Sept. 14th, 1999: SEC Study Group: TAO and Quality of Service in CORBA

• Moderator: liuxj
• Scribe:

• Started: 2PM
• Ended: 3:20PM

• Study materials
• Notes
• Related issues
• Concluding notes

Study materials

• The Design of the TAO Real-Time Object Request Broker

  Summary (quoted from http://www.cs.wustl.edu/~schmidt/corba-research-realtime.html)

  Many real-time application domains can benefit from flexible and open distribute d architectures, such as those defined by the CORBA specification. CORBA is an emerging architecture for distributed ob ject computing being standardized by the OMG. Although it is well-suited for conventional request/response applica tions, CORBA is not yet suited for real-time applications due to the lack of key quality of service (QoS) features and optimizations.

  This paper makes three contributions to the design of real-time CORBA systems. F irst, it illustrates how to extend the CORBA specification and optimize CORBA implementations, so that CORBA it is suit able for real-time systems. Second, it describes how to develop a real-time scheduling service for CORBA tha t can provide QoS guarantees for deterministic real-time applications. Finally, the paper presents performance me asurements that demonstrate common sources of priority inversion and non-determinism in CORBA implementations.

  We will decide which aspects of TAO to study in detail in the study group on Friday, Sept. 10.

• Some additional materials on TAO:
  • Introduction to TAO
  • Overview of TAO
  • TAO Real-time Performance on Real-time Operating Systems

If time is enough, we will discuss the current effort in OMG to provide Quality of Service (QoS) control in CORBA. What follows is quoted from http://www.omg.org/news/pr98/compnent.html

• Minimum, Fault-Tolerant, and Real-Time CORBA
  Minimum CORBA is primarily intended for embedded systems. Embedded systems, once they are finalized and burned into chips for production, are fixed, and their interactions with the outside network are predictable - they have no need for the dynamic aspects of CORBA, such as the Dynamic Invocation Interface or the Interface Repository that supports it, which are therefore not included in Minimum CORBA. The URL for the Minimum CORBA specification is http://www.omg.org/cgi-bin/doc?orbos/98-08-04.

  Real-time CORBA standardizes resource control - threads, protocols, connections, and so on - using priority models to achieve predictable behavior for both hard and statistical realtime environments. Dynamic scheduling, not a part of the current specification, is being added via a separate request for proposals (RFP). The URL for the Real-Time CORBA specification is http://www.omg.org/cgi-bin/doc?orbos/99-02-12; an erratum is http://www.omg.org/cgi-bin/doc?orbos/99-03-29.

  Fault-tolerance for CORBA is being addressed by an RFP, also in process, for a standard based on entity redundancy, and fault management control. The URL for all information on this RFP is http://www.omg.org/techprocess/meetings/schedule/Fault_Tolerance_RFP.html.

Notes

Related issues

Concluding notes