How Distributed Logging Works in WSO2 Stratos.

Why we need distributed Logging ???????

Stratos is a distributed clustered setup where we have several applications such as ESB Servers,Application Servers, Identity Servers, Governance Servers, Data Services Sever etc  deployed together to work with each other to serve as Platform as a Service. Each of these servers are deployed in a clustered environment, where there will be more than one node for a given server and depending on the need, there will be new nodes spawned dynamically inside this cluster. And all these servers are fronted through an Elastic load balancer and depending on the request the load balancer will send requests to a selected node in a round robin fashion.

What would you do when there is an error occurs in a deployment like above where there are 13 different types of servers running in production and each of these servers are clustered and load balanced across 50+ servers?. This would be a nightmare for the system administrators to log-in into each server and grepping for the logs to identify the exact caused of the error. This is why distributed application deployment's  needs to keep a centralized application logs. These centralize logs should also be kept in a high scalable data storage in an ordered manner with easy access.So that the users (administrators,developers) can easily accesses  logs, whenever something goes unexpected, with the least amount of filtering  to pinpoint the exact cause of the issue.

When designing a logging  system like above, there are several things you need to consider.

1. Capturing the right information inside the LogEvent – You have to make sure all the information you need in order to monitor your logs is aggregated in the LogEvent. For example in a cloud deployment setup you have to make sure not only the basic log details(logger,date,log level) are not enough to  point a critical issue. You further needs tenant information (user/domain), Host information (to identify which node is sending what), Name of the server (from which server you are getting the log) etc. These information is very critical when it comes to analyzing and monitor logs in an efficient way.
2. Send logs to a centralized system in a nonblocking asynchronous manner so that monitoring will not affect the performance of the applications.
3. High availability and Scalability
4. Security – Stratos can be deployed and hosted in public clouds therefore, its important to make sure the logging system is high secured.
5. How to display system/application logs in an efficient way with filtering options along with log rotation.

Those are the 5 main aspects which were mainly concerned when designing the distributed logging architecture. Since Stratos support multitenancy we made sure that logs can be separated by tenants, services, and applications.

MT-Logging with WSO2 BAM 2.0

WSO2 BAM 2.0 provide a rich set of tool for aggregation, analyzing and presentation for large scale data sets and any monitoring scenario can be easily modeled according to the BAM architecture. We selected WSO2 BAM as the backbone of our logging architecture mainly because it provides high performance with non intrusiveness along with high scalability and security. Since those are the crucial factors essential for a distributed logging system WSO2 BAM became the idol candidate for MT-Logging architecture.

Publishing Logs to BAM  

We implemented a Log4JAppender to send LogEvents to bam. There we used BAM Data agents get Log Data across to BAM. BAM data agents send data using thrift protocol which gives us high performance message through put as well as it is non blocking and asynchronous. When publishing Log events to BAM we make sure the Data Stream is created per tenant, per server, per date. When the data stream is initialized there will be a unique column family created per tenant, per server per date and the logs will be stored in that column family in a predefine keyspace in cassandra cluster.

The Data stream defines the set of information which needs to be stored for a particular LogEvent and can be modeled into a Data Model.

Data Model which is used for Log Event.

{'name':'log. tenantId. applicationName.date','version':'1.0.0', 'nickName':'Logs', 'description':'Logging Event',

'metaData':[{'name':'clientType','type':'STRING'} ], 

'payloadData':[

   {'name':'tenantID','type':'STRING'},

   {'name':'serverName','type':'STRING'},

   {'name':'appName','type':'STRING'},

   {'name':'logTime','type':'LONG'},

   {'name':'priority','type':'STRING'},

   {'name':'message','type':'STRING'},

   {'name':'logger','type':'STRING'},

   {'name':'ip','type':'STRING'},

   {'name':'instance','type':'STRING'},

   {'name':'stacktrace','type':'STRING'}

 ] }

We extend org.apache.log4j.PatternLayout a in order to capture tenant information, server information and node information and wrap it with log4j LogEvent.

Log Rotation and Archiving

Once we send the log events to BAM the logs will be saved in a Cassandra cluster. WSO2 BAM provides a rich set of tools to create analytic and schedule task. Therefore, we used these hadoop task to rotate logs daily and archive them and store it in a secure environment. In order to do that we use a hive query which will run daily as a cron job. It will read Cassandra data store, retrieve all the column families per tenant per application and archive them in to gzip format.

The hive Query which is used to rotate logs daily

set logs_column_family = %s;

set file_path= %s;

drop table LogStats;

set mapred.output.compress=true;

set hive.exec.compress.output=true;

set mapred.output.compression.codec=org.apache.hadoop.io.compress.GzipCodec;

set io.compression.codecs=org.apache.hadoop.io.compress.GzipCodec;

CREATE EXTERNAL TABLE IF NOT EXISTS LogStats (key STRING,

payload_tenantID STRING,payload_serverName STRING,

payload_appName STRING,payload_message STRING,

payload_stacktrace STRING,

payload_logger STRING,

payload_priority STRING,payload_logTime BIGINT) 

STORED BY 'org.apache.hadoop.hive.cassandra.CassandraStorageHandler' 

WITH SERDEPROPERTIES ( "cassandra.host" = %s,

"cassandra.port" = %s,"cassandra.ks.name" = %s,

"cassandra.ks.username" = %s,"cassandra.ks.password" = %s,

"cassandra.cf.name" = ${hiveconf:logs_column_family},

"cassandra.columns.mapping" = 

":key,payload_tenantID,

payload_serverName,payload_appName,payload_message,

payload_stacktrace,payload_logger,payload_priority,

payload_logTime" );

INSERT OVERWRITE  DIRECTORY 'file:///${hiveconf:file_path}' 

select 

concat('TID[',payload_tenantID, ']\t',

'Server[',payload_serverName,']\t',

'Application[',payload_appName,']\t',

'Message[',payload_message,']\t',

'Stacktrace ',payload_stacktrace,'\t',

'Logger{',payload_logger,'}\t',

'Priority[',payload_priority,']\t'),

concat('LogTime[',

(from_unixtime(cast(payload_logTime/1000 as BIGINT),'yyyy-MM-dd HH:mm:ss.SSS' )),']\n') as LogTime from LogStats

ORDER BY LogTime

Once we archived the logs we will send these archived logs to HDFS file system. The archived logs can be further analysed using map-reduce jobs, for long term data analytics

Advantages of sending Logs to WSO2 BAM

1. Asynchronous and None Blocking Data publishing
2. Receives and Stores Log Events Cassandra Cluster which is high scalable and a big Data Repository
3. Rich tools set for analytics
4. Can be shared with CEP for real time Log Event analysis.
5. Can provide Logging tool boxes and dashboards for system administrators using WSO2 BAM
6. High performance and non-intrusiveness
7. Big data analysis
1. Daily log information analytic - Analyse cassandra data storage
2. Long term log information - Analyse HDFS file system using map-reduce

Monitoring and Analyzing System Logs 

• Using the Log Viewer
  Both application and system logs can be displayed using the management console of a given product. Simply log-in to Management console and under monitor there are two links 1. System logs which has system logs of the running server 2) Application Logs which has application level logs (this can be services/web applications) for a selected application. This makes it easy for users to filter logs by the application they develop monitor logs up to application level.
• Dashboards and Reports
  System administrators can log-in to WSO2 BAM and create their own dashboards and reports, so the can monitor their logs according to their Key performance Indicators. For example if they want to monitor number of fatal errors occur per given month for a given node.
• SMS Alerts and Emails
  Not just dashboards and Reports ... Combining WSO2 BAM with WSO2 CEP you can get real time alerts like trigger emails, SMS so that System administrators can instantly get to know when your system is going through an unexpected behavior.

View Logs Using the Log Viewer - Current Log

View Logs Using the Log Viewer - Archived Logs

All these rich set of monitoring capabilities can be in built into your deployment using Stratos Distributed Logging system. Where you don’t have to worry about always going to the system administrators for logs whenever something goes wrong in your application :).

Sneak Peek at WSO2 BAM 2.0 & How to Install BAM Data Agents in WSO2 Products

In a fast growing company, enterprise data plays a major role when it comes for decision making and other top level business activities. When I say enterprise data, it can be anything which is an asset to your company, for example

1. It can be the data coming into your system (Employee Information, Product Information Sales data etc)
2. It can be mediation data (who is accessing your services/application, when and how)
3. Request,response and faulty count for your services.

These row data can be crucial and also it is very important to analyze and convert these data into information in order provide business intelligence for decision makers.

WSO2 BAM is mostly used in SOA environments because when it comes to SOA environment monitoring your data means monitor your services. Most of your business functionalites are exposed as services, for example if you want to insert set of records to your data base you will expose set of data services to do it or if you want to mediate some services you need to create proxy service. You can monitor these kind of data using WSO2 Buisness activity monitor Server.

If you look at BAM highlevel architecture BAM can be modelled according to three major components

1. Aggregation – BAM Data Agents which publish data in to BAM Data storage
2. Analytics - Analyzers which analyzed Data in BAM storage
3. Presentation – Gadgets which displays key performance indicators of analyzed information
   
   
   
   
   

You can monitor any business modeling scenario according to these components and BAM architecture is modelled around these three components.

Aggregation – basically this means getting your data into BAM (capturing/collecting data into BAM). BAM data are sent using events, you can capture important set of data and make it as an event stream. I will give more details on events stream in my next posts :) but for the moment all you need to know is capture many data as possible when you are sending data to BAM more data means more business intelligence.

Analytics – After you capture your data you need to make your data meaningful (basically converting data into information) by analyzing your storage data. In order to do that you need to do some data operation (aggregation, merging, sorting ordering) and ultimately build some key performance indicators which will be needed for business intelligence. In BAM you will be able to write your own analyzers (custom analyzers) using hive/hadoop and also these queries can be saved and scheduled accordingly. We will dig deep into how to write hive queries using bam and how to analyze data and create KPIs using data in future.

Presentation – Once you analyze your data, you might need to visualize your KIPs (using bar charts tables) and build your own dashboards in order to visualize your information to decision makers. And not just visualizing you might need to send these analyzed data to needed parties using reporting alerts daily to the topper management etc. WSO2 BAM will provide rich set of tools to do those task without much coding effort. It provides a gadget editor tool which give you a drag and drop kind of way to create your gadgets from your analyzed data or you can connected to reporting o do some complex event processing and send emails etc just by using set of configurations.

Referance http://mackiemathew.files.wordpress.com/2012/01/bamarchitecture.png

Now that we discussed the main architecture behind BAM and also bit about the functionalities of BAM (you can go through BAM samples and install bam samples in order to get in depth knowledge on BAM)

Lets see how we can use BAM to monitor your services.

For this I am going to use WSO2 ESB and we will see how we can monitor service statistics using BAM.

First we need to install BAM data agents inside ESB.

How to install BAM data agents in ESB?

Download P2 Profile which will contain BAM Data agent features. Download WSO2 ESB Latest packs. Go to ESB_HOME/bin and start up the server.

Login to Management Console of WSO2 ESB using user credentials (default is admin, admin).  

Go to Configure -> Features and Click on Add Repository.

Click on add Repository, You need to give a meaningful name for the repository name, I am going to give it as My_REPO and give the path to your P2 Profile and click on add.

Once you add the repository you will be redirected to a page which contains available features. You need to install BAM data agent features therefore, type BAM on Filter by feature name and untick group feature by category and click on find.

Tick on following features BAM Mediation Data Agent Aggregate, BAM Mediator Aggregated,BAM Service Data Agent Aggregate and click install.

Read and accept  License Agreement and click next. Once the installation is finished restart the server.

Once you have installed the BAM data agents you will see newly installed features under Configure.
1. Service Data Publishing, 2. Mediation Data Publishing 3. BAM Server Profiling.

How to Configure Service Data Agent ?

You can click on Service Data Publishing to send your Service Data to WSO2 BAM. In order to do that you need to Download and Start up BAM (if you are running ESB on the same machine you need to change the offset{BAM_HOME->repository->conf->carbon.xml set offset to 1}.

Go to ${WSO2ESB_HOME}/repository/conf/etc and open bam.xml file. Please make sure that you enable the ServiceDataPublishing.
The bam.xml should have the following configuration:

   <BamConfig>
        <ServiceDataPublishing>enable</ServiceDataPublishing>
   </BamConfig>

NOTE: By default the this is disabled, and the BAM publishing won't occur even though you proceed the below steps and changed in the mentioned UI. Therefore please enable the ServiceDataPublishing to use with WSO2 BAM.
Then in the ESB side go to Service Data Publishing, Give the BAM Server URL which will be the thrift ports started in BAM server (tcp://localhost:7611), give BAM credentials (default is admin,admin)  and click on update.

Now if you invoke some services from ESB side the service data will get published to bam. Now to check to confirm whether your data is in BAM you can go to BAM Management Console Check it by connecting to Cassandra Explorer.

In this post I have only explained an intro to BAM 2.0 and how to send service data to bam From my next session I will explain how to send your enterprise data to BAM and how you can do analytics and presentation using WSO2 BAM tool kits.

How to send mails using WSO2 ESB (sending your payload data to e-mail)

Suppose you have a web service which returns some data and you want to send that data into a mail... WSO2 ESB provides an easy mechanism to do this by creating a proxy service.

First get your endpoint (web service endpoint which returns data ).

Step 1 - Enable mail transport in axis2.xml.

Go to your axis2.xml (under WSO2ESB_HOME/repository/conf/axis2/), and uncomment mailto transportSender as shown below.

 <transportSender name="mailto" class="org.apache.axis2.transport.mail.MailTransportSender">

        <parameter name="mail.smtp.host">smtp.gmail.com</parameter>
        <parameter name="mail.smtp.port">587</parameter>
        <parameter name="mail.smtp.starttls.enable">true</parameter>
        <parameter name="mail.smtp.auth">true</parameter>
        <parameter name="mail.smtp.user">synapse.demo.0</parameter>
        <parameter name="mail.smtp.password">mailpassword</parameter>
        <parameter name="mail.smtp.from">synapse.demo.0@gmail.com</parameter>
  </transportSender>

Step 2 Creating the proxy Service.

Go WSO2 ESB, start up the server. Under Main menu -> Axis2 Services -> Add -> Proxy Service. Click on Custom Proxy Service. Give an appropriate Proxy Service Name. (Give the WSDL URL as your requirement)

Step 3 - Define Endpoint

In the define endpoint section click on define inline, click on create -> Address Endpoint and give the address end point of your service which you get data from. I am going to invoke the Data Service which i created in my previous blog. And my Address endpoint will be

Step 4 - Creating the Out Sequence. Go to Out sequence -> Define Inline

In the In Out sequance We need to add a
A Log Mediator - Which logs the incoming message
Three Property Mediators
    1. Subject - Which will be the subject of our mail
    2. MessageType - Message Type of our mail
    3. ContentType - Content Type of our mail
    4. Send mediator - Send the mail to our email address

To add the log mediator, Click on add child -> Core -> Log.  And in the log mediator give the Log level as full.

To add the three properties,  Click on add child -> Core -> Property. And add three properties one by one.
property name="Subject" value="CEP Event" scope="transport" type="STRING"
property name="MessageType" value="text/html" scope="axis2" type="STRING"
property name="ContentType" value="text/html" scope="axis2"  type="STRING"

To add the send mediator Click on add child -> Core -> Send. And Select Endpoint Type -> Define inline -> Address Endpoint -> mailto:amani.soysa@gmail.com

Once you add the three properties and the log mediator your out sequance editor should look like below.

Click save and close and finish creating your proxy Service.

<proxy xmlns="http://ws.apache.org/ns/synapse" name="MyMailProzy" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">

   <target>
      <inSequence />
      <outSequence>
         <log level="full" />
         <property name="Subject" value="CEP Event" scope="transport" />
         <property name="MessageType" value="text/html" scope="axis2" type="STRING" />
         <property name="ContentType" value="text/html" scope="axis2" />
         <property name="OUT_ONLY" value="true" scope="default" type="STRING" />
         <send>
            <endpoint>
               <address uri="mailto:amani.soysa@gmail.com" />
            </endpoint>
         </send>
      </outSequence>
      <endpoint>
         <address uri="http://localhost:9765/services/PersonsDataService" />
      </endpoint>
   </target>
   <publishWSDL uri="http://localhost:9765/services/PersonsDataService?wsdl" />
   <description></description>
</proxy>

You can invoke your proxy service by going to try it in the service list, and you should get a mail according to your payload. My next blog post will show how we can receive emails to WSO2 ESB using a standard email client.

A Song best suited for WSO2 ESB!! :)

Who - Magic Bus 

Songwriters: PETER TOWNSHEND

Every day I get in the queue (Too much, the Magic Bus)
To get on the bus that takes me to you (Too much, the Magic Bus)
I'm so nervous, I just sit and smile (Too much, the Magic Bus)
Your house is only another mile (Too much, the Magic Bus)
Thank you, driver, for getting me here (Too much, the Magic Bus)
You'll be an inspector, have no fear (Too much, the Magic Bus)
I don't want to cause no fuss (Too much, the Magic Bus)
But can I buy your Magic Bus? (Too much, the Magic Bus)
Nooooooooo!

I don't care how much I pay (Too much, the Magic Bus)
I wanna drive my bus to my baby each day (Too much, the Magic Bus)
*[Magic Bus, Magic Bus, Magic Bus
Magic Bus, Magic Bus, Magic Bus
Give me a hundred (Magic Bus)
I won't take under (Magic Bus)
Goes like thunder (Magic Bus)
It's a bus-age wonder (Magic Bus)

Magic Bus, Magic Bus, Magic Bus, Magic Bus
I want it, I want it, I want it...(You can't have it!)
Think how much you'll save...(You can't have it!)]
I want it, I want it, I want it, I want it ... (You can't have it!)

Thruppence and sixpence every day
Just to drive to my baby
Thruppence and sixpence each day
'Cause I drive my baby every way

Magic Bus, Magic Bus, Magic Bus, Magic Bus, Magic Bus...
I want the Magic Bus, I want the Magic Bus, I want the Magic Bus...

I said, now I've got my Magic Bus (Too much, the Magic Bus)
I said, now I've got my Magic Bus (Too much, the Magic Bus)
I drive my baby every way (Too much, the Magic Bus)
Each time I go a different way (Too much, the Magic Bus)
I want it, i want it, I want it, I want it ...

Every day you'll see the dust (Too much, the Magic Bus)
As I drive my baby in my Magic Bus (Too much, the Magic Bus)

How to use WSO2 Payload mediator - Calling data service insertion using payload mediator

In my previous blog I showed how to use an iterate mediator to iterate through a soap message. In this post I am going to explain how WSO2 ESB payload mediator works.

Lets say you have a service which provides set of data and you want to call a data service insert operation. This message is generated from a data service, which access a database table and get set of records from the database. Please refer "How to create a MYSQL data service using WSO2 data services Server" If you want to create the data service and generate the below Request,

<Keys xmlns="http://ws.wso2.org/dataservice">
<Key>
    <P_Id>1</P_Id>
    <LastName>Soysa</LastName>
    <FirstName>Amani</FirstName>
    <Address>361 Kotte Road Nugegoda</Address>
    <City>Colombo</City>
 </Key>
 <Key>
    <P_Id>2</P_Id>
    <LastName>Bishop</LastName>
    <FirstName>Peter</FirstName>
    <Address>300 Technology BuildingHouston</Address>
    <City>London</City>
 </Key>
 <Key>
    <P_Id>3</P_Id>
    <LastName>Clark</LastName>
    <FirstName>James</FirstName>
    <Address>Southampton</Address>
    <City>London</City>
 </Key>
 <Key>
    <P_Id>4</P_Id>
    <LastName>Carol</LastName>
    <FirstName>Dilan</FirstName>
    <Address>A221 LSRC Box 90328 </Address>
    <City>Durham</City>
 </Key>
</Keys>

Lets see how we can use this data set which will come to WSO2 ESB as a soap request and we need to extract soap payload data and send them to a data service. First we need to use the iterate mediator  which will iterate the soap request if you have more than one data set. And we need to create the data service soap request using the payload mediator.

   <payloadFactory>
  <format>
     <p:InsertPerson xmlns:p="http://ws.wso2.org/dataservice">
        <p:P_Id>?</p:P_Id>
        <p:LastName>?</p:LastName>
        <p:FirstName>?</p:FirstName>
        <p:Address>?</p:Address>
        <p:City>?</p:City>
     </p:InsertPerson>
  </format>
  <args>
     <arg expression="//P_Id/text()" />
     <arg expression="//LastName/text()" />
     <arg expression="//FirstName/text()" />
     <arg expression="//Address/text()" />
     <arg expression="//City/text()" />
  </args>
</payloadFactory>

Once we create the payload mediator then we can create a send mediator to insert data to data service

  <send>

     <endpoint>

        <address uri="http://localhost:9765/services/MyFirstDSS/" />

     </endpoint>

  </send>

When you add everything together your proxy service will look like shown below.

<proxy xmlns="http://ws.apache.org/ns/synapse" name="AssetProxyService" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">
  <target>
     <inSequence>
         <iterate xmlns:m="http://ws.wso2.org/dataservice" id="iter1" expression="//m:Keys/m:Key">
           <target>
              <sequence>
                 <payloadFactory>
                    <format>
                       <p:InsertPerson xmlns:p="http://ws.wso2.org/dataservice">
                          <p:P_Id>?</p:P_Id>
                          <p:LastName>?</p:LastName>
                          <p:FirstName>?</p:FirstName>
                          <p:Address>?</p:Address>
                          <p:City>?</p:City>
                       </p:InsertPerson>
                    </format>
                    <args>
                       <arg expression="//P_Id/text()" />
                       <arg expression="//LastName/text()" />
                       <arg expression="//FirstName/text()" />
                       <arg expression="//Address/text()" />
                       <arg expression="//City/text()" />
                    </args>
                 </payloadFactory>
                 <send>
                    <endpoint>
                       <address uri="http://localhost:9765/services/MyFirstDSS/" />
                    </endpoint>
                 </send>
              </sequence>
           </target>
        </iterate>
     </inSequence>
  </target>
  <description />
</proxy>

How to Use Iterator Mediator to Iterate through SOAP message Using WSO2 ESB

Lets say you have a soap response coming from a your service and you need to go through that soap message and get/transform that data and send to another service ... and you have no way of doing it??? WSO2 ESB provide a solution to do this in few easy steps.
Lets look at the following soap message. This message is generated from a data service, which access a database table and get set of records from the database. Please refer "How to create a MYSQL data service using WSO2 data services Server" If you want to create the data service and generate the below response.

SOAP response.



<Keys xmlns="http://ws.wso2.org/dataservice">

  <Key>
     <P_Id>1</P_Id>
     <LastName>Soysa</LastName>
     <FirstName>Amani</FirstName>
     <Address>361 Kotte Road Nugegoda</Address>
     <City>Colombo</City>
  </Key>
  <Key>
     <P_Id>2</P_Id>
     <LastName>Bishop</LastName>
     <FirstName>Peter</FirstName>
     <Address>300 Technology BuildingHouston</Address>
     <City>London</City>
  </Key>
  <Key>
     <P_Id>3</P_Id>
     <LastName>Clark</LastName>
     <FirstName>James</FirstName>
     <Address>Southampton</Address>
     <City>London</City>
  </Key>
  <Key>
     <P_Id>4</P_Id>
     <LastName>Carol</LastName>
     <FirstName>Dilan</FirstName>
     <Address>A221 LSRC Box 90328 </Address>
     <City>Durham</City>
  </Key>

</Keys>

Lets see how we can create a proxy service to get these data and we will log the retrieve data using a log mediator.
Before we start you need to have wso2ESB server and start it up. And login to ESB management console.

Step 1 -  Creating the Custom Proxy - Basics Settings

First give proxy service Name and the targetted WSDL file as shown below. (For the WSDL file you can give WSDL file of the Data service which can be access through the data service-> Service Dashboard)

Step 2 - Defining the Endpoint

Once you are done with basic settings then you need to click on next and Define the endpoint. Click on define endpoint inline  and give the address end point of the created data service.

Step 3 - Defining the Out Sequence.

You need to put the iterator mediator inside the out sequence in order to iterate through the incoming soap message. Therefore, go to Define Out Sequence -> Define Inline -> Add 

Click on Add child ->Advance -> Iterate. 

When you scroll down you will get a wizard where you need to enter some information. Give 

Iterate ID - iter1

Iterate Expression*  //m:Keys/m:Key { Dont forget to add the name space to the iterate expression}  

Namespace prefix m 

Namespace url  http://ws.wso2.org/dataservice    

  

Lets add some log mediators to print the data as shown below (to add log mediator got to add child under target click on core and log).

Once you have added the log mediator and a send mediator inside the target. Once you have done it your design view editor should look like below.

Click on save and close to go back to the proxy service editor and click on finish to finish creating the proxy service.

Once you create the proxy service, your synapse configuration should look like below.

<proxy xmlns="http://ws.apache.org/ns/synapse" name="IteratorProxyService" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">

  <target>

     <outSequence>

        <iterate xmlns:m="http://ws.wso2.org/dataservice" id="iter1" expression="//m:Keys/m:Key">

           <target>

              <sequence>

                 <log level="custom">

                    <property name="P_Id" expression="//m:P_Id/text()" />

                    <property name="LastName" expression="//m:LastName/text()" />

                    <property name="FirstName" expression="//m:FirstName/text()" />

                    <property name="Address" expression="//m:Address/text()" />

                    <property name="City" expression="//m:City/text()" />

                 </log>

                 <send />

              </sequence>

           </target>

        </iterate>

     </outSequence>

     <endpoint>

        <address uri="http://localhost:9765/services/MyFirstDSS/" />

     </endpoint>

  </target>

  <publishWSDL uri="http://172.16.60.1:9765/services/MyFirstDSS?wsdl" />

  <description></description>

</proxy>

If you go to the try it feature inside the service dashboard of your proxy service. You can invoke GetPeople operation to test your proxy service.

Once you invoke that following log will be logged in to your console window

[2012-08-15 14:37:59,078]  INFO - LogMediator P_Id = 1, LastName = Soysa, FirstName = Amani, Address = 361 Kotte Road Nugegoda, City = Colombo

[2012-08-15 14:37:59,084]  INFO - LogMediator P_Id = 2, LastName = Bishop, FirstName = Peter, Address = 300 Technology BuildingHouston, City = London

[2012-08-15 14:37:59,089]  INFO - LogMediator P_Id = 3, LastName = Clark, FirstName = James, Address = Southampton, City = London

[2012-08-15 14:37:59,092]  INFO - LogMediator P_Id = 4, LastName = Carol, FirstName = Dilan, Address = A221 LSRC Box 90328 , City = Durham

Creating Music Notation using LiliPond

Lilipond is a music engraving program, which produce high quality music notation and send them into PDF format. One of the most interesting thing you can do using lilipond is, you can use lilipond for your music programming. If you follow their syntax properly you can create music applications very easily.

Lets get a kick start on lilipond.
Before you begin you need to download lilipond depending on your operating system.

For this demostration I am going to show how you can create the popular song "Twinkle Twinkle Little Star" Using lili pond.

There are three main things we need to consider when creating a song.in lili Pond

1. How to create the melody ? (the treble clef notes)
2. How are we going to accompany them? (base notes)
3. Are we going to produce a midi file to our notation.

Creating a melody

In lilipond most of the pitches can be given relatively to a given octave. for example

\relative c {
  \clef bass
  c d e f
  g a b c
  d e f g
}

Above notes are relative to the middle octave. And if you want to create octaves lower o higher you can use " ,  " (comma)  or " ' ". This is called octave changing mark in lilipond. And also default time signature is 4/4 and default clef is treble clef. Sharp {#} are defined as ("is") and flats (b) are defined as ("es"). For example if you want to create a# then the notation is like "ais". Ok those are the very basic principles of lilipond but if you want to create more complicate notations please refer the use guide.

Lets start our song. Here we are not using relatives we are using standard notation. So I am going to create a lead sheet which only has the treble clef notes and the chords are indicated on top of each bar.

\score {
{
<<
\chords  {f1 c1 g1 d1:m g1 d1:m f1 c1  }
\new Staff { \time 4/4c'4 c'4 g'4 g'4 a'4 a'4 g'2 f'4 f'4 e'4 e'4 d'4 d'4 c'2 f'4 f'4 e'4 e'4 d'4 d'4 c'2 f'4 f'4 e'4 e'4 d'4 d'4 c'2 }
>>
}
 \layout { }
\midi { }
}

Score represents its a lead sheet. And to represent chords  you need the notation "\chords" here you can define what type of chords you want and the duration on that chord.
   f1 - means fmajor and it will last  4 beats (breave).
   d1:m - means its DMinor it will also last 4 beats.
Like wise you can define your codes

By using new Staff you can give music notations such as crochests, minims rest etc depending on the cleff. If you dont have a clef then the default is treble. you can also define time signature, And the duration of the notes are given by numbers. C4 - one beat C2 - two beats , C1- four beats etc.

Lets look at our twinkle twinkle song notation

Creating MIDI

 
If you want to create a midi file as well you need to put /midi() then it will create a midi file of the song you created.

Creating Piano sheets

Creating piano sheets can also be done similarly. Only difference is you need have two staves other than one.

Example ..

\relative c'' {
  \new PianoStaff <<
    \new Staff { \time 4/4 c4 e8 g8 g4, e4 e}
    \new Staff { \clef bass c,2 e4 g e2 b'4 g}
  >>
}

Creating Fret Sheets.

If you want to create guitar tabs for notation for your songs there is an option to create fretsheets. In order to do that you need to include FretBoards  liberary and give your notation as shown below.

Example...

\include "predefined-guitar-fretboards.ly"
<<
\context FretBoards {
  \chordmode {
    c1:m e
  }
}
\relative c'' {
    \new Staff { \time 4/4 c4 e g g, e2 e} 
}
>>

How to create service specific logs for WSO2 ESB

In this post I am going to talk how you can create differant log files depending on your proxy service using WSO2 ESB. Lets say you have a proxy service deployed in ESB and you need to filter out the logs generated by that given proxy service. You can  do this in three easy steps using wso2 logging-mgt feature.

Step 1 - Creating a proxy service with LogMediator

In order to try this out you need to create a proxy service which uses log-mediator so we can easily generate logs comming from that proxy service.

So this is my proxy service

<proxy xmlns="http://ws.apache.org/ns/synapse" name="MyProxyService" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">

  <target>

     <inSequence>

        <log level="full">

           <property name="MESSAGE" value="****************Inside in sequance*********************" />

        </log>

     </inSequence>

     <outSequence>

        <log level="full">

           <property name="Message2" value="************Inside out sequance ************************" />

        </log>

        <send />

     </outSequence>

     <endpoint>

        <address uri="https://appserver.stratoslive.wso2.com/services/t/amani123.com/WeatherService/" />

     </endpoint>

  </target>

  <publishWSDL uri="http://appserver.stratoslive.wso2.com/services/t/amani123.com/WeatherService?wsdl" />

</proxy>

Step2 - Adding Service Level log appender to send logs to differant log file location

WSo2 logging-mgt feature use standard apache log4j framework therefore, you need to change log4j properties in order to create appenders. We will create a new appender call MY_PROXY_APPENDER


log4j.additivity.MY_PROXY_APPENDER=false
log4j.appender.MY_PROXY_APPENDER=org.apache.log4j.DailyRollingFileAppender
log4j.appender.MY_PROXY_APPENDER.File=${carbon.home}/repository/logs/${instance.log}/wso2-esb-my-proxy${instance.log}.log
log4j.appender.MY_PROXY_APPENDER.Append=true
log4j.appender.MY_PROXY_APPENDER.layout=org.apache.log4j.PatternLayout
log4j.appender.MY_PROXY_APPENDER.layout.ConversionPattern=%d{HH:mm:ss,SSS} [%X{ip}-%X{host}] [%t] %5p %c{1} %m%


Here we are defining what kind of an appender, we will use DailyRollingFileAppender you can change the appender type depending on your need such as DBAppender,SyslogAppender etc And also you need to give appender properties like file location, which patternlayout you need to use and the log pattern you need. ALl these are configurable depending on your need.

Step 3 - Adding your logger in the root logger.

You need to aknowlege the newly created Appender in log4j.logger to map MyProxyServic to the SERVICE_LOGGER. The logger will be under Service_Logger so you need to specify your appender as shown below.

 log4j.category.SERVICE_LOGGER.MyProxyService =INFO, PROXY_APPENDER


Thats it!! you can go to {CARBON_HOME}/repository/logs to view your newly created proxy service specific log file!!!!

Enabling VFS transport marks certain services as 'faulty'. How to resolve this?

When enabling the VFS transport in the WSO2 admin console there are a number of axis2 services which are marked as being faulty. None of these services (the default Echo service is one of these) have the VFS transport configured explicity in their transports list.
The message shown in the admin console for each of these faulty services is 'Unable to configure the service echo for the VFS transport: Service doesn't have configuration information for transport vfs. This service is being marked as faulty and will not be available over the VFS transport.'

Why it happens? and How to Resolve it?
   

This is because when you enable VFS transport that transport gets enabled to other services as well (including axis2 services) But they don't have necessarry properties needed for VFS to be properly enabled. So when you enable VFS ESB default axis2 services like echo/version services will get faulty. There are two ways to resolve this issue. Since WSO2 ESB is not meant to deploy Application service and it should be used as routing/hub purposes you can undeploy those services. However, if you still want to keep those axis2 services you can go to services.xml and add http and https transports as shown below.

<service name="echo">

   <schema elementFormDefaultQualified="false"/>
   <description>
       This service echos the input provided to it.
   </description>
     <transports>
      <transport>https</transport>
      <transport>http</transport>
   </transports>
   <parameter name="ServiceClass" locked="true">org.wso2.carbon.core.services.echo.Echo</parameter>

</service>

Once you added them you need to redeploy the services.

How To Use Validate Mediator to Validate the SOAP request using WSO2 ESB

Lets say you have a service with the following soap request and you need to validate the input message,  through a proxy service, for those kind of instances you can use WSO2 ESB Validate Mediator.

For this demonstration I am going to create a proxy service which is deployed and hosted under my tenant in StratosLive you can use the same service for sample purposes. This is a service which takes an input string and send a response along with the given input String.

My End point is
http://appserver.stratoslive.wso2.com/services/t/amani123.com/HelloService/              
The WSDL for my Service
http://appserver.stratoslive.wso2.com/services/t/amani123.com/HelloService?wsdl

First Lets Create a proxy service which access this service

 <proxy name="MyValidatorProxy"

          transports="https http"
          startOnLoad="true"
          trace="disable">
      <description/>
      <target>
         <inSequence>
            <log level="full">
               <property name="Message" value="Inside Insequance"/>
            </log>
            <send>
               <endpoint>
                  <address uri="http://appserver.stratoslive.wso2.com/services/t/amani123.com/HelloService/"/>
               </endpoint>
            </send>
         </inSequence>
         <outSequence>
            <send/>
         </outSequence>
      </target>
      <publishWSDL uri="http://appserver.stratoslive.wso2.com/services/t/amani123.com/HelloService?wsdl"/>
   </proxy>

Go to ESB Management Console and copy paste the following code in Source View (Under Main -> Service Bus -> Source View) and click on update.

This will create a proxy service which will create the service I hosted in my tenant.

You can invoke this service by going into Services List and click on try it. Which is a client we use to invoke the service.

Now When you click on the try-it, you will get redirected to a page which has a request and a response.
So for a given request like this

<body>

   <p:greet xmlns:p="http://www.wso2.org/types">
      <!--0 to 1 occurrence-->
      <name>Amani</name>
   </p:greet>
</body>

You should get a response like this.

<ns:greetResponse xmlns:ns="http://www.wso2.org/types">

   <return>Hello World, Amani !!!</return>
</ns:greetResponse>

So lets see how we can validate the request. Lets say you want to make sure the value of the name element is not empty and you want to enforce that for every service innovation there must be a value for the Name element. Then you need to use the ESB validate Mediator.

In order to create a proxy with a validate mediator we need to create a XSD schema. I have created a schema to validate the name element of the request.

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"

xmlns:ns1="http://org.apache.axis2/xsd" xmlns:ns="http://www.wso2.org/types"
attributeFormDefault="qualified" elementFormDefault="unqualified"
targetNamespace="http://www.wso2.org/types">
<xs:element name="greet">
<xs:complexType>
<xs:sequence>
<xs:element minOccurs="1" name="name" >
 <xs:simpleType>
        <xs:restriction base="xs:string">
            <xs:minLength value="1" />
        </xs:restriction>
    </xs:simpleType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>

Here the main thing you need to focus is this part

<xs:element minOccurs="1" name="name" >

 <xs:simpleType>
        <xs:restriction base="xs:string">
            <xs:minLength value="1" />
        </xs:restriction>
    </xs:simpleType&gt;
</xs:element>

We are using the restriction element which says to restrict the type as String and the input should be a non-zero value (basically this means element cannot be empty). Now we need to upload this in the registry.

Uploading the validation schema in the registry.

Go to Browse in the Registry menu. And there click on config and under that click on Add New Resource. And upload the file as xsd file.

Add Validator Mediator

<validate>

        <schema key="conf:/HelloSchema.xsd"/>
               <on-fail>
                  <makefault version="soap11">
                     <code xmlns:tns="http://www.w3.org/2003/05/soap-envelope" value="tns:Receiver"/>
                     <reason value="Invalid Request!!!"/>
                     <role/>
                  </makefault>
                  <log level="full" />
                  <property name="RESPONSE" value="true"/>
                  <header name="To" action="remove"/>
                  <send/>
                  <drop/>
               </on-fail>
            </validate>

In here we add the Schema from the registry, If the validation fails it will send a message saying "Invalid Request" and we will terminate the flow using the drop mediator.

Now we will ad this validate mediator in the in sequence of our proxy service.

<proxy xmlns="http://ws.apache.org/ns/synapse" name="MyValidatorProxy" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">

   <target>
      <inSequence>
         <log level="full">
            <property name="Message" value="Inside Insequance"/>
         </log>
         <validate>
            <schema key="conf:/HelloSchema.xsd"/>
            <on-fail>
               <makefault version="soap11">
                  <code xmlns:tns="http://www.w3.org/2003/05/soap-envelope" value="tns:Receiver"/>
                  <reason value="Invalid Request!!!"/>
                  <role/>
               </makefault>
               <log level="full"/>
               <property name="RESPONSE" value="true"/>
               <header name="To" action="remove"/>
               <send/>
               <drop/>
            </on-fail>
         </validate>
         <send>
            <endpoint>
               <address uri="http://appserver.stratoslive.wso2.com/services/t/amani123.com/HelloService/"/>
            </endpoint>
         </send>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
   </target>
   <publishWSDL uri="http://appserver.stratoslive.wso2.com/services/t/amani123.com/HelloService?wsdl"/>
   <description></description>
</proxy>
                              
Now if you invoke this using try it without a content in the name element you will get the message as Invalid Request.

Request

<body>

   <p:greet xmlns:p="http://www.wso2.org/types">
      <!--0 to 1 occurrence-->
    <name></name>
   </p:greet>
</body>

Response

<soapenv:Fault xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">

   <faultcode>tns:Receiver</faultcode>
   <faultstring>Invalid Request!!!</faultstring>
</soapenv:Fault>