Subject: APPN End Node Validation

From: "Allen, Michael" <[email-masked]>
Date: Fri, 14 Apr 95 16:46:00 PDT

We have reviewed "SNAP APPN V1.0 End Node Conformance FV Test Items", dated 
 October 7, 1994, submitted by Data Connection Limited, and we have some 
comments and concerns that we would like to share.

First of all, I would like to compliment the authors on a well organized and 
thorough document.  This document is potentially quite useful to product 
developers looking for guidance in performing thorough internal testing of 
an APPN product.

However, we are concerned about the proposal to adopt this document as a 
conformance specification for APPN EN products.  The implication of a 
conformance specification is that companies must certify that their products 
conform to it or they will not be able to say that their products implement 
APPN.  Our concerns with the current proposal center around the following 
 points:

1.  The document has a strong emphasis upon the internal interactions 
between node components, based upon the architecture reference model.   But 
internal interactions within a product are not subject to standardization by 
the APPN architecture.  Product developers have the freedom to create 
internal designs that may differ significantly from the architecture model. 
 The architecture node model was never intended to be more than just an 
example, an illustration, a prototype.

2.  The document attempts to be exhaustive in its coverage of APPN 
functions, options, and error cases.  While this may seem to be an excellent 
goal, we are concerned that it is an impractical goal because of its scope. 
 It would be very difficult to create a suite of test cases that actually 
implemented all of the tests described in this proposal.

Although we are not opposed to a conformance specification for APPN 
products, we do believe that conformance activity should be given a lower 
priority than interoperability testing, such as the connect-a-thon. 
 However, given that this group is considering a proposal for a conformance 
specification, we would like to provoke some more discussion.  We believe 
that an APPN conformance specification should have the following 
characteristics:

1.  An APPN conformance specification should be based upon external flows 
rather than internal interactions between node components in the 
architectural model.  There are two reasons for this:

    a.  External flows are observable and can be validated independently by 
standardized test suites

    b.  The architecture itself does not require that implementations match 
the internal architecture model

2.  An APPN conformance specification should consist of a set of basic 
assurance tests.  If we attempt to create an exhaustive conformance 
specification, covering everything in the APPN architecture, certification 
becomes a very large task, and independent validation via standardized test 
suites becomes impractical.  We believe that verifiable conformance, even if 
it does not attempt to cover every detail of the architecture and every 
possible network scenario, is more valuable than self certification.

We believe that these characteristics of conformance align with customer 
expectations.  Their expectation is that APPN certification means that a 
product will interoperate reliably with existing APPN products in real-world 
networks.  Internal design details of a product are not a significant 
factor, certainly not in comparison to how well a product meets the 
requirements for a particular application, and its demonstrated performance, 
reliability, and ease of installation and use.

To stimulate this discussion, we have created a proposal document titled 
"APPN End Node Basic Assurance Tests" and placed it on the AIW FTP server. 
 The file is

     aiw/validation/doc/entest.ps

Please let me know if you have difficulty printing the document.  It was 
created with Microsoft Word 6.0 and formatted for a postscript device.

I look forward to talking with you at the AIW.

Regards,
Mike Allen

..............................................
[email-masked]        
206-844-3505

Wall Data, Inc.
P.O. Box 1120
Duvall, WA  98021