Class ResolveContext
resolve
operation.
Resolve Contexts:
- Specify the mandatory and optional resources to resolve. The mandatory and optional resources must be consistent and correct. For example, they must not violate the singleton policy of the implementer.
- Provide
capabilities
that the Resolver can use to satisfyrequirements
via thefindProviders(Requirement)
method - Constrain solutions via the
getWirings()
method. A wiring consists of a map of existingresources
towiring
. - Filter requirements that are part of a resolve operation via the
isEffective(Requirement)
.
A resolver may call the methods on the resolve context any number of times during a resolve operation using any thread. Implementors should ensure that this class is properly thread safe.
Except for insertHostedCapability(List, HostedCapability)
, the
resolve context methods must be idempotent. This means that resources
must have constant capabilities and requirements and the resolve context must
return a consistent set of capabilities, wires and effective requirements.
- Version:
- $Id: f92eae32ab6fadb25e13d226458d6af50e8dcbba $
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprivate static <T> Collection
<T> abstract List
<org.osgi.resource.Capability> findProviders
(org.osgi.resource.Requirement requirement) Find Capabilities that match the given Requirement.Collection
<org.osgi.resource.Resource> Return the resources that must be resolved for this resolve context.Collection
<org.osgi.resource.Resource> Return the resources that the resolver should attempt to resolve for this resolve context.abstract Map
<org.osgi.resource.Resource, org.osgi.resource.Wiring> Returns the wirings for existing resolved resources.abstract int
insertHostedCapability
(List<org.osgi.resource.Capability> capabilities, HostedCapability hostedCapability) Add aHostedCapability
to the list of capabilities returned fromfindProviders(Requirement)
.abstract boolean
isEffective
(org.osgi.resource.Requirement requirement) Test if a given requirement should be wired in the resolve operation.
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Constructor Details
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ResolveContext
public ResolveContext()
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Method Details
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getMandatoryResources
Return the resources that must be resolved for this resolve context.The default implementation returns an empty collection.
- Returns:
- The resources that must be resolved for this resolve context. May be empty if there are no mandatory resources.
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getOptionalResources
Return the resources that the resolver should attempt to resolve for this resolve context. Inability to resolve one of the specified resources will not result in a resolution exception.The default implementation returns an empty collection.
- Returns:
- The resources that the resolver should attempt to resolve for this resolve context. May be empty if there are no mandatory resources.
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emptyCollection
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findProviders
public abstract List<org.osgi.resource.Capability> findProviders(org.osgi.resource.Requirement requirement) Find Capabilities that match the given Requirement.The returned list contains
Capability
objects where the Resource must be the declared Resource of the Capability. The Resolver can then add additionalHostedCapability
objects with theinsertHostedCapability(List, HostedCapability)
method when it, for example, attaches fragments. ThoseHostedCapability
objects will then use the host's Resource which likely differs from the declared Resource of the corresponding Capability.The returned list is in priority order such that the Capabilities with a lower index have a preference over those with a higher index. The resolver must use the
insertHostedCapability(List, HostedCapability)
method to add additional Capabilities to maintain priority order. In general, this is necessary when the Resolver uses Capabilities declared in a Resource but that must originate from an attached host.Each returned Capability must match the given Requirement. This implies that the filter in the Requirement must match as well as any namespace specific directives. For example, the mandatory attributes for the
osgi.wiring.package
namespace.- Parameters:
requirement
- The requirement that a resolver is attempting to satisfy. Must not benull
.- Returns:
- A list of
Capability
objects that match the specified requirement.
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insertHostedCapability
public abstract int insertHostedCapability(List<org.osgi.resource.Capability> capabilities, HostedCapability hostedCapability) Add aHostedCapability
to the list of capabilities returned fromfindProviders(Requirement)
.This method is used by the
Resolver
to add Capabilities that are hosted by another Resource to the list of Capabilities returned fromfindProviders(Requirement)
. This function is necessary to allow fragments to attach to hosts, thereby changing the origin of a Capability. This method must insert the specified HostedCapability in a place that makes the list maintain the preference order. It must return the index in the list of the insertedHostedCapability
.- Parameters:
capabilities
- The list returned fromfindProviders(Requirement)
. Must not benull
.hostedCapability
- The HostedCapability to insert in the specified list. Must not benull
.- Returns:
- The index in the list of the inserted HostedCapability.
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isEffective
public abstract boolean isEffective(org.osgi.resource.Requirement requirement) Test if a given requirement should be wired in the resolve operation. If this method returnsfalse
, then the resolver should ignore this requirement during the resolve operation.The primary use case for this is to test the
effective
directive on the requirement, though implementations are free to use any effective test.- Parameters:
requirement
- The Requirement to test. Must not benull
.- Returns:
true
if the requirement should be considered as part of the resolve operation.
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getWirings
Returns the wirings for existing resolved resources.For example, if this resolve context is for an OSGi framework, then the result would contain all the currently resolved bundles with each bundle's current wiring.
Multiple calls to this method for this resolve context must return the same result.
- Returns:
- The wirings for existing resolved resources. The returned map is unmodifiable.
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