Anthony Wiles

1
TD011 STF 213 Status Report (formerly STF187)
(Jens Grabowski, Gyorgy Rethy, Ina
Schieferdecker, Anthony Wiles, Colin Willcock)

• Anthony Wiles
• MTS34
• Rome, April 2002

2
TTCN-3 Edition 2

• For approval (V.2.2.0)
• DES 201 873-1 2 Core Language
• DES 201 873-2 2 Tabular Format
• DES 201 873-3 2 Graphical Format
• DES 201 873-4 1 Operational Semantics
• Issues
• Changes to Core
• Changes and Additional changes to Tabular Format
• Graphical Format (Ina)
• Part 4 - ES or TR?
• CR mechanism
• Use of TTCN-3 by TIPHON

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CRs resulting from vote

• Over 100 CRs received after extended voting
  period
• Mainly from Ericsson
• All resolved to agreement of STF213/Ericsson/TTCN-
  3 list etc)
• All changes are tracked in document CR list
• Catagories of comments
• Editorial (17)
• Test Components (2)
• String/character types/values (10)
• Type compatability etc. (12)
• Import (8)
• Regular expressions (3)
• BNF (4 TTCN-3 list)
• Test steps (1)
• ASN1 (7)
• Encoding (3)
• Miscellaneous (40)

4
Changes to the Core (1) (from v.1.1.0 not just
CRs)

• Editorial/restructuring
• General editorials, corrections to examples, etc.
• Operational semantics -gt Part 4
• Predefined functions included from TS 101 875
• Clarifications
• Scope mechanism, allowed connection of PTCs
• Structural equivalence/type compatability issues
• Corrections/simplifications
• BNF
• Consitent/simpler Import mechanism
• Named alts -gt teststeps -gt altsteps (macro --gt
  functional)
• Timers (no negative values, zero values)

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Changes to the Core (2)

• Corrections/simplifications (cont)
• Operator precedence revised
• PTCs (e.g., scope of PTC identifiers)
• Verdicts (set.verdict -gt setverdict)
• ASN.1 issues (named bits/identifiers, mapping)
• Additions/improvements
• Regular expressions
• Power operators
• Refinement of the port model
• Return value on expressions
• Addition of superset/subset
• Any type
• Additional types (short, long, strings) by
  encoding)
• Ranges for float

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Changes not done

• Default encoding for TTCN-3
• Should be opened as new WI if needed
• Power operators
• Not urgent - can be added later
• IDL Interface
• Should be opened as new WI if needed
• Some work done outside ETSI
• External global timer
• Should be done in connection wit RT TTCN-3

7
Early CRs on v2.2.0

• Received some CRs on v.2.2.0
• One or two BNF corrections
• Few editorials
• Keyword table param -gt parameters
• Change example for referencing nested fields
• Can approve version 2.2.0 here in Rome and fix
  these points in the meantime?
• Put 2.2.0 to vote meanwhile STF213 produces
  2.2.1?
• Produce 2.2.1 then vote? When?

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Changes to the Tabular Format (from v.1.1.0 not
just CRs)

• Some editorials
• A few corrections
• Better format/layout (not technical)
• Brought in-line with changes in Core Language
• Have received some late comments which should be
  fixed
• No real technical change - corrections to mapping
  BNF, examples, references, couple of
  clarifications
• Accepted by the TFT Editor (Thomas Wernitz)
• Can approve version 2.2.0 here in Rome and fix
  these points in the meantime?
• Put 2.2.0 to vote meanwhile STF213 produces
  2.2.1?
• Produce 2.2.1 then vote? When?

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Part 3 - GFT

• Presentation by Ina
• Co-ordination with ITU-T
• OMG (Testing Profile)?

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Part 4 - Operational Semantics

• An ES or TR?
• Plan was to produce version 1 for approval in
  April
• Version 2 in October
• Go to ES twice in same year .!
• Propose to downgrade to TR for version 1 (April)
  and go for ES in October
• Or no approval at this meeting (go straight to
  v2)
• Problem - What to refer to from Part 1?
• TR (which will soon be replaced by )?
• ES (to appear)?
• Nothing?

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CR Mechanism

• CR Mechanism is in place
• Can be found on http//www.etsi.org/ptcc/Change_re
  quest/ptccttcn3cr.htm
• Direct links from MTS Portal and PTCC Website
• Defines Rules and Procedure
• Submission by CR only (downloadable template)
• Full solutions must be provided
• Mailing list TTCN3CR_at_list.etsi.fr
• Initial follow-up (record, number, status, etc) -
  Gyorgy Rethy
• Resolution by STF213, SG, MTS (in that order)
• Discussion (but not decision) on TTCN3 mailing
  list
• Final follow up
• All CRs plus Status List on web)
• Some proposal for text version of CR template
• Word is ETSI standard format
• Need Word formatted solutions, not ASCII

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Use of TTCN in EP TIPHONTM

• EP TIPHONTM
• Telecommunications and Internet protocol
  Harmonization Over networks
• EP TIPHON WG6 Testing and Validation
• STF196 Test specs based on TIPHONTM profiles
  for
• H.225 (TTCN-2)
• H.245 (TTCN-2)
• H.248 (TTCN-2)
• SIP (TTCN-3)
• OSP (TTCN-3)
• BICC (TTCN-2)
• Security - ?
• Interoperability scenarios for H.323-SIP
  interworking (Text)

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What is SIP?

• Session Initiation Protocol, draft RFC2543
• IETF Internet control protocol for
• establishing, changing and tearing down voice and
  multimedia calls
• Like http (sipanthony.wiles_at_etsi.fr)
• Can build services like web pages
• Client-Server behaviour (simple)
• SIP Components
• Use Agents
• SIP Servers (proxy server, redirect server)
• SIP messages are text based
• Defined by a quite complex BNF
• Loose syntax

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Status of TIPHONTM SIP Conformance Test
Specifications

• IETF SIP draft RFC 2543 bis4
• 437 Test Purposes (TSSTP)
• Complete TTCN-3 ATS April 2002 (pure SIP)
• Currently validating ATS on experimental test
  platform
• Will be input to 10th SIPit April 2002
• Fully validated test suite May-June 2002
• Upgrade to bis9 (RFC) July-September
• Upgrade to TIPHON profile based on finalized RFC
  September-December

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Issues with testing SIP (1)

• Behaviour relatively straightforward
• TTCN-3 address type and map function are useful
• SIP Messages are unstructured (ASCII text)
• Pure text gt many messages perhaps with only
  small differences
• Can send as pure text
• but on receive how to match?
• Control vs Readability
• Should we structure (sub-structure) each message
• Or rely on pattern-matching?
• . Or compromise?

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Issues with testing SIP (2)

• Where to place PCO
• Directly over TCP/UDP
• or allow some processing by test system
• Need some form of test adapter
• Does some form of preprocessing
• E.g., remove duplicate spaces and CRLF
• Breaks message into SIP headers (To, From, Via )
• Converts to TTCN-3 types (and vice versa)
• Mapping is defined as part of the ATS
• TTCN-3 module
• Sending of invalid or 'unusual' SIP messages done
  as pure text

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Conceptual SIP Test Architecture
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A Typical SIP Message(Simplified)
SIP/2 200 OK From userBltsipxxx_at_yyy.zzzgt To
userAltsipaaa_at_bbb.cccgt CSeq 1
INVITE Content-Length 0
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SIP Message in TTCN-3(Readability vs
Controllability)
Parameterisation
template SIP_RESPONSE MyResponse (charstring
StatusCode) SIP_Version
"SIP/2.0", Status_Code StatusCode, // use
of parameter Reason_Phrase
"OK", Message_Headers ResponseHeaders, //
Substructure Message_Body omit // SDP
info. Not present template SIP_ HEADERS
ResponseHeaders // setof charstring "From
userBltsipxxx_at_yyy.zzzgt", "To
userAltsipaaa_at_bbb.cccgt", "CSeq 1
INVITE", "Content-Length "
int2char(MBLength), // All other headers are
ignored
Substructure
Setof type
Could use regexps
Function call
Wild cards
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What is OSP?

• Open Settlement Protocol, TS 101 321 V.2.1.1
• Facilitates the exchange of inter-domain
• Pricing
• Authorization
• and Settlement Information
• between Internet telephony operators.
• Works between multiple administrative domains in
  a secure manner
• XML- based
• ASN.1 for authorization
• Can be used with SIP or H.323

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Status of TIPHONTM OSP Conformance Test
Specifications

• TS 101 321 V.2.1.1
• 30 Test Purposes (TSSTP)
• Protocol is very open
• TIPHON profile gt more TPs
• No authorization tests yet gt more TPs
• Currently validating TTCN-3 ATS on experimental
  test platform
• Remote OSP server in US
• Complete June 2002
• May add new test cases in the Autumn (v2)
• E.g., authorization
• if base standard or profile develops

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Issues with testing OSP (1)

• Also simple Client - Server behaviour
• No problem for TTCN-3
• Interleaved behaviour useful (easily handles
  permutations of expected behaviour)
• OSP messages defined in XML
• Need to map OSP XML DTD to TTCN-3
• Not particularly difficult
• A generic mapping would be useful
• Security and Authorization (optionally) uses
  ASN.1
• Not a problem for ATS
• More complex test system as it has to switch
  between XML and ASN.1 encoding
• Not included in this first version of ATS

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Issues with testing OSP (2)

• Where to place PCO
• Directly over TCP or UDP
• or allow some processing by test system?
• Need some form of test adapter
• Does some form of preprocessing
• Converts XML message to TTCN-3 types (and vice
  versa)
• Mapping is defined as part of the ATS
• Sending of invalid or 'unusual' OSP messages done
  as pure XML (ASCII)

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Conceptual OSP Test Architecture
IUT SIP Implementation
TTCN-3 OSP
Adaptation Layer
HTTP
HTTP
SSL TCP
TCP
SSL TCP
TCP
IP
IP
LAN
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A Typical OSP Message in XML
lt!ELEMENT PricingIndication ( Timestamp,
SourceInfo, DestinationInfo, Currency, Amount,
Increment, Unit, Service, ValidAfter, ValidUntil
)gt lt!ATTLIST PricingIndication componentId ID
REQUIREDgt lt!ELEMENT Timestamp
(PCDATA)gt lt!ATTLIST Timestamp critical (true
false) "true"gt
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OSP Message in TTCN-3(Mapping to XML)
type record PricingIndication ID_DTD msgIdFiel
d, CDATA_DTD randField, ID_DTD compIdField,
Timestamp timestamp, SourceInfo sourceInfo, D
estinationInfo destinationInfo, Currency curren
cy, Amount amount, Increment increment, Unit
unit, Service service, ValidAfter validAf
ter, ValidUntil validUntil with encode
(msgIdField, randField, compIdField)
XML_ATTRIBUTE type record Timestamp ENUM_DT
D criticalField (true,false), PCDATA_DTD v
alueField with encode (criticalField)
XML_ATTRIBUTE
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Validation

• Have implemented experimental testing platforms
  for SIP and OSP
• Main task is the implementation of the adaptation
  layers
• Validation of SIP test cases
• Early demonstration at 7th SIPit (March 2001)
• Demonstrated at IMTC Winterop (Dec. 2001)
• Soon able to execute 400 test cases
• Will provide conformance testing 'service' at
  10th SIPit (April 2002)
• Validation of OSP test cases
• Achieved initial connection to remote IUT
  (Transnexus OSP server)
• Full validation will start in March/April
• Finish in June 2002

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Conclusions

• Specific problems when dealing with text-based
  protocols
• How to represent messages
• TTCN-3 has several advantages (over TTCN-2)
• Trigger
• Address type
• Map operations
• Interleaved behaviour
• Data types such as set and set of (no need to use
  ASN.1)
• Regular expressions
• Programming paradigm closer to datacom community
• Have implemented and executed the test suites
• So we know it works!
• Learning curve TTCN-2 -gt TTCN-3 not too high
• ETSI TBs will use TTCN-3 if there is tool (test
  system) support
• TIPHON, 3GPP

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Acknowledgements

• EP TIPHONTM
• Chairman Mr. Hans Van Der Veer
• WG6 Chairman Mr. Klaus Sambor
• STF 176 SIP/OSP team
• Frederique Aurouet, ACACIA (SIP)
• Csaba Koppany, Ericsson (SIP)
• Theo Vassilou-Gioles, Testing Technologies (SIP)
• Scott Moseley, FSCOM (SIP/OSP)
• Sebastian Mueller, FSCOM (OSP)
• Jean-Claude Wattelet, Wattelet Telecoms (OSP)
• Background support
• Nokia, NetTest, Alcatel, Nortel

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• Thank you!