Find and Replace Strings in Linux with Grep and Sed

It would be very useful if we can find a string in multiple files and replace it with a new string. It takes a single line of code to do that :

grep -rl matchstring somedir/ | xargs sed -i 's/string1/string2/g'

matchString - the string you want to find
string1 - same string you want to find
string2 - new string that you want to replace with


eg :
I need to find the string "foo" and replace it with "bar"

grep -rl 'foo' ./ | xargs sed -i 's/foo/bar/g'  

 There is a nice post on describing more on this:
http://vasir.net/blog/ubuntu/replace_string_in_multiple_files/

WSO2 ESB Message Stores with WSO2 MB 2.0 -M2

When using JMS Message stores in WSO2 ESB, there is a small difference scenario need to be followed 

 other than in the article written by charith http://wso2.org/library/articles/2011/12/implementing-store-forward-messaging-patterns-wso2esb-part-2

We need to place "andes-client-0.13.wso2v1.jar" , "slf4j.api_1.6.1.jar" and "slf4j.log4j12_1.6.1.jar" libraries in the root lib directory of wso2 ESB before starting the server. 

Note : Offset configuration is not working in the M2 release of MB 2.0. So  you need to change the offset value of ESB instead of MB and the connection String should be like:

connectionfactory.QueueConnectionFactory = amqp://admin:admin@clientID/carbon?brokerlist='tcp://localhost:5672'

WSO2 Message Broker 2.0 - M2 Released

WSO2 integration development team is pleased to announce that the feature freezed version of WSO2 Message Broker 2.0 is released. In this release we have added Clustering support for Message broker where it can act as a distributed Message broker.

You can find the documentation on different cluster scenarios,setup information in the deployment guide in the doc pack. 

http://people.wso2.com/~charith/

You can find the current issues here

https://wso2.org/jira/browse/CARBON/component/10761

WSO2 MB - Samples : SQS SOAP Client Sample

Many users experiencing problems when testing this sample.



Here i am going to mention few simple steps to execute this sample.

1. Download WSO2MB 1.0.2 pack from http://wso2.org/downloads/message-broker

2. Extract and start the product.

3. Log in to the admin console of MB with credentials admin/admin



4. Navigate to the WSDL2Java tool which can be found in "Tools" left menu



5. Copy and paste the url of sqs wsdl to the provided test box in the "uri" option

6. Press generate button which can be found in the bottom of that page and it will give you the
zip file of generated source pack and save it.

7. Extract the source pack to your project folder. Once you extracted it, you can see a structure like :
.
|-- build.xml
|-- pom.xml
`-- src
`-- com
`-- amazonaws
`-- queue
`-- doc
`-- _2009_02_01
|-- MessageQueueCallbackHandler.java
|-- MessageQueueStub.java
|-- QueueServiceCallbackHandler.java
`-- QueueServiceStub.java


8. Go inside the project folder where you can find the above pom.xml file in the command line. Create the idea project by typing "mvn idea:idea".

9. Open the created project with IDEA

10. Add the SQSClient class to the project.

11. Change the "accessKey" and the "secretAccessKey" to the keys which can be found at "Home > Manage> Message Boxes(SQS)> Access Keys" of wso2mb server.


12.Build the project and execute the sqs client




NOTE:

Possible errors to be occurred when building the project

"cannot find symbol method createOMElement(org.apache.axiom.om.OMDataSource,javax.xml.namespace.QName)"

This is due to version mismatch of the axiom. Valid version of all axiom libraries is the version specified in the pom.xml

eg: 1.2.11.wso2v1

But where there are axiom libraries which is different from the above version, it gives above error.

You need to remove that version mismatching library from your class path .
Eg: axiom-api-1.2.7.jar

With this way you can get rid of this problem.

Allowing a port from firewall in ubuntu

Lets say the port we need to make open from firewall is "2181"

$sudo ufw allow 2181

ZooKeeper Increase maximum number of connections

When using zookeeper you may get the following exception:

org.apache.zookeeper.KeeperException$ConnectionLossException:
KeeperErrorCode = ConnectionLoss for /foo.XXXXXXXX
at org.apache.zookeeper.KeeperException.create(KeeperException.java

At the same time if you view the log of zookeeper you will see the the following warning :

WARN org.apache.zookeeper.server.NIOServerCnxn: Too many connections from /127.0.0.1 - max is 10

This is due to the default maximum number of connections configured in zookeeper.

You can overcome this by setting up the maximum number of connections in zoo keeper configuration file.(conf/zoo.cfg)

Add following entry to zoo.cfg file and restart zooKeeper. It will set maximum number of connections to 30.

"maxClientCnxns=30"

Killing multiple java processes at once

There are situations we need to kill multiple java processes at once. We can do it by killing all java processes. But there may be requirements to kill some filtered out java processes.

Lets say i have some processes which are running with details "OnceInOrderLoadTest.jar". I can kill all processes running with that details as bellow.


ps ax | grep OnceInOrderLoadTest.jar |grep -v grep | awk '{print $1}'| xargs kill -9