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MQSeries.net Forum Index » WebSphere Message Broker (ACE) Support » Invoke a Java Compute Node's Method from other java class

Invoke a Java Compute Node's Method from other java class

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er_pankajgupta84

Posted: Wed Mar 25, 2009 11:33 pm Post subject: Invoke a Java Compute Node's Method from other java class

Master

Joined: 14 Nov 2008
Posts: 203
Location: charlotte,NC, USA

Hi..

Can we invoke a method defined in a Java compute Node's java class from the other java classes.

I have the following requirement..

I have written one method DbOperation() which will accept 4 parameters
- DataSource Name
- Query string
- Input Assembly
- New Assembly

This method will then create a SQLStatement and then execute it and store the result set in new assembly..

My problem is I have to use this method at different places (JCN)...so I have to replicate this method at all those java compute node's java file..

Is there any way i can store this method at some common location and invoke it at rest of the places.

As this method has createSQLStatement function so it has to be in some JCN java class.

Here is the method defination:

private void selectDatabase(MbMessageAssembly contact admin,String p_dataSrcName, String P_QueryString,MbMessageAssembly p_newAssembly) throws MbException {

MbSQLStatement l_sqlStatement = null;

try {
String l_statement = "SET OutputRoot.XMLNS.Records[] = PASSTHRU('"+P_QueryString+"')";

int l_ITrnstionType = MbSQLStatement.SQL_TRANSACTION_COMMIT;

l_sqlStatement = createSQLStatement(p_dataSrcName, l_statement,
l_ITrnstionType);

l_sqlStatement.setThrowExceptionOnDatabaseError(false);

l_sqlStatement.select(contact admin, p_newAssembly);
}}

rekarm01

Posted: Sun Mar 29, 2009 3:44 pm Post subject: Re: Invoke a Java Compute Node's Method from other java clas

Grand Master

Joined: 25 Jun 2008
Posts: 1415

er_pankajgupta84 wrote:

Can we invoke a method defined in a Java compute Node's java class from the other java classes?

Here is the method definition:

Code:

private void selectDatabase(...) throws MbException {
...
l_sqlStatement = createSQLStatement(...);
...
}

Java does not allow invoking private methods from other classes; such methods must have either public, protected, or default access.

er_pankajgupta84 wrote:

Is there any way i can store this method at some common location and invoke it at rest of the places?

As this method has createSQLStatement function so it has to be in some JCN java class.

The method does not have to be in some JCN java class. It can be defined as a method in an unrelated class, by adding an argument of type MbJavaComputeNode. For example:

Code:

public class UnrelatedClass {
public static void selectDatabase(MbJavaComputeNode jcn, ...) throws MbException {
...
l_sqlStatement = jcn.createSQLStatement(...);
...
}
}

Code:

public class MyJCN extends MbJavaComputeNode {
public void evaluate(MbMessageAssembly assembly) throws MbException {
...
UnrelatedClass.selectDatabase(this, ...);
...
}
}

Alternatively, the method can be defined in an abstract JCN class, and inherited by JCN subclasses. For example:

Code:

public abstract class AbstractJCN extends MbJavaComputeNode {
public abstract void evaluate(MbMessageAssembly assembly) throws MbException;
protected void selectDatabase(...) throws MbException {
...
l_sqlStatement = createSQLStatement(...);
...
}
}

Code:

public class MyJCN extends AbstractJCN {
public void evaluate(MbMessageAssembly assembly) throws MbException {
...
selectDatabase(...);
...
}
}

fjb_saper

Posted: Sun Mar 29, 2009 8:53 pm Post subject:

Grand High Poobah

Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY

I think more revealing is following in his Java call:

Quote:

try {
String l_statement = "SET OutputRoot.XMLNS.Records[] = PASSTHRU('"+P_QueryString+"')";

I would urge him to check if this syntax is acceptable in Java for the statement... I would have expected something like this:

Code:

String i_statement = "PASSTHRU(" + P_QueryString + ")";
mymbelement = i_statement.execute();

or something similar... Anyways OutputRoot.XMLNS.Records should be passed as Reference and looked at in MbElement format ??

Have fun

_________________
MQ & Broker admin

er_pankajgupta84

Posted: Sun Mar 29, 2009 9:51 pm Post subject:

Master

Joined: 14 Nov 2008
Posts: 203
Location: charlotte,NC, USA

Thanks for your replies....

It's really a great information...

Regarding public & private method...it was pretty obvious stuff...
Regarding execution of query..again its the obvious stuff...

My point of discussion was how to invoke jcn's method from other jcn...

I have one last question... i.e. declaring an abstract JCN java class is legal and accepted as best practice....or not....same goes for passing this the this pointer as argument...

Have you guys used this thing in your code at anytime...

Thanks again for the valuable information ...

fjb_saper

Posted: Tue Mar 31, 2009 2:14 am Post subject:

Grand High Poobah

Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY

er_pankajgupta84 wrote:

Abstract Class used in Java development ... pretty obvious stuff...

_________________
MQ & Broker admin

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