Eranda's Blog

Configurable Governance Artifacts with Governance API

2012-01-02T00:37:00.000-08:00

Previously I discussed about how to extend WSO2 Governance Registry. Now lets see how we can access those extensions using governance API.

Adding a new Artifact
To create a new Artifact you can use the following code. Here registry refers to valid org.wso2.carbon.registry.core.Registry object and projectKey refers to shortName in the registry extension file.

import org.wso2.carbon.governance.api.generic.GenericArtifactManager;
import org.wso2.carbon.governance.api.generic.dataobjects.GenericArtifact;

GenericArtifactManager artifactManager = new GenericArtifactManager(registry, projectKey);
GenericArtifact artifact  = artifactManager.newGovernanceArtifact(new QName("http://www.example.com","event"));
artifactManager.addGenericArtifact(artifact);

Update a Artifact
To make further changes to a Artifact which already in the registry you can use updateGenericArtifact() method.

artifact.addAttribute("EventName","Running");
artifactManager.updateGenericArtifact(artifact);

Remove a Artifact
To remove a Artifact you should have the reference to that Artifact, which can be retrieve using artifact.getId(). Then you can use removeGenericArtifact() method to remove the Artifact.

String artifactId = artifact.getId();
artifactManager.removeGenericArtifact(artifactId);

Retrieve a Artifact
To retrieve a Artifact you can use getGenericArtifact method().

GenericArtifact artifact = artifactManager.getGenericArtifact(artifactId);

NOTE: In ordered to use getGenericArtifact method you have to have the Artifact reference ID. If you don't have it you can use the discovery method discussed below.

Discover a Artifact
Using the service discovery methods, you can retrieve Artifacts that match a given criteria. Here is an example on how to retrieve a set of Artifacts that has the attributes:

Key - EventName
Value - Running

GenericArtifact[] artifacts = artifactManager.findGenericArtifacts(new GenericArtifactFilter() {
    public boolean matches(GenericArtifact genericArtifact) throws GovernanceException {
        String attributeVal = artifact.getAttribute("EventName");
        if(attributeVal != null && attributeVal == "Running"){
            return true;
        }
        return false;
    }
});

Associate a Lifecycle to the Artifact
To associate a Lifecycle to the Artifact you can use attachLifecycle() method.

artifact.attachLifecycle("LifeCycleName");
artifactManager.updateGenericArtifact(artifact);

Retrieving Dependents And Dependencies
To get the dependents and dependancies of an Artifact you can use getDependents(), getDependencies() methods.

GovernanceArtifact[] dependents = artifact.getDependents();
GovernanceArtifact[] dependencies = artifact.getDependencies();

maven2 and maven3 : m2 repository

2011-12-29T09:13:00.000-08:00

Early of my post I discussed about keeping maven2 and maven3 in the same machine. But I forgot to discuss about the .m2 repository. Please note that the m2 repositories of maven2 and maven3 cannot be the same. Because there are some differences in pom files in maven3 which maven2 cannot understand. So we have to keep two different spaces for maven2 and maven3. If you use one of these then you can use the default m2 repository directly instead you have to rm -rf your existing m2 repository if you going with maven3. If you want to keep both here is a tip you can follow.
First decide which one take default and which one take a custom place (you can put both in a custom place also). Then you have to change the settings.xml of maven.
Settngs.xml file can be found in following places and you can change any of it.

The Maven install: $M2_HOME/conf/settings.xml
A user's install: ${user.home}/.m2/settings.xml

Now you have to add the following part to the settings.xml file.

/path/to/local/repo

Now you are done.

Note: If you used aptitude to install maven then maven install settings.xml can be found in /etc/maven2.

WSO2 Governance Registry-Configurable Governance Artifacts part-4

2011-12-29T05:27:00.000-08:00

In my previous posts I discussed about how to add new meta data model. In this post I am going to discuss about how to add a menu item by adding a menu element to the registry extension file.


    governance_list_processes_menu                   
    List                                 
    org.wso2.carbon.event.mgt.ui.i18n.Resources 
    governance_processes_menu      
    ../generic/list.jsp                          
    key=process                      
    region3    
    1                                    
    manage                   
    ../images/list.gif                     
    /permission/admin/manage/resources/govern/processes/list

The menu definitions are standard to the Carbon Platform, and you can copy any generic menu configuration into this block. Given below is a simple description of the elements in above elements.

id - Menu identifier
i18n-key - Name for the new menu item appeared in the list get from the Resource.properties file for the given key
i18n-bundle - Place where you put the Resource.properties file
parent-menu - Parent menu
link - On click
url-params - Parameters parse on url
region - Which reagion this belongs
order - Appearance number in the list
style-class - CSS
icon - Icon
require-permission - User permission required to see the menu

However, if there is a specifying menu items to point to JSPs that have been specifically created for representing governance artifacts it need to be mindful of some parameters.

1. ../generic/add_edit.jsp requires the parameters,

key, which has to be equal to artifactkey defined above.
lifecycleAttribute, which is the attribute used to define the lifecycle.
breadcrumb, which is the title of the breadcrumb link for the add_edit.jsp page.

2. ../generic/list.jsp requires key, which has to be equal to artifactkey defined in the registry extension file.
3. ../generic/configure.jsp requires the parameters,

key, which has to be equal to artifactkey defined in the registry extension file.
lifecycleAttribute, which is the attribute used to define the lifecycle.
breadcrumb, which is the title of the breadcrumb link for the configure.jsp page.
add_edit_region, the value of the region parameter of the add_edit.jsp page. This is same as the region which you'd specify in the menu definition that you'd use to create a link to the add_edit.jsp page.
add_edit_item, the value of the item parameter of the add_edit.jsp page. This is same as the menu id which you'd specify in the menu definition that you'd use to create a link to the add_edit.jsp page.
add_edit_breadcrumb, which is the title of the breadcrumb link for the add_edit.jsp page.

WSO2 Governance Registry-Configurable Governance Artifacts part-3

2011-12-21T22:17:00.000-08:00

In the first and second part I described how to create a registry extension file. Now I am going to describe how to deploy it in the WSO2 Governance Registry. You can download WSO2 Governance Registry from here.

1. Extract the downloaded zip file to any place you like.
2. Start up the WSO2 Governance Registry
execute: sh GREG_HOME/bin/wso2server.sh
3. Go to Main->Browse->Detail view and add the registry extension file to any location you like.
4. Sign-out and Sign-in
5. Now you can see Event and Events in Metadata Add and List pans.

6. Click Event in Add pan. You can see a window use to add an Event.

7. Fill the given fields and see whether all the items work properly. If not you have made a mistake in the registry extension file.
8. Press Save.
9. Click Events in List pan. You can see a list of Events you saved.

10. When you click on one you can see the data you saved as follows.

Or you can see the content in standard view by clicking Standard view.

Now you can try your custom artifact by changing registry extension file.

WSO2 Governance Registry-Configurable Governance Artifacts part-2

2011-12-21T04:19:00.000-08:00

In the first part I discussed about creating a registry extension file up to content element. In this post I try to cover how to create a content which describe the data model of the artifact.
Here is a sample content.


    <table name="Details">
        
            Name
        
        
            Date
        
        
            Venue
        
    </table>
    <table name="Rules">
        
            Gender
            
                male
                female
            
        
        
            Description
        
        
            Auther
        
    </table>
    <table name="Participants">
        
            HouseName
        
        
            Contact
            
                TitansLegionsCloud BotsWild Boars
            
        
    </table>
    <table name="Service Lifecycle">
        
            Lifecycle Name
            
        
    </table>
    <table name="SLA" columns="3">
        
            Document TypeURLComment
        
        
            SLA
        
        
            SLA1
        
        
            SLA2
        
    </table>

Artifact datamodel can be sub-catagorized under different topics. This separation can be acheive by introducing table element. You can see there are five table elements in the above sample registry extension file. table element consists of different fields. There are several types of fields.

text
text-area
options
option-text

Now lets look at how each type and some of their attributes associated with it.

text
Defines a text field.


 Name

path and url attributes

SLA

path attribute is set then input expected to be a path. Also enabling this gives the option of browsing within the repository. But you can type the path as well.
If url attribute is set then the input expected to be a url.
If the input is a url or a path to a source in the repository then you can use both as in the example appear.

text-area
Defines a text area field.


 Description

options
Defines a field with a combo-box with the given values.


 Gender
 
  male
  female

option-text
Defines a composite field with a options field and a text field. Values of the options field need to define as a child element of field.


 Contact
 
  TitansLegionsCloud BotsWild Boars

maxoccurs attribute


 Contact
 
  TitansLegionsCloud BotsWild Boars

This attribute enables store multiple entries under same field.

Here is how it looks like after saving multiple values.

Since maximum occurrance is unbounded this can keep unlimited entries. If you want limit the number you can define maxoccurs to bounded value.

Associating a lifecycle using options field

options field can be use to select a lifecycle to the artifact instance using above code. This will list down the existing lifecycles to choose one which will associated with the instance. Not associating a lifecycle is also possible. This can be done by adding the following field.


 Lifecycle Name

Multi-type attributes

reqired attribute
required attribute makes a field required in order to create a artifact instance. In here I used the reqired attribute for text type, it can be used with other types also. Required fields are indicated using a red star as shown in the figure below.


 Name

Table attributes

columns attribute
columns attribute is use to set the number of fields in each row. Following fields are put in to the table in the order of they appear. Also number of heading child elements in the subheading element needs to be same as the number of columns.

<table name="External Links" columns="3">
 
  Document TypeURLComment
 
 
  URL
 
 
  URL1
 
 
  URL2
 
</table>

Now we have an idea about elements of registry extension file. In the next part we will see how we can add this extension to the WSO2 Governance Registry.

WSO2 Governance Registry-Configurable Governance Artifacts part-1

2011-12-20T21:20:00.000-08:00

WSO2 Governance Registry give the full flexibility over extending its functionalities and capabilities. One of its configurable capability is extending its Metadata model in a way such that anyone can store any custom type of data like Services, WSDLs, etc. which are already there. This only needs to add a XML file (registry extension or .rxt file) as a resource to the registry which include the new Metadata model artifact. Here I am discussing about creattion of registry extension file which introduce a Event data model.


    event
    /events/@{details_name}
    details_name
    http://www.wso2.com/rxt/event
    
        
            
                
            
        
        
            
                
            
        
    
    
        <table name="Details">
            
                Name
            
            
                Date
            
            
                Venue
            
        </table>
        <table name="Rules">
            
                Gender
                
                    male
                    female
                
            
            
                Description
            
            
                Auther
            
        </table>
        <table name="Participants">
            
                HouseName
            
            
                Contact
                
                    TitansLegionsCloud BotsWild Boars
                
            
        </table>
        <table name="Service Lifecycle">
            
                Lifecycle Name
                
            
        </table>
        <table name="SLA" columns="3">
            
                Document TypeURLComment
            
            
                SLA
            
            
                SLA1
            
            
                SLA2
            
        </table>

Now lets identify main elements one by one.

artifactType element

This is the root element of the new artifact which is going to define. It has several attributes.

type - Define the mediatype of the artifact. This should be in the format of "application/vnd.[SOMENAME]+xml". SOMENAME can contain any alphanumeric character, '-' (hyphen) or '.' (period).
shortName - Short name for the artifact
singularLabel - Singular label of artifact
pluralLabel - Plural label of artifact
hasNamespace - Whether artifact has a namespace (boolean)
iconSet - Icon set number which use as the artifact icons

artifactKey element

event

This element defines the unique key which can be used to identify the artifact. This key is used when fetching configurations and loading customized UIs.

storagePath element

/consumers/@{namespace}/@{name}

This is the path where the instance data of artifact is stored. When evaluate this expression, it automatically replace @{name} with the name of the artifact, and @{namespace} with the namespace of the artifact. In addition to name and namespace, you can also specify any other attribute in the format @{ATTRIBUTE_NAME}. e.g. /trunk/processes/@{business_domain}/@{overview_version}

nameAttribute element

details_name

This is the main attribute which define the name of the artifact. This must be in the format, {$table}_{$base-column}.

namespaceAttribute element

http://www.wso2.com/rxt/event

This attribute which you will define the namespace of the artifact. some artifacts might not need a namespace, and therefore, this is optional. Namespaces are found in artifacts related to Web Services, but might not be common to others such as Policy and SLA.

ui element

This element define the view of the data instances when browsing for that data type. It can include the list of data types which are in the content of the artifact.

relationships element

relationships defines the relationships between the newly created artifact and other artifacts. We can find three types here.

isConsumedBy - Artifact which consume newly created artifact
uses - Artifact which use newly created artifact
usedBy - Artifact used by the newly created artifact

content element


    <table name="Details">
        
            Name
        
        
            Date
        
        
            Venue
        
    </table>
    <table name="Rules">
        
            Gender
            
                male
                female
            
        
        
            Description
        
        
            Auther
        
    </table>
    <table name="Participants">
        
            HouseName
        
        
            Contact
            
                TitansLegionsCloud BotsWild Boars
            
        
    </table>
    <table name="Service Lifecycle">
        
            Lifecycle Name
            
        
    </table>
    <table name="SLA" columns="3">
        
            Document TypeURLComment
        
        
            SLA
        
        
            SLA1
        
        
            SLA2
        
    </table>

This element defines the data model of the new artifact. Also it will use to auto-generate the ui of instantiate artifacts.
We will discuss about content in the next post.

Started my career life with WSO2

2011-12-18T21:26:00.000-08:00

I finished my degree from University of Moratuwa at the end of last month. Soon after the finishing, we were asked to join WSO2 as we selected from the interviews. So I had a busy "end November" with preparation (filling docs and boring stuff).

If I describe in one sentence, WSO2 is a open source middleware company which provide middleware stack for enterprise solutions.

1st December 2011, it is the first day at office and there were 21 fresh graduates who join WSO2 in the same day. Actually I am not exited because there were lot of familiar faces in WSO2 who were there at my intern. In the very first day we were assigned to different sub-products in WSO2 SOA platform. I was assigned to WSO2 Governance Registry.

maven2 - maven3 and java.lang.NoClassDefFoundError: org/codehaus/plexus/classworlds/launcher/Launcher

2011-12-15T02:11:00.000-08:00

I typically use maven2 as my builder manager and I had to install maven3 to use in the same machine for build a new source code. I used following simple hack for this.
1. Download and extract maven3 distribution to any place as you prefer.
(MAVEN3_HOME = path of root of the extracted distribution)
2. Rename one of the mvn file in MAVEN3_HOME/bin
You can use rename MAVEN3_HOME/bin/mvn mvn3 or mv MAVEN3_HOME/bin/mvn mvn3
3. Add MAVEN3_HOME/bin to the environment variable in /etc/environment or /etc/bash.bashrc
4. Restart the shell/terminal
Now you can use both maven2 and maven3 using mvn and mvn3 commands.

Also you cannot use maven2 and maven3 shared m2 repository. You can do that by allocating different spaces for maven2 m2 repo and maven3 m2 repo. For more details click here.

After doing this when I execute mvn3 clean install I got the following exception.

Exception in thread "main" java.lang.NoClassDefFoundError: org/codehaus/plexus/classworlds/launcher/Launcher

Solution:
First guess: The cause of this should be installing maven2 and maven3 in the same machine. But theoretically this cannot happened. Because we invoke maven2 and maven3 using different commands which locates in different places.
Second guess: There may some environmental variable which belongs to maven2 accessed by maven3. Fortunately the second guess was right. I exported M2_HOME in /etc/bash.bashrc file which direct to the maven2 root. After commenting out that piece of code mvn3 clean install worked fine for me.
WARNING: Programs which uses M2_HOME variable may not work properly after this modification.

NOTE: This is only one cause which throws this exception. There may more. Here is another example which throws the same exception but when executing maven2.

Thrift, Scribe, Hive, and Cassandra: Open Source Data Management Software

2011-06-14T22:12:00.000-07:00

I found a old but has some valued set of slides which may useful.

My implementation for GSoC

2011-04-08T11:26:00.001-07:00

Apache Cassandra/ Cassandra-cli

2011-02-08T07:23:00.000-08:00

I found a bit new conceptual database system which is totally different from the traditional RDBMS. You may not known that this database system is the main database system used in your favorite (==!my) facebook and twitter. So what is it?? It's Apache Cassandra.
Apache Cassandra firstly owned by facebook and then it contributed the code to the Apache Software foundation at 2008. The interesting part of this database system is that uses both nice concepts,

Bigtable: A Distributed Storage System for Structured Data by Google Inc.
Dynamo: Highly Available Key Value Store by Amazon.com

For more information you can refer the papers.

In this post I want give a little introduction to this new concepts and show some usages of it. First lets know about some key concepts (may bit weird for a traditional RDBMS users) which is totally different from the RDBMS. Here there is no concepts like database, schema, table, and row. Also the meaning of the column is bit different. But we can do a mapping between the RDBMS and these concepts which you will see later in this post.

Here we go...........

Keyspace: Collection of "column family"s
Column Family: Collection of "key"s
Super Column Family: Collection of "column family"s. This use to create a column family tree structure in a Keyspace.
Key: A unique identifier to identify a row in a "column family"
Column: Use to store data. This contain three values name, value and timestamp

Now lets try this concepts. For this I use the cassandra-cli tool.

What you need?

Java 1.6 (Open and Sun)

Apache Cassandra

First we need to start the Apache Cassandra by executing the following command

sudo sh CASSANDRA_HOME/bin/cassandra -f

This command will start the cassandra server in localhost port 9160. (We can use the cassandra as a clustered database which I will discuss it in a later post). The -f argument will cause the Cassandra to remain in the foreground and log to standard out.

Then we can use the cassandra-cli tool by executing the following command

CASSANDRA_HOME/bin/cassandra-cli -host localhost -port 9160

Now we can use the commands in the command line. As appear when starting you can use, help or ? to help and exit or quit to exit from the cassandra-cli.

First we should create a Keyspace.

Command:

create keyspace Keyspace1

Then we can create a column family in that keyspace. To do this we have to select the keyspace which we going to create the column family.

Command:

use Keyspace1

Creating the column family

Command:

create column family Users with comparator=UTF8Type and default_validation_class= UTF8Type

Here I used with comparator=UTF8Type and default_validation_class=UTF8Type attributes to make the default column type to UTF8Type.

We can use this column family to store data. As an example lets think we want to use my details,

First name: Eranda

Last name: Sooriyabandara

Age: 24

Commands:

set Users[eranda][first]='Eranda'

set Users[eranda][last]='Sooriyabandara'

set Users[eranda][age]=long(42)

Here eranda is the key of a row and first, last and age are the columns. This means the three commands I mentioned above are to add values to a single row. long(42) is to set the age column value to long.

Now lets try retrieving data from Cassandra. To this we can use the key as follows,

Command:

get Users[eranda]

Results:

=> (column=age, value=42, timestamp=1297178199133000)

=> (column=first, value=Eranda, timestamp=1297178178790000)

=> (column=last, value=Sooriyabandara, timestamp=1297178188354000)

Returned 3 results.

Now lets see how I executed these commands in my machine.

If you remember I mentioned that we can map the concepts between RDBMS and Cassandra which you may already feel. But you must remember there is a difference.

database-keyspace

schema-super column family

table-column family

key-row

For more details you can refer Cassandra wiki.

Data Presentations Cassandra Sigmod

2011-01-26T10:23:00.001-08:00

Check out this SlideShare Presentation:

Apache ODE Jacob part 1 - Introduction

2010-11-23T09:54:00.000-08:00

Here I am going to introduce some topics related to Jacob which is the framework which provides the mechanism necessary to deal with two key issues in implementing BPEL constructs in Apache ODE. The interesting part of this framework is it can be use to achieve,

Resistance of execution state
Concurrency

without using Java Thread (I must say it's a Java framework).

Here I am not going to talk about how BPEL constructs are designed using Jacob, instead what I am going to talk is the behavior, how to use it to write programs etc... This is my first post and will continue till I am not find anything new in Jacob. In this first post I like to introduce some basic Jacob concepts. If you don't understand this don't worry, because it is necessary to see them in a program to understand. So just remember there are such things as follows.

JacobObject/ JacobRunnable

JacobObject is the simplest element use in Jacob which can be created by extending a Java class using JacobRunnable. JacobRunnable is a command pattern which implement run() method. Further we can say all the JacobObjects should have this run() method implemented.

Channels

Channels are use to communicate between JacobObjects. In this channels we should defined the methods which we use the channels to invoke. There are various channel types which we can found in Jacob and we will discuss them in later.

Channel Listeners or Method Lists

When we create a channel there should be a JacobObject which listening to the channel till the other JacobObject invoke a method. This is done using a Channel Listener.

JacobVPU, ExecutionQueueImpl

This is where Jacob is processed. JacobVPU uses ExecutionQueueImpl to put all the artifacts (mostly channels and reactions) used in processing. When we add JacobObjects to the VPU queue in runtime, VPU popped them up and executed them, and that's it.

According to references (I listed them below) "Jacob VPU is responsible for persisting and its internal state, like serialize or de-serialize the object", but I don't have and idea yet about it.

There is an short way to create Channels and ChannelListeners in compile time using a channel interface, by adding @ChannelType annotation as follows,

Channel interface

import org.apache.ode.jacob.ap.ChannelType;

@ChannelType

public interface Call {

public void answer();

public void reject();

public void engage();

}

Channel

public interface CallChannel extends org.apache.ode.jacob.
Channel,
org.apache.ode.jacob.examples.HelloWorld.Call

{
}

ChannelListener

import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;

public abstract class CallChannelListener
extends org.apache.ode.jacob.ChannelListener <org.apache.ode.jacob.examples.HelloWorld.CallChannel
>
implements org.apache.ode.jacob.examples.HelloWorld.Call
{

   /**
*
*/
private static final long serialVersionUID = 1L;
private static final Log __log = LogFactory.getLog(org.apache.ode.jacob.examples.HelloWorld.Call
.class);

   protected Log log() { return __log; }

   protected CallChannelListener(org.apache.ode.jacob.examples.HelloWorld.
CallChannel channel) {
   super(channel);
   }
}

To write this article I used three articles which were previously published,

Exploring ODE part II: Jacob Framework by Jeff Yu http://jeff.familyyu.net/2010/01/exploring-apache-ode-source-code-part.html
Wiki page of Apache ODE Jacob http://wiki.apache.org/ode/Jacob
Documentation of Apache ODE Jacob http://ode.apache.org/jacob.html

When you read this you may find some places where I misunderstood, please let me and others know about it.

How To Register The Nickname On Freenode

2010-10-08T12:26:00.000-07:00

I thought to register my nickname in freenode because I want to keep my nickname as it is for a long time. (If not registered there is no guarantee that the same nickname can be used. Because anyone can assigned that nickname. After registering the registered nickname can be used only by using its owners password.)

This is the steps to follow to register on freenode,

First open the IRC client (Here I used X-chat)
Then select the FreeNode and click connect
Here is an image which shows that window.

NOTE: If you are using another client then you can connect to the freenode using the following command
/server irc.freenode.net

Now you are connect to the freenode
Then you will get a window that can connect to a IRC channel
And you can use it to connect it to any IRC channel (Here I am connecting to the Apache Derby IRC)
Or you can use Server->Join a Channel to join a prefered IRC channel.

Now lets do the registering

To do that enter the following commands in the text-box which is use for do the normal chatting.

(It is not a must to connect to the IRC to do the registration. But you have to connect to the freenode before registering)

Setting the nickname

/nick nickname

Registering the nickname

/msg nickserv register password your_email

This command will log you as the nickname owner

/msg nickserv identify password

Verify the registration

Go to the email account and get the verification code send by the NickServ

Then pass that verification code as other commands using the text-box.

Now you are done with the registering in freenode with your nick name.

Congratulations.....!!!

Silent killer

2010-07-21T07:49:00.000-07:00

If you using UBUNTU or OTHER LINUX OS be aware of the silent killer
"rm -rf" - it removes everything without a warning. Once removed recovery may not be possible or extremely hard.

Transfer files one machine to another 2

2010-07-21T07:44:00.000-07:00

I blog about two methods in the first and here is the second part which describes about
1. sshfs method
2. secret most easy two ways

SSHFS(mounting remote directory)

Here I am going to describe how to copy a file to remote machine using mounting it on to your machine. Lets see how to do that,
First you need sshfs install in your machine. You can do that by executing following command
sudo apt-get install sshfs.
Then what you have to do is create a folder in your machine where you want to mount the directory.
For example lets create a directory named eranda in Desktop.
Now you have to change the own of that folder, and it's content.
To do that execute the following command
chown -r username.username directory
eg: chown -r eranda.eranda Desktop/eranda

Now ready to mount the image.
You can mount the directory using the following command.
sshfs -o idmap=user username@remote-host:remote-directory your_directory
eg:sshfs -o idmap=user ishan@10.0.0.2:Desktop/xxx /home/eranda/Desktop/eranda

Now you can see the whole content of the xxx directory of the remote machine in your mounted folder. Now you can do r, w, x, copy from, copy to, delete, anything using that directory as a your local directory.
WARNING: All the changes that you done to this is changes to the original directory

As our main target now you can copy to/from remote machine.

After doing what you want you can unmount the directory as follows.
fusermount -u /home/eranda/Desktop/eranda

Two easy ways

1. Use a flash/portable drive etc...
2. Use a CD/DVD/Blue Ray etc...

NOTE: When you connect to the remote machine using ssh, scp or sshfs you always need to type the password of that user. If you doing it frequently you can save a passkey to that machine which will allow you to access without password. Now lets see how can we do that.

First you need to create a key.
ssh-keygen -t rsa
Now save it in the remote machine. To do that you first you should change your current location to home. Then execute the following command.
cat .ssh/id_rsa.pub | ssh user@remote.host 'cat >>.ssh/authorized_keys'

Special thanks to Damitha Kumarage, Tech lead at WSO2 Inc.

Transfer files one machine to another 1

2010-07-21T02:56:00.000-07:00

These days I transfer files one machine to another frequently. There are few ways to do that.

1. scp (ssh)

2. using apache server

3. sshfs (by mounting remote directory)

4. the most easy two ways (this can be used even you don't know the ip address)

In this post I covered first two and will cover the next two in the 2nd part.

SCP (SSH)

To do this you need to install ssh-client in your machine and ssh-server in the other machine.

If you use Ubuntu in your machine you can install this by using sudo apt-get install openssh-client or openssh-server or you can download it and install from here.

If you have install ssh-client and server in your both machines then you can copy files from each another. To do this you can use the following command.

copy a file from remote machine to your machine

=>scp user@remote.host:file-path path-to-save

eg: copy a remote file named remotefile.txt which located in Desktop of the remote machine to your Desktop

scp eranda@10.0.0.4:Desktop/remotefile.txt ./Desktop

copy a file from your machine to remote machine

=>scp file-path user@remote.host:path-to-save

eg:copy a file named remotefile.txt which located in Desktop of your machine to the Desktop of a remote machine

scp ./Desktop/myfile.txt eranda@10.0.0.4:/home/eranda/Desktop

Using apache server

For this you have to have apache server install in your machine. If you do not have you can install using the command sudo apt-get install apache2 or you can download and install the apache server from here.

After installing apache2 your server should be up and running.

You can see that by going to the URL http://localhost/

You can see this kind of message in it.

------------------------------------------------------------------------------

It works!

This is the default web page for this server.

The web server software is running but no content has been added, yet

-----------------------------------------------------------------------------

If you see a Server Not Found 404 message, then you should start the apache2 server. You can do that by as follows

change directory to /usr/local/apache2

and execute the following commands

./clean.sh

./start.sh

Now lets start the file transferring.

First make directory in the location /var/

Put the file you want to copy to remote machine in that folder

For example I created a directory eranda in /var/ and put two of my files in that.

Now go to the remote machine and open a browser

Go to the URL http://your_machine_/your_folder_name (eg: http://10.0.0.4/eranda/)

You can see the files you put in the folder in your machine as follows

Now what you have to do is double click on the file you need and it will start downloading.

Special thank goes to Damitha Kumarage, Tech lead at WSO2 Inc.

How to do Apache Derby Testing

2010-06-20T00:22:00.000-07:00

Here I am going to log some important things which I had done during test Derby.

Here I have done two testings.

derbyall test
JUnit test

Before test Derby make sure that you build the trunk (need to put junit.jar (download) file in the tools/java folder if you don't skip the tests). You can build the truck by executing "ant all" command in the trunk and it will create classes folder which include build files.

To run the test you need to set some class variables. One is path to classes which includes Derby build files. And path to the following jar files

JUnit.jar (download)
jakarta-oro-2.0.8.jar(download)

Here is my CLASSATH setting command I used,

export CLASSPATH=/home/eranda/Desktop/DERBY/trunk/classes:/home/eranda/Desktop/DERBY/trunk/tools/java/junit.jar:/home/eranda/Desktop/DERBY/trunk/tools/java/jakarta-oro-2.0.8.jar

Now we can start the the testing.

NOTE: Need to do the test in a separate folder not to mixes with others.

To run the derby all tests,

java org.apache.derbyTesting.functionTests.harness.RunSuite derbyall

This will do derbyall test and give you result files. Among them there are few important files which summarize the tests.

derbyall_report.txt- in which include the summery of the tests
derbyall_pass.txt- in which include the tests passed
derbyall_fail.txt- in which include the tests failed

To run the JUnit all tests,

java -Xmx512m -XX:MaxPermSize=128m junit.textui.TestRunner org.apache.derbyTesting.functionTests.suites.All

Normally I pump this JUnit test results to a file by adding the following piece of code to the above execution.

>junitAll.out 2>&1

In JUnit tests it will return dots(.) for every passes test, 'E' for every error tests and 'F' for every failures. Also at the end it will show the stack trace of every errors and failures.

If it need to run single test then it can be run using the following command,

java junit.textui.TestRunner PathToFile.TestName

for example I ran following command to test the InbetweenTest which is a JUnit test for testing the inbeween syntax.

java junit.textui.TestRunner org.apache.derbyTesting.functionTests.tests.lang.InbetweenTest

Here I want to thank Bryan Pendleton (Apache Derby committer) whom I learnt most of this from.

Fedora add sudoers

2010-05-30T07:22:00.000-07:00

I install a fresh copy of Fedora in my virtual machine and it troubled me with sudo. When I use sudo in the terminal it gave me something like the current user is not in the /etc/sudoers file. So I did as follows and rid from it.
First I log into root using "su -" (then I had to enter the password)
Then I change the mode of /etc/sudoers file so that we can write to it by executing the command chmod +w /etc/sudoers.
Thirdly I add eranda ALL=(ALL) ALL
eranda is my username of my user account in fedora.
Then I remove the writing mode if the /etc/sudoers file using chmod -w /etc/sudoers

I thought it was the finish and execute sudo but it gave me another error.
sudo: /etc/sudoers is mode 0640, should be 0440 (to execute this you need root privileges)

then I change the mode of /etc/sudoers to 440 by executing chmod 440 /etc/sudoers
Finally I can use sudo in my machine.
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Web Service Client

2010-05-25T12:08:00.000-07:00

I discuss about how to create the stub of the web service and check whether it works. Now I am going to discuss how to create a client program which uses the web service. Here I am going to create a client program to my favorite web service "HelloService".
I thought it would be better to know about how things work.
First of all what is a stub? In simple language it is the interface which represent web service in the client side. So using stub we can work with the web service as it is in the same project/package.
Then why we use Axis2? This is which do the communication between stub and the web service. For this Axis2 use SOAP(Simple Object Access Protocol) messages. Here two Axis2 servers are involved.
The first one is in the client side and the other one is in the server side. Client side Axis2 server is responsible for create SOAP messages which invoke the web service through the stub, and catch and execute the response SOAP message which send by the  server side Axis2 server. The Server side Axis2 server is responsible for catch the SOAP message which the client side Axis2 server send and invoke the web service, and create a SOAP message to the response of the web service and send it to the client side Axis2 server. (The process is more complex than this)
Now lets finish the client implementation.
First of all take a look at the stub to see how it gave an interface to the remote service(need to have a rough idea).
You will see all the parameters of the the web service are represent as java classes and their values should set through setter methods and the output is also implemented as a class and we have to use getter method to get the real output (you may not understand this but you will realize your self when creating the client class).
now follow the following steps to create a client class.....
1. Create a java class with main method.
2. Import the package which include the "stub" into your class. This step can be skipped if you creating the class in the same package.
3. Create a object of the stub class (my stub class name is HelloServiceStub.java) in the your class.
4. Let my stub object be "stub" and the method I need to invoke in the web service be sayHello().
   Then you see that you can access that method using the stub object. (for example stub.sayHello())
   But the thing is the parameters you need to parse to that method cannot be directly send as a String, Integer or like that data type.
   We can use the IDE or you can look at the stub to see what parameters we need to parse through sayHello() . In my case it need to parse a SayHello object. (This SayHello java class is in the stub)
   Then create a object of the class it need.
   SayHello sayHello = new Sayhello();
   Then set the value you need to send as parameters for the actual method.
   sayHello.setName(name);
   Then send the sayHello object as the parameter of the method as stub.sayHello(sayHello);

5. Now its time to get the response
   Response is always come as an java class object. So we need to get it to a related class reference object.
   Use IDE or stub to see the response class type and get the response to it as follows. For my case it returns a SayHelloResponse object.(This SayHelloResponse java class is in the stub)
   SayHelloResponse helloMsg = stub.sayHello(sayHello);
   So at the end we can use that respond class to get the needed output.
   String output = helloMsg.get_return();
   If you use System.out.print(output); to print you can see the output print in the console.
   After all my Hello client look like as follows

6. After creating the client class you can run it as a java application which print the web service result.
I send Eranda as the input and and I got the result as "Hello Eranda"

PS: When you creating the object you have to use a try-catch around some lines to catch the RemoteException. and AxisFault exceptions (so you need to import java.rmi.RemoteException and org.apache.axis2.AxisFault classes)

Web service client using eclipse axis2 plugin

2010-05-24T11:47:00.000-07:00

Few months ago I blog how to deploy a web service and today I am going to create a client for that web service.
Here is the java class which I am going to deploy as the service.

package WebServices;

/**
* @author Eranda
*
*/
public class HelloService {
public String sayHello(String name){
return "Hello "+name;
}

}

This we service take a "name" and return Hello name.

The following things should be done after deploying the service to verify it's existance.

Go to your browser and check whether your web service is deployed or not. Use http://localhost:8080/ProjectName/services/listServices to check it. If it doesn't show the web service list then you have to deploy your service again properly.

Here is the page you have to have.

Now click on the service name of what you deployed. It will show you the wsdl of the web service. Now copy the URL of the wsdl.

Then go to eclipse and then select File->new->Other->Web Service Client and click Next.

You can see a window like follows,

Copy the wsdl URL to Service Definition textbox.
Set the slider to Start Client.
Then click Server link and see whether the server is selected and set Web service runtime to axis2.

Click OK
Then goto Client project: Axis2 link and set the Web service client name as your preference or leave it as it is.

Click OK
And then click Next

Then the project will create and the following window appears.

Set the parameters with your values or you may use default.
Check the box Generate a JUnit test case to test the service and click Finish and the web service stub and the test case will create after that.

Here is the look of the project after doing that.

To test the web service you can use the test case which create automatically. To do this right click on the test class (here it is HelloServiceTest.java) Run As->JUnit Test
If all the test are successful then your client side is working correctly. Later we will see how to write a class to invoke the web service methods and get results.

PS: Some times you may get Axis faults. This exception throws because of the wrong server host in stub. By correcting the stub(there are 2 places to correct) with the correct host name you can make it correct. (This host change thing mostly occurred because of the dynamic IP of the internet connections.)
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SOA-based Business Integration with Eclipse BPEL and Apache ODE

2010-05-22T12:50:00.001-07:00

Check out this SlideShare Presentation:

SOA-based Business Integration with Eclipse BPEL and Apache ODE

View more presentations from Tammo van Lessen.

PATH variable went wrong

2010-05-09T07:45:00.000-07:00

Today I update /etc/bash.bashrc and set PATH variable wrong. This cause the terminal malfunction. Because the files need to function the commands are not exported. So I can't even open a file with terminal.
Shoot this trouble is simple(but I tried last 2 hours to shoot this :D)
What I have done is add /usr/bin to the PATH by executing export PATH=$PATH:/usr/bin
Then I could used the terminal as normal and correct the bash.bashrc file.

My GSoC proposal

2010-04-07T20:41:00.001-07:00

Proposal Title:Add compatibility tests to explore behavior differences between Derby and other DBMS implementations

Student Name: Eranda Sooriyabandara

Student E-mail:070468D@gmail.com

Organization/Project: Apache Software Foundation Derby DB project

Assigned Mentor: Bryan Pendleton

Proposal Abstract:

As the name of the project spells this project is to create a compatibility test for Apache Derby for explore the behavior differences between Derby and the other DBMSs such as Oracle, SQL server, MySQL, PosgreSQL etc...

In this project I've seen there are three parts which I am mentioned here and describe in the Detailed description,

Identified the differences of the functionalities and options between the DBMSs. Also in this part I can document the differences of Apache Derby and other DBMSs. It mainly 3 parts as Bryan mentioned,
I. Check which SQL fetchers implemented in the DBMSs according to the SQL 99/2003/2008 standards.
II. Check which JDBC methods supported by DBMSs.
III. Check the Platform support and the behavior of DBMSs in each Platform.
Analyse the data collected in the first step and decide which tests must be include in the test bundle. After finalizing the tests I can start implementing the tests.
Third and the final step is to test each DBMSs using the test create a comparison between Derby and other DBMSs to see what improvements do we need to do to Derby to be more likely to satisfy the users needs.

Detailed Description:

Project:

This project is to create a compatibility test which can identified the main differences between Derby and other major DBMSs. After creating this compatibility test we can identify what main functionalities lack in Derby which different kinds of people expecting in a DBMS. As an example some people needs DBMS which can withstand overloads. When we knows about the lacking main functions in Derby we can improve them so that this can be much popular than now. For creating this compatibility test I follow up the following procedures which I summarized on the abstract.

When adding a compatibility test case we need to consider what tests do we need to add in. To do this we have to compare with the other DBMSs such as Oracle, MySQL,SQL server,Sybase etc... So my first thing on this project is to compare DBMSs. According to this I did a sample general comparison of Derby and MySQL which you can find on http://emsooriyabandara.blogspot.com/2010/04/derby-vs-mysql_02.html. Also I gather facts on Derby and MySQL SQL and I will able to create SQL comparison of Derby and MySQL soon.

Then I should analyse the data I gathered to find which tests do I need to add to the test case. When selecting tests I thought I should give priorities to functionalities which DBMS users expect from a DBMS. Also I thought to analyse other DBMSs for their specialties and to find how they achieve them. For example oracle is popular for its security which has three way to achieve them 1.Transparent data encryption 2.Network encryption 2.Strong authentication which I am willing to discuss when I am comparing DBMSs' "Access control and security".

Implementing the compatibility test need time other than method because when we come to this step we are know what do we want to test.

After implementing the test case we have to test against each DBMS. So we can collect statistics. This statistics we can use to improve Derby. This is the most important part of the project because we can directly identify the functionalities Derby does not support, create them as major issues and implement them.

This project I choose for the intern because I like testing and analysis. Also when I am converting Derby tests into Junit I familiar with the Derby SQL and Derby JDBC methods. Also I referred Database System Concepts book for one of my course module so that I have better knowledge in database concepts and can be able to use to check compatibility. The other reason is I choose this is up to today I used many database management systems and I am familiar with using them.

Time Line:

May 24-June 7- Comparing SQL vs DERBY fetchers.Also make a comparison on SQL functional availability in different DBMSs.

June 7-June 21-Implementing test cases for check availability of identified important SQL functions.

June 21-July 5- Comparing JDBC functions available in different DBMSs.

July 5-July 19-Implementation test case for check JDBC functions.

July 12-Submit midterm evaluation

July 19-August August 10-Check previously made test cases in different platforms using each DBMSs.

August 10-August 16-Publish results and conclusion.

About Me:

I am Eranda Sooriyabandara (Weerasekara Mudiyanselage Eranda Mahesh Sooriyabandara). I am currently a student of Department of Computer Science and Engineering at University of Moratuwa Sri Lanka. Currently I am under my intern period at WSO2 Lanka pvt Limited which is an Open Source company in Sri Lanka.

Additional Information:

This is my second time of applying on Google Summer of Code and in the first time I did Apache Derby test and fix convert test into JUnit project and successfully completed that. Under that I completed several test conversions and several bug fixing as follows,

as tests

DERBY-4318 convert inbetween.sql to JUnit
DERBY-4317 convert columnDefaults.sql to JUnit
DERBY-4248 convert checkConstraints.sql to JUnit
DERBY-4187 Convert altertable.sql to JUnit

as bugs

DERBY-4282 strange behavior with the "update... where current c1" in the CheckConstraintTest
DERBY-4256 allow alter table to increase the maximum size of a blob and a clob
DERBY-4244 ALTER TABLE Sanity ASSERT in add column with autocommit off

Also for my school project I did complete two other test conversions

DERBY-4424 Convert outerjoin.sql into JUnit
DERBY-4423 Convert dropTable.sql into JUnit

Also currently I am working on the bug DERBY-2785 ij "describe" built in command cannot describe a table named "run" and it's work is almost done.

Derby vs MySQL

2010-04-02T21:48:00.000-07:00

Derby vs MySQL

This document describe about the differences about the DBMSs Apache Derby and MySQL.

1. Operating system support

OS\DBMS	Derby	MySQL
Windows	Yes	Yes
Mac OS	Yes	Yes
Linux	Yes	Yes
Unix	Yes	Yes
Amigo OS	No	Yes
Symbian	No	Yes

MySQL supports all most of the OS than the Apache Derby. The reason is Apache Derby need java to run it.

2. Fundamental fetchers

Fetcher\ DBMS	Derby	MySQL
ACID	yes	yes
Referential Integrity	yes	yes
Transactions	yes	yes
Unicode	yes	partial
Interface	SQL	SQL
DBMS\feacher	Derby	MySQL
ACID	yes	yes

ACID- Atomicity/ Consistency/ Integrity/ Durability

MYSQL partially support the Unicode and Apache Derby fully supports the Unicode. MySQL supports- UCS-2 encoding /UTF-8 encoding.

3. Limits

fetcher \DBMS	Derby	MySQL
Max DB size	?	unlimited
Max table size	?	MyISAM 256TB
Max row size	?	64KB
Max column per row	1012(5000 in view)	4096
Max blob/clob size	2,147,483,647 chars	4GB ( long text/long blob )
Max char size	254 varchar	32672
Max number size	?	64bits
Min DATE	0001-01-01	1000
Max DATE	31/12/9999	9999
Max column name size	128	64
Max number size	?	64bits

We can see here there are number of limitations of Apache Derby than MySQL. The main reason for this is the limitations of java. For example,

Because of java array size limit is 231

I. Number of chars in names are limited

II. Number of row s per table is limited

III. Number of column per table is limited

IV. Characters in data types like CHAR,VARCHAR is limited.

4. Tables and views

DBMS	Derby	MySQL
Temp table	Yes	Yes
Materialized view	No	No

Both DBMSs are not capable of creating materialized views. But materialized view is very important when using DBMS in data warehousing.

5. Indexes

DBMS	Derby	MySQL
R-/R+ tree	No	MyISAM only
Hash	No	Memory, Cluster(NDB), InnoDB tables only
Expressions	No	No
Partial	No	No
Reverse	No	No
Bitmap	No	No
GIST	No	No
GIN	No	No

6. Database capabilities

DBMS	Derby	MySQL
Union	Yes	Yes
Intersect	Yes	No
Except	Yes	No
Inner join	Yes	Yes
Outer join	Yes	Yes
Inner selects	?	Yes
Merge join	?	Yes
Blobs and Clobs	Yes	Yes
Common table expressions	No	No
Windowing function	No	No

7. Other objects

DBMS	Derby	MySQL
Data domain	No	No
Cursor	Yes	Yes
Trigger	Yes	Yes
Function	Yes	Yes
Procedure	Yes	Yes
External routing	Yes	Yes

8. Partitioning

DBMS	Derby	MySQL
Range	No	Yes
Hash	No	Yes
Composite(Range+Hash)	No	Yes
List	No	Yes
Shadow	?	?
Native Replication API	?	?

9. Data types

DBMS	Derby	MySQL
Type system	Static	Static
Integer	SMALLINT(16 bits) INT(32 bits) BIGINT(64 bits)	TINYINT(8 bits) SMALLINT(16 bit) MEDIUMINT(24 bit) INT(32 bit) BIGINT(64 int)
Floating point	FLOAT(32 bits) DOUBLE(64 bits) REAL(32 bits)	FLOAT(32 bit) DOUBLE(64 bit)
Decimal	DECIMAL NUMERIC	DECIMAL
String	CHAR VARCHAR CHARFORBITDATA LONGVAR- CHARFORBITDATA CLOB	CHAR VARCHAR TEXT
Binary	BLOB	BLOB
Date/Time	DATE TIME TIMESTAMP	DATETIME DATE TIMESTAMP YEAR
Boolean	BOOLEAN	BOOLEAN
Other	SET	ENUM SET

10. Access control

DBMS	Derby	MySQL
Native network encryption	Yes (can use with or without)	Yes (SSL with 4.0)
Brute-force protection	Yes	No
Enter price directory compatibility	Yes	No
Password complexity rules	?	No
Patch access	?	Partial No security page
Run unprivileged	Yes	Yes
Audit	?	?
Resource limit	?	?
Separation of duties between admin/ operator backup like RBAC	?	?
Security certification	No	No