Debugging an Oracle PL/SQL WEB Application hangs browser and dev tool - visual-studio

Question

I am fairly new to PL/SQL and have been assigned to maintain a PL/SQL system that uses WEB pages generated with PL/SQL as a front end (PL/SQL Web Application?). Because of the complexity of the application, I am trying to get the debugger from Oracle Developer Tools for Visual Studio (11.2.0.3.15) or Oracle's SQL Developer working.
I can not kick off the application from the development environment, so I am using the
DBMS_DEBUG_JDWP.CONNECT_TCP('10.15.1.177', '4000') and DBMS_DEBUG_JDWP.DISCONNECT() procedures in the package that I am trying to debug.
When the Oracle debug listener is started in Visual Studio, Tools -> Start Oracle External Application Debugger, this message appears in the output window:
PL/SQL Debugger starts. PL/SQL Debugger is listening on host:
10.15.1.177 and port: 4000.
In Oracle SQL Developer this message is shown
Debug listener (port=4000 Timeout=0 Local address=10.15.1.177)
Using Visual Studio, If the webpage is accessed and there are no breakpoints, the following messages appears the output window.
A database has connected to the PL/SQL Debugger on host: 10.15.1.177
and port: 4000. The thread 0x1 has exited with code 0 (0x0). A
database has disconnected from the PL/SQL Debugger on host:10.15.1.177
and port: 4000.
If there is a break-point anywhere in the package, before, between, or after the DBMS_DEBUG_JDWP statements, both the WEB browser and the development environment hang. Visual Studio sits with "Not Responding" until it is terminated.
In Oracle SQL Developer the WEB page hangs. If the listener is stopped then the web page can not be displayed because there is no listener available.
I do not have control over the Oracle server, but since it established a connection, I assume there is no firewall blocking the port.?
Does someone have an idea what I missed?
I have been told that you can not debug PL/SQL packages that generate web pages, but have not found any documentation indicating that is a problem.

Answer 1

I have been working with mod_plsql for quite some time and in my personal experience the best (if not only) way to debug such an application is to instrument your source code.
The debugger(s) works fine for pl/sql code that can be execute outside the browser but for code the interacts with mod_plsql it is in my experience best to instrument the code with tracing and logging message and use them to follow the program flow.
We use a quite sophisticated logging framework but it all comes down to a simple table where to store the log messages and an (autonomous) procedure that inserts log messages in this table.
Example:
CREATE TABLE logtab (id NUMBER, when DATE, text VARCHAR2(2000));
CREATE SEQUENCE logseq;
CREATE OR REPLACE
PROCEDURE dolog(text IN VARCHAR2)
IS
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
INSERT INTO logtab (id, when, text) VALUES (logseq.NEXTVAL, SYSDATE, SUBSTR(text, 1, 2000));
COMMIT;
END dolog;
/
EXECUTE dolog('test');