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 package com.sun.grizzly;

 /**

  * <p>

  * This class implement the "Chain of Responsibility" pattern (for more info, 

  * take a look at the classic "Gang of Four" design patterns book). Towards 

  * that end, the Chain API models a computation as a series of "protocol filter"

  * that can be combined into a "protocol chain". 

  * </p><p>

  * The API for ProtocolFilter consists of a two methods (execute() and 

  * postExecute) which is passed a "protocol context" parameter containing the 

  * dynamic state of the computation, and whose return value is a boolean 

  * that determines whether or not processing for the current chain has been 

  * completed (false), or whether processing should be delegated to the next 

  * ProtocolFilter in the chain (true). The owning ProtocolChain  must call the

  * postExectute() method of each ProtocolFilter in a ProtocolChain in reverse 

  * order of the invocation of their execute() methods.

  * </p><p>

  * The following picture describe how it ProtocolFilter(s) 

  * </p><p><pre><code>

  * -----------------------------------------------------------------------------

  * - ProtocolFilter1.execute() --> ProtocolFilter2.execute() -------|          -

  * -                                                                |          -

  * -                                                                |          -

  * -                                                                |          -

  * - ProtocolFilter1.postExecute() <-- ProtocolFilter2.postExecute()|          -    

  * -----------------------------------------------------------------------------

  * </code></pre></p><p>

  * The "context" abstraction is designed to isolate ProtocolFilter

  * implementations from the environment in which they are run 

  * (such as a ProtocolFilter that can be used in either IIOP or HTTP parsing, 

  * without being tied directly to the API contracts of either of these 

  * environments). For ProtocolFilter that need to allocate resources prior to 

  * delegation, and then release them upon return (even if a delegated-to 

  * ProtocolFilter throws an exception), the "postExecute" method can be used 

  * for cleanup. 

  * </p>

  * @author Jeanfrancois Arcand

  */

 public interface ProtocolChain{

     /**

      * {@link ProtocolChain} result attribute name.

      */

     public static final String PROTOCOL_CHAIN_POST_INSTRUCTION = 

             "ChainPostInstruction";

     /**

      * Add a {@link ProtocolFilter} to the list. {@link ProtocolFilter}

      * will be invoked in the order they have been added.

      * @param protocolFilter {@link ProtocolFilter}

      * @return {@link ProtocolFilter} added successfully (yes/no) ?

      */

     public boolean addFilter(ProtocolFilter protocolFilter);

     /**

      * Remove the {@link ProtocolFilter} from this chain.

      * @param theFilter {@link ProtocolFilter} 

      * @return {@link ProtocolFilter} removed successfully (yes/no) ?

      */

     public boolean removeFilter(ProtocolFilter theFilter);

     /**

      * Insert a {@link ProtocolFilter} to the list at position 'pos'.

      * @param pos The insertion position 

      * @param protocolFilter {@link ProtocolFilter}

      */

     public void addFilter(int pos, ProtocolFilter protocolFilter);

     /**

      * Execute using the {@link Context} instance.

      * @param context <code>Context<code>

      * @throws java.lang.Exception 

      */

     public void execute(Context context) throws Exception;

 }