[QPID-6140] [C++ Messaging] UI Gotchya in Hello World example

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.30
• Fix Version/s: 0.31
• Component/s: C++ Examples

Environment

Fedora 19, trunk build

• Assignee: Unassigned
• Reporter: Charles E. Rolke
• Created: 09/Oct/14 14:52
• Updated: 19/Mar/15 12:22
• Resolved: 04/Nov/14 21:35

Description

Modifying hello_world.cpp to add a simple property to a message

            Message message("Hello world");
            message.getProperties()["id"] = 1;

fails:

Linking CXX executable hello_world
/usr/bin/ld: CMakeFiles/hello_world.dir/hello_world.o: undefined reference to symbol '_ZN4qpid5types7VariantC1ERKS1_'
/usr/bin/ld: note: '_ZN4qpid5types7VariantC1ERKS1_' is defined in DSO /home/chug/git/qpid/build/src/libqpidtypes.so.1 so try adding it to the linker command line
/home/chug/git/qpid/build/src/libqpidtypes.so.1: could not read symbols: Invalid operation
collect2: error: ld returned 1 exit status
make[2]: *** [examples/messaging/hello_world] Error 1
make[1]: *** [examples/messaging/CMakeFiles/hello_world.dir/all] Error 2
make: *** [all] Error 2
*** Failure: Exit code 2 ***

What? What's with qpid::types::Variant? The user is adding a property as specified in the Messaging API spec.

To fix this a user must find hello_world in the cmake file and add 'qpidtypes' as a link library, rerun cmake, and then rebuild. Strictly speaking qpidtypes isn't needed for the simplest hello_world case. That said, qpidtypes is linked to qpidmessaging and must be available for hello_world to run.

Adding qpidtypes to hello_world's target_link_libraries will help new users experiment with Qpid Messaging more fluently.