {
return new BigInteger(130, this.random).toString(32); }

42. HttpRequest Modifications
interface HttpRequest { …
HttpCookie getCookie();
HttpSession getSession();
void setSession(HttpSession session); }

43. RequestHandlerImpl Modification
Create a new method called createSession(HttpContext httpContext, HttpResponse result)
Check if the session is null of if the cookie doesn't contain the key "sessionId"
If any of the above is true create a new session and set the cookie
The cookie should be "HttpOnly"

44. Other Modifications
The server implementation should keep a map containing all of the sessions
The AppRouteConfig should be passed to the server

45. Hand-Made Server
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46. License
This course (slides, examples, demos, videos, homework, etc.) is licensed under the "Creative Commons Attribution- NonCommercial-ShareAlike 4.0 International" license
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47. Trainings @ Software University (SoftUni)
Software University – High-Quality Education, Profession and Job for Software Developers
softuni.bg
Software University Foundation
softuni.org
Software Facebook
facebook.com/SoftwareUniversity
Software University Forums
forum.softuni.bg
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