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- https://source.sakaiproject.org/svn/basiclti/trunk/basiclti-docs/resources/docs/sakai-api-test/
- https://github.com/csev/sakai-lti-test/
Common Problems
Offloaded SSL - If SSL connections terminate outside of Tomcat, e.g. in Apache or your load balancer, the SSP TP will refuse to authenticate launch requests unless Tomcat is tricked into thinking it is actually receiving SSL requests. This is typically done by adding the following attributes to the <Connector> in <tomcat>/conf/server.xml responsible for receiving traffic from the SSL termination point:
...
| No Format |
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scheme="https" proxyPort="443" secure="true" |
404 After Launch - The launch itself doesn't seem to error out and the user is redirected to a /ssp-platform URL, but gets a 404 at that location. This is often caused by one or more of the following being misconfigured in SSP_CONFIGDIR/ssp-platform-config.properties:
| No Format |
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environment.build.uportal.server=ssp.institution.edu
environment.build.uportal.protocol=https
environment.build.uportal.context=/ssp-platform |
Launch Failures or Target Failures - Messages in the SSP log should describe the technical problem associated with launch failures without requiring any special logging configuration, especially for 'test' launches. If you are not seeing such logs, try increasing the log level for the LtiLaunchErrorHandler component. In SSP_CONFIGDIR/logback.xml:
| No Format |
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<logger name="org.jasig.ssp.util.security.lti.LtiLaunchErrorHandler" level="warn" /> |
If the problem seems to have to do with the target receiving unexpected launch parameters or the launch failure suggests a problem with unexpected LTI launch parameters and the TC's request debugging tools are insufficient, try increasing logging in the OAuth package. In SSP_CONFIGDIR/logback.xml:
| No Format |
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<logger name="org.springframework.security.oauth" level="debug" /> |
In particular, look for messages containing the string "Verifying signature", which won't provide an unprocessed view onto the original launch parameters, but will give you a very good idea of what all was in the original request.
The Tomcat RequestDumperValve is another option for getting at the original request in a less processed format, although it can have side-effects which may disrupt the LTI message authentication process.