Subject: RE: [Rfid] XML vs. Text vs. Binary

From: [email-masked]
Date: Tue, 2 Aug 2005 14:20:45 -0500

Viewpoint from another hardware vendor: 

If SLRRP gains traction we'll probably want to adapt it to a reader module
with a serial interface to maintain a common interface between readers.
However, if SLRRP is XML-based I don't think it will be viable for serial
I/O.  A minimal text protocol is marginal over serial.  Adding XML (even if
minimal) pushes the bandwidth over the top.

I agree with the human readable arguments of text vs binary.  With text
we've experienced lower training and support costs, faster time-to-market,
etc.  However, I foresee RFID development becoming more specialized with the
proliferation of readers in the supply chain.  It's likely that vertical
application developers will only concern themselves with a high-level
ALE-like interface.  RFID middleware developers will grapple with the
low-level interfaces.  We have a group of network programmers that tell me
they prefer a binary interface.  They have tools (LAN analyzers, etc.) to
work with binary so they're not concerned with human readable.  They argue
that programming to a binary interface is easier/higher performance than
parsing text.

Rob Buck
RFID Software Architect
Intermec Technologies, Corp.
Ofc: 641-472-3082
Cell: 319-573-5294
 
-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Margaret Wasserman
Sent: Saturday, July 23, 2005 8:15 AM
To: Marshall Rose
Cc: [email-masked]
Subject: Re: [Rfid] XML vs. Text vs. Binary

Hi Marshall,

I think we are mostly in agreement about the technical trade-offs, 
but for some reason that doesn't lead us to the same conclusion...

At 9:16 AM +0530 7/23/05, Marshall Rose wrote:
>this brings us back full circle: as soon as you have any level of 
>nesting, human type-in becomes problematic. as soon as you decide 
>that human type-in isn't mandatory, it is trivial to include a 
>standard library to do the heavy lifting while the humans invoke the 
>tool using textual commands.

Yes, if there is any significant nesting, I agree that a human will 
not be able to type the commands in from memory and/or by glancing at 
a reference sheet.  However, I don't see any reason why this protocol 
would require significant nesting, at least for the types of commands 
that a human is likely to use directly.

With a text encoding, a human could also have certain prepared 
commands and be able to cut and paste them into the interface -- a 
command to reset autonomous operation, for example, or to set a 
reader to its default state.  Or they could write simple scripts that 
would send specific commands or command sequences.

>in other words, from where i sit, XML, cXML, etc., enjoy all the 
>drawbacks of both purist approaches.

Correct, from a "human typing" standpoint, XML, cXML and a 
specialized text encoding are all roughly equivalent.  However, in my 
opinion, they are all much better than a binary encoding.

There are two factors involved here, and all three of these choices 
(XML, binary or specialized encodings) are fundamentally different 
WRT these factors:

(1) Can the incoming stream be parsed by a widely available parser, 
or is a specialized parser necessary.  XML parsers are available for 
all likely client systems, but a specialized text encoding or  a 
binary encoding would require a specialized parser.  BTW, subsetting 
XML _does not_ require a specialized parser.  Reader vendors might 
want to includes a specialized (smaller or faster) parser and simply 
reject XML constructs that are not included in the subset, but 
clients could use a regular XML parser for this purpose.

(2) Can text processing tools be used to send control messages and 
interpret the responses, or would binary processing be required. 
Both XML and a specialized text encoding would allow text processing 
of the messages and results, while a binary encoding would require 
binary processing.

You've indicated that it is possible, with a binary encoding, for 
clients to run a tool that gives them text-based access.  That's 
true, but users would need to _get_ that tool from somewhere...  So, 
we are back to requiring specialized code on the client side to 
access this protocol.

This isn't a religious issue with me -- I've just learned the 
benefits of text-based encoding the hard way, and I don't want to 
deal with another binary protocol...  So, for the moment, we may have 
to just agree to disagree.  We'd obviously need to resolve this 
before we can move ahead, though.

Only a few of us have expressed any opinion on this subject. Are 
there others out there that have an opinion?  There are two questions 
that I'd especially like to hear answered by specific other people on 
this list:

(1) I'd like to hear from other reader vendors about whether they 
think that XML would place a prohibitive burden on their readers. It 
has been asserted that XML would have prohibitive system requirements 
for the reader.  That certainly isn't true of ThingMagic's networked 
readers.  In fact, using a standard parser, like XML, would reduce 
our development (especially debugging) and testing costs 
substantially, and would make it more likely that we would implement 
this protocol.

(2) It would be very interesting to know if RFID users would see any 
benefit to a text-based encoding.  Are there folks on this list who 
have RFID installed in real-world or even pilot installations (not 
just a few units in a test lab)?  Do you have any opinions about 
whether the ability to access the reader using text-based tools from 
a client system that doesn't have a specialized client (or library) 
installed would be useful?  Or do you see this as having little/no 
value?

Margaret

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---

From: Bud Biswas <[email-masked]>
Date: Tue, 2 Aug 2005 12:50:12 -0700 (PDT)

I see the usefullness of both XML and binary to different vendors. Altho' it is true that programmers will generally prefer binary to work with, XML is also useful to a different user community (non programmers). My preference would be to see that Readers support binary as mandatory and XML as optional along with the Middleware supports binary as input from reader (mandatory) and XML input as optional. This will allow us to build both "thin" readers as well as "heavy duty" readers where the readers support XML also and may include the middleware software.
 
Bud Biswas

[email-masked] wrote:
Viewpoint from another hardware vendor: 

Rob Buck
RFID Software Architect

-----Original Message-----

Hi Marshall,

Margaret

Polaris Networks
your source for rfid test tools

---

From: Arjun Roychowdhury <[email-masked]>
Date: Tue, 2 Aug 2005 16:31:39 -0400

I am new to the RFID ietf group - however, I do believe it is normal
at the IETF to author requirement documents in situations like this
when there are clearly benefits of both XML and Binary. There have
been several discussions in various groups about XML vs. Binary and
unless there are clearly agreed upon requirements for the protocol in
question, I am pretty sure the discussions will never converge.

In the past, there have been other protocols that support both XML and
binary 'profiles' - however, that does add cost & complexity for the
vendor community.

There are two obvious disadvantages to XML - size and speed. However,
unless there is some concrete discussion on what really size and speed
means relative to the requirements of this interface, that discussion
cannot conclude, again.

I come from the applications space (VoIP, specifically) and my current
interest in RFID network side protocol lies in how to tie it with the
application layer protocol (for location based services) and therefore
naturally think XML suits better for this need.

However, I would love to see a specific requirement document that
gives this community a chance to discuss this issue in a more
structured manner.

regds
arjun

On 8/2/05, Bud Biswas <[email-masked]> wrote:
> I see the usefullness of both XML and binary to different vendors. Altho' it
> is true that programmers will generally prefer binary to work with, XML is
> also useful to a different user community (non programmers). My preference
> would be to see that Readers support binary as mandatory and XML as optional
> along with the Middleware supports binary as input from reader (mandatory)
> and XML input as optional. This will allow us to build both "thin" readers
> as well as "heavy duty" readers where the readers support XML also and may
> include the middleware software.
>  
> Bud Biswas
> 
> 
> low-level interfaces. We have a! group of network programmers that tell me
> >nesting, human! type-in becomes problematic. as soon as you decide 
> (2) Can ! text processing tools be used to send control messages and 
> Only a few of us have expressed any opinion on this subject. Are there
> others out there that have an opinion? There are two questions 
> whether the ability to access t! he reader using text-based tools from 

-- 
Arjun Roychowdhury

---

From: Scott Barvick <[email-masked]>
Date: Tue, 02 Aug 2005 17:25:11 -0400

Rob and Bud raise a topic that has not yet been fully addressed in the
midst of this discussion - the notion of multiple representations of the
protocol.   

This is even different from the carrying the PDUs over multiple
transports (e.g. TCP, serial, ethernet).  As raised in a previous
thread, the concept of supporting transport of SLRRP PDUs over a non-TCP
(serial) transport, while not currently in the initial SLRRP scope, does
not seem to pose a significant burden in terms of specifying,
implementing, or testing.  All of the differences are isolated in the
transport, and the same core protocol code is executed regardless of how
you transport the PDUs to a particular peer.   

However, the idea of specifying different encodings (profiles),
particularly in the case of human readable vs. binary is something that
I feel would not result in an efficient standard nor an efficient
standard development experience.  You end up with not a single protocol,
but as many protocols as you have representations, and the only thing
common about them may be an initial capabilities exchange.  Each
representation then needs the full round of functional, system, and
interoperability testing that would go with any new protocol.  Of
course, interoperability in this sense means only between
implementations of the same encoding, not implicitly for the all
encodings of the protocol.  The base goals to date have been to focus on
a single representation that would have the widest applicability so that
a standard could be developed and deployed as quickly as possible. 

My thoughts only, of course.  I'm sure there are others out there.

Scott  

On Tue, 2005-08-02 at 15:50, Bud Biswas wrote:
> I see the usefullness of both XML and binary to different vendors.
> Altho' it is true that programmers will generally prefer binary to
> work with, XML is also useful to a different user community (non
> programmers). My preference would be to see that Readers support
> binary as mandatory and XML as optional along with the Middleware
> supports binary as input from reader (mandatory) and XML input as
> optional. This will allow us to build both "thin" readers as well as
> "heavy duty" readers where the readers support XML also and may
>         Only a few of us have expressed any opinion on this subject.
>         Are there others out there that have an opinion? There are two
>         questions 
> ______________________________________________________________________