Fast, Efficient Transactions

Avoiding connection setup/reset costs

There are several ways to support transactions efficiently. Both have shortcomings.

Out-of-band signalling

Aggregating connections so that congestion is fair per-user, rather than per-connection, is hard.

• Hard to aggregate state for fairness
  • Per-user division of resources
• E.g., Transaction TCP (T/TCP)

In-band signalling

Muxing several transfers over a single end-to-end connection makes per-user fairness easier to manage, but also makes it harder to implement. This ends up being like "IP over TCP", using the TCP connection as a unit of link and loss. It can be harder to preempt and cancel a file transfer when its so encapsulated.

• Easier to support per-user fairness
• Inhibits network cooperation
  • File as a unit of loss
  • Component cancellation
• E.g., Multi-part MIME encapsulation
• E.g., HTTP encapsulation

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