爲什麼ActiveMQ的5.14.x無法啓動嵌入駱駝的JMS組件2.18.3

Question

下面是簡單的彈簧引導工程（版本1.5.2）來演示該問題：

https://github.com/lanwen/camel-jms-activemq-test

它阿帕奇駱駝版本2.18.3

分支master一切工作正常，因爲activemq-camel=5.14.4和camel-jms=2.16.3（從中得到及物動詞）

春季啓動應用程序與日誌正常啓動：

2017-04-22 00:53:19.647 INFO 97217 --- [   main] o.a.camel.spring.SpringCamelContext  : Apache Camel 2.18.3 (CamelContext: camel-1) is starting 
2017-04-22 00:53:19.662 INFO 97173 --- [   main] o.apache.activemq.broker.BrokerService : Apache ActiveMQ 5.14.4 (localhost, ID:lanwen-osx3.local-62145-1492811599544-0:1) is starting 
2017-04-22 00:53:19.665 INFO 97173 --- [   main] o.apache.activemq.broker.BrokerService : Apache ActiveMQ 5.14.4 (localhost, ID:lanwen-osx3.local-62145-1492811599544-0:1) started 
2017-04-22 00:53:19.665 INFO 97173 --- [   main] o.apache.activemq.broker.BrokerService : For help or more information please see: http://activemq.apache.org 
2017-04-22 00:53:19.682 INFO 97173 --- [   main] o.a.activemq.broker.TransportConnector : Connector vm://localhost started 
2017-04-22 00:53:19.702 INFO 97173 --- [   main] o.a.camel.spring.SpringCamelContext  : Route: route1 started and consuming from: activemq://queue:to-write?asyncConsumer=true 
2017-04-22 00:53:19.703 INFO 97173 --- [   main] o.a.camel.spring.SpringCamelContext  : Total 1 routes, of which 1 are started. 
2017-04-22 00:53:19.704 INFO 97173 --- [   main] o.a.camel.spring.SpringCamelContext  : Apache Camel 2.18.3 (CamelContext: camel-1) started in 0.466 seconds 
2017-04-22 00:53:19.709 INFO 97173 --- [   main] ru.yandex.test.writer.MyTestApplication : Started MyTestApplication in 2.437 seconds (JVM running for 2.911) 

但是當你用camel-jms=2.18.3開始（如駱駝的主要版本，分支not_working）

事情出錯，該日誌：

2017-04-22 00:56:38.070 INFO 97195 --- [   main] o.a.camel.spring.SpringCamelContext  : Apache Camel 2.18.3 (CamelContext: camel-1) is starting 
... 
2017-04-22 00:56:43.590 WARN 97195 --- [ActiveMQ Task-1] o.a.a.t.failover.FailoverTransport  : Failed to connect to [tcp://localhost:61616] after: 10 attempt(s) continuing to retry. 

但是，如果我們將activemq-camel更改爲5.13.4與camel-jms=2.18.3它再次正常工作...

爲什麼ActiveMQ的5.14.x不與駱駝的JMS 2.18.x工作？

Answer 1

如果你看一下最新的駱駝的ActiveMQ 1.15.5（https://mvnrepository.com/artifact/org.apache.activemq/activemq-camel/5.14.5）依賴列表中，你會發現它已經camel-jms作爲依賴，但版本1.16.3。所以，沒有必要爲你單獨添加camel-jms1.18.x依賴於你的POM，因爲這將覆蓋的ActiveMQ已經使用，這是一個兼容的1.16.x版本。

所以基本上，問題是您正在嘗試使用更新的不兼容版本camel-jms。當您單獨添加1.18.xcamel-jms依賴，該組元的ActiveMQ將使用這個版本，這是不符合其1.16.x版本兼容，因此，該錯誤。

如果您需要使用ActiveMQ，那麼您可能需要查看camel-jms1.16.x是否適合您。