Thursday, February 8, 2018

Apache DBCP Connection Pool Issue

I'm using this Apache DBCP for Connection Pool purpose. One thing I notice is that, every time there's a network failure in between my application and the database (Sql Server), yes it will generate Socket Write Failure/Error exception, and subsequent few calls would somehow cause the  getConnection() of BasicDataSource to freeze. 

I troubleshooted this by monitoring the Processes in the Activity Monitor in Sql Server. I saw there's always a Connection created each time I fired a request. That Connection would just stay, I think my application was using this particular Connection for multiple firing of requests. If I killed this particular Connection then fire a few more times, then I managed to reproduce the issue where the getConnection() was giving no response. 

After a lot of trial and error, finally I found the resolution - maxIdle of the BasicDataSource. The default maxIdle for BasicDataSource is 8, therefore I just need to set maxIdle as zero. This time, although I fired many many times , I did not see any Connection stays in the Process of Activity Monitor anymore! No more Connection Pool freeze! 


Sunday, January 21, 2018

Camel-Context(DSL) only, No Coding! How to Log? How to Handle Error? How to Configure Retry? How to work out the Property Placeholder?

I'm excited to have found new way in Apache Camel to build specific feature without writing any single code, which has always been my way due to time constraint and flexibility (to make everything configurable and every exception handled properly). It was a long winding process with many many rounds of trial and error.

What I'm trying to achieve here is very simple, just read file and SFTP to the other side and Backup the original Source File! If this would have been done in a Java/Groovy and registered as a Spring Bean, then it shall be very fast. However I chose to do it the Camel-way!


  1. In your Camel-Context.xml (Spring DSL), declare a Route.  
  2. The <From> should be the File EIP. Remember to set a "Delay" for the file polling interval. 
  3. Next, use the SFTP EIP for the <To>


Done. So simple! However...

I want to LOG the entire process, such as:  

  1. What Are the Files Being Picked Up? 
  2. Whether the SFTP is Successful or Failed?  
  3. Was the SFTPed file moved to a Backup folder? 
For my own knowledge, I was using 2 ways to log:
  1. Camel's Log EIP - To log Route process + Error to the Application-specific log. 
  2. Camel's Log - To log Error to the General Error log. 
**For Error, will be written to both logs. 

Camel's Log EIP 
<camel:log message="[MyTimer2] SFTP Begins ${file:name}" loggingLevel="DEBUG" logName="myTimer2Logger" />
**${file:name} here is a kind of Reserved Keyword inside Camel's. It's called the File Expression language and this specific one will output the name of the file picked up in the log.  

Camel's Log
<camel:to uri="log:error-rollingFileAppender?level=ERROR&amp;showCaughtException=true&amp;showStackTrace=true" />
** First Parameter (in this case - error-rollingFileAppender) refers to the Appender setup in my Application's LogBack.xml


Question, where should I place my LOG Error Block? I should only LOG Error upon Exception right? 

First, I tried the <DoTry> - <DoCatch> way, I put my LOG Error function within <DoCatch>. However, there is a flaw here! Upon SFTP Exception, the File:// will still regard the SFTP as successful and continued to move file to the Backup folder. 

Finally I found the right way, use <OnException>! So just put the Log Error block inside your <OnException>, which is inside the <Route>! 


<camel:exception>java.lang.Exception</camel:exception>
<camel:to uri="log:error-rollingFileAppender?  level=ERROR&amp;showCaughtException=true&amp;showStackTrace=true" />
<camel:log message="[MyTimer2] File Transmission Error ${exception.stacktrace}" loggingLevel="ERROR" logName="myTimer2Logger" />
</camel:onException> 


Is that all? Nope.

I wanted to Retry for a fixed number of times upon any kind of Exception! 

Easy. Just declare the below:

<camel:redeliveryPolicyProfile id="myRedelivery" retryAttemptedLogLevel="ERROR" maximumRedeliveries="${H2MaxRetry}" redeliveryDelay="${H2RetryDelay}" />

Then add this as the "redeliveryPolicyRef" to your Route.

Last but not least, I wanted to set all the properties, such as the Input Directory, the SFTP host, username, password and etc in a single properties file

Here's the trick:
Use <Endpoint> for your File:// and SFTP:// 
Somehow only Endpoint allows Spring Property Placeholder! 

<camel:endpoint id="send_source" uri="file://${app.dir}/filewatcher/anz_output?delay=${myTimer2}&amp;move=${app.dir}/filewatcher/anz_backup/$simple{file:name}.done&amp;moveFailed=${app.dir}/filewatcher/anz_bad"/>
<camel:endpoint id="send_remote" uri="sftp://${H2hostname}${H2Path}?username=${H2user}&amp;password=${H2password}&amp;soTimeout=${H2SocketTimeout}&amp;binary=${H2Binary}"/>

**These properties placeholder are stored in the properties file configured at the PlaceholderConfigurer



Saturday, November 11, 2017

Apache CXF - Camel tips on WSDL Validation

I wanted to perform WSDL validation against incoming SOAP Payload.

Here's what I did:

1) In applicationContext.xml,

<cxf:cxfEndpoint id="MyEndPoint" address="http://locahost:test/" serviceClass="com.test.Test" wsdlURL="test.wsdl"  >
       
<cxf:properties>
            <entry key="schema-validation-enabled" value="true"/>
        </cxf:properties>

</cxf:cxfEndpoint>
2) In camel-context.xml, 
<camel:route id="myService">
   <camel:from uri="MyEndPoint?dataFormat=
POJO"/>
...
</camel:route>
**It is compulsory to use POJO so that it will trigger JAXB validation. Otherwise you won't see any effect. Read this RedHat's document for further study. 

Friday, November 10, 2017

Apache CXF - Camel tips on Working On HTTP Response Header

Apache Camel provides so many features. It is like a blackbox.

I wanted to change the default value of the Http Response Header, for example to set no-cache to the Cache-Control. Here's what I did:

1) Create SoapInterceptor class by extending org.apache.cxf.binding.soap.interceptor.AbstractSoapInterceptor
public class SoapInterceptor extends AbstractSoapInterceptor {
2) In the constructor, set the below line: 
        super(Phase.PRE_PROTOCOL);
        getAfter().add(SAAJInInterceptor.class.getName());
**For Phase, please read this documentation from RedHat . If you wanna become an expert in terms of this, you need to test it out one by one to master its behavior. I think it is wise to include that kind of effort to your project timeline. 

3) Implement the handleMessage(SoapMessage message) method. 
3) Inside this handleMessage, I obtain the HttpServletResponse from the below line: 
HttpServletResponse httpResponse = (HttpServletResponse) message.get(AbstractHTTPDestination.HTTP_RESPONSE);
4) Now I can set the following: 
httpResponse.setHeader("Cache-Control", "no-cache, no-store");
5) Next, in applicationContext.xml,
<cxf:cxfEndpoint id="MyEndPoint" address="http://localhost/test" serviceClass="com.test.Test" >
<cxf:inInterceptors>
            <bean id="inInterceptor1" class="com.test.interceptor.SoapInterceptor" />
        </cxf:inInterceptors>

</cxf:cxfEndpoint>

Friday, April 14, 2017

One URL, Different Certificates

Yesterday I encountered one very weird issue where the web service that my application consumes, actually generates entirely different certificates if you access from browser!

That's a new finding for me. 

What I do normally is to download the SSL certificate from internet browser such as IE. After that I will add the SSL certificate that I downloaded to my application's truststore. This way has worked many and many times before and has never gone wrong. 

However, unfortunately this time the above method did not work anymore. I then troubleshooted the application by enabling the Java SSL Debug mode by adding the JVM parameter "-Djavax.net.debug=ssl" so that my application would print out the SSL debug information to the STDOUT. From there I spotted this line "certificate_unknown", then I further confirmed the CN details of the SSL certificate received by my application from the Web Service Provider is different that the one that I've added to my application's truststore. 

Next I chose to retrieve the SSL certificate by using openssl. I installed OpenSSL for Windows , then ran the following command "openssl s_client -connect host:port" to fetch the SSL certificate details. I saved the details as a CER file, then added that CER to my truststore and hooray my SSL handshake issue is gone! 

Thursday, July 30, 2015

Composite Sensor (sensor.xml) for Oracle SOA

There's a logging feature (Composite Audit Level, under 'Settings') in Oracle's Enterprise Manager Console. However, usually you will not enable it in production environment because the feature captures too much detail(even the payload!) for every transaction and hence could lead to low storage level issue if your "composite" is expected to process too many transactions every minute.

Nevertheless, we still need to capture at least one of two detail for each transaction and such detail can be very useful when coming to problem troubleshooting.

So what do we do without enabling the 'logging' feature? We use the "Composite Sensors". At code level, this composite sensor is a xml with the name "sensor.xml". At Enterprise Manager's level, an composite sensor icon will appear in each transaction line. Just click on that and it will open up a new window that shows the detail.



Friday, April 24, 2015

Run Software in Hidden Mode

Many years ago I was building a Car Workshop Management System. The client is a Car Workshop in Johor. Basically the client uses this software to take order, to track work progress and to generate receipt to customers. The software is able to generate "Account Summary" as well showing the total sales and receipts over a period of time.

One day my boss came to me with a new requirement. The client wanted to have a "secret" mode of the software. Under this secret mode, the client can show to Tax Officers different series of sequence number for invoices and receipts.

So in the software we keep two IDs with running number as the value, one is the "real" invoice number and another one is the "fake" invoice number. So when the client runs the software under "secret" mode, the Account Summary report will show only those transactions with fake number.

Ha ha. What a fun memory!