Transcript CIMIQ-X WBEM Services

CXWS:
Re-thinking CIMOM
Architecture
Architectural Overview
What is CXWS?
A Java-based CIMOM technology with:
• Clean conceptual basis
• Lightweight instances
• Simplified provider development
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
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
Superior Provider Interface
• Java WBEM Services (WBEMSolutions),
OpenWBEM, Pegasus all have isomorphic
provider interfaces
o Merely “pass through” the original client
request, without adding value
• CXWS’ basic provider interface is one
method, two arguments
o The surprise: it’s not just simpler, it’s also
more powerful!
Association Creation: UML
JWS Providers
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enumerateInstances
enumerateInstanceNames
getInstance
associations, associationNames
references, referenceNames
createInstance, setInstance, deleteInstance
execQuery
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.
Fewer Execution Paths
for (Iterator paths = enumerateInstanceNames(…);
paths.hasNext(); )
{
CIMInstance inst =
getInstance((CIMObjectPath) paths.next(), …);
. . .
}
Fewer Execution Paths
for (Iterator insts = enumerateInstances(…);
insts.hasNext(); )
{
CIMInstance inst = (CIMInstance) insts.next();
. . .
}
Client exercises a new code path
Code stops working!
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.
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);
}
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
Instance Receivers
• Originally conceived to avoid constantly
concatenating Vectors
• Serendipitously, opens the door to:
o Streaming results
o Asynchrony
o Reporting partial operation failure
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
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
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()));
}
}
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()));
}
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 viceversa.
• CIM_SystemDevice: trivial to identify the
CIM_System associated with a
CIM_Device
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()
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.
Query Processing
select hba.index, port.index
from AixHbaPort port,
AixHostBusAdapter hba,
AixHbaControlledBy cb
where hba.manufacturer =
“QLogic”
and port = cb.dependent
and hba = cb.antecedent
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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
Query Processing
select hba.index, port.index
from AixHbaPort port,
AixHostBusAdapter hba,
AixHbaControlledBy cb
where hba.manufacturer =
“QLogic”
and port = cb.dependent
and hba = cb.antecedent
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);
}
}
The CXWS Eco-System
• CXWS framework
• CIM-XML over HTTP
servlet (DSP0200,
DSP0201)
• CIM-RMI interface (JSR47)
• 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
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
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\"";
};
Generated Provider Interface
• Automated tool generates Java symbolic
constants from CIM namespace:
o Class names
o Property names
o ValueMap values
• Also generates static members for the
class and property objects, not just names.
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);
. . .
}