Woes wiring up an ejb to use a database control

Question

first my question & then background:
how do i wire up an ejb to use a database control jcx object so that the dbcontrol is instantiated at runtime?
here's the scene:
i created a java page flow from a database control & this works correctly, but i also need to be able to expose some of the functionality to another deployed application. this application, incidentally is not a workshop application; but rather is a hand-coded war.
the first application (a workshop app) renders forms that use a database control to persist the data. it only uses one table & therefore, there is only one pojo. as i mentioned, this resides in web project & works correctly. i abstracted my dbcontrol & my pojo to a separate java controls project & built this as a library. the jpf still has no problems seeing the dbcontrol.
there is a second application (a non workshop app) that needs to be able to use a method provided by the dbcontrol. i created an ejb in a third project in the first application that makes the call to dbcontrol in the exact same way that the jpf did. but i am finding, however, that the dbcontrol is null whenever the ejb makes the call to it's method.
here's the more detailed design:
i started with a database control. i mapped to my datasource, wrote out the sql for the methods i wanted & generated the pageflow from this. i rewrote the pageflow/jsps to suit my needs & everything just works. i did notice at the time that i generated the page flow that the dbcontrol was never instantiated. here is a snippet of the jpf:
<pre>
public class SiteAlertMessageManagementController extends PageFlowController {
* This is the control used to generate this pageflow
* @common:control
private SiteAlertMessageDBControl dbControl;
public Forward getCurrentMessage() {  
SiteAlertMessage currentMessage = dbControl.getCurrentMessage();
</pre>
because SiteAlertMessageDBControl is an interface, i assumed that the '@common:control' annotation told weblogic what it needed to know in order to instantiate a runtime class of time SiteAlertMessageDBControl. because it just worked, i never questioned this.
with the form read/write functionality complete, i assumed i could quickly wrap an ejb around the dbcontrol method & be done with it. i soon realized that i could not create an ejb inside a web project & that an ejb project would not have classpath visibility to my dbcontrol & pojo, so i put the dbcontrol & the pojo into a java control project & made a library out of this. i double checked that the web project could see the classes in the library & they could.
so i created a separate ejb project that also could now see the classes in the library. i thought i was in the home stretch. i now have these projects in my first application:
administrationControls, administrationWeb, & administrationEjb. i moved the administrationControls.jar & the administrationEjb.jar over to the WEB-INF/lib directory of my (remember: non-workshop) war & wired up the code to pull the bean off jndi tree to make the rmi call. but it didn't work. so i backtracked & created a new jsp back in my workshop project that would make the same rmi call so that i could use the debugger. with this as the background, here is my specific problem.
what i noticed is that the ejb code itself works correctly. i guess i should show it as well.
<pre>
public class SiteAlertMessagesAPI extends GenericSessionBean implements SessionBean {
* This is the control used to generate this pageflow
* @common:control
private SiteAlertMessageDBControl dbControl;
public void ejbCreate() {
// Your code here
* @ejbgen:remote-method
public SiteAlertMessage getCurrentMessage() throws Exception {
SiteAlertMessage message = null;
try {
// dbControl is null here
message = dbControl.getCurrentMessage();
catch (Exception e) {
e.printStackTrace();
return message;
</pre>
the problem is that my dbControl object is null. what i did was cut & paste the code from the jpf over to my bean. like i stated earlier, i assumed that the annotation would tell weblogic to instantiate an instance. this was obviously not the case. incidentally, i rewrote my ejbCreate() method like this:
<pre>
public void ejbCreate() {
// Your code here
dbControl = new SiteAlertMessageDBControl();
</pre>
but workshop gives me a "error: this type is abstract and thus cannot be instantiated" warning.
my question is: how do i wire up an ejb to use a database control jcx object so that the dbcontrol is instantiated at runtime?
any light you could shed on this would be most appreciated. thanks,
doug

Answer 1

Hi,
unfortunatly, it's not possible to use a control outside a control or a
web service...
Emmanuel
douglas thomas a ?crit :
first my question & then background:
how do i wire up an ejb to use a database control jcx object so that the dbcontrol is instantiated at runtime?
here's the scene:
i created a java page flow from a database control & this works correctly, but i also need to be able to expose some of the functionality to another deployed application. this application, incidentally is not a workshop application; but rather is a hand-coded war.
the first application (a workshop app) renders forms that use a database control to persist the data. it only uses one table & therefore, there is only one pojo. as i mentioned, this resides in web project & works correctly. i abstracted my dbcontrol & my pojo to a separate java controls project & built this as a library. the jpf still has no problems seeing the dbcontrol.
there is a second application (a non workshop app) that needs to be able to use a method provided by the dbcontrol. i created an ejb in a third project in the first application that makes the call to dbcontrol in the exact same way that the jpf did. but i am finding, however, that the dbcontrol is null whenever the ejb makes the call to it's method.
here's the more detailed design:
i started with a database control. i mapped to my datasource, wrote out the sql for the methods i wanted & generated the pageflow from this. i rewrote the pageflow/jsps to suit my needs & everything just works. i did notice at the time that i generated the page flow that the dbcontrol was never instantiated. here is a snippet of the jpf:
<pre>
public class SiteAlertMessageManagementController extends PageFlowController {
* This is the control used to generate this pageflow
* @common:control
private SiteAlertMessageDBControl dbControl;
public Forward getCurrentMessage() {  
SiteAlertMessage currentMessage = dbControl.getCurrentMessage();
</pre>
because SiteAlertMessageDBControl is an interface, i assumed that the '@common:control' annotation told weblogic what it needed to know in order to instantiate a runtime class of time SiteAlertMessageDBControl. because it just worked, i never questioned this.
with the form read/write functionality complete, i assumed i could quickly wrap an ejb around the dbcontrol method & be done with it. i soon realized that i could not create an ejb inside a web project & that an ejb project would not have classpath visibility to my dbcontrol & pojo, so i put the dbcontrol & the pojo into a java control project & made a library out of this. i double checked that the web project could see the classes in the library & they could.
so i created a separate ejb project that also could now see the classes in the library. i thought i was in the home stretch. i now have these projects in my first application:
administrationControls, administrationWeb, & administrationEjb. i moved the administrationControls.jar & the administrationEjb.jar over to the WEB-INF/lib directory of my (remember: non-workshop) war & wired up the code to pull the bean off jndi tree to make the rmi call. but it didn't work. so i backtracked & created a new jsp back in my workshop project that would make the same rmi call so that i could use the debugger. with this as the background, here is my specific problem.
what i noticed is that the ejb code itself works correctly. i guess i should show it as well.
<pre>
public class SiteAlertMessagesAPI extends GenericSessionBean implements SessionBean {
* This is the control used to generate this pageflow
* @common:control
private SiteAlertMessageDBControl dbControl;
public void ejbCreate() {
// Your code here
* @ejbgen:remote-method
public SiteAlertMessage getCurrentMessage() throws Exception {
SiteAlertMessage message = null;
try {
// dbControl is null here
message = dbControl.getCurrentMessage();
catch (Exception e) {
e.printStackTrace();
return message;
</pre>
the problem is that my dbControl object is null. what i did was cut & paste the code from the jpf over to my bean. like i stated earlier, i assumed that the annotation would tell weblogic to instantiate an instance. this was obviously not the case. incidentally, i rewrote my ejbCreate() method like this:
<pre>
public void ejbCreate() {
// Your code here
dbControl = new SiteAlertMessageDBControl();
</pre>
but workshop gives me a "error: this type is abstract and thus cannot be instantiated" warning.
my question is: how do i wire up an ejb to use a database control jcx object so that the dbcontrol is instantiated at runtime?
any light you could shed on this would be most appreciated. thanks,
doug