如何获取在Guvnor中创建BRL并查询Drools服务器的事实

Question

我在Guvnor遵守BRL规则。。我正在尝试使用Drools服务器从我的应用程序中执行规则（此解决方案是因为在生产中我可以使用更多服务器，并可能提高性能……对此不确定，因为这是我的公司第一次使用Drools）。。

所以基本上规则是。。给定一个对象路由设置属性“selectedOutboundJourney”，我上传到guvnor的一个jar中，我想获取另一个设置了属性“selectedReturnJourney”的对象。。（但是否可能得到相同的对象？？）实际上，我得到了一个Route对象，其中SelectedReturnTravely为null。

考虑到我遇到的麻烦，我不确定使用BRL是否是一个好的解决方案。。对于那些想要更改规则或创建新规则的非技术人员来说，它似乎很容易使用。

无论如何

这是我在Guvnor中创建的BRL：

rule "Selected Return for Dover - Calais"
   dialect "mvel"
    when
        Route( selectedOutboundJourney == "DOCA" )
    then
        Route fact0 = new Route();
        fact0.setSelectedReturnJourney( "CADO" );
        insertLogical( fact0 );
        end

这是我正在使用的代码：

final List<Command> commands = new ArrayList<Command>();
final Command insertObjectCommand = CommandFactory.newInsert(input, RESULT, true, "default");
final Command getObjectCommand = CommandFactory.newGetObjects();
final Command fireAllRulesCommand = CommandFactory.newFireAllRules();
commands.add(insertObjectCommand);
commands.add(getObjectCommand);
commands.add(fireAllRulesCommand);

final ExecutionResults executionResults = droolsHttpClient.callDroolsServer(commands);
return executionResults.getValue(RESULT);

DroolsHttpClient类是：

public ExecutionResults callDroolsServer(final List<Command> commands) throws  DroolsException
{
    PostMethod postMethod = null;
    try
    {
        final HttpClient httpClient = new HttpClient();
        final String droolsServerHost = Config.getString(PoferriesrulesengineConstants.DROOLS_SERVER_HOST, "");
        final int droolsServerPort = Config.getInt(PoferriesrulesengineConstants.DROOLS_SERVER_PORT, 0);
        httpClient.getHostConfiguration().setHost(droolsServerHost, droolsServerPort);

        final String droolsServerUrl = Config.getString(PoferriesrulesengineConstants.DROOLS_SERVER_URL, "");
        postMethod = new PostMethod(droolsServerUrl);

        final BatchExecutionCommand command = CommandFactory.newBatchExecution(commands, PoferriesrulesengineConstants.DROOLS_SESSION);
        final XStream xStreamMarshaller = BatchExecutionHelper.newXStreamMarshaller();
        final String xmlCommand = xStreamMarshaller.toXML(command);

        final StringRequestEntity request = new StringRequestEntity(xmlCommand, MediaType.TEXT_PLAIN_VALUE, CharEncoding.UTF_8);
        postMethod.setRequestEntity(request);

        httpClient.executeMethod(postMethod);
        if (postMethod.getStatusCode() != 200)
        {
            throw new RuntimeException("Drools Communication Error, code: " + postMethod.getStatusCode());
        }
        final String response = postMethod.getResponseBodyAsString();

        final ExecutionResults executionResults = (ExecutionResults) xStreamMarshaller.fromXML(response);
        return executionResults;
    }
    catch (final Exception e)
    {
        throw new DroolsException(e.getMessage());
    }
    finally
    {
        postMethod.releaseConnection();
    }
}

如果我使用下面这样的DRL，那么不用getObjectCommand就可以完美地表达：

rule "Selected Return Routes for Dover Calais"

    when
    r : Route(selectedOutboundJourney == "DOCA")
then
    r.setSelectedReturnJourney("CADO")

end

有人能帮我吗？

Answer 1

假设在执行以下规则后，知识会话开始时只有一个事实

rule "Selected Return for Dover - Calais"
dialect "mvel"
when
    Route( selectedOutboundJourney == "DOCA" )
then
    Route fact0 = new Route()
    fact0.setSelectedReturnJourney( "CADO" )
    insert( fact0 )
end

您的会话中将有两个事实，因为您刚刚插入了第二个事实。

Route: selectedOutboundJourney = "DOCA", selectedReturnJourney=null
Route: selectedOutboundJourney = null, selectedReturnJourney="DACO"

如果要修改原始事实，请使用以下规则：

rule "Selected Return Routes for Dover Calais"
when
   $r : Route(selectedOutboundJourney == "DOCA")
then
   modify ($r) {
     selectedReturnJourney = "CADO"
   }
end