C. O'Ryan, D. C. Schmidt, F. Kuhns, M. Spivak, J. Parsons, I. Pyarali, and D. Levine, "Evaluating Policies and Mechanisms for Supporting Embedded, Real-Time Applications with CORBA 3.0," in Proceedings of the 6 IEEE Real-Time Technology and Applications Symposium, (Washington DC), IEEE, May 2000.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....made to enhance these middleware with features to support special purpose applications. For example, the CORBA specification has been enhanced to include multithreading, priority based scheduling, and controlled priority inversion at the ORB level to support real time and embedded applications [74, 68]. Similar efforts have been made to augment Java to support real time features [66, 27] A recently adopted CORBA specification also provides directives for constructing fault tolerant CORBA objects using replication [24] Orthogonal to the above efforts, which accommodate the needs of modern ....

C. Ryan et al. Evaluating Policies and Mechanisms for Supporting Embedded, Real-Time Applications with CORBA 3.0. In Proc. of the IEEE Real-Time Technology and Applications Symposium, June 2000.

....engine. The IDL to C mapping must support buffer loaning techniques. The support of these buffer pools should not remain a private feature of only some ORB implementations. These are just examples to clarify better what we call the need for architectural support. The CORBA 3. 0 specification [40] is without any doubt on the way to become a strong competitor to other middleware approaches in the high performance processing domain. 7. Ongoing work Similar to the SPINE project we intend to use our executive not only in the main CPUs, but also in intelligent network cards. For this purpose ....

C. O'Ryan, D. C. Schmidt, F. Kuhns, M. Spivak, J. Parsons, I. Pyarali and D. L. Levine. "Evaluating Policies and Mechanisms for Supporting Embedded, Real-Time Applications with CORBA 3.0", Proceedings of the Sixth IEEE Real-Time Technology and Applications Symposium (RTAS 00), Washington D.C., USA, May 31-June 2, 2000.

.... on Real time CORBA has explored many dimensions of ORB design and performance, including scalable event processing [4] request demultiplexing [5] I O subsystem [6] and protocol [7] integration, connection management [8] and explicit binding [9] architectures, asyn1 chronous [10] and synchronous [11] concurrent request processing, and IDL stub skeleton optimizations [12] In this paper, we consider how to achieve end to end predictability using Real time CORBA. We first describe the end to end critical code path of remote CORBA invocations to identify sources of unbounded priority inversions. ....

....priority for the duration of processing the request. # Explicit binding mechanisms, which are described in Sidebar 4. Explicit binding enables clients to bind themselves to server objects using pre allocated connections, priority bands, and private connections. TAO offers an implementation [11] of this feature for Real time CORBA. TAO s connection cache is extended to keep track of the QoS properties of the connections, which includes priority banding and privacy attributes. 3 Experimentation Setup This section describes the Real time CORBA testbed and experiments used to evaluate ....

C. O'Ryan, D. C. Schmidt, F. Kuhns, M. Spivak, J. Parsons, I. Pyarali, and D. Levine, "Evaluating Policies and Mechanisms for Supporting Embedded, Real-Time Applications with CORBA 3.0," in Proceedings of the 6 IEEE Real-Time Technology and Applications Symposium, (Washington DC), IEEE, May 2000.

....demultiplexing [5] I O An ORB endsystem consists of network interfaces, I O subsystem, and other OS mechanisms, and ORB middleware capabilities. subsystem [6] and protocol [7] integration, connection management [8] and explicit binding [9] architectures, asynchronous [10] and synchronous [11] concurrent request processing, and IDL stub skeleton optimizations [12] In this paper, we consider how to achieve end to end predictability using Real time CORBA. We first describe the end to end critical code path of remote CORBA invocations to identify sources of unbounded priority inversions. ....

....priority for the duration of processing the request. # Explicit binding mechanisms, which are described in Sidebar 4. Explicit binding enables clients to bind themselves to server objects using pre allocated connections, priority bands, and private connections. TAO offers an implementation [11] of this feature for Real time CORBA. TAO s connection cache is extended to keep track of the QoS properties of the connections, which includes priority banding and privacy attributes. 3 Experimentation Setup This section describes the Real time CORBA testbed and experiments used to evaluate ....

C. O'Ryan, D. C. Schmidt, F. Kuhns, M. Spivak, J. Parsons, I. Pyarali, and D. Levine, "Evaluating Policies and Mechanisms for Supporting Embedded, Real-Time Applications with CORBA 3.0," in Proceedings of the 6 th IEEE Real-Time Technology and Applications Symposium, (Washington DC), IEEE, May 2000.

....connections and 1 An ORB endsystem consists of network interfaces, I O subsystem and other OS mechanisms, and ORB middleware capabilities. 1 # Memory resources via buffering requests in queues and bounding the size of thread pools. 3] presents an overview of the RT CORBA features and [4] explains how communication resources are configured and controlled efficiently in TAO [5] which is our highperformance, real time implementation of CORBA. There are two general strategies for implementing RTCORBA thread pools. The first strategy uses the HalfSync Half Async pattern [6] where ....

C. O'Ryan, D. C. Schmidt, F. Kuhns, M. Spivak, J. Parsons, I. Pyarali, and D. Levine, "Evaluating Policies and Mechanisms for Supporting Embedded, Real-Time Applications with CORBA 3.0," in Proceedings of the 6 th IEEE Real-Time Technology and Applications Symposium, (Washington DC), IEEE, May 2000.

.... and a DII and DSI implementation, it lacks an IDL compiler, an Interface Repository and Implementation Repository, and a Portable Object Adapter (POA) TAO implements all these missing features and provides newer CORBA features, asynchronous method invocations [29] real time CORBA [19] features [30], and fault tolerance CORBA features [31, 32] Lack of IIOP optimizations: Due to the excessive marshaling demarshaling overhead, data copying, and high levels of function call overhead, SunSoft IIOP performs poorly over high speed networks. Therefore, we applied a range of optimization ....

C. O'Ryan, D. C. Schmidt, F. Kuhns, M. Spivak, J. Parsons, I. Pyarali, and D. Levine, "Evaluating Policies and Mechanisms for Supporting Embedded, Real-Time Applications with CORBA 3.0," in Proceedings of the 6 th IEEE Real-Time Technology and Applications Symposium, (Washington DC), IEEE, May 2000.

....and finterface that. This framework must provide adaptivity encompassing the end to end resources needed to address QoS requirements of next generation applications that involve cooperation of multiple systems. One promising architectural framework that meets these requirements is our TAO [6, 7] implementation of the Realtime CORBA specification [8] Real time CORBA is a COTS middleware standard that supports end to end predictability for operations in fixed priority 1 CORBA applications. As shown in Figure 1, the Real time CORBA specification deOS KERNEL OS I O SUBSYSTEM NETWORK ....

C. O'Ryan, D. C. Schmidt, F. Kuhns, M. Spivak, J. Parsons, I. Pyarali, and D. Levine, "Evaluating Policies and Mechanisms for Supporting Embedded, Real-Time Applications with CORBA 3.0," in Proceedings of the 6 th IEEE Real-Time Technology and Applications Symposium, (Washington DC), IEEE, May 2000.

....of TAO s pluggable protocols framework. These services are responsible for creating ORB protocol objects dynamically and associating them with specific connections. They also interpret profiles and create object references on the server. By employing patterns and leveraging TAO s realtime features [19], protocol implementors can design highperformance IOPs that enforce stringent QoS properties. The connection management services are implemented with connectors, acceptors, reactors and registries that keep track of available protocols, create protocol objects, and interpret profiles and object ....

....(1 byte) Request Service Context (at least 4 bytes) and Request Principal (at least 4 bytes) GIOPlite reduces the number of bytes transfered across the backplane per operation. Another optimization that pertains to avionics mission computing involves the use of buffered one way operations [19]. TAO s pluggable protocols framework has been optimized to send a series of queued one way requests in a smaller number of ORB messages. For example, Figure 6 depicts the case where one way CORBA invocations are buffered in the ORB for later delivery. In this case, a series of one way invocations ....

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C. O'Ryan, D. C. Schmidt, F. Kuhns, M. Spivak, J. Parsons, I. Pyarali, and D. Levine, "Evaluating Policies and Mechanisms for Supporting Embedded, Real-Time Applications with CORBA 3.0," in Proceedings of the 6 th IEEE Real-Time Technology and Applications Symposium, (Washington DC), IEEE, May 2000.

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