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Oracle® REST Data Services Installation and Configuration Guide
Release 2.0

E25066-10
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PDF · Mobi · ePub

B Troubleshooting

This appendix contains information on troubleshooting.

Topics:

B.1 Enabling Debug Tracing

Add the following setting to the Oracle REST Data Services configuration file named: defaults.xml to enable debug tracing.

<entry key="debug.debugger">true</entry>

When this setting is present in defaults.xml, detailed logging information that may help with problem diagnosis is appended to the Oracle REST Data Services log output. This setting should not be enabled on production systems due to the performance impact of outputting large amounts of data to the log.

B.2 Enabling Detailed Request Error Messages

Add the following setting to the Oracle REST Data Services configuration file named: defaults.xml to enable detailed request error messages.

<entry key="debug.printDebugToScreen">true</entry>

When this setting is present in defaults.xml, any request that produces an error response includes a detailed message, including a stack trace. This setting must not be enabled on productions systems due to the risk of sensitive information being revealed to an attacker.

B.3 Configuring Application Express Static Resources with Oracle REST Data Services

When using Oracle REST Data Services, a blank page might be displayed when attempting to access an Oracle Application Express page, for example, when attempting to display http://server:port/ords/. This problem is caused by an improper configuration of Application Express static resources, which causes the JavaScript and CSS resources required by Application Express not to be found and the Application Express page not to render correctly.

The specific cause can be any of the following:

  • Forgetting to ensure that the Application Express static images are located on the same server as the Oracle REST Data Services instance

  • Forgetting to deploy i.war on WebLogic Server or GlassFish

  • Specifying an incorrect path when using the java -jar ords.war static command to generate i.war

  • Configuring Application Express to use a nondefault context path for static resources (/i) and not specifying the same context path (using the --context-path option) when using java -jar ords.war static

  • Moving, renaming, or deleting the folder pointed to by i.war after deploying i.war

  • When running in Standalone mode, entering an incorrect path (or not specifying a path) when prompted on the first run of Standalone mode

  • When running in Standalone mode, entering an incorrect path with the --static-images option

  • Upgrading to a new version of Application Express and forgetting to reconfigure and redeploy i.war to point to the static resources for the new Application Express version, or in Standalone mode forgetting to update the location by using the --apex-images option

To help in diagnosing the problem, you can try to access the apex_version.txt file. For example, if your Application Express deployment is located at http://example.com/ords/ and your static resources have been deployed at http://example.com/i/, use a browser to access the following URL:

http://example.com/i/apex_version.txt

If you get a 404 Not Found error, then check the preceding list of possible specific causes, including i.war not being deployed or not pointing to a folder containing Application Express static resources.

If a plain text file is displayed, it should contain text like the following:

Application Express Version:  4.2.1

Check that the version number matches the version of Application Express that is deployed on the database. If the numbers do not match, check if you have made an error mentioned in the last item in the preceding list of possible specific causes, because Oracle REST Data Services is not configured to use the correct version of the Application Express static resources to match the Application Express version in the database.

If you need help in solving the problem, check the information in this book about creating and deploying i.war for your environment, such as WebLogic Server or Glassfish.

You can also get detailed help on the static listener command by entering the following at a command prompt:

java -jar ords.war help static