JavaRestService.java

/*
** Module   : JavaRestService.java
** Abstract : Details of a REST service specification, which is implemented as a Java API call.
**
** Copyright (c) 2022, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description----------------------------------------
** 001 CA  20220323 Created initial version.
**     CA  20220405 Added authentication and authorization for web requests.  When this is enabled, the target
**                  API call will be executed under the authenticated FWD context, and not the agent's context.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
** 
** Additional terms under GNU Affero GPL version 3 section 7:
** 
**   Under Section 7 of the GNU Affero GPL version 3, the following additional
**   terms apply to the works covered under the License.  These additional terms
**   are non-permissive additional terms allowed under Section 7 of the GNU
**   Affero GPL version 3 and may not be removed by you.
** 
**   0. Attribution Requirement.
** 
**     You must preserve all legal notices or author attributions in the covered
**     work or Appropriate Legal Notices displayed by works containing the covered
**     work.  You may not remove from the covered work any author or developer
**     credit already included within the covered work.
** 
**   1. No License To Use Trademarks.
** 
**     This license does not grant any license or rights to use the trademarks
**     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
**     of Golden Code Development Corporation. You are not authorized to use the
**     name Golden Code, FWD, or the names of any author or contributor, for
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**     You may not represent yourself as Golden Code Development Corporation or FWD.
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**     Golden Code Development Corporation, FWD, or any author or contributor to
**     the covered work, without written authorization.
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**     versions of the covered work must be marked in a reasonable way to make it
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**     attribution required in this license.
*/

package com.goldencode.p2j.rest;

import java.lang.reflect.*;
import java.util.*;

import com.goldencode.p2j.util.*;

/**
 * Invocation implementation for REST service which are mapped to APIs written directly in Java.
 */
public class JavaRestService
extends RestService
{
   /** The Java class defining this REST service. */
   private final Class<?> cls;
   
   /** 
    * The Java method (in the target {@link #cls class}) which implements this service.  Must be a public 
    * instance or static method; for an instance method, the Java class must have a no-argument constructor
    * and must not be abstract.
    */
   private final Method method;
   
   /**
    * Create a new REST service implemented in a Java method.
    * 
    * @param    cls
    *           The target class.
    * @param    m
    *           The target method.
    * @param    ls
    *           The service signature, as it appears at the method annotation.
    * @param    key
    *           The service key.
    * @param    timeout
    *           The invocation timeout.
    */
   public JavaRestService(Class<?>               cls, 
                          Method                 m, 
                          LegacyService          ls, 
                          ServiceKey             key, 
                          int                    timeout) 
   {
      super(ls, null, key, timeout);
      
      this.cls = cls;
      this.method = m;
      
      try
      {
         if (!Modifier.isPublic(cls.getModifiers()))
         {
            // public class
            throw new IllegalStateException("Class " + cls.getName() + " must be public!");
         }
         if (!Modifier.isPublic(m.getModifiers()))
         {
            // public method
            throw new IllegalStateException("Method " + m.getName() + " in class " + cls.getName() + 
                                            " must be public!");
         }
         if (Modifier.isAbstract(m.getModifiers()))
         {
            // non-abstract method
            throw new IllegalStateException("Method " + m.getName() + " in class " + cls.getName() + 
                                            " must not be abstract!");
         }
         if (Modifier.isAbstract(cls.getModifiers()) && !Modifier.isStatic(m.getModifiers()))
         {
            // static method for abstract classes
            throw new IllegalStateException("Method " + m.getName() + " in class " + cls.getName() + 
                                            " must be static!");
         }
         if (!Modifier.isStatic(m.getModifiers()) && cls.getConstructor() == null)
         {
            // instance method must have a default constructor at the class
            throw new IllegalStateException("To register method " + m.getName() + " in class " + cls.getName() + 
                                            " as a service, the class must have a default constructor!");
         }
      } 
      catch (NoSuchMethodException | 
             SecurityException e)
      {
         throw new RuntimeException("Could not register method " + m.getName() + " in class " + cls.getName(), 
                                    e);
      }
      
      buildDefinitionParameters();
   }

   /**
    * Invoke this service.
    * 
    * @param    helper
    *           The appserver helper used to execute the requests.
    * @param    token
    *           When not null, it represents the token of a FWD context created for an authenticated and 
    *           authorized web service call.  The API call will be performed in that context.
    * @param    args
    *           The arguments.  Any change to a mutable argument will be reflected back at the caller.
    *           
    * @return   The returned value.
    */
   @Override
   public Object invoke(AppServerHelper helper, String token, Object[] args)
   {
      JavaInvokeConfig cfg = new JavaInvokeConfig(cls, method);
      cfg.setWebServiceToken(token);
      cfg.setArguments(args);

      return helper.invoke(timeout, cfg);
   }
   
   /**
    * Get the parser to be used for parsing the arguments, to be attached to the service's parser.
    * 
    * @param    argumentsParser
    *           The service's parser.
    *           
    * @return   Always a new {@link LegacyArgumentsParser} instance.
    */
   @Override
   protected ArgumentsParser getParser(ServiceArgumentsParser argumentsParser)
   {
      return new JavaArgumentsParser(argumentsParser);
   }

   /**
    * Get the serialized to be used for writing the response arguments.
    * 
    * @param    argumentsSerializer
    *           The service's serializer.
    *           
    * @return   Always a {@link LegacyArgumentsSerializer} instance.
    */
   @Override
   protected ArgumentsSerializer getSerializer(ResponseArguments argumentsSerializer)
   {
      return new JavaArgumentsSerializer(argumentsSerializer);
   }
   
   /**
    * Build the parameter definitions, from the {@link LegacyServiceParameter} annotations at the method
    * definition.  This will set the {@link RestService#definitionParameters}.
    */
   @Override
   protected void buildDefinitionParameters()
   {
      List<LegacyServiceParameter> params = new ArrayList<>();
      for (LegacyServiceParameter param : ls.parameters())
      {
         if (!param.returnValue())
         {
            params.add(param);
         }
      }
      
      definitionParameters = params.toArray(new LegacyServiceParameter[0]);
   }
}