org.kie.api.runtime.StatelessKieSession Maven / Gradle / Ivy
/*
* Copyright 2013 Red Hat, Inc. and/or its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.kie.api.runtime;
import java.util.Map;
import org.kie.api.KieBase;
import org.kie.api.event.KieRuntimeEventManager;
import org.kie.api.runtime.process.StatelessProcessSession;
import org.kie.api.runtime.rule.StatelessRuleSession;
/**
* StatelessKieSession provides a convenience API, wrapping KieSession. It avoids the need to
* call dispose(). Stateless sessions do not support
* iterative invocations, the act of calling execute(...) is a single
* shot method that will internally instantiate a KieSession, add all the user data and execute user commands, call fireAllRules, and then
* call dispose(). While the main way to work with this class is via the BatchExecution Command as supported by the CommandExecutor interface,
* two convenience methods are provided for when simple object insertion is all that's required.
*
*
* Simple example showing a stateless session executing for a given collection of java objects using the convenience api. It will iterate the collection inserting
* each element in turn
*
*
* KieServices kieServices = KieServices.Factory.get();
* KieContainer kContainer = kieServices.getKieClasspathContainer();
* StatelessKieSession kSession = kContainer.newStatelessKieSession();
* kSession.execute( collection );
*
*
*
* If this was done as a single Command it would be as follows:
*
*
* KieCommands kieCommands = kieServices.getCommands();
* kSession.execute( kieCommands.newInsertElements( collection ) );
*
*
*
* Note if you wanted to insert the collection itself, and not the iterate and insert the elements, then kieCommands.newInsert( collection ) would do the job.
*
*
*
* The KieCommands interface details the supported commands, all of which can be marshalled using XStream and the BatchExecutionHelper. BatchExecutionHelper provides details
* on the XML format as well as how to use Drools Pipeline to automate the marshalling of BatchExecution and ExecutionResults.
*
*
*
* StatelessKieSession support globals, scoped in a number of ways. I'll cover the non-command way first,
* as commands are scoped to a specific execution call. Globals can be resolved in three ways. The StatelessKieSession
* supports getGlobals(), which returns a Globals instance. These globals are shared for ALL execution calls, so be especially careful of mutable
* globals in these cases - as often execution calls can be executing simultaneously in different threads. Globals also supports a delegate, which
* adds a second way of resolving globals. Calling of setGlobal(String, Object) will actually be set on an internal Collection, identifiers in this internal
* Collection will have priority over supplied delegate, if one is added. If an identifier cannot be found in
* the internal Collection, it will then check the delegate Globals, if one has been set.
*
*
* Code snippet for setting a session scoped global:
*
* StatelessKieSession kSession = kContainer.newStatelessKieSession();
* kSession.setGlobal( "hbnSession", hibernateSession ); // sets a global hibernate session, that can be used for DB interactions in the rules.
* kSession.execute( collection ); // this will now execute and will be able to resolve the "hbnSession" identifier.
*
*
*
* The third way is execution scopped globals using the CommandExecutor and SetGlobal Commands:
*
*
*
* List<Command> cmds = new ArrayList<Command>();
* cmds.add( kieCommands.newSetGlobal( "list1", new ArrayList() ) );
* cmds.add( kieCommands.newInsert( new Person( "jon", 102 ) ) );
*
* kSession.execute( kieCommands.newBatchExecution( cmds ) );
*
*
*
* The CommandExecutor interface also supports the ability to export data via "out" parameters. Inserted facts, globals and query results can all be returned.
*
*
*
* List<Command> cmds = new ArrayList<Command>();
* cmds.add( kieCommands.newSetGlobal( "list1", new ArrayList(), true ) );
* cmds.add( kieCommands.newInsert( new Person( "jon", 102 ), "person" ) );
* cmds.add( kieCommands.newQuery( "Get People" "getPeople" );
*
* ExecutionResults results = ksession.execute( kieCommands.newBatchExecution( cmds ) );
* results.getValue( "list1" ); // returns the ArrayList
* results.getValue( "person" ); // returns the inserted fact Person
* results.getValue( "Get People" );// returns the query as a QueryResults instance.
*
*/
public interface StatelessKieSession
extends
StatelessRuleSession,
StatelessProcessSession,
CommandExecutor,
KieRuntimeEventManager {
/**
* @return the Globals store
*/
Globals getGlobals();
/**
* Sets a global value on the globals store
*
* @param identifier the global identifier
* @param value the value assigned to the global identifier
*/
void setGlobal(String identifier,
Object value);
/**
* Registers a channel with the given name
*
* @param name the name of the channel
* @param channel the channel instance. It has to be thread safe.
*/
void registerChannel(String name,
Channel channel);
/**
* Unregisters the channel with the given name
*
* @param name
*/
void unregisterChannel(String name);
/**
* @return a map with all registered channels.
*/
Map getChannels();
/**
* @return the KieBase reference from which this stateless session was created.
*/
KieBase getKieBase();
}