Sample 0107 - Using RDBMS event tables

Introduction

This sample demonstrates how to set up an execution plan to filter out credit card transactions that makes use of an in-memory event table to identify blacklisted transactions. This sample uses Event simulator for inputs and the logger publisher for logging the outputs to the CEP console.

The execution plan used in this sample are as follows:

@from(eventtable = 'rdbms' , datasource.name = 'WSO2_CARBON_DB' , table.name = 'CEPSample0107CardUserTable')
define table CardUserTable (name string, cardNum string, blacklisted bool) ;

Given above is the table definition,

Defines a table named CardUserTable with the given attributes.
The annotation '@from' is used to link the table to an RDBMS event table named CEPSample0107CardUserTable and the data source used to access the table as WSO2_CARBON_DB (this is the datasource of the default H2 database that is shipped with WSO2 CEP. If needed you can define a separate data source pointing to some other DB such as MySQL and use it here.)

from CardUserStream
select * 
insert into CardUserTable;

The first query,

Processes the events received through the CardUserStream
Selects all the attributes under the select clause, from each event received.
Inserts it to the CardUserTable.

from BlackListStream
select cardNo as cardNum, true as blacklisted  
update CardUserTable
	on cardNum == CardUserTable.cardNum;

The second query,

Processes the events received through the BlackListStream
Selects cardNo and renames it as cardNum, introduces a new attribute named blacklisted with the value 'true' under the select clause, for each event received.
Updates the CardUserTable with the condition cardNum == CardUserTable.cardNum. Here the 'blacklisted' attribute in the table will be updated with the new value.

from PurchaseStream#window.length(1) as p join CardUserTable as c
	on  p.cardNo == c.cardNum and c.blacklisted == false
select p.cardNo as cardNo, c.name as name, p.price as price
insert into WhiteListPurchaseStream ;

The third query,

Defines a length window that keeps 1 event of the input stream PurchaseStream.
Joins it with the CardUserTable with the condition p.cardNo == c.cardNum and c.blacklisted == false. In this condition, the events with blacklisted == true in the table gets filtered out and then the remaining events will be joined based on the card number.
Emits those events as output events through the TransformedRoomTempStream.

from DeleteAllUsers 
delete CardUserTable
	on deleteAll == true;

The last query is used to clean up the table from an external trigger event through DeleteAllUsers stream,

It processes the events received through the DeleteAllUsers.
Checks for the condition deleteAll == true and if it's true, deletes all the records in the CardUserTable.

Prerequisites

See Prerequisites in CEP Samples Setup page.

Building the sample

Start the WSO2 CEP server with the sample configuration numbered 0107. For instructions, see Starting sample CEP configurations. This sample configuration does the following:

Points the default Axis2 repo to <CEP_HOME>/sample/artifacts/0107 (by default, the Axis2 repo is <CEP_HOME>/repository/deployment/server).

Executing the sample

Log into the CEP management console which is located at https://localhost:9443/carbon.
Go to Tools -> Event Simulator. Under the 'Multiple Events' section, you can see 4 files listed there which contains some sample data as follows.
The userEvents.csv file contains sample data that is used to fill the in-memory CardUserTable. Click play start sending events to fill the table.
The blackListUserEvents.csv file contains sample data that is used to mark user entries in CardUserTable as blacklisted. Click play to start sending blacklisted events and mark some table entries as blacklisted.
The purchaseEvents.csv contains credit card transactions data. Play it and send the transaction data.
After sending sample events from purchaseEvents.csv, you will be able to see the outputs as follows.