Xcode includes a data modeling tool (also known as Data Model Editor or simply a modeler) that facilitates the creation of entities, defining attributes, and the relationships among them.
The Browser view displays two panes, the Entity pane and the Properties pane, for defining entities and their respective properties.
At the time the message was written, there were not any worker threads, or child processes in V1.3, available to process additional requests.
I.e., all child processes/threads are already in use handling existing requests.
If you need to compare values like dates you have two options.
For comparing a date against a fixed value, you can simply use the date validator and specify its $min or $max property.