Setting up Mediation Data Agent

BAM Mediation Data Agent is used to collect statistics related to mediation data from WSO2 ESB and send to WSO2 BAM. The BAM server receives data events via its Thrift API. This is a binary protocol that enables fast data transmission between the ESB and BAM. It is possible to configure BAM Mediation Data Agent early so that you can predefine the statistics to be extracted from mediation data of ESB. In the configuration panel, specify the BAM server (Thrift server) related information and properties to be extracted from the Configuration Context of ESB. Also specify the Event Stream related parameters uniquely identified by a name and a version.

Configuration steps are as follows:

Installing BAM Mediation Data Agent Aggregate in the ESB

The following installation instructions apply to WSO2 ESB version 4.5.x onwards.

Download WSO2 ESB version 4.5.x or later from http://wso2.com/products/enterprise-service-bus. Since BAM Mediation Data Agent Aggregate feature is available by default from ESB 4.6.0 onwards, you do not have to install it separately if you use a newer ESB version.
When running both ESB and BAM servers concurrently, you must change the port of one server in order to prevent port conflicts. This is done by applying an offset in file <ESB_HOME>/repository/conf/carbon.xml. Change the value in xpath Server/Ports/Offset from 0 to some other integer. For example,
```

 
<Offset>2</Offset>
```
Start the ESB server by executing the following commands from <ESB_HOME>/bin.
- on Linux wso2server.sh
- on MS Windows wso2server.bat
After starting the server, log in to ESB's management console ( https://localhost:9443+offset/carbon )
In the management console, go to Configure > Features menu.
In the Repository Management tab, select and add a P2 repository either from a URL or a file. For instructions, see Managing the Feature Repository.

WSO2 features are available in Equinox P2 repository at http://dist.wso2.org/p2/carbon/releases. Repositories are listed there by WSO2 Carbon platform versions. Check the WSO2 Release Matrix, identify the WSO2 Carbon version that your product is based on and get the repository that is based on that Carbon version.
After adding the repository, go to Available Features tab. From the repository drop-down list, select the one you added above. The, click Find Features.
From the list of features that appears, select BAM Mediation Data Agent Aggregate feature and Install.
After the installation is done, restart the ESB server.

Configuring and using the BAM Mediation Data Agent

The sections below describe, through an example scenario, how to use the BAM Mediation Data Agent to log mediation statistics data into a Cassandra Database:

Configuring the BAM Mediation Data Agent

Enable statistics in <ESB_HOME>/repository/conf/carbon.xml file as follows:
```
<StatisticsReporterDisabled>false</StatisticsReporterDisabled>
```
Log in to the ESB management console and select Mediation Data Publishing in the Configure menu.
The Mediation Data Publisher Configuration window opens. Fill in the field. By default the Stream name must be bam_mediation_stats_data_publisher. For example,
The fields of the above page are described below:

Enable Mediation Stats: Select this option to enable the agent.
Stream Definition Configuration:
- Stream Name : Any string value with alpha-numeric characters.
- Version : Stream version distinguishes different streams with the same stream name. Default version is 1.0.0.
- Nick Name : This is a user-preferred nick name to the stream name in alpha-numeric characters. Useful when stream name is lengthy and you want to keep a shorter alias for convenience.
- Description : A description about the stream identified by Stream Name, Stream Version pair. Description should also consist of alpha-numeric characters.
BAM Credentials:
- BAM URL : IP address of the BAM server. Port must be the thrift port (e.g., tcp://127.0.0.1:7611). Add a comma-separated list of server URLs here to ensure that the load is distributed among many servers. It minimizes effects of a failure of one node.
- Username and Password: BAM Thrift login user name and password. Default values are admin/admin.
Properties: BAM receives events from different data agents. You can associate a property to uniquely identify the events triggering from one agent. This feature is particularly useful in a clustered environment.

Setting up the backend server for ESB endpoint

In order to test the functionality of the BAM Mediation Data Agent, create an Endpoint service as the WSDL proxy service and define a sample WSDL proxy service as follows:

Navigate to <ESB_HOME>/samples/axis2Server/src/SimpleStockQuoteService and build the backend service with Apache Ant (Install Ant 1.7.0 or higher from http://ant.apache.org).
Go to <ESB_HOME>/samples/axis2Server and run the Axis2 server.
- In Linux, axis2server.sh
- In Windows, axis2server.bat
Test whether the proxy service WSDL exists in http://localhost:9000/services/SimpleStockQuoteService?wsdl.

Adding a proxy service to WSO2 ESB

These are the steps to create a sample WSDL Proxy Service to test the BAM Mediation Data Agent.

Log in to ESB management console and select Add > Proxy Service from the Main menu.
In the Create Proxy Service from Template page that opens, click WSDL Based Proxy link to create a new WSDL-based proxy.
The WSDL Based Proxy page opens. Fill the form and click Create. For example,
The fields are described below. The ones marked with * are mandatory.
- Proxy Service Name: Name of the proxy. e.g., Simple_Stock_Quote_Service_Proxy.
- WSDL URI: http://localhost:9000/services/SimpleStockQuoteService?wsdl
- WSDL Service: SimpleStockQuoteService
- WSDL Port: SimpleStockQuoteServiceHttpSoap11Endpoint
The Deployed Services page opens. Select the newly-created proxy (e.g., Simple_Stock_Quote_Service_Proxy) to access its service dashboard.
In the proxy service's dashboard that opens, click Enable Statistics in category Specific Configuration.

Sending messages to the ESB

When you come to this stage, make sure all previous steps are completed in order to test the BAM Mediation Data Agent. In this last step, you can send custom messages through the previously-created WSDL Proxy Service and test whether they are correctly stored in the Cassandra database. This is only an example, but the steps to use the BAM Mediation Data Agent in a production environment are similar.

Navigate to <ESB_HOME>/samples/axis2Client and build the backend service with Apache Ant as follows:

ant stockquote -Daddurl=https://localhost:8244/services/Simple_Stock_Quote_Service_Proxy -Dmode=fullquote -Dsymbol=testString

Daddurl value must be given from the HTTPS endpoint located in Simple_Stock_Quote_Service_Proxy service's dashboard. To access its dashboard, log in to ESB's management console and click Services > List menu in the Main menu. Then, click the Simple_Stock_Quote_Service_Proxy service from the Deployed Services page. Instead of the testString for symbol, you can use any preferred string.

Once done, the BAM Mediation Data Agent in the Simple_Stock_Quote_Service_Proxy service sends statistics from the ESB to the column family with the given stream name in key-space EVENT_KS in the Cassandra database. Use Cassandra Explorer in BAM to see the data in the Cassandra database. For example,

Descriptions of the above column names are as follows.

Event Property Name	Type	Description
Description	Stream definition configuration data	Description of the event stream.
Name	Stream definition configuration data	Name of the stream.
Nick_Name	Stream definition configuration data	Nick name of the stream.
StreamId	Stream definition configuration data	ID of the stream.
Timestamp	Stream definition configuration data	Timestamp of the event at the time it is getting published.
Version	Payload data	Version of the stream.
payload_avg_processing_time	Payload data	Average time to process the payload by ESB.
payload_count	Payload data	Number of messages received by ESB.
payload_direction	Payload data	Whether the payload is an incoming/outgoing message from/to ESB.
payload_fault_count	Payload data	If the message has been encountered any fault when serving the request, then this will be incremented as 1. If request successfully served, this count will be 0.
payload_max_processing_time	Payload data	Maximum time to process the payload by ESB.
payload_min_processing_time	Payload data	Minimum time to process the payload by ESB.
payload_resource_id	Payload data
payload_stats_type	Payload data
payload_timestamp	Payload data	The time of when the request came into WSO2 service hosting server (WSO2 AS), not the time which the event was received by BAM server.

Analyzing the mediation statistics

BAM mediation statistics metrics are similar to the metrics used by General ESB mediation statistics component. Mediation statistics are widely used monitoring features where functional components of the ESB, sequences, proxy services and endpoints directly get involved in processing messages. The BAM Mediation Statistics feature enables a server/tenant administrator to collect runtime statistics on these three types of functional components and view them through an interactive BAM Dashboard. This feature provides a simple but effective way to determine the runtime performance of the ESB. The collected statistical data can be used to analyze network traffic patterns and draw rough estimates on how the service bus will be used in the future. One of the most enticing attributes of the mediation statistics feature is that it can be configured in a fine-grained manner. In other words, it allows a user to collect data on only a specified set of sequences, proxy services and endpoints.

All statistics collected by the mediation component is aggregated for time duration and published to BAM as an event. That is, mediation statistics events are not sent for every request. Rather, the server aggregates request measures for a period of time and sends an event to BAM. For more information on the measures of mediation statistics, see this article in WSO2 library: http://wso2.com/library/articles/2010/06/wso2-esb-mediation-statistics-can-numbers-tell-about-your-soa.