...
The core XBlock library is built around the assumption that Runtimes will be implemented for each application. Because of that design intention, there are methods on Runtimes such as handler_url
and local_resource_url
which really only make sense to be implemented by the hosting application. Unfortunately, in the existing edx-platform implementation, some of the XBlock runtimes are actually supplied by the Modulestore (upon construction of XBlocks and XModuleDescriptors), rather than being supplied by the runtime. This leads to a number of workarounds for those application specific methods, as well as an amount of trickery and juggling so that XBlocks, XModules, and XModuleDescriptors are provided with both the appropriate Runtime and appropriate FieldData for the Application context that they are being used in.
...
- Large delta before the new functionality is usable by courses
- Need a minimal set of pure XBlocks before one could actually run a course
- Need to write data bindings for FieldData
- This could be a port of SplitModuleStore
- This could be a new data storage format
- Need to update all places in LMS and Studio that use Modulestore to use the new pure runtime
- Unclear whether all modulestore functionality can even be supported yet by a pure XBlock system
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Glossary
XModule
The precursor to XBlock. This class is responsible for generating a student-facing HTML rendering of course content. It is bound to a particular student on instantiation.
XModuleDescriptor
DescriptorSystem
This class provides an interface between XModuleDescriptors and the rest of edx-platform. The intention is to abstract the XModuleDescriptor away from the details about how external systems are implemented.
ModuleSystem
As with DescriptorSystem, this class exists to provide an interface between the XModule and the rest of the LMS. It has become a dumping ground for many responsibilities, which will in the future be abstracted as XBlock services instead.
"Pure" XBlock
This is used to mean an XBlock that doesn't inherit from XModule or XModuleDescriptor, and accesses none of the DescriptorSystem or ModuleSystem interfaces to access edx-platform.