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package javax.servlet.http;

import java.util.Set;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


Build a request to be pushed.
According section 8.2 of RFC 7540, a promised request must be cacheable and
safe without a request body.

A PushBuilder is obtained by calling HttpServletRequest.newPushBuilder(). Each call to this method will a new instance of a PushBuilder based off the current 
HttpServletRequest, or null. Any mutations to the returned PushBuilder are not reflected on future returns.


The instance is initialized as follows:

 

The path method must be called on the PushBuilder instance before the call to push. Failure to do so must cause an exception to be thrown from push, as specified in that method.


A PushBuilder can be customized by chained calls to mutator methods before the push() method is called to initiate an asynchronous push request with the current state of the builder. After the call to push(), the builder may be reused for another push, however the implementation must make it so the path(String) and conditional headers (defined in RFC 7232) values are cleared before returning from push. All other values are retained over calls to push(). 
Since:Servlet 4.0
/** 
 * Build a request to be pushed.
 * 
 * According section 8.2 of RFC 7540, a promised request must be cacheable and
 * safe without a request body.
 *
 * <p>A PushBuilder is obtained by calling {@link
 * HttpServletRequest#newPushBuilder()}.  Each call to this method will
 * a new instance of a PushBuilder based off the current {@code
 * HttpServletRequest}, or null.  Any mutations to the returned PushBuilder are
 * not reflected on future returns.</p>
 *
 * <p>The instance is initialized as follows:</p>
 *
 * <ul>
 *
 * <li>The method is initialized to "GET"</li>
 *
 * <li>The existing request headers of the current {@link HttpServletRequest}
 * are added to the builder, except for:
 *
 * <ul>
 *   <li>Conditional headers (defined in RFC 7232)
 *   <li>Range headers
 *   <li>Expect headers
 *   <li>Authorization headers
 *   <li>Referrer headers
 * </ul>
 *
 * </li>
 *
 * <li>If the request was authenticated, an Authorization header will 
 * be set with a container generated token that will result in equivalent
 * Authorization for the pushed request.</li>
 *
 * <li>The session ID will be the value returned from {@link
 * HttpServletRequest#getRequestedSessionId()}, unless {@link
 * HttpServletRequest#getSession(boolean)} has previously been called to
 * create a new {@link HttpSession} prior to the call to create the
 * {@code PushBuilder}, in which case the new session ID will be used as
 * the PushBuilder's requested session ID.  Note that the session ID
 * returned from the request can effectively come from one of two
 * "sources": a cookie or the URL (as specified in {@link
 * HttpServletRequest#isRequestedSessionIdFromCookie} and {@link
 * HttpServletRequest#isRequestedSessionIdFromURL}, respectively).  The
 * session ID for the {@code PushBuilder} will also come from the same
 * source as the request.</li>
 *
 * <li>The Referer(sic) header will be set to {@link
 * HttpServletRequest#getRequestURL()} plus any {@link
 * HttpServletRequest#getQueryString()} </li>
 *
 * <li>If {@link HttpServletResponse#addCookie(Cookie)} has been called
 * on the associated response, then a corresponding Cookie header will be added
 * to the PushBuilder, unless the {@link Cookie#getMaxAge()} is &lt;=0, in which
 * case the Cookie will be removed from the builder.</li>
 *
 * </ul> 
 *
 * <p>The {@link #path} method must be called on the {@code PushBuilder}
 * instance before the call to {@link #push}.  Failure to do so must
 * cause an exception to be thrown from {@link
 * #push}, as specified in that method.</p>
 * 
 * <p>A PushBuilder can be customized by chained calls to mutator
 * methods before the {@link #push()} method is called to initiate an
 * asynchronous push request with the current state of the builder.
 * After the call to {@link #push()}, the builder may be reused for
 * another push, however the implementation must make it so the {@link
 * #path(String)} and conditional headers (defined in RFC 7232) 
 * values are cleared before returning from {@link #push}.
 * All other values are retained over calls to {@link #push()}.
 *
 * @since Servlet 4.0
 */
public interface PushBuilder {
    
Set the method to be used for the push.


Params:
  • method – the method to be used for the push.
Throws:
  • NullPointerException – if the argument is null
  • IllegalArgumentException – if the argument is the empty String,
        or any non-cacheable or unsafe methods defined in RFC 7231,
        which are POST, PUT, DELETE, CONNECT, OPTIONS and TRACE.
Returns:this builder.
/** 
     * <p>Set the method to be used for the push.</p>
     * 
     * @throws NullPointerException if the argument is {@code null}
     *
     * @throws IllegalArgumentException if the argument is the empty String,
     *         or any non-cacheable or unsafe methods defined in RFC 7231,
     *         which are POST, PUT, DELETE, CONNECT, OPTIONS and TRACE.
     *
     * @param method the method to be used for the push.  
     * @return this builder.
     */
    public PushBuilder method(String method);
    
    
Set the query string to be used for the push. The query string will be appended to any query String included in a call to path(String). Any duplicate parameters must be preserved. This method should be used instead of a query in path(String) when multiple push() calls are to be made with the same query string. 
Params:
  • queryString – the query string to be used for the push.
Returns:this builder.
/**
     * Set the query string to be used for the push.  
     *
     * The query string will be appended to any query String included in a call
     * to {@link #path(String)}.  Any duplicate parameters must be preserved.
     * This method should be used instead of a query in {@link #path(String)}
     * when multiple {@link #push()} calls are to be made with the same
     * query string.
     * @param  queryString the query string to be used for the push. 
     * @return this builder.
     */
    public PushBuilder queryString(String queryString);
    
    
Set the SessionID to be used for the push.
The session ID will be set in the same way it was on the associated request (ie
as a cookie if the associated request used a cookie, or as a url parameter if
the associated request used a url parameter).
Defaults to the requested session ID or any newly assigned session id from
a newly created session.

Params:
  • sessionId – the SessionID to be used for the push.
Returns:this builder.
/**
     * Set the SessionID to be used for the push.
     * The session ID will be set in the same way it was on the associated request (ie
     * as a cookie if the associated request used a cookie, or as a url parameter if
     * the associated request used a url parameter).
     * Defaults to the requested session ID or any newly assigned session id from
     * a newly created session.
     * @param sessionId the SessionID to be used for the push.
     * @return this builder.
     */
    public PushBuilder sessionId(String sessionId);
    
    
Set a request header to be used for the push.  If the builder has an
existing header with the same name, its value is overwritten.


Params:
  • name – The header name to set
  • value – The header value to set
Returns:this builder.
/** 
     * <p>Set a request header to be used for the push.  If the builder has an
     * existing header with the same name, its value is overwritten.</p>
     *
     * @param name The header name to set
     * @param value The header value to set
     * @return this builder.
     */
    public PushBuilder setHeader(String name, String value);
    
    
Add a request header to be used for the push.


Params:
  • name – The header name to add
  • value – The header value to add
Returns:this builder.
/** 
     * <p>Add a request header to be used for the push.</p>
     * @param name The header name to add
     * @param value The header value to add
     * @return this builder.
     */
    public PushBuilder addHeader(String name, String value);

    
Remove the named request header.  If the header does not exist, take
no action.


Params:
  • name – The name of the header to remove
Returns:this builder.
/** 
     * <p>Remove the named request header.  If the header does not exist, take
     * no action.</p>
     *
     * @param name The name of the header to remove
     * @return this builder.
     */
    public PushBuilder removeHeader(String name);

    
Set the URI path to be used for the push. The path may start with "/" in which case it is treated as an absolute path, otherwise it is relative to the context path of the associated request. There is no path default and path(String) must be called before every call to push(). If a query string is present in the argument path, its contents must be merged with the contents previously passed to queryString, preserving duplicates. 
Params:
  • path – the URI path to be used for the push, which may include a
query string.
Returns:this builder.
/** 
     * Set the URI path to be used for the push.  The path may start
     * with "/" in which case it is treated as an absolute path,
     * otherwise it is relative to the context path of the associated
     * request.  There is no path default and {@link #path(String)} must
     * be called before every call to {@link #push()}.  If a query
     * string is present in the argument {@code path}, its contents must
     * be merged with the contents previously passed to {@link
     * #queryString}, preserving duplicates.
     *
     * @param path the URI path to be used for the push, which may include a
     * query string.
     * @return this builder.
     */
    public PushBuilder path(String path);
    
    
Push a resource given the current state of the builder,
the method must be non-blocking.

Push a resource based on the current state of the PushBuilder.
Calling this method does not guarantee the resource will actually
be pushed, since it is possible the client can decline acceptance
of the pushed resource using the underlying HTTP/2 protocol.


If the builder has a session ID, then the pushed request will
include the session ID either as a Cookie or as a URI parameter
as appropriate. The builders query string is merged with any
passed query string.


Before returning from this method, the builder has its path,
conditional headers (defined in RFC 7232) nulled. All other fields
are left as is for possible reuse in another push.


Throws:
  • IllegalStateException – if there was no call to path on this instance either between its instantiation or the last call to push() that did not throw an IllegalStateException.
/**
     * Push a resource given the current state of the builder,
     * the method must be non-blocking.
     *
     * <p>Push a resource based on the current state of the PushBuilder.
     * Calling this method does not guarantee the resource will actually
     * be pushed, since it is possible the client can decline acceptance
     * of the pushed resource using the underlying HTTP/2 protocol.</p>
     *
     * <p>If the builder has a session ID, then the pushed request will
     * include the session ID either as a Cookie or as a URI parameter
     * as appropriate. The builders query string is merged with any
     * passed query string.</p>
     *
     * <p>Before returning from this method, the builder has its path,
     * conditional headers (defined in RFC 7232) nulled. All other fields
     * are left as is for possible reuse in another push.</p>
     *
     * @throws IllegalStateException if there was no call to {@link
     * #path} on this instance either between its instantiation or the
     * last call to {@code push()} that did not throw an
     * IllegalStateException.
     */
    public void push();
    
    
Return the method to be used for the push.

Returns:the method to be used for the push.
/**
     * Return the method to be used for the push.
     *
     * @return the method to be used for the push.
     */
    public String getMethod();

    
Return the query string to be used for the push.

Returns:the query string to be used for the push.
/**
     * Return the query string to be used for the push.
     *
     * @return the query string to be used for the push.
     */
    public String getQueryString();

    
Return the SessionID to be used for the push.

Returns:the SessionID to be used for the push.
/**
     * Return the SessionID to be used for the push.
     * 
     * @return the SessionID to be used for the push.
     */
    public String getSessionId();

    
Return the set of header to be used for the push.

The returned set is not backed by the PushBuilder object, so changes in the returned set are not reflected in the PushBuilder object, and vice-versa.


Returns:the set of header to be used for the push.
/**
     * Return the set of header to be used for the push.
     *
     * <p>The returned set is not backed by the {@code PushBuilder} object,
     * so changes in the returned set are not reflected in the
     * {@code PushBuilder} object, and vice-versa.</p>
     *
     * @return the set of header to be used for the push.
     */
    public Set<String> getHeaderNames();

    
Return the header of the given name to be used for the push.

Params:
  • name – the name of the header
Returns:the header of the given name to be used for the push.
/**
     * Return the header of the given name to be used for the push.
     * @param name the name of the header
     *
     * @return the header of the given name to be used for the push.
     */
    public String getHeader(String name);

    
Return the URI path to be used for the push.

Returns:the URI path to be used for the push.
/**
     * Return the URI path to be used for the push.
     *
     * @return the URI path to be used for the push.
     */
    public String getPath();
}