Issues Raised

TCP-Like Message Transmission.

It is recommended the CMA be modified to be more strongly based on TCP for its message transmission. This would include adopting TCP terminology and deviating from TCP-like service only where necessary.

CAETI Address Space?

An address space that precisely identifies the end points of CMA message exchange needs to be defined. Otherwise, CMA message exchange is not well-defined.

Address Mapping?

In addition to the address space, a mapping between CAETI addresses and the sender and receiver parameters of CMA messages needs to be defined.

Connection Management?

The CMA does not provide any means of managing connections -- e.g., opening a connection, closing a connection or getting the status of a connection. Following TCP connection management is recommended.

Connection Performance?

It seems intended that CAETI connections be implemented either by HTTP, SMTP/POP3, or directly by TCP/IP. Neither HTTP nor SMTP/POP3 are transmission protocols as is TCP, and there service characteristics differ greatly. For example, TCP reliably delivers octets in sequence. This is not a property of HTTP or SMTP/POP3 service. The performance characteristics of these three protocols also differ greatly. For example, although in principle, the learning space demo that was presented in Arlington could have been done using SMTP, performance would have made it totally impractical. To get adequate performance, a more direct use of TCP was required; and because the CMA does not provide the means for TCP connection management, it appears that the CMA cannot support the kind of learning space that was demonstrated in Arlington.

Homogenous Traffic?

Does the traffic over a CAETI address consist only of CMA messages, or can other kinds of messages also flow over the address? This model assumes homogenous CMA traffic. Heterogeneous traffic may be a more realistic assumption.

Message Recognition?

If the message traffic is heterogeneous, how are CMA message types to be distinguished from other kinds of messages?

Message Integrity?

What are the well-formedness requirements CMA messages beyond the syntax that is given in [CAT, 96a]? For example, what are the mandatory parameters? At a minimum, the sender and receiver parameters appear to be mandatory.

Traffic Integrity?

What are the requirements, if any, of the sequence in which CMA message can be exchanged?

Message Packaging.

Some operations will be required to disassemble CMA message sequences into ASCII character sequences and to reassemble ASCII sequences into message sequences. Functionally, these operations will need to satisfy the relation

 reassemble(disassemble(y)=y

for message sequences y.