[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Elliotte Rusty Harold on Web Services
On Monday 10 February 2003 16:25, Mark Baker wrote: > On Mon, Feb 10, 2003 at 04:03:09PM +0000, Alaric B. Snell wrote: > > No, they don't, despite both being protocols used to fetch stuff. Neither > > do HTTP, LDAP, ODBC, IMAP, POP3, finger, ftp, tftp, fsp, etc. > > interoperate; yet all of them are based around the concept of fetching > > something. They were all designed to be too specific, trying to limit > > their horizons in the hope of spending less effort on design, but that > > cost was paid later in the effort of expanding the design... > > Not that I agree, but your point is what? That we need a generic "fetch > stuff" layer 6 protocol? > > The problem with that - if that is indeed what you mean - is that > layer 6 isn't where you define "fetch stuff"; that's for layer 7. *scratches head* layer 6 is presentation, the mapping from abstract information to strings of bits... XML and ASN.1 and MIME and so on are layer 6. > So what's needed is not a common layer 6 protocol on which new "fetch > stuff" protocols can be constructed, but a generic layer 7 protocol that > can provide a network interface to those protocols. Hmmm, I sense much confusion. I'm talking about what, in the ISO 7-layer model, is called a Service Element. Layer 6 defined ASN.1. Layer 7 defined applications like email and file transfer, but on top of a kind of toolkit (why not another layer? because the interrelationships start getting complex and nonlinear; it doesn't stack neatly, I gather) of Service Elements. ROSE - Remote Operations Service Element - was your general 'request/response protocol for making applications with'. ACSE - can't remember the acronym; Assocation Control Service Element IIRC - does something to do with managing long-term connections. There's stuff to do with transactions and so on too. And on top of that sat the actual application protocols; the SEs are not protocols themselves, they are more like protocol toolkits. More like the convention in most IETF protocols of single line commands and three-digit response codes, found within SMTP and POP3 and others. But they allow the actual applications to be built on top of something higher-level than raw TCP or UDP! > MB ABS -- A city is like a large, complex, rabbit - ARP
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