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package com.sun.net.httpserver;

import com.sun.net.httpserver.spi.HttpServerProvider;

import java.io.IOException;
import java.net.BindException;
import java.net.InetSocketAddress;
import java.util.concurrent.Executor;

This class implements a simple HTTP server. A HttpServer is bound to an IP address and port number and listens for incoming TCP connections from clients on this address. The sub-class HttpsServer implements a server which handles HTTPS requests. 
One or more HttpHandler objects must be associated with a server in order to process requests. Each such HttpHandler is registered with a root URI path which represents the location of the application or service on this server. The mapping of a handler to a HttpServer is encapsulated by a HttpContext object. HttpContexts are created by calling createContext(String, HttpHandler). Any request for which no handler can be found is rejected with a 404 response. Management of threads can be done external to this object by providing a Executor object. If none is provided a default implementation is used. 
  Mapping request URIs to HttpContext paths
When a HTTP request is received, the appropriate HttpContext (and handler) is located by finding the context whose path is the longest matching prefix of the request URI's path. Paths are matched literally, which means that the strings are compared case sensitively, and with no conversion to or from any encoded forms. For example, given a HttpServer with the following HttpContexts configured: 
description
     

         

             
Context
             
Context path
         
     
     

             
ctx1
"/"
             
ctx2
"/apps/"
             
ctx3
"/apps/foo/"
     

The following table shows some request URIs and which, if any context they would
match with:
description
     

         

             
Request URI
             
Matches context
         
     
     

         
"http://foo.com/apps/foo/bar"
ctx3
         
"http://foo.com/apps/Foo/bar"
no match, wrong case
         
"http://foo.com/apps/app1"
ctx2
         
"http://foo.com/foo"
ctx1
     

Note about socket backlogs
When binding to an address and port number, the application can also
specify an integer backlog parameter. This represents the maximum number of incoming TCP connections which the system will queue internally. Connections are queued while they are waiting to be accepted by the HttpServer. When the limit is reached, further connections may be rejected (or possibly ignored) by the underlying TCP implementation. Setting the right backlog value is a compromise between efficient resource usage in the TCP layer (not setting it too high) and allowing adequate throughput of incoming requests (not setting it too low). 
Since:
1.6/**
 * This class implements a simple HTTP server. A {@code HttpServer} is bound to an IP address
 * and port number and listens for incoming TCP connections from clients on this address.
 * The sub-class {@link HttpsServer} implements a server which handles HTTPS requests.
 *
 * <p>One or more {@link HttpHandler} objects must be associated with a server
 * in order to process requests. Each such {@code HttpHandler} is registered with
 * a root URI path which represents the location of the application or service
 * on this server. The mapping of a handler to a {@code HttpServer} is
 * encapsulated by a {@link HttpContext} object. HttpContexts are created by
 * calling {@link #createContext(String,HttpHandler)}.
 * Any request for which no handler can be found is rejected with a 404 response.
 * Management of threads can be done external to this object by providing a
 * {@link java.util.concurrent.Executor} object. If none is provided a default
 * implementation is used.
 *
 * <p> <a id="mapping_description"></a> <b>Mapping request URIs to HttpContext paths</b>
 *
 * <p>When a HTTP request is received, the appropriate {@code HttpContext}
 * (and handler) is located by finding the context whose path is the longest
 * matching prefix of the request URI's path. Paths are matched literally,
 * which means that the strings are compared case sensitively, and with no
 * conversion to or from any encoded forms. For example, given a {@code HttpServer}
 * with the following HttpContexts configured:
 *
 * <table class="striped"><caption style="display:none">description</caption>
 *      <thead>
 *          <tr>
 *              <th scope="col"><i>Context</i></th>
 *              <th scope="col"><i>Context path</i></th>
 *          </tr>
 *      </thead>
 *      <tbody>
 *              <tr><th scope="row">ctx1</th><td>"/"</td></tr>
 *              <tr><th scope="row">ctx2</th><td>"/apps/"</td></tr>
 *              <tr><th scope="row">ctx3</th><td>"/apps/foo/"</td></tr>
 *      </tbody>
 * </table>
 *
 * <p>The following table shows some request URIs and which, if any context they would
 * match with:
 * <table class="striped"><caption style="display:none">description</caption>
 *      <thead>
 *          <tr>
 *              <th scope="col"><i>Request URI</i></th>
 *              <th scope="col"><i>Matches context</i></th>
 *          </tr>
 *      </thead>
 *      <tbody>
 *          <tr><th scope="row">"http://foo.com/apps/foo/bar"</th><td>ctx3</td></tr>
 *          <tr><th scope="row">"http://foo.com/apps/Foo/bar"</th><td>no match, wrong case</td></tr>
 *          <tr><th scope="row">"http://foo.com/apps/app1"</th><td>ctx2</td></tr>
 *          <tr><th scope="row">"http://foo.com/foo"</th><td>ctx1</td></tr>
 *      </tbody>
 * </table>
 *
 * <p><b>Note about socket backlogs</b>
 *
 * <p>When binding to an address and port number, the application can also
 * specify an integer <i>backlog</i> parameter. This represents the maximum
 * number of incoming TCP connections which the system will queue internally.
 * Connections are queued while they are waiting to be accepted by the
 * {@code HttpServer}. When the limit is reached, further connections may be
 * rejected (or possibly ignored) by the underlying TCP implementation. Setting
 * the right backlog value is a compromise between efficient resource usage in
 * the TCP layer (not setting it too high) and allowing adequate throughput of
 * incoming requests (not setting it too low).
 *
 * @since 1.6
 */

public abstract class HttpServer {

    
Constructor for subclasses to call.
/**
     * Constructor for subclasses to call.
     */
    protected HttpServer() {
    }

    
Creates a HttpServer instance which is initially not bound to any local address/port. The HttpServer is acquired from the currently installed HttpServerProvider. The server must be bound using bind(InetSocketAddress, int) before it can be used. 
Throws:
IOException – if an I/O error occurs
Returns:
an instance of HttpServer/**
     * Creates a {@code HttpServer} instance which is initially not bound to any
     * local address/port. The {@code HttpServer} is acquired from the currently
     * installed {@link HttpServerProvider}. The server must be bound using
     * {@link #bind(InetSocketAddress,int)} before it can be used.
     *
     * @throws IOException if an I/O error occurs
     * @return an instance of {@code HttpServer}
     */
    public static HttpServer create() throws IOException {
        return create (null, 0);
    }

    
Create a HttpServer instance which will bind to the specified InetSocketAddress (IP address and port number). A maximum backlog can also be specified. This is the maximum number of queued incoming connections to allow on the listening socket. Queued TCP connections exceeding this limit may be rejected by the TCP implementation. The HttpServer is acquired from the currently installed HttpServerProvider 
Params:
addr – the address to listen on, if null then bind(InetSocketAddress, int) must be called to set the address
backlog – the socket backlog. If this value is less than or equal to zero,
               then a system default value is used
Throws:
IOException – if an I/O error occurs
BindException – if the server cannot bind to the requested address,
or if the server is already bound
Returns:
an instance of HttpServer/**
     * Create a {@code HttpServer} instance which will bind to the
     * specified {@link java.net.InetSocketAddress} (IP address and port number).
     *
     * A maximum backlog can also be specified. This is the maximum number of
     * queued incoming connections to allow on the listening socket.
     * Queued TCP connections exceeding this limit may be rejected by the TCP
     * implementation. The {@code HttpServer} is acquired from the currently
     * installed {@link HttpServerProvider}
     *
     * @param addr the address to listen on, if {@code null} then
     *             {@link #bind(InetSocketAddress, int)} must be called to set
     *             the address
     * @param backlog the socket backlog. If this value is less than or equal to zero,
     *                then a system default value is used
     * @throws IOException if an I/O error occurs
     * @throws BindException if the server cannot bind to the requested address,
     * or if the server is already bound
     * @return an instance of {@code HttpServer}
     */

    public static HttpServer create(InetSocketAddress addr, int backlog) throws IOException {
        HttpServerProvider provider = HttpServerProvider.provider();
        return provider.createHttpServer (addr, backlog);
    }

    
Binds a currently unbound HttpServer to the given address and port number. A maximum backlog can also be specified. This is the maximum number of queued incoming connections to allow on the listening socket. Queued TCP connections exceeding this limit may be rejected by the TCP implementation. 
Params:
addr – the address to listen on
backlog – the socket backlog. If this value is less than or equal to
               zero, then a system default value is used
Throws:
BindException – if the server cannot bind to the requested address
or if the server is already bound
NullPointerException – if addr is null/**
     * Binds a currently unbound {@code HttpServer} to the given address and
     * port number. A maximum backlog can also be specified. This is the maximum
     * number of queued incoming connections to allow on the listening socket.
     * Queued TCP connections exceeding this limit may be rejected by the TCP
     * implementation.
     *
     * @param addr the address to listen on
     * @param backlog the socket backlog. If this value is less than or equal to
     *                zero, then a system default value is used
     * @throws BindException if the server cannot bind to the requested address
     * or if the server is already bound
     * @throws NullPointerException if addr is {@code null}
     */
    public abstract void bind(InetSocketAddress addr, int backlog) throws IOException;

    
Starts this server in a new background thread. The background thread
inherits the priority, thread group and context class loader
of the caller.
/**
     * Starts this server in a new background thread. The background thread
     * inherits the priority, thread group and context class loader
     * of the caller.
     */
    public abstract void start();

    
Sets this server's Executor object. An Executor must be established before start() is called. All HTTP requests are handled in tasks given to the executor. If this method is not called (before start()) or if it is called with a null Executor, then a default implementation is used, which uses the thread which was created by the start() method. 
Params:
executor – the Executor to set, or null for default implementation
Throws:
IllegalStateException – if the server is already started/**
     * Sets this server's {@link java.util.concurrent.Executor} object. An
     * {@code Executor} must be established before {@link #start()} is called.
     * All HTTP requests are handled in tasks given to the executor.
     * If this method is not called (before {@link #start()}) or if it is called
     * with a {@code null Executor}, then a default implementation is used,
     * which uses the thread which was created by the {@link #start()} method.
     *
     * @param executor the {@code Executor} to set, or {@code null} for  default
     *                 implementation
     * @throws IllegalStateException if the server is already started
     */
    public abstract void setExecutor(Executor executor);


    
Returns this server's Executor object if one was specified with setExecutor(Executor), or null if none was specified. 
Returns:
the Executor established for this server or null if not set./**
     * Returns this server's {@code Executor} object if one was specified with
     * {@link #setExecutor(Executor)}, or {@code null} if none was specified.
     *
     * @return the {@code Executor} established for this server or {@code null} if not set.
     */
    public abstract Executor getExecutor() ;

    
Stops this server by closing the listening socket and disallowing
any new exchanges from being processed. The method will then block
until all current exchange handlers have completed or else when
approximately delay seconds have elapsed (whichever happens sooner). Then, all open TCP connections are closed, the background thread created by start() exits, and the method returns. Once stopped, a HttpServer cannot be re-used. 
Params:
delay – the maximum time in seconds to wait until exchanges have finished
Throws:
IllegalArgumentException – if delay is less than zero/**
     * Stops this server by closing the listening socket and disallowing
     * any new exchanges from being processed. The method will then block
     * until all current exchange handlers have completed or else when
     * approximately <i>delay</i> seconds have elapsed (whichever happens
     * sooner). Then, all open TCP connections are closed, the background
     * thread created by {@link #start()} exits, and the method returns.
     * Once stopped, a {@code HttpServer} cannot be re-used.
     *
     * @param delay the maximum time in seconds to wait until exchanges have finished
     * @throws IllegalArgumentException if delay is less than zero
     */
    public abstract void stop(int delay);

    
Creates a HttpContext. A HttpContext represents a mapping from a URI path to a exchange handler on this HttpServer. Once created, all requests received by the server for the path will be handled by calling the given handler object. The context is identified by the path, and can later be removed from the server using this with the removeContext(String) method. 
 The path specifies the root URI path for this context. The first
character of path must be '/'.
The class overview describes how incoming request URIs are
mapped to HttpContext instances.
Params:
path – the root URI path to associate the context with
handler – the handler to invoke for incoming requests
Throws:
IllegalArgumentException – if path is invalid, or if a context
already exists for this path
NullPointerException – if either path, or handler are null
API Note:
The path should generally, but is not required to, end with '/'. If the path does not end with '/', eg such as with "/foo" then this would match requests with a path of "/foobar" or "/foo/bar".
Returns:
an instance of HttpContext/**
     * Creates a {@code HttpContext}. A  {@code HttpContext} represents a mapping
     * from a URI path to a exchange handler on this  {@code HttpServer}. Once
     * created, all requests received by the server for the path will be handled
     * by calling the given handler object. The context is identified by the
     * path, and can later be removed from the server using this with the
     * {@link #removeContext(String)} method.
     *
     * <p> The path specifies the root URI path for this context. The first
     * character of path must be '/'.
     *
     * <p>The class overview describes how incoming request URIs are
     * <a href="#mapping_description">mapped</a> to HttpContext instances.
     *
     * @apiNote The path should generally, but is not required to, end with '/'.
     * If the path does not end with '/', eg such as with {@code "/foo"} then
     * this would match requests with a path of {@code "/foobar"} or
     * {@code "/foo/bar"}.
     *
     * @param path the root URI path to associate the context with
     * @param handler the handler to invoke for incoming requests
     * @throws IllegalArgumentException if path is invalid, or if a context
     * already exists for this path
     * @throws NullPointerException if either path, or handler are {@code null}
     * @return an instance of {@code HttpContext}
     */
    public abstract HttpContext createContext(String path, HttpHandler handler);

    
Creates a HttpContext without initially specifying a handler. The handler must later be specified using HttpContext.setHandler(HttpHandler). A HttpContext represents a mapping from a URI path to an exchange handler on this HttpServer. Once created, and when the handler has been set, all requests received by the server for the path will be handled by calling the handler object. The context is identified by the path, and can later be removed from the server using this with the removeContext(String) method. 
The path specifies the root URI path for this context. The first character of path must be
'/'.
The class overview describes how incoming request URIs are
mapped to HttpContext instances. 
Params:
path – the root URI path to associate the context with
Throws:
IllegalArgumentException – if path is invalid, or if a context
already exists for this path
NullPointerException – if path is null
API Note:
The path should generally, but is not required to, end with '/'. If the path does not end with '/', eg such as with "/foo" then this would match requests with a path of "/foobar" or "/foo/bar".
Returns:
an instance of HttpContext/**
     * Creates a HttpContext without initially specifying a handler. The handler
     * must later be specified using {@link HttpContext#setHandler(HttpHandler)}.
     * A {@code HttpContext} represents a mapping from a URI path to an exchange
     * handler on this {@code HttpServer}. Once created, and when the handler has
     * been set, all requests received by the server for the path will be handled
     * by calling the handler object. The context is identified by the path, and
     * can later be removed from the server using this with the
     * {@link #removeContext(String)} method.
     *
     * <p>The path specifies the root URI path for this context. The first character of path must be
     * '/'.
     *
     * <p>The class overview describes how incoming request URIs are
     * <a href="#mapping_description">mapped</a> to {@code HttpContext} instances.
     *
     * @apiNote The path should generally, but is not required to, end with '/'.
     * If the path does not end with '/', eg such as with {@code "/foo"} then
     * this would match requests with a path of {@code "/foobar"} or
     * {@code "/foo/bar"}.
     *
     * @param path the root URI path to associate the context with
     * @throws IllegalArgumentException if path is invalid, or if a context
     * already exists for this path
     * @throws NullPointerException if path is {@code null}
     * @return an instance of {@code HttpContext}
     */
    public abstract HttpContext createContext(String path);

    
Removes the context identified by the given path from the server.
Removing a context does not affect exchanges currently being processed
but prevents new ones from being accepted.
Params:
path – the path of the handler to remove
Throws:
IllegalArgumentException – if no handler corresponding to this
path exists.
NullPointerException – if path is null/**
     * Removes the context identified by the given path from the server.
     * Removing a context does not affect exchanges currently being processed
     * but prevents new ones from being accepted.
     *
     * @param path the path of the handler to remove
     * @throws IllegalArgumentException if no handler corresponding to this
     * path exists.
     * @throws NullPointerException if path is {@code null}
     */
    public abstract void removeContext(String path) throws IllegalArgumentException;

    
Removes the given context from the server.
Removing a context does not affect exchanges currently being processed
but prevents new ones from being accepted.
Params:
context – the context to remove
Throws:
NullPointerException – if context is null/**
     * Removes the given context from the server.
     * Removing a context does not affect exchanges currently being processed
     * but prevents new ones from being accepted.
     *
     * @param context the context to remove
     * @throws NullPointerException if context is {@code null}
     */
    public abstract void removeContext(HttpContext context);

    
Returns the address this server is listening on
Returns:
the InetSocketAddress the server is listening on/**
     * Returns the address this server is listening on
     *
     * @return the {@code InetSocketAddress} the server is listening on
     */
    public abstract InetSocketAddress getAddress();
}