Known Issues

In this chapter known issues of the karabo framework are listed. These known issues are expected!

C++ API

  • The FileDataLogReader will start indexing a property on property history request. The first request will receive a remote exception. Any subsequent request until the indexing is complete will result in an empty set.

  • Data logged into InfluxDB may take a while to be available for reading. The availability interval depends on the writing load on the InfluxDB infra-structure. This is not a Karabo issue, and maybe observed from other InfluxDB clients as well (e.g. Grafana). During the phase of migration of data from the legacy system to the one based on InfluxDB at European XFEL, writing loads way beyond normal usage ones were handled by the InfluxDB infra-structure. In such a scenario, intervals in the order of minutes could be observed for the data to be ready for reading.

  • For the getConfigurationFromPast operation, the InfluxLogReader will return the values of all properties that were in the full device schema(*) at the requested timepoint. This is implemented to make sure that properties whose timestamps are set by an external source will be retrieved. This requirement clashes with some corner cases in which properties appear in the static schema for historic reasons and are never meant to be set. For those properties, the returned value is set to the latest recorded value earlier than the requested timepoint. Configurations that include such historic “frozen” properties constitute an imperfect record and could be not directly applicable to the device. Given the conflicting requirements, the latest recorded value is kept in the record returned by the getConfigurationFromPast operation and the possible removal of the historic “frozen” property is left to the user.

    (*) The static device schema is merged with any schema injection that occurs during the lifetime of the device to yield its full device schema.

Bound Python API

  • Failure on instantiation generates an exception in all 3 APIs. In the Bound Python API, this exception is not reported to the caller. With Karabo >= 2.14 the exceptions are reported to the caller.
  • Bound API does not support CHAR_ELEMENT, (U)INT8_ELEMENT, (U)INT16_ELEMENT

Middlelayer API

  • The MDL API cannot set Attributes on runtime in elements which are in Nodes.
  • The DeviceNode comes with a few limitations: Technically, a DeviceNode represents network related code in a schema. A device developer will only end up in onInitialization when ALL deviceNodes are connected. Schema initialization happens before and device nodes are part of schema. There is no feedback if you are connected or not. The proxy misses schema injections of the connected Device.

Tools

The packaging management handled with the karabo script is rudimentary and has the following shortcomings:

  • The package names are case insensitive on the default package repository (XFEL-internal gitlab). This is not a limitation of the tool per se but a limitation of the repository server.

Karabo GUI

  • Renaming a macro file will not shutdown the instantiated instances. This is expected behavior and will not be prevented.
  • Karabo Scene Links are not synchronized with their target name. Renaming a target scene will not change the name stored in the scene link.
  • Vector of strings can be edited in an line-edit widget. For in this widget the comma is interpreted as a string separator. If one needs to input strings containing commas, one should use the edit button. Note that the line-edit widget will split the values with commas again when it is edited. This shortcoming is outweighed by the usefulness of being able to edit a vector of strings without a dialog.
  • An empty string is interpreted as a vector of 0 elements. If one needs a vector with an empty string, they can use the edit button on the gui.
  • Common Nodes do not have a direct value, but are containers. From the graphical user interface, if a property within a Node is changed in the Configurator (GUI), the Node will not reflect a CHANGING (blue) background.
  • It can happen that devices crash and do not send their instanceGone signal to the gui servers. Hence, in rare situations, devices are visible in the GUI client although they are not online.