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DB2 Delta Server
SBP
data-access-patterns.html
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{% summary page %}This pattern presents the DB2 Delta Server allowing the data grid to receive updates from the database conducted by applications that are not using the data grid as their system of record (Non-Aware Data-Grid Clients){% endsummary %} {% tip %} Author: Chris Roffler
Recently tested with GigaSpaces version: XAP 9.6
Last Update: Nov 2013
{% endtip %}

Overview

Almost every large enterprise system includes legacy applications or backend systems that are communicating with the enterprise main database system for reporting, batch processing, data mining, OLAP and other processing activity. These applications might not need to access the data grid to improve their performance or scalability. They will be using the database directly. Once these systems perform data updates , removing data or add new records to the database, these updates might need to be reflected within the data grid. This synchronization activity ensures the data grid is consistent and up to date with the enterprise main database server.

<iframe width="640" height="390" src="//www.youtube.com/embed/tBdphj2hjXk" frameborder="0" allowfullscreen></iframe>

The Delta Server described with this pattern responsible for getting notifications from the database for any user activity (excluding data grid updates) and delegate these to the data grid. You may specify the exact data set updates to be delegated to the data grid.

Scenario

We have an In Memory Data Grid (IMDG) that is used for querying information. The initial load of the IMDG was performed from a DB2 Database. The IMDG is not used as a system of record in this case meaning that any changes to the objects in the IMDG are not propagated back into the Database. Non-Aware Data-Grid Clients are updating the Database. These updates (insert,update and delete) need to be reflected in the IMDG.

{%align center%} {%endalign%}

We will show you how you can implement this scenario with XAP. A fully functional example is available for download.

Prerequisites

  • DB2 Advanced Server 10+ installation using default user (db2inst1) and group (dasadmin1)
  • MQ Server 7+ installed using the default user group mqm and add user db2inst1 to mqm group

Installation

For simplicity, we install and execute this demo using the DB2 default user db2inst1. Log in to the Linux machine using the user db2inst1. download the sample code and extract to a folder say /home/db2inst1/db2mqrep. We'll refer to this path as DEMO_HOME.

The following jar files are needed for this example:

{%highlight java%}

These files must be copied from the MQ server that you are running against.

CL3Export.jar CL3Nonexport.jar com.ibm.mq.axis2.jar com.ibm.mq.commonservices.jar com.ibm.mq.defaultconfig.jar com.ibm.mq.headers.jar com.ibm.mq.jar com.ibm.mq.jmqi.jar com.ibm.mq.jms.Nojndi.jar com.ibm.mq.pcf.jar com.ibm.mq.postcard.jar com.ibm.mq.soap.jar com.ibm.mq.tools.ras.jar com.ibm.mqjms.jar com.ibm.msg.client.commonservices.wmq.jar rmm.jar dhbcore.jar

Other jars:

connector.jar fscontext.jar jms.jar jndi.jar jta.jar ldap.jar log4j-1.2.17.jar providerutil.jar

{%endhighlight%}

Prepare the db demo files

Change directory to the db2mqrep directory. We'll execute a script that creates the db2sampl database PUBSRC and configures it for this demo. Execute the script democreatedb.sh using the command from a terminal window:

{%highlight java%} ./democreatedb.sh {%endhighlight%}

If your db2inst1 home directory doesn't match the script, please update the path to the exact one on your installation.

You should see the following message on your terminal window: {%highlight java%} Creating database "PUBSRC"... Connecting to database "PUBSRC"... ......... {%endhighlight%}

Setting up the MQ Queue Managers

If the db2inst1 account is not part of the mqm group, then you need to add it to the group. In this step we will setup the replication for the data base changes. Execute the following script using the asnclp command: {%highlight java%} asnclp -f demomq.asnclp {%endhighlight%}

The output on the console should look something like this: {%highlight java%}

CMD: asnclp session set to q replication;

==== CMD: create mq script config type E

..... {%endhighlight%}

The previous script generates a shell script which needs to be executed. Let's make this file executable first. {%highlight java%} chmod u+x qrepl.pubsrc.mq_aixlinux.sh {%endhighlight%}

Execute using the following command: {%highlight java%} ./qrepl.pubsrc.mq_aixlinux.sh {%endhighlight%}

You should now see output on the console similar to below: {%highlight java%} WebSphere MQ queue manager created. Directory '/var/mqm/qmgrs/PUBSRC' created. The queue manager is associated with installation 'Installation1'. Creating or replacing default objects for queue manager 'PUBSRC'. Default objects statistics : 74 created. 0 replaced. 0 failed. .......... {%endhighlight%}

To setup the asnclp session to replicate, execute the file demopub.asnclp {%highlight java%} asnclp -f demopub.asnclp {%endhighlight%}

You should see the following output: {%highlight java%}

CMD: asnclp session set to q replication;

==== CMD: set run script now stop on sql error on; ............. {%endhighlight%}

Create a directory called myQCap inside your current folder and cd to it and execute the following command:

{%highlight java%} asnqcap capture_server=PUBSRC {%endhighlight%}

This will capture the actual replication information. You should see the following output: {%highlight java%} ASN0600I "Q Capture" : "" : "Initial" : Program "mqpub 10.1.0 (Level s120403, PTF LINUXAMD64101)" is starting. ASN7010I "Q Capture" : "ASN" : "WorkerThread" : The program successfully activated publication or Q subscription "EMPLOYEE0001" (send queue "ASN.PUBSRC.DATA", publishing or replication queue map "PUBSRC.ASN") for source table "DB2INST1.EMPLOYEE".

...........

{%endhighlight%}

Running the Demo

Step 1: Start the xap agent

{%highlight java%} \XAP_HOME\bin\gs-agent.sh {%endhighlight%}

Step 2: Set environment variables for MQ

{%highlight java%} export MQ_JAVA_INSTALL_PATH=/opt/mqm/java export MQ_JAVA_DATA_PATH=/var/mqm export MQ_JAVA_LIB_PATH=/opt/mqm/java/lib64 {%endhighlight%}

Step 3: Start the Delta Server

{%highlight java%} java -Djava.library.path=/opt/mqm/java/lib64 -cp "/opt/mqm/java/lib:./*" com.gigaspaces.mq.listener.DB2SpaceListener -qmgr PUBSRC -queue ASN.PUBSRC.DATA -time 60000 -out DEPFiles {%endhighlight%}

Make sure you include all the jars that are MQS specific.

Step 4: Update the data base to force notifications

{%highlight java%}

db2 connect to PUBSRC

db2 "insert into employee(empno, firstnme, lastname, edlevel,workdept) values ('000015','MARK','POTTER',18,'C01')";

db2 "insert into employee(empno, firstnme, lastname, edlevel,workdept) values ('000016','SALLY','JOHNSON',18,'A00')";

{%endhighlight%}

If you start the XAP Administration UI you should see under "mySpace" the entries we have inserted into the data base.