THE HIGH LEVEL ARCHITECTURE FEDERATE CONFORMANCE TESTING PROCESS (REVISED) Margaret Loper, Thom McLean, Margaret Horst, Kyle Crawford Georgia Tech Research Institute Georgia Institute of Technology 347 Ferst Drive Atlanta, Georgia 30332 Keywords High Level Architecture, Compliance Testing, Test Process, Test Tools ABSTRACT: Conformance testing is the process of verifying that an implementation performs in accordance with a particular standard. HLA Conformance testing ensures that a federate performs in accordance with the Interface Specification and the Object Model Template (OMT) standards, per the HLA compliance checklist. In order to determine if a federate performs in accordance with the interface specification and OMT, a series of conformance tests are conducted. This paper describes the current state of the test process and the tests that implement the process. U.S. Department of Defense (DoD) federates will follow the process described in this paper to determine compliance with HLA. 1. Introduction The HLA Compliance process has two parts: Conformance and Certification. Conformance is the process of verifying that an implementation performs in accordance with a particular standard . HLA Conformance testing ensures that a federate performs in accordance with the Interface Specification  and the Object Model Template (OMT)  standards, per the HLA compliance checklist . In order to determine if a federate performs in accordance with the interface specification and OMT, a series of conformance tests are conducted, as described in the remainder of this paper. Certification is the process of validating that a federate has been tested for conformance. This means that once a federate has completed conformance testing, the test results must be validated before the federate can be certified as “HLA Compliant.” A Certification Agent who is accredited by the government executes the certification process. The Certification Agent is legally responsible for validating a federate’s conformance test results. It is important to note that conformance is specific to a federate, not a federation. Therefore once a federate has passed conformance testing and has been certified as HLA Compliant, it can be reused as often as needed in federations. Also note, HLA Compliance does not guarantee federation interoperability, rather it is the first step. 2. Overview of the Conformance Process Conformance testing is a four-step process, as shown in Figure 1. The process described below is the one the DoD will follow to determine if a federate complies with the HLA. More details on the conformance tests can be found in the remainder of this paper. T h e T e st P ro c ess F e d e ra te U n d er T e st STEP 1 C e r t if ic a t io n A g e n t R e q u e s t I n f o r m a tio n o n T e s t P r o c e s s a n d S u b m it A p p lic a tio n C heck C o m p lia n c e D a ta b a s e A d m in P r o c e d u r e s a n d C o n f o r m a n c e G u id e STEP 2 S u b m it C o n f o r m a n c e N o te b o o k : S O M , C o n f o r m a n c e S ta te m e n t, S c e n a r io D a ta R e tu r n S O M T e s t R e s u lts , I F T e s t D a ta ( F O M a n d T e s t S e q u e n c e ) , a n d T e s t D a te STEP 3 S u b m it T e s t E n v ir o n D a ta a n d .r id /.f e d file s ; C o n f ir m T e s t S e q u e n c e a n d D a te C o n f ir m T e s t I n f o ( D a te , S e q u e n c e , E n v ir o n ) STEP 4 E x e c u te I F T e s t R e tu r n I F T e s t R e s u lts a n d C S R C onduct SO M and C o n fo r m a n c e X - C h e c k T e s ts ; G e n e r a te T e s t D a ta C h eck T est S c h e d u le L o g D a ta a n d A n a ly z e , G e n e r a te T e s t R e s u lts Figure 1: HLA Conformance Test Process In Step 1 of the Conformance process, the developers of a federate request information on the test process from the Certification Agent by completing a HLA test application. The Certification Agent checks the official Compliance Database to determine the federate’s priority for compliance testing and responds with administrative procedures and the Conformance Guide which describes the conformance tests. It is important to note that the test process is initiated by the federate developer, not the Certification Agent, and it is the responsibility of the federate developer to ensure that the federate under test (FUT) represents a stable and mature release of code. Ideally, the test process should be initiated late in beta testing, so that the actual tests are performed on the release version of the code. In Step 2 of the test process, the federate developer submits the Conformance Notebook (CN) to the Certification Agent. The CN includes the Simulation Object Model (SOM), the Federate Conformance Statement (CS), and, as an option, Scenario Data. The CS is a record of the Interface services a federate can invoke and respond to (described in section 3.3 below); Scenario data describes existing scenarios the federate can execute which invoke the Interface services asserted in the CS. The Certification Agent checks the SOM for conformance to the OMT (“SOM Conformance Test”) and, once conformant, the Certification Agent checks the SOM against the CS for consistency (“Conformance Cross-Check”). Results for the first two tests are then returned to the federate developer. Once the FUT successfully passes the SOM and Conformance Cross-Check tests, the Certification Agent uses the SOM, CS and Scenario data to generate a Test Sequence and Test FOM to be used by the FUT during the Interface (IF) test. The Test Sequence and Test FOM indicate the services the federate must invoke and the range of data it must use to prove it implements the Interface services correctly. The Test FOM and Test Sequence are described in Section 3.3. In addition to the IF test data, the Certification Agent sends the federate developer instructions for downloading the version of the Run Time Infrastructure (RTI) that is instrumented for testing. The FUT is required to use this particular RTI version for IF testing. The Certification Agent proposes a date and time for IF testing based on other testing commitments in a schedule maintained by the Certification Agent. In Step 3, the federate developer reviews the Test FOM and Test Sequence generated by the Certification Agent, download and install the RTI to use for testing at the developer’s site, and submit test environment data to the Certification Agent. At this point, both the federate developer and the Certification Agent confirms the test date and time. The FUT must be able to connect to the RTI that is instrumented for testing and must be prepared to conduct the test sequence multiple times. In Step 4 of the test process, the IF test is executed by the federate developer and the Certification Agent. The IF Test uses two types of input data to verify the correct implementation of the Interface services by the federate. First is Nominal test data, which ensures that the FUT can invoke and respond to all services for which it is capable, per its CS. The second type of data is the Representative SOM (RepSOM), which ensures that the FUT is capable of invoking and responding to services using the range of data contained in its SOM (as suggested by the Scenario data if supplied). The Certification Agent logs service data from the test, analyze the data, generate test results, and return a Certification Summary Report (CSR) to the federate developer. The CSR is the official record of HLA compliance for the specific version of the federate code tested. 3. Conformance Tests The conformance processes for the object model template and interface specification are distinct but related. For each standard, there are several distinct tests a FUT must complete. Then to test the rules, a consistency test is performed between the OMT and IF. These tests are described below. 3.1 SOM Conformance Testing In accordance with Federate compliance checklist item 1, a federate must have a Simulation Object Model in the OMT format. In order to facilitate automated testing, the SOM is tested using the OMT Data Interchange Format (DIF) . The DIF is a standard file exchange format used to store and transfer object models between OMT development tools. The SOM conformance test process has three parts: Parseability: ensure the SOM DIF is readable, Completeness: ensure that all required data in tables have been completed, Consistency: ensure that data are consistent across tables. The parseability test is not strictly part of conformance, but is a requirement of the automated testing process, which ensures that the DIF is readable. The completeness and consistency checks are conducted in accordance with the OMT Test Procedures . 3.1.1 Parseability The parseability tests ensure that the Object Model conforms to the DIF standard . Because of the specificity of the DIF, simply parsing the DIF file can reveal many potential problems in an object model. The parseability test is completed simply through a parse tool, which is programmed to accept only DIF conformant data. 3.1.2 Completeness and Consistency The completeness of an object model ensures that it is self-sufficient. That is, it goes beyond what is specifically required in the DIF format definition to ensure that each element of the object model is fully defined, and all dependencies are resolvable. For example, if a class is defined as having a superclass, the completeness checks ensure that the definition of that superclass exists. Consistency checks enforce context dependent rules on the object model, which are not defined in the DIF. The consistency checks are designed to catch logic errors in the definition of an object model. Below are examples of the specific checks for parseability, completeness and consistency used in one of the Object Model Development Tools developed under DMSO sponsorship . Object Model Check for the existence of at least one class. Classes 1. The class name is checked in order to make sure it conforms to the OMT DIF 2. 3. 4. 5. specification. [REF 5, section 2.2 Basic BNF Constructs]. The class name is checked to make sure it does not conflict with another class. [REF 3, section 3.1.1 Purpose/Rationale]. The number of superclasses is checked to insure that the class does not inherit from more than one superclass. [REF 3, section 3.1.1 Purpose/Rationale]. The Publish and Subscribe options are checked depending on the model type of FOM or SOM. [REF 3, section 3.12]. Class definitions are checked to insure that each class has its own textual description. Attributes 1. The attribute name is checked in order to make sure it conforms to the C standard for user declared variables. [REF 5, section 2.2 Basic BNF Constructs]. 2. The attribute name is checked to make sure it does not conflict with another attribute in its owning class. [REF 3, section 3.3.2] 1. The attribute name is then checked to make sure it does not conflict with another attribute that is inherited by its owning class. Subclass attributes are not checked at this point because as classes are checked all superclasses and subclasses are checked and any duplicate attributes are detected in the hierarchy. [REF 3, section 3.3.2] 3. Transferable and Acceptable options are checked. For a SOM the legitimate combinations are T-Transferable, AAcceptable, TA, and N-Neither. For a FOM, the legitimate combinations are TA and N. [REF 3, section 3.3.2 Table Format]. 4. Updateable and Reflectable options are checked. For a SOM the legitimate combinations are U- Updateable, RReflectable, and UR. For a FOM, the only legitimate combination is UR. [REF 3, section 3.3.2 Table Format]. 5. Class definitions are checked to insure that each attribute has its own textual description. 3.2 Conformance Cross-Check Testing The conformance cross-check rules, shown in Table 1, list each OMT Table with its required interface services, corresponding Interface Specification  reference, and OMT  reference. For the cross-check test, the services asserted in the FUT’s Conformance Statement are compared to the services implied by the FUT’s SOM to determine if the two specifications are consistent. 3.3 Interface Testing In accordance with Federate compliance checklist items 2-6, a federate must be capable of supporting the services in the Interface Specification, and as specified in its SOM. The services a federate can invoke and respond to are recorded in a Federate Conformance Statement. The Conformance Statement, in the format indicated in Table 2, is a list of all the interface services with their corresponding Interface Specification  reference, OMT  reference, HLA Compliance Checklist  reference, and whether the service is optional or mandatory, per the Compliance Checklist. A FUT is required to complete the Conformance Statement indicating which services the federate supports when submitting the Conformance Notebook. Only the services specifically asserted in the Conformance Statement are tested using the procedures outlined in the IF Specification Test Procedures . Two types of input data are used to verify the correct implementation of the services asserted in the Conformance Statement. The Nominal test data ensures that the FUT can invoke and respond to all services for which it is capable per its CS. The Representative SOM (RepSOM) test data ensures that the FUT is capable of invoking and responding to services using the range of data contained in its SOM, as suggested by Scenario Data (if supplied by the FUT in its Conformance Notebook). In order to pass the interface tests, the federate must execute a Test Sequence (scenario) which proves it can invoke and respond to the services as specified in the nominal and RepSOM test data. The Test Sequence can be based on a federate’s existing scenario data (if scenario data submitted) or it can be arbitrarily generated by the certification agent. These tests are described more fully below. OMT Table Object Class (P) (S) Object Interaction (I) (S) (R) Attribute/Parameter (T) Active (T) Passive (A) Active (A) Passive (U) (R) IF Service Name OMT Reference IF Reference Publish Object Class Register Object Subscribe Object Class Attributes Discover Object sec 3.1.2, page 10 sec 3.1.2, page 10 sec 3.1.2, page 10 sec 3.1.2, page 10 3.1 4.2 3.3 4.4 Publish Interaction Class Send Interaction Subscribe Interaction Class Receive Interaction Receive Interaction Update Attribute Values Publish Object Class sec 3.2.2, page 19 sec 3.2.2, page 20 sec 3.2.2, page 20 sec 3.2.2, page 20 sec 3.2.2, page 20 sec 3.2.2, page 20 sec 3.2.2, page 20 3.2 4.6 3.4 4.7 4.7 4.3 3.1 Request Attribute Ownership Divestiture Attribute Ownership Divestiture Notification† Update Attribute Values Publish Object Class Request Attribute Ownership Release† Attribute Ownership Acquisition Notification† Update Attribute Values Publish Object Class Request Attribute Ownership Acquisition Attribute Ownership Acquisition Notification† Update Attribute Values Request Attribute Ownership Assumption† Attribute Ownership Acquisition Notification† Update Attribute Values Update Attribute Values Publish Object Class Reflect Attribute Values Subscribe Object Class Attributes sec 3.3.2, page 27 5.1 sec 3.3.2, page 27 5.3 sec 3.3.2, page 27 sec 3.3.2, page 27 sec 3.3.2, page 27 4.3 3.1 5.6 sec 3.3.2, page 27 5.4 sec 3.3.2, page 27 sec 3.3.2, page 27 sec 3.3.2, page 28 4.3 3.1 5.5 sec 3.3.2, page 28 5.4 sec 3.3.2, page 28 sec 3.3.2, page 28 4.3 5.2 sec 3.3.2, page 28 5.4 sec 3.3.2, page 28 sec 3.3.2, page 28 sec 3.3.2, page 28 sec 3.3.2, page 28 sec 3.3.2, page 28 4.3 4.3 3.1 4.5 3.3 Table 1: Conformance Cross Check (v0.2, 10 April 1997) SERVICE GROUP Create/Destroy Join/Resign Pause/Resume Save/Restore SERVICE Create Federation Execution Destroy Federation Execution Join Federation Execution Resign Federation Execution Request Pause Initiate Pause† Paused Achieved Request Resume Initiate Resume† Resume Achieved Request Federation Save Initiate Federate Save† Federation Save Begun Federation Save Achieved Request Restore Initiate Restore† Restore Achieved IF Ref 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 OMT Ref None None None None None None None None None None None None None None None None None Check List Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 Item 6 M/O M M M M O O O O O O O O O O O O O Supported? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No No Table 2: (Partial) Conformance Statement 3.3.1 Nominal Test Data 3.3.2 Representative SOM Test Data The Nominal test data ensures that the FUT can invoke and respond to all services for which it is capable. As shown in Figure 2, the Conformance Statement is compared to the Master Sequence to create the Nominal Sequence of services that the FUT can support. The Master Sequence is a dependency tree of all services defined in the IF Specification . Where true dependencies exist (e.g., Publish before Update), the Master Sequence shows a mandatory ordering. If no dependency exists (e.g., Update and Pause), the Master Sequence ordering is arbitrary. Therefore, the Nominal sequence is an ordering of IF services the federate can invoke. If the FUT can invoke and respond to all services in the IF specification, its nominal sequence is equivalent to the Master sequence. The RepSOM test data ensures that the FUT is capable of invoking and responding to services using the range of data contained in its SOM. For example, a FUT may be capable of representing multiple objects, attributes, and interactions. Instead of attempting an exhaustive test using all combinations of the objects, attributes, and interactions, a subset of the SOM is chosen by the Certification Agent, which represents a valid range of SOM data. This “logical subset” forms the FUT’s Test FOM that is the basis for RepSOM testing. The RepSOM test data is generated from the SOM and available Scenario Data submitted with the Conformance Notebook, as shown in Figure 2. The logical subset is derived from the SOM by a set of rules, which select one to three instances from each object, attribute, and interaction table. FUT Conformance Notebook of FUT’s SOM Figure 2: NominalSubset and RepSOM Tests Used to Create Test Sequence SOM RepSOM Available Scenario Data + Conformance Statement ∩ Master Sequence Test FOM & Test Sequence FUT Nominal Sequence RTI Sequence of services FUT can support Sequence of all services in IFSpec 3.3.3 IF Test Sequence Taking the Nominal Sequence and expanding it by the RepSOM data generates the final Test Sequence, as shown in Figure 2. The final Test Sequence is, therefore, context sensitive as compared to the nominal sequence. The FUT should be prepared to execute the Test Sequence multiple times within the Test Federation, as specified by the Certification Agent. The Certification Agent logs service interactions via Management Object Model (MOM) interaction reports, for later analysis and report generation. 4. Test Instructions This section describes how to prepare for the Conformance tests. 4.1 Conformance Notebook The Conformance Notebook is the information a FUT brings to the test and is comprised of three items: the Simulation Object Model, Conformance Statement, and (optional) Scenario Data. The SOM should be submitted in OMT Data Interchange Format as described in . The CS (shown in part in Table 2) can be submitted in hardcopy or electronically. If submitted electronically, the CS must be an ascii text file which contains the name of every I/F service, indicating with YES or NO whether the federate supports each particular service. The following notation gives an example of the beginning of a CS file: createFederationExecution YES destroyFederationExecution YES JoinFederationExecution YES resignFederationExecution YES requestPause NO initiatePause NO … The last part of the Conformance Notebook is the Scenario Data. This part of the Conformance Notebook is optional and is not required for conformance testing. The purpose of Scenario Data is to assist the Certification Agent in developing the RepSOM for the FUT. It is recognized that developing a scenario which satisfies the requirements of the Test Sequence can be both labor intensive and costly for some federates. It is not the intent of the RepSOM test to add cost and complexity to conformance testing. Therefore a federate can submit existing Scenario Data in its Conformance Notebook to aid the Certification Agent in developing a Test FOM test that meets the objectives of the conformance tests. The format for submitting the scenario data is shown in Figure 3. Figure 3: Scenario Data Format, v 0.1, 25 April 1997 (Scenario (meta-data) (Objects (Object_name instance_count controlled (Attrib_name transferred acquired) (Attrib_name transferred acquired) ..... ) ) (Interactions (Interaction_name controlled (Parameter_name) (Parameter_name) .... ) ) ) 4.1.1 Interface Test Set-Up On test day, the FUT shall be prepared to execute the test sequence using the version of the RTI instrumented for testing. The federate developer must show the testing representative all configuration files relevant to the test. To conduct a test for the interface specification, at least two federates are required. The first federate is the FUT, which contains the implementation being tested. The second and subsequent auxiliary federates are present, as required by the FUT, to demonstrate the test sequence. For example, the FUT may be designed to function in a federation with others like itself, therefore, multiple instances of the FUT are could be used as auxiliary federates. If, on the other hand, a FUT is designed to work as a specialized subsystem within a broader framework, the FUT would require a sufficiently sophisticated set of auxiliary federates to provide all necessary input and output for the test sequence. In either case, it is the responsibility of the federate developer to ensure that all necessary auxiliary federates are present and operating during each test period. For the purpose of conformance testing, a specially configured federate, referred to as the Test Utility, must also be present and performs federation management activities during the test period. The Test Utility subscribes to Management Object Model level attributes to record service interactions between the FUT and the RTI. The FUT and Test Utility are connected via the RTI, as shown in Figure 4. FUT executes test sequence using scenario and auxiliary federates, as required Test Utility joins federation and logs service invocations using MOM Auxiliary Federates present during testing IF Test Sequence Test Utility FUT Service Interaction Report Log MOM data is then analyzed using Nominal and RepSOM data Analysis RTI IF Test Report IF Test Report is generated Figure 4: Interface Test Configuration Along with the environment data submitted in Step 3, the FUT submits the .rid and .fed file used to initialize the RTI. The Test Utility is configured to operate in the execution with the FUT. During the start of the test period, the Test Utility is initialized and joins the execution after the FUT has created and joined the federation execution. The Test Utility initializes and begins logging service invocations via MOM  service interaction reports. Upon completion of a test sequence, the logging may be stopped at any time, and the test log is immediately labeled and stored for post processing. The final step of the interface testing involves the post processing of the test logs. The Interaction Report Post Processor tool is designed to reduce and analyze Service Interaction Report Logs to determine whether each service in the test sequence was demonstrated and whether the classes, interactions, and attributes specified in the RepSOM were demonstrated. 5. Certification Summary Report Once the conformance tests are completed, the Certification Agent generates a Certification Summary Report (CSR), as shown in Figure 5. The CSR stands as the official record of conformance testing. Once the Certification Agent has verified the data as correct, and the FUT has successfully completed all tests, the Certification Agent can certify the FUT is HLA Compliant. Federate Under Test Information Name Version Number Developer’s Point of Contact for Testing Test Configuration RTI Federation Executive (fedex) Host Application Programmer’s Interface (API) Used Federate Hardware Federate Software .fed and .rid Files Test Results Object Model Tests Pass/Deficiencies with comments Conformance Cross-Check Tests Pass/Deficiencies with comments Interface Tests Pass/Deficiencies with comments Supporting Information SOM (in DIF) Conformance Statement Test FOM Test Sequence Figure 5: Certification Summary Report  6. References      Knightson, K.: OSI Protocol Conformance Testing: IS 9646 Explained, McGraw-Hill, New York, 1993. Defense Modeling and Simulation Office, High Level Architecture Interface Specification, Version 1.1, 4 February 1997. Defense Modeling and Simulation Office, High Level Architecture Object Model Template, Version 1.1, 12 February 1997. Defense Modeling and Simulation Office, High Level Architecture Compliance Checklist, Version 1.1, 2 March 1997. Defense Modeling and Simulation Office, High Level Architecture Object Model Template Data Interchange Format, Version 1.2, 10 March 1997.    Defense Modeling and Simulation Office, High Level Architecture Object Model Template Test Procedures, Version 1.0, 5 September 1996. Aegis Research Corporation, Software Design Specification for OMDT Version 1.0 Beta, Module Consistency Checker, 27 February 1977. Defense Modeling and Simulation Office, High Level Architecture Interface Specification Test Procedures, Version 1.1, 25 April 1997. Defense Modeling and Simulation Office, High Level Architecture Management Object Model, Version 0.2, 17 October 1996.