Jason Stull

I took a Myers-Briggs test once. Yes, at best, tests like this are just for fun. Persons should not be branded with the results by oneself or others. However, I think it's OK to recognize that one prefers visual activities. The question then becomes: What career makes sense where one can exercise this preference and add some collective value?

As they say in hip-hop these days, Rohit, "I feel you". I'm also very visually oriented. I'm also a Java developer and have to visually represent and breakdown all kinds of complex problems. These problems are usually in the form of complex business domains. I think there is a huge need for developers who can visually represent complex business concepts and their relationships (Person, Organization, Role, Product, Order, Facility, ...) UML is a great tool for this whether it is used on a white-board or in a modeling tool. It is true that many of us are "stuck" doing maintenance or refactorings on older code, but I think visual representation is just as critical here as it is in new development.

Hi Ranchers,
I'm going through the Whizlabs simulator right now where an example of "round-robin load balancing" was given. I read somewhere that techniques such as distributing load via round-robin or randomly is load sharing. Alternatively, load balancing is more sophisticated and involves analyzing a given set of servers to see who is least busy then distributing accordingly. Is this splitting hairs or should I be worried about this for the exam?
Many Thanks,
j

Greetings,

It seems that handling non-string data types such as dates and wrapped primitives is akward in Struts. I guess it would be nice if I didn't have to convert all my non-string values to Strings when copying them in to a FormBean and convert them back again when going from the FormBean to the JavaBean. Is this a job for a custom tag, or is this functionality already built in to Struts somewhere? Thanks for listening!
-j

Hi Stan,
Thanks for your reply. So you use a caching/factory system to not only instantiate, but pool your web app resources? If I've interpreted this right, in very general terms, what are the caching and creational strategies used (ie., a hashtable and reflection, etc.)?

Hello Ranchers,

Let's say I have a web application consisting of 20 JavaBeans. Depending on the Use Case in play during a Session, only certain beans will get used. What's the best strategy for constructing the beans, such that only one instance of each will be created per Session. Is it a case where if the bean is asked for, it will be created on-demand? Do I use factories? The beans do have some helpers, such as DAOs. Alternately, do I construct all the object instances (JavaBeans, DAOs, etc.) for the application at logon time? As always, thanks for your time! :-)
-j

Hi Ranchers,

I'm starting work on a web application that will have around 300 users, where around 200 of those users will be using the application at any given time. In terms of scalability, am I at the point where EJBs make sense for this application in terms of scalability? The web application contains some heavy business logic and a lot of CRUD type data access behavior.

Hi Jesse,
I also work in the Midwest. At bigger corporations, I've seen more of an openness to hiring "minorities" (whites are now statically a minority). The problems I see, at least in my locality, are with small companies, especially well established ones in the 'burbs. A lot of the people running these places have kooky, old school race fear. I don't think they want to be racist necessarily, but they can't seem to quell the fear that has been taught to and bred in to them. I come to this from lots of observation. So my advice, for what very little it is worth, would be to focus on large corporations or small/medium companies closer to the urban core. In theory, they should be more progressive in their hiring practices. Sorry if I've offended anybody with my observations. In fairness, I'm another white joe who works in the 'burbs. Additionaly, the advices on a software portfolio, learning hot technologies like Struts, and getting involved in an open source project, are spot on. I would add some kind of volunteer experience, maybe even something where you mentor kids in technology, to that list.

Check this out:
Jboss JBuilder OpenTool

ejb-jar.xml
<entity> <display-name>Cd</display-name> <ejb-name>Cd</ejb-name> <local-home>org.jas.CdHome</local-home> <local>org.jas.Cd</local> <ejb-class>org.jas.CdBean</ejb-class> <persistence-type>Container</persistence-type> <prim-key-class>java.lang.Integer</prim-key-class> <reentrant>False</reentrant> <cmp-version>2.x</cmp-version> <abstract-schema-name>Cd</abstract-schema-name> <cmp-field> <field-name>cdId</field-name> </cmp-field> <cmp-field> <field-name>cdName</field-name> </cmp-field> <cmp-field> <field-name>cdArtist</field-name> </cmp-field> <primkey-field>cdId</primkey-field> </entity>
jboss-cmpjdbc.xml
<jbosscmp-jdbc> <defaults> <datasource>java:/MSACCESSDS</datasource> <datasource-mapping>MSACCESS2000</datasource-mapping> <create-table>false</create-table> <remove-table>false</remove-table> <read-only>false</read-only> </defaults> <enterprise-beans> <entity> <ejb-name>Cd</ejb-name> <table-name>CD</table-name> <cmp-field> <field-name>cdId</field-name> <column-name>CD_ID</column-name> </cmp-field> <cmp-field> <field-name>cdName</field-name> <column-name>CD_NAME</column-name> </cmp-field> <cmp-field> <field-name>cdArtist</field-name> <column-name>CD_ARTIST</column-name> </cmp-field> </entity> </enterprise-beans> </jbosscmp-jdbc>
jboss.xml
<jboss> <enterprise-beans> <entity> <ejb-name>Cd</ejb-name> <local-jndi-name>Cd</local-jndi-name> </entity> </enterprise-beans> </jboss>
add to standardjbosscmp-jdbc.xml (Not pretty, but actually works):
<type-mapping> <name>MSACCESS2000</name> <row-locking-template>SELECT ?1 FROM ?2 with (rowlock) WHERE ?3</row-locking-template> <pk-constraint-template>CONSTRAINT ?1 PRIMARY KEY (?2)</pk-constraint-template> <fk-constraint-template>ALTER TABLE ?1 ADD CONSTRAINT ?2 FOREIGN KEY (?3) REFERENCES ?4 (?5)</fk-constraint-template> <alias-header-prefix>t</alias-header-prefix> <alias-header-suffix>_</alias-header-suffix> <alias-max-length>32</alias-max-length> <subquery-supported>true</subquery-supported> <true-mapping>1</true-mapping> <false-mapping>0</false-mapping> <mapping> <java-type>java.lang.Integer</java-type> <jdbc-type>INTEGER</jdbc-type> <sql-type>NUMBER</sql-type> </mapping> <mapping> <java-type>java.lang.String</java-type> <jdbc-type>VARCHAR</jdbc-type> <sql-type>TEXT</sql-type> </mapping> </type-mapping>
[ April 13, 2004: Message edited by: Jason Stull ]

As long as we are hacking on cmp entity beans. One thing I hate about them is the total lack of flexibility. We have some pretty complex entities and some fairly complicated searches to go along with them. I think that EJBQL still doesn't have enough features. At one time we did do direct mapping of CMP EJBs to db tables. This scheme was dog-slow. And try as hard as we could, we never beat the performance of SessionBean + BMP EJBs + DAO. I'm studying for the SCEA right now, and all the study materials I've come across basically delegate CMP EJBs to cases where, "Data is not complex and performance is not critical".

"Expecting a +ve reply", whahuh???
Could you be more specific about what you are trying to accomplish? MBean configuration from msaccess-service.xml should look like:
<mbean code="org.jboss.resource.connectionmanager.LocalTxConnectionManager" name="jboss.jca:service=LocalTxCM,name=MSACCESSDS"> <depends optional-attribute-name="ManagedConnectionFactoryName"> <!--embedded mbean--> <mbean code="org.jboss.resource.connectionmanager.RARDeployment" name="jboss.jca:service=LocalTxDS,name=MSACCESSDS"> <attribute name="JndiName">MSACCESSDS</attribute> <attribute name="ManagedConnectionFactoryProperties"> <properties> <!-- format of URL is "jdbc :-o dbc :mrgreen: SNNAME" --> <config-property name="ConnectionURL" type="java.lang.String">jdbc :-o dbc:MyAccessDB</config-property> <config-property name="DriverClass" type="java.lang.String">sun.jdbc.odbc.JdbcOdbcDriver</config-property> </properties> </attribute> <!--Below here are advanced properties --> <!--hack--> <depends optional-attribute-name="OldRarDeployment">jboss.jca:service=RARDeployment,name=JBoss LocalTransaction JDBC Wrapper</depends> </mbean> </depends> <depends optional-attribute-name="ManagedConnectionPool"> <!--embedded mbean--> <mbean code="org.jboss.resource.connectionmanager.JBossManagedConnectionPool" name="jboss.jca:service=LocalTxPool,name=MSACCESSDS"> <attribute name="MinSize">0</attribute> <attribute name="MaxSize">50</attribute> <attribute name="BlockingTimeoutMillis">5000</attribute> <attribute name="IdleTimeoutMinutes">15</attribute> <!--criteria indicates if Subject (from security domain) or app supplied parameters (such as from getConnection(user, pw)) are used to distinguish connections in the pool. Choices are ByContainerAndApplication (use both), ByContainer (use Subject), ByApplication (use app supplied params only), ByNothing (all connections are equivalent, usually if adapter supports reauthentication)--> <attribute name="Criteria">ByContainer</attribute> </mbean> </depends> <depends optional-attribute-name="CachedConnectionManager">jboss.jca:service=CachedConnectionManager</depends> <depends optional-attribute-name="JaasSecurityManagerService">jboss.security:service=JaasSecurityManager</depends> <attribute name="TransactionManager">java:/TransactionManager</attribute> <!--make the rar deploy! hack till better deployment--> <depends>jboss.jca:service=RARDeployer</depends> </mbean>

Hi Kyle,
A follow-up question. Does direct mapping from cmp bean to db table mean that db tables should be denormalized? I guess I'm just wondering how this approach impacts performance and if granularity is still an issue.

JMS Client Code:
private Queue sendToQueue; private Queue replyToQueue; private QueueSession session; private QueueSender queueSender; private QueueReceiver queueReceiver; private QueueConnectionFactory qcf; //Send P to P message public void sendPtoPMessage(String sendToQueueName, String replyToQueueName) throws Exception { try { setupPtoP(sendToQueueName, replyToQueueName); queueReceiver = session.createReceiver(replyToQueue); queueReceiver.setMessageListener(this); queueSender = session.createSender(sendToQueue); Message msg = messageFactory.create(session); msg.setJMSReplyTo(replyToQueue); queueSender.send(msg); } catch(Exception e){ JmsHelper.cleanUp(conn, session); throw e; } } //Set up P to P private void setupPtoP(String sendToQueueName, String replyToQueueName) throws Exception { Object tmp = ctx.lookup("ConnectionFactory"); //JBoss Connection Factory qcf = (QueueConnectionFactory)tmp; conn = qcf.createQueueConnection(); sendToQueue = (Queue)ctx.lookup("queue/" + sendToQueueName); if(replyToQueueName != null) replyToQueue = (Queue)ctx.lookup("queue/" + replyToQueueName); session = conn.createQueueSession(false, QueueSession.AUTO_ACKNOWLEDGE); conn.start(); }
ejb-jar.xml
<message-driven> <display-name>SomeMDB</display-name> <ejb-name>SomeMDB</ejb-name> <ejb-class>org.jas.SomeMDBean</ejb-class> <transaction-type>Container</transaction-type> <message-driven-destination> <destination-type>javax.jms.Queue</destination-type> </message-driven-destination> <resource-ref> <res-ref-name>jms/QCF</res-ref-name> <res-type>javax.jms.QueueConnectionFactory</res-type> <res-auth>Container</res-auth> </resource-ref> </message-driven>
jboss.xml
<message-driven> <ejb-name>SomeMDB</ejb-name> <destination-jndi-name>queue/SomeQueue</destination-jndi-name> <resource-ref> <res-ref-name>jms/QCF</res-ref-name> <jndi-name>java:/ConnectionFactory</jndi-name> </resource-ref> </message-driven>

Hi Bhaskar,
As long as the MS Access DataSource is bound to JNDI, this example should get you going:
public class AccessTesterBean implements SessionBean { ...... public void testAccessDS() { Connection con = null; Statement s = null; try { Context ctx = new InitialContext(); DataSource msAccessDS = (DataSource)ctx.lookup("java:/MSACCESSDS"); con = msAccessDS.getConnection(); s = con.createStatement(); ResultSet rs = s.executeQuery("SELECT * FROM CD"); while(rs.next()){ System.out.println("CD INFO: ID = " + rs.getInt("CD_ID") + " NAME = " + rs.getString("CD_Name")); } } catch(Exception e){ throw new EJBException("Failed executing public void testAccessDS(): ", e); } finally { try{s.close();}catch(Exception e2){}//try to close statement try{con.close();}catch(Exception e3){}//try to close connection } } } ..... }