ACTIVEMQ研究和分析.docx
《ACTIVEMQ研究和分析.docx》由会员分享，可在线阅读，更多相关《ACTIVEMQ研究和分析.docx（54页珍藏版）》请在冰豆网上搜索。
ACTIVEMQ研究和分析
研究目标
Ø熟悉activemq的原理和开发接口
⏹特点
Thenewfeaturesandenhancementsinthisreleaseinclude:
∙Additionaladvisorymessagesformessagesdelivered/consumedfastproducers/slowconsumers,Usagelimits,Slavesbecomemastersetc.
∙Enhancedsslcontextconfigurationthroughspring/xbean
∙Newindividualacknowledgemodeformessageconsumption
∙Abilitytoconfiguretheautomaticdiscardingoftheitemsbeingsenttothedeadletterqueue
∙AbilitytolimitthemaximumnumberofconnectionstoaBroker
∙Abilitytoconfigureseparatelock
DatasourceforJDBCMasterslave.
∙activemq-camelandactivemq-connection-poolnowhavetheirownmodules,nolongerinactivemq-core
∙ThedefaultActiveMQConnectionFactory
brokerUrlnowusesthefailovertransport.
∙UsesApacheCamel1.5
.
⏹Amq启动过程分析
采用spring
org.apache.activemq.xbeanXBeanBrokerService
org.apache.activemq.broker.BrokerService
org.apache.activemq.xbean.BrokerFactoryBean
org.apache.camel.spring.CamelContextFactoryBean
org.apache.activemq.util.MemoryPropertyEditor
⏹数据格式
CamelsupportsapluggableDataFormat
toallowmessagestobemarshalledtoandfrombinaryortextformatstosupportakindofMessageTranslator.
Thefollowingdataformatsarecurrentlysupported
∙ArtixDataServices
∙Bindy
∙CSV
∙EDI
∙FlatpackDataFormat
∙HL7DataFormat
∙JAXB
∙JSON
∙Serialization
∙String
∙TidyMarkup
∙XmlBeans
∙XMLSecurityDataFormat
∙XStream
∙ZipDataFormat
Unmarshalling
IfyoureceiveamessagefromoneoftheCamelComponentssuchasFile,HTTPorJMSyouoftenwanttounmarshalthepayloadintosomebeansothatyoucanprocessitusingsomeBeanIntegrationorperformPredicateevaluationandsoforth.TodothisusetheunmarshalwordintheDSLinJavaortheXmlConfiguration.
Forexample
DataFormatjaxb=newJaxbDataFormat（"com.acme.model"）;
from（"activemq:
My.Queue"）.
unmarshal（jaxb）.
to（"mqseries:
Another.Queue"）;
TheaboveusesanamedDataFormatofjaxbwhichisconfiguredwithanumberofJavapackagenames.YoucanifyoupreferuseanamedreferencetoadataformatwhichcanthenbedefinedinyourRegistrysuchasviayourSpringXMLfile.
YoucanalsousetheDSLitselftodefinethedataformatasyouuseit.ForexamplethefollowingusesJavaserializationtounmarshalabinaryfilethensenditasanObjectMessagetoActiveMQ
from（"file:
//foo/bar"）.
unmarshal（）.serialization（）.
to（"activemq:
Some.Queue"）;
Marshalling
Marshallingistheoppositeofunmarshalling,whereabeanismarshalledintosomebinaryortextualformatfortransmissionoversometransportviaaCamelComponent.Marshallingisusedinthesamewayasunmarshallingabove;intheDSLyoucanuseaDataFormatinstance,youcanconfiguretheDataFormatdynamicallyusingtheDSLoryoucanrefertoanamedinstanceoftheformatintheRegistry.
ThefollowingexampleunmarshalsviaserializationthenmarshalsusinganamedJAXBdataformattoperformakindofMessageTranslator
from（"file:
//foo/bar"）.
unmarshal（）.serialization（）.
marshal（"jaxb"）.
to（"activemq:
Some.Queue"）;
⏹事务模型
⏹点对点传输模式
⏹发布订阅模式
UsingRoutingLogic
Anotheroptionistoexplicitlylistthepublish-subscriberelationshipinyourroutinglogic;thiskeepstheproducerandconsumerdecoupledbutletsyoucontrolthefinegrainedroutingconfigurationusingtheDSLorXmlConfiguration.
UsingtheFluentBuilders
RouteBuilderbuilder=newRouteBuilder（）{
publicvoidconfigure（）{
from（"seda:
a"）.multicast（）.to（"seda:
b","seda:
c","seda:
d"）;
}
};
⏹请求响应模式
ForexamplewhenusingJMSwithInOutthecomponentwillbydefaultperformtheseactions
∙createbydefaultatemporaryinboundqueue
∙settheJMSReplyTodestinationontherequestmessage
∙settheJMSCorrelationIDontherequestmessage
∙sendtherequestmessage
∙consumetheresponseandassociatetheinboundmessagetotherequestusingtheJMSCorrelationID（asyoumaybeperformingmanyconcurrentrequest/responses）.
⏹消息群发
静态群发
Thefollowingexampleshowshowtoroutearequestfromaninputqueue:
aendpointtoastaticlistofdestinations
RouteBuilderbuilder=newRouteBuilder（）{
publicvoidconfigure（）{
from（"seda:
a"）.multicast（）.to（"seda:
b","seda:
c","seda:
d"）;
}
};
动态群发
UsuallyoneofthemainreasonsforusingtheRecipientList
patternisthatthelistofrecipientsisdynamicandcalculatedatruntime.ThefollowingexampledemonstrateshowtocreateadynamicrecipientlistusinganExpression（whichinthiscaseitextractsanamedheadervaluedynamically）tocalculatethelistofendpointswhichareeitheroftypeEndpoint
orareconvertedtoaStringandthenresolvedusingtheendpointURIs.
UsingtheFluentBuilders
RouteBuilderbuilder=newRouteBuilder（）{
publicvoidconfigure（）{
from（"seda:
a"）.recipientList（header（"foo"））;
}
};
TheaboveassumesthattheheadercontainsalistofendpointURIs.Thefollowingtakesasinglestringheaderandtokenizesit
from（"direct:
a"）.recipientList（
header（"recipientListHeader"）.tokenize（","））;
Iteratablevalue
Thedynamiclistofrecipientsthataredefinedintheheadermustbeiteratablesuchas:
▪java.util.Collection
▪java.util.Iterator
▪arrays
▪org.w3c.dom.NodeList
▪Camel1.5.1:
asingleStringwithvaluesseparatedwithcomma
▪anyothertypewillberegardedasasinglevalue
UsingtheSpringXMLExtensions
//camel.apache.org/schema/spring">
a"/>
$foo
Forfurtherexamplesofthispatterninuseyoucouldlookatoneofthejunittestcase
UsingdelimiterinSpringXML
AvailableasofCamel1.5.1
InSpringDSLyoucansetthedelimiterattributeforsettingadelimitertobeusediftheheadervalueisasingleStringwithmultipleseparatedendpoints.
a"/>
--usecommaasadelimiterforStringbasedvalues-->
SoifmyHeadercontainsaStringwiththevalue"activemq:
queue:
foo,activemq:
topic:
hello,log:
bar"thenCamelwillsplittheStringusingthedelimitergivenintheXMLthatwascomma,resultinginto3endpointstosendto.YoucanusespacesbetweentheendpointsasCamelwilltrimthevaluewhenitlookuptheendpointtosendto.
Note:
InJavaDSLyouusethetokenizertoarchivethesame.TherouteaboveinJavaDSL:
from（"direct:
a"）.recipientList（header（"myHeader"）.tokenize（","））;
消息路由
TheMessageRouter
fromtheEIPpatternsallowsyoutoconsumefromaninputdestination,evaluatesomepredicatethenchoosetherightoutputdestination.
Thefollowingexampleshowshowtoroutearequestfromaninputqueue:
aendpointtoeitherqueue:
b,queue:
corqueue:
ddependingontheevaluationofvariousPredicateexpressions
UsingtheFluentBuilders
RouteBuilderbuilder=newRouteBuilder（）{
publicvoidconfigure（）{
from（"seda:
a"）.choice（）.when（header（"foo"）.isEqualTo（"bar"））.to（"seda:
b"）
.when（header（"foo"）.isEqualTo（"cheese"））.to（"seda:
c"）.otherwise（）.to（"seda:
d"）;
}
};
Choicewithoutotherwise
Ifyouuseachoicewithoutaddinganotherwise,anyunmatchedexchangeswillbedroppedbydefault.Ifyouprefertohaveanexceptionforanunmatchedexchange,youcanaddathrowFaulttotheotherwise.
....otherwise（）.throwFault（"Nomatchingwhenclausefoundonchoiceblock"）;
动态路由
publicclassRouterBean2{
@RecipientList
publicStringroute（@Header（"customerID"）StringcustIDStringbody）{
if（custID==null）returnnull;
return"activemq:
Customers.Orders."+custID;
}
}
publicclassMyRouteBuilderextendsRouteBuilder{
protectedvoidconfigure（）{
from（"activemq:
Orders.Incoming"）.beanRef（"myRouterBean","route"）;
}
}
⏹可靠传输
CamelsupportstheGuaranteedDelivery
fromtheEIPpatternsusingthefollowingcomponents
∙Fileforusingfilesystemsasapersistentstoreofmessages
∙JMSwhenusingpersistentdelivery（thedefault）forworkingwithJMSQueuesandTopicsforhighperformance,clusteringandloadbalancing
∙JPAforusingadatabaseasapersistencelayer
⏹消息转换
from（"activemq:
SomeQueue"）.
beanRef（"myTransformerBean","myMethodName"）.
to（"mqseries:
AnotherQueue"）;
Wherethe"myTransformerBean"wouldbedefinedinaSpringXMLfileordefinedinJNDIetc.YoucanomitthemethodnameparameterfrombeanRef（）andtheBeanIntegrationwilltrytodeducethemethodtoinvokefromthemessageexchange.
oryoucanaddyourownexplicitProcessortodothetransformation
from（"direct:
start"）.process（newProcessor（）{
publicvoidprocess（Exchangeexchange）{
Messagein=exchange.getIn（）;
in.setBody（in.getBody（String.class）+"World!
"）;
}
}）.to（"mock:
result"）;
oryoucanusetheDSLtoexplicitlyconfigurethetransformation
from（"direct:
start"）.transform（body（）.append（"World!
"））.to（"mock:
result"）;
⏹消息过滤
ThefollowingexampleshowshowtocreateaMessageFilterrouteconsumingmessagesfromanendpointcalledqueue:
awhichifthePredicateistruewillbedispatchedtoqueue:
b
UsingtheFluentBuilders
RouteBuilderbuilder=newRouteBuilder（）{
publicvoidconfigure（）{
from（"seda:
a"）.filter（header（"foo"）.isEqualTo（"bar"））.to（"seda:
b"）;
}
};
YoucanofcourseusemanydifferentPredicatelanguagessuchasXPath,XQuery,SQLorvariousScriptingLanguages.HereisanXPathexample
from（"direct:
start"）.
filter（）.xpath（"/person[@name='James']"）.
to（"mock:
result"）;
UsingtheSpringXMLExtensions
//camel.apache.org/schema/spring">
a"/>
$foo='bar'
b"/>
⏹消
升级会员 