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Red Hat JBoss Fuse - Integrating Database, Java Bean and Restful Services in EAP, Spring DSL

We have talked about how to start develop application in EAP with Spring DSL, out of all the three ways of developing Camel in EAP, this is probably easiest to do to. And in this post we are going to take that example a bit more further, show you how to integrate with Databases, Java beans in the application, creating a servlet and lastly setup a Restful webservice. If you would like to know how to do it in Java DSL with CDI, please go to this blogpost.

For this currency exchange project, I have store the exchange rate in the h2 database. What we are going to do is to display the entire exchange rate on the webpage provided by a restful web service and provide a servlet that takes in the amount of money and the currency to exchange to, send them back to server, calculated and return the result. So here are the things I am going to do


  • Database
  • Java Bean
  • Servlet
  • Restful Web Services

Database
Of course we want to use the datasources in EAP. So first thing first, create the datasource in EAP. Make sure you started the JBoss EAP. Go to Configuration, select Connector and then to datasources.

  • Name :MyCamelDS
  • JNDI Name: java:jboss/datasources/MyCamelDS


 Select the Driver we are going to use, and it's h2 this case,

Enter the

  • Connection URL: jdbc:h2:file:~/h2/fuseoneap;AUTO_SERVER=TRUE
  • Username: sa
  • Password: 


Change the min and max pool size to 1 and 10. And then enable the MyCamelDS datasource.


Once we get the datasource ready, we can then use it by looking it up in our Spring Camel DSL.

Add the new jee namespace in the Spring XML file,

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:jee="http://www.springframework.org/schema/jee"
    xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd

       http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee.xsd">

Lookup the datasource in JNDI, by using jndi-lookup provided by jee. 

<jee:jndi-lookup id="MyCamelDS" jndi-name="java:jboss/datasources/MyCamelDS"/>

And then we can go on using the datasource with our SQL component, the same as we would use it in other container.

  <route id="allcurrencies">
    <from uri="direct:getCurrencies"/>
    <to uri="sql:select * from currencyexchange?dataSource=MyCamelDS"/>
    <marshal>
      <json library="Jackson"/>
    </marshal>

  </route>

Java Bean
Create a Java class that has a method takes in amount of money and currency to exchange.

  public class CurrencyConvertor {
    public double convertUSD(double amt, ArrayList<Map<String, Object>> data){
      Double rate = (Double)data.get(0).get("rate");
      return amt*rate;
    }

  }

In Spring Camel Route, the same as in normal Fuse Application, binding the Java bean we created in the context.


   <bean id="currencyconvertor" class="com.redhat.demo01.CurrencyConvertor"/>

And call the bind bean using the Bean Component. 

  <route id="covertcurrency">
    <from uri="direct:getCurrency"/>
    <log message="Got currency: ${headers.amt} and amt${headers.currency}"/>
    <choice>
      <when>
        <header>currency</header>
        <to uri="sql:select * from currencyexchange where currencycode= :#currency ?dataSource=MyCamelDS"/>
        <log message="exchange rate ====&gt; ${body[0][rate]}"/>
        <bean ref="currencyconvertor" method="convertUSD(${headers.amt},${body})"/>
      </when>
      <otherwise>
        <log message="nothing to lookup"/>
        <transform>
          <constant>nothing to lookup</constant>
        </transform>
      </otherwise>
    </choice>
  </route>

  

Servlet
We need to setup the Servlet, under webapp, create the WEB-INF/web.xml file. Right click on Deployment Descriptor and choose Generate Deployment Descriptor Stub. It will create an empty web.xml file for you.

Add the servlet setting in the web.xml and publish it 

  <servlet>
    <servlet-name>camel</servlet-name>
    <servlet-class>org.apache.camel.component.servlet.CamelHttpTransportServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>

  <servlet-mapping>
    <servlet-name>camel</servlet-name>
    <url-pattern>/services/*</url-pattern>
  </servlet-mapping>

Once it's done, we can then use the Servlet component in Camel, it will publish a servlet endpoint through the Servlet we set earlier.

  <route id="servletCurrencies">
    <from uri="servlet:/currencies?servletName=camel&amp;matchOnUriPrefix=true"/>
    <to uri="direct:getCurrencies"/>
  </route>

Restful Web Service
The Restful web services needs to have the CamelHttpTransportServlet setup too, since we have already done that in Servlet, all we have to do is to builds Rest endpoints as consumers in Rest DSL. And then configure it to servlet.

    <restConfiguration component="servlet" bindingMode="json" contextPath="/camel">
      <dataFormatProperty key="prettyPrint" value="true"/>
    </restConfiguration>
    <rest path="/currenciesrest">
      <get uri="/">
        <to uri="direct:getCurrencies"/>
      </get>
    </rest> 

That's all you have to do. You can find the entire project code here.

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這個題目很多人叫我寫,可是這題目好大,這分明就是整死我咩~
所以我會分幾段慢慢寫。

JBoss 的 SubsystemDatasource WebWeb Service EJB Hibernate JMSJCAJVM 調校OS (作業系統)

先來看一下 DataSource Subsystem, DataSource 的部分主要是針對Connection Pool 做調校。

通常,程式都會需要跟資料庫界接,電腦在本機,尤其是在記憶體的運算很快,但是一旦要外部的資源連接,就是會非常的耗資源。所以現在的應用程式伺服器都會有個Pool 放一些先連接好的 資料庫connection,當程式有需要的時候就可以馬上提供,而不用花那些多餘的資源去連接資料庫。

這就是為什麼要針對Connection Pool 去做調校。

以下會討論到的參數,都是跟效能比較有關係,Datasource 還有很多參數,像是檢核connection 是否正確的,我都不會提到。如果你追求的是非常快速的效能,那我建議你一個檢核都不要加。當然,這樣就會為伺服器上面執行的程式帶來風險。這就是你要在效能與正確,安全性上面的取捨了。 (套句我朋友說的話,不可能又要馬兒好,又要馬兒不吃草的..)

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min-pool-size 

Connection Pool 最少會存留的connection 數量

max-pool-size 

Connection Pool 最多可以開啓的 connection 數量

prefill

事先將connection pool 裡面建立好min-pool-size 的connection.

我的建議是觀察一下平常程式要用到的量設定為 min-pool-size 。
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