A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 1 Conformance Testing of CORBA Services using Tree and Tabular Combined Notation Alexey Mednonogov Helsinki University of Technology Telecommunications Software and Multimedia Laboratory March 2000, Espoo FINLAND

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 2 Applications and Techniques n n Common Object Request Broker Architecture m m Middleware architecture for transparent communication in heterogeneous environment (platform, language, location) m m Interoperable, robust, high-performance solutions m m Seamless interconnection of multi-vendor services n n Conformance testing of CORBA using TTCN m m TTCN is a mature standardized framework for reusable and automated testing of telecommunication systems m m Key success factor for ensuring reliability of distributed Internet-based CORBA services and applications

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 3 Object Management Architecture n n CORBA is the communications heart of OMA Reference Model n n ORB is a low-level subsystem responsible for transparent communication of objects n n CORBAservices define system interfaces complementing the basic functionality of ORB n n CORBAfacilities provide standard frameworks for defining universal rules of engagement for CORBA- based collaborating objects Object Management Architecture Reference Model

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 4 CORBA Middleware Architecture n n Interface Definition Language (IDL) acts as a primary contract between servers and clients, abstracting from the details of implementation, location in the network and the platform used n n A client can introspect contents of Interface Repository (IFR) to find out which requests can be processed by a specific server and what data types are used n n A server advertises its presence to clients by its Interoperable Object Reference (IOR) OMG Common Object Request Broker Architecture

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 5 Conformance Testing Architecture

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 6 CORBA Services Testing Methodology m m Application-level CORBA clients and servers are being tested using remote test method in a single-party testing context (SPyT) m m Low-level ORB protocols (GIOP/IIOP) and all other ORB components are assumed to be functioning properly m m CORBA/TTCN gateway exploits DII, DSI & IFR to convert TTCN ASP to dynamic request / response and vice versa m m As SUT cannot distinguish whether static or dynamic invocation scheme has been used, the implementation details of test environment are completely transparent from SUT perspective

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 7 IDL/TTCN Mapping: Overview IDL-to-TTCN Mapping Rules in a Nutshell m m Related work of GMD FOKUS & JIDM (NMF and X/Open) shall be acknowledged (basic concepts for mapping IDL operations, type definitions etc. to TTCN language)

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 8 IDL/TTCN Mapping: Details   “Bit stuffing” concept is used for mapping IDL compound identifiers to a single TTCN identifier (symbolic chain “_i” acts as a separator and all “_” characters are duplicated, e.g. IDL “ModA_::_ModB::IntC”  TTCN “PCO1_iModA___i__ModB_iIntC” ) m m CALL_ID field is introduced into every Exception, Call & Reply ASP to uniquely identify operation calls m m Several forms of Registration ASP are defined for binding a specific TTCN PCO with CORBA client or server object m m Our mapping allows catching group of exceptions defined within one IDL module/interface in one TTCN constraint

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 9 IDL/TTCN Mapping: Data Types m m In most cases, IDL data types are naturally mapped to ASN.1 types without complications m m Mapping for IDL “union” shall include information about exact value of discriminator IDL “any” type is a real challenge!

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 10 CORBA/TTCN Gateway: Overview m m Acts as an intermediary between Test System and SUT m m The gateway itself is a CORBA-based Java application (ORBacus from OOC Inc. + OpenTTCN from OES Oy) m m Distributed and interpreted nature of the test environment speeds up design of Abstract Test Suite (ATS), as well as facilitates testing in multi-party context (concurrent TTCN) m m Relatively low performance of Java language is not of crucial importance, as performance measurements in conformance testing are not usually involved

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 11 CORBA/TTCN Gateway: Architecture n n Builder, Visitor & Adapter design patterns are used n n Visitor introspects ASP coming from the test environment n n Builder constructs ASP either from server response or from client operation call n n Adapter performs a technical conversion of information from IFR into internal format n n Asynchronous mode of DII is used, what allows design of concurrent test suites or even simultaneous execution of several test suites served by one gateway component

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 12 Testing Gateway Functionality m m Two groups of test cases, 9 test cases in each group m m One group for testing CORBA servers, another one for testing CORBA clients m m A minimum set of tests of gateway states

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 13 Test Session Example n n Two typical stages of testing CORBA service: m m registering a CORBA object (pCREG_IOR) m m issuing (or accepting) actual operation calls n n IOR used for binding a PCO with CORBA server is supplied to ATS in form of PIXIT parameter

A. Mednonogov / Helsinki University of Technology / Conformance Testing of CORBA Services Using TTCN / / Page 14 Conclusions m m TTCN framework facilitates practical testing of active service components (servers), as it provides formal and standardized means for reusable & automated testing of telecom systems m m Yet, TTCN does not show up enough flexibility in emulating a full-scale functionality of a typical CORBA servant, making TTCN-oriented processing of requests coming from reactive components (clients) look relatively awkward m m If SUT mostly contains active parts (which is normally the case in testing CORBA services), then TTCN framework shall undoubtedly be preferred