Jobs RequestType discriminator seems to not work every

[einari]

We're getting exceptions like the following:

[einari]

Suggestion to fix:

• Introduce a IJobRequest interface that all Job request types implements
• Change the Request on JobState to be of type IJobRequest
• Custom MongoDB Serializer for IJobRequest interface
• Remove JobName - as it just reflects the JobType (Type.Name)
• Change JobType to use Type.Name only
• Use the JobType (Concept) that we store on the JobState
• Serializer could have a Map (Dictionary) of JobType enum to actual JobType

[woksin]

JobType now is the assembly fully qualified name and it is actually used to get the correct Grain for an IJob based on the JobState because JobType has an implicit converter to Type. If we change it to Type.Name, the same as JobName, then we cannot do that anymore.

How will the MongoDB Serializer for IJobRequest work? Doesn't it need to know about all the different implementations of IJobRequest? How will it know which CLR Type to convert the BSON document to?

[einari]

The lock in to the CLR type is actually the biggest problem with this. It would then potentially break a system from one version to another with Jobs being hydrated while upgrading if we change the namespace or name of the job.

We would need to have something that holds a map of JobType string to the CLR Type.

public interface IJobTypeManager
{
     JobType GetJobTypeFor(Type type);
     Type GetClrTypeFor(JobType type);
     Type GetRequestClrTypeFor(JobType type);
}

This could discover anything that implements IJob and also the IJob<TRequest> interface.
By default it would take the CLR Type.Name as the JobType while discovering.

But we could easily support overriding this, which would prove handy when renaming and wanting
to have backwards compatibility.

By introducing a JobTypeAttribute:

[....]
public class JobTypeAttribute(string jobType);

On a Job we would typically then add:

[JobType]
public class CatchUpObserver
{
}

[woksin]

Good idea. That makes sense

[einari]

And probably even better name for it would be IJobTypes so we don't add those pesky postfixes we don't like :)

[woksin]

Pr her #1693 however I'm having issues understanding how to implement the bson serializer