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Transis is a group communication system that supports efficient group multicast for high availability.

Transis is developed in the High Availability Laboratory at the Computer Science Department of the Hebrew University of Jerusalem.

Research Leads:

• Prof. Danny Dolev is the head of the Transis group.
• Dr. Dahlia Malkhi

The Transis communication system supports process group communication. Groups are conveniently identified by a name (a string) that is selected by the user, such that messages are addressed to the entire group by specifying the group name. Using the group abstraction, the communication subsystem relieves the user from identifying the targets of messages explicitly, and from finding the network routes to them. In addition, it guarantees all-or-none delivery semantics, and handles message losses and transient network failures transparently.

Transis provides several forms of group multicast operations: FIFO ordered, causally ordered, totally ordered, and safely delivered. The multicast operations differ in their semantics and in their cost (e.g. latency). Generally, FIFO and causal communication are the cheapest and fastest. Intuitively, causal communication guarantees that a response to a certain message will never be delivered before the message. This makes programming somewhat easier, much in the same way that FIFO guarantees make it easier to program two-party interaction. Totally ordered communication incurs a higher delay, and is useful for supporting replicated information, of any kind. The safe multicast guarantees that delivery of a message occurs after all the machines in the network have received a copy of the message. It incurs the largest delay, because it explicitly waits for acknowledgment from all the participating machines.

The Transis approach to advanced group communication has acquired a wide recognition in the academic community, mainly due to the following desirable properties:

1. It employs a highly efficient multicast protocol, based on the Trans protocol (developed by Melliar-Smith et al. at UCSB), that utilizes available hardware multicast.
2. It can sustain extremely high communication throughput due to its effective flow control mechanism, and its simple group design.
3. Is supports partitionable operation, and provides the means for consistently merging components upon recovery.

Related Links:

• Distributed Algorithms and Systems Home Page.
• The Horus project at Cornell University
• Broadcast. ESPRIT Basic Research Project
• The Newtop system
• The Arjuna projrct
• The Relacs project
• Phoenix
• The RMP Project at NASA/WVU Software Research Laboratory Home Page
  
• Amoeba
• The Multicast Transport Protocol Home Page.
  
• Operating Systems Laboratory headed by Andre Schiper at the Swiss Federal Institute of Technology - Lausanne (EPFL)
  
• The CORBA FAQ and Tutorial
  
• The Pegasus project (operating system support for multimedia systems).
  
• Multi-media group toolkits.
  
• TDS group at MIT
  
• Local CORBA Resources
  

The Transis logo was designed by Eyal Ofek.