CXWS: Re-thinking CIMOM Architecture

1. CXWS: Re-thinking CIMOM Architecture Architectural Overview

2. What is CXWS? A Java-based CIMOM technology with: • Clean conceptual basis • Lightweight instances • Simplified provider development

3. Clean Conceptualization • Object-oriented framework (meta-objects actually do things) • Properties really get and set values • Instances and classes are always fully functional, even if lazily realized

4. Lightweight Instances • CIM class definitions impose structure on CIM instances • CXWS leverages this structure as meta-data for instances • A CxInstance is little more than a CxClass reference and an array of object values • CxProperty objects know just which value to get or set (no overhead, no searching) • Provision for lazily-populated instances, built directly from an object path

5. Superior Provider Interface • Java WBEM Services (WBEMSolutions), OpenWBEM, Pegasus all have isomorphic provider interfaces • Merely “pass through” the original client request, without adding value • CXWS’ basic provider interface is one method, two arguments • The surprise: it’s not just simpler, it’s also more powerful!

6. Association Creation: UML

7. JWS Providers • enumerateInstances • enumerateInstanceNames • getInstance • associations, associationNames Are you kidding me? • references, referenceNames • createInstance, setInstance, deleteInstance • execQuery

8. CXWS Providers • Typical “observational” providers implement just one method. • An interface allowing manipulation of objects adds three methods (create, update, delete), but implementation is optional. • Support for “lazy” instances is also optional; adds one additional method.

9. Fewer Execution Paths for (Iterator paths = enumerateInstanceNames(…); paths.hasNext(); ) { CIMInstance inst = getInstance((CIMObjectPath) paths.next(), …); . . . }

10. Fewer Execution Paths for (Iterator insts = enumerateInstances(…); insts.hasNext(); ) { CIMInstance inst = (CIMInstance) insts.next(); . . . } Client exercises a new code path Code stops working!

11. Basic Provider Interface void enumerateDirectInstances (CxCondition cond, InstanceReceiver r) throws Exception • A single all-purpose enumeration method with a simple signature. • The condition argument tells what instances the caller wants. • Candidate instances are passed to InstanceReceiver callback.

12. A Simple Provider public void enumerateDirectInstances(CxCondition cond, InstanceReceiver r) throws Exception { for (int ii = 0; ii < getHbaCount(); ++ii) { r.test(makeHbaInstance(ii)); } } private CxClass cc = …; private CxProperty hbaIndex = cc.getExpectedProperty(“HbaIndex”); private CxClass hbaName = cc.getExpectedProperty(“HbaName”); private CxInstance makeHbaInstance(int ii) { Object[] values = cc.getDefaultValues(); hbaIndex.set(values, new Integer(ii)); hbaName.set(values, getHbaName(ii)); // . . . return new CxInstance(cc, values); }

13. Conditions • A generalization of object path • Like a WHERE clause in a query, but only refers to one class (the condition’s domain) • No parsing required • Support simple but powerful forms of reasoning

14. Instance Receivers • Originally conceived to avoid constantly concatenating Vectors • Serendipitously, opens the door to: • Streaming results • Asynchrony • Reporting partial operation failure

15. Typical Conditions • For enumerateInstances: condition = CxCondition.ALWAYS • For getInstance: condition encodes object path • For references, associators: condition expresses a constraint on the “role” property (inferred if necessary) • Providers should not make assumptions about the nature of the condition

16. Provider Structure • Step one: nested loops • Step two: each loop body becomes a separate method; “select or search” control strategy • Step three (unusual): alternative selection strategies

17. Provider Example (Step 1) public void enumerateDirectInstances(CxCondition cond, InstanceReceiver r) throws Exception { for (Iterator systems = getAllSystems(); systems.hasNext(); ) { System system = (System) systems.next(); for (Iterator devices = system.getAllDevices(); devices.hasNext(); ) r.test(makeInstance((Device) devices.next())); } }

18. Provider Example (Step 2) public void enumerateDirectInstances(CxCondition cond, InstanceReceiver r) throws Exception { if (cond.hasRestriction(systemName)) enumeratePerSystem(getSystem((String) cond.getRestriction(systemName)), cond, r); else for (Iterator systems = getAllSystems(); systems.hasNext(); ) enumeratePerSystem((System) systems.next(), cond, r); } private void enumeratePerSystem(System system, CxCondition cond, InstanceReceiver r) { if (cond.hasRestriction(deviceId)) r.test(makeInstance (system.getDevice((String) cond.getRestriction(deviceId)))); else for (Iterator devices = system.getAllDevices(); devices.hasNext(); ) r.test(makeInstance((Device) devices.next())); }

19. Association Providers • Can be written like any other provider • Or… use AssociationProvider abstract class, based on “relations” • Relations describe how to compute the Antecedent from the Dependent, or vice-versa. • CIM_SystemDevice: trivial to identify the CIM_System associated with a CIM_Device

20. Implementing CIM Methods • CXWS dispatches CIM methods using Java reflection • Provider just implements a Java method whose name and type signature matches that of the CIM method • Providers don’t have to dispatch methods, in the style of invokeMethod()

21. Provider Interface Extensions • LifecycleProvider adds createInstance, setProperties, deleteInstance. • PartialInstanceProvider allows an object path to be used as an instance. If and when access to non-key properties is required, the provider’s retrieveValues method will be called. • DispatchingMethodProvider allows a provider to take more active control over dispatching a CIM method call.

22. The WHERE clause can be processed into a necessary condition for any variable Providers already know how to optimize their search based on conditions, without additional work The condition tends to be more specific if other variables’ values can be assumed, so… The query engine tries to be clever in ordering query variables Query engine recursively processes query variables to achieve effect of nested loops select hba.index, port.index from AixHbaPort port, AixHostBusAdapter hba, AixHbaControlledBy cb where hba.manufacturer = “QLogic” and port = cb.dependent and hba = cb.antecedent Query Processing

23. Pseudo-code for execution plan: foreach (hba such that manufacturer = “Qlogic”) { foreach (cb such that antecedent = hba) { // port is uniquely // determined let port = cb.dependent; produce(hba.index, port.index); } } select hba.index, port.index from AixHbaPort port, AixHostBusAdapter hba, AixHbaControlledBy cb where hba.manufacturer = “QLogic” and port = cb.dependent and hba = cb.antecedent Query Processing

24. CXWS framework CIM-XML over HTTP servlet (DSP0200, DSP0201) CIM-RMI interface (JSR-47) Streaming RMI interface for CIMOM RMI interface for host agents MOF compiler Query engine Simple instance repository JwsProviderConverter adapts Java WBEM Services (JWS) providers to CXWS Reflective CIM model for controlling the CIMOM Interface generator for constructing Java interfaces from CIM class definitions The CXWS Eco-System

25. Cxws_ClassToProvider Management of CXWS is performed by operating on a CIM model of CXWS itself, in the root/reflection namespace: • All CIM classes modeled as instances of the CIM class CXWS_Class. • All Java provider instances exposed by CXWS_Provider CIM class. • Creating an instance of CXWS_ClassToProvider association actually binds a CIM class to its provider. • Separates provider from CIM class definition

26. CXWS_ClassToProvider Example #pragma namespace("root/reflection") instance of CXWS_ClassToProvider { Antecedent = "root/reflection:CXWS_Provider." "JavaName=\"com.appiq.cimom.aix.AixComputerSystemProvider\""; Dependent = "root/reflection:CXWS_Class." "NamespaceName=\"root/cimv2\"," "Name=\"APPIQ_AixComputerSystem\""; };

27. Generated Provider Interface • Automated tool generates Java symbolic constants from CIM namespace: • Class names • Property names • ValueMap values • Also generates static members for the class and property objects, not just names.

28. Generated Interface /**** Interface file generated from CIM class definition for APPIQ_AixComputerSystem ****/ public interface AixComputerSystemProviderInterface extends Provider { public static final String APPIQ_AIX_COMPUTER_SYSTEM = "APPIQ_AixComputerSystem"; . . . public static final String CREATION_CLASS_NAME = "CreationClassName"; public static final String DEDICATED = "Dedicated"; public static final UnsignedInt16 DEDICATED_ACCESS_SERVER = new UnsignedInt16(9); . . . public static final String _CLASS = "APPIQ_AixComputerSystem"; public static final String _NAMESPACE = "root/cimv2"; public static final String _SUPER = "APPIQ_ComputerSystem"; public static final CxNamespace _namespace = CxNamespace.getExistingNamespaceOrNull(_NAMESPACE); public static final CxClass _class = _namespace.getExpectedClass(_CLASS); public static final CxProperty caption = _class.getExpectedProperty(CAPTION); public static final CxProperty description = _class.getExpectedProperty(DESCRIPTION); . . . }