Christian.Huitema@MIRSA.INRIA.FR (Christian Huitema) (06/30/89)
Both Amanda Walker and J. Zweig mention that production system should not encode the ASN-1 in real time, but should use "canned encodings", e.g. tables of pre encoded commands, on the basis that ASN.1 is nothing but a complex "way of specifying packet formats". This may be true for some other protocols, e.g. XDR, but is hardly a solution in the case of ASN-1/BER for the following reasons: * ASN-1/BER encodings are variable in length. Suppose you use it in X-Window to address a pixel: you will use the INTEGER model. Then, pixel number 127 will be referred to by the ASN1/BER value "02017f"; pixel number 128 will be referred to as "02010080". Just explain me how you build up your table... * ASN-1/BER encodings are not unique: one can choose primitive or structured encoding for strings, the order of the components in a SET is variable, there are many ways to encode a floating point number. As a consequence, some on line decoding cannot be avoided. Canned encodings have a value in some circumstances, one of the best example being that of a file server: if the file are stored on the disk in ASN-1/BER encoding, then the server will not have to encode/decode them during connections. Which boils down to saying that canned incoding is good for canned information... and probably inadequate for randomly generated values. Christian Huitema