12.1 Node management function
The node management function controls processing, storage and communication functions within a node.
The node management function is provided by each nucleus at one or more node management interfaces.
Each capsule uses a node management interface distinct from the node management interfaces used by other capsules in the same node.
The node management function
-- manages threads;
-- accesses clocks and manages timers;
-- creates channels and locates interfaces;
Within the architecture defined by this Reference Model, the node management function is used by all other functions.
12.1.1 Thread management
Node management interfaces provides functions to spawn and fork threads within a capsule and to join, delay and synchronize threads within a capsule.
12.1.2 Clock access and timer management
Node management interfaces provides functions to determine the current time in a specified clock management domain and to start, monitor and cancel timers.
12.1.3 Channel creation and interface location
Node management interfaces provides functions to
a) enable binding between an engineering object within a capsule and an instance of the trading function;
b) make an engineering interface available for binding to objects in other capsules;
c) establish a binding between an engineering object within a capsule and a set of other engineering objects (identified by engineering interface references);
d) from a specified engineering interface reference, determine the channel type and communications interface it implies.
1 The use of interactions b) and c) is explained in 8.2.3.
2 Interaction d) exposes the information content of the interface reference, enabling it to be stored or transformed for use in an different interface reference management domain.
Making an interface available for binding to objects in other capsules - interaction b) above - consists of the following actions:
-- assigning an engineering interface reference within a nominated engineering interface reference management domain;
-- assigning a communications interface through which bindings to the interface can be established;
-- assigning a channel type to the interface.
12.1.4 Capsule template instantiation and capsule deletion
Node management interfaces provide functions to instantiate capsule templates and to delete capsules.
Capsule template instantiation consists of the following steps:
-- allocation of processing, storage and communication functions for a new capsule in the same node as the nucleus providing the node management interface;
-- creating a capsule manager for the new capsule;
-- creating a capsule management interface in the new capsule manager;
-- producing an identifier for the capsule management interface;
-- creating a capsule control interface for the new capsule in the nucleus;
-- producing an identifier for the capsule control interface.
The capsule control interface produced by capsule template instantiation enables deletion of the capsule (e.g., when its manager has failed).
Deletion of a capsule deletes all objects in the capsule.
12.2 Object management function
The object management function checkpoints and deletes objects.
When an object belongs to a cluster that can be deactivated, checkpointed or migrated, the object must have an object management interface in which it provides one or more of the following functions:
-- checkpointing the object;
-- deleting the object.
1 Thus different object management interfaces can have different interface types depending upon which functions they support.
2 Checkpointing an object produces information suitable for incorporation into a cluster checkpoint.
3 When an object is deleted, stubs, binders, protocol objects and interceptors supporting bindings to the object can be deleted.
The object management function is used by the cluster management function.
12.3 Cluster management function
The cluster management function checkpoints, recovers, migrates, deactivates or deletes clusters and is provided by each cluster manager at a cluster management interface, comprising one or more of the following functions with respect to the managed cluster:
-- modifying cluster management policy (e.g., for the location of checkpoints of its cluster, for the use of the relocation function to trigger reactivation or recovery of the cluster);
-- deactivating the cluster;
-- checkpointing the cluster;
-- replacing the cluster with a new one instantiated from a cluster checkpoint (i.e., deletion followed by recovery);
-- migrating the cluster to another capsule (using the migration function);
-- deleting cluster.
NOTE - Thus different cluster management interfaces can have different interface types depending upon which functions they support.
The behaviour of a cluster manager is constrained by the management policy for its cluster. Cluster checkpointing and deactivation is only possible if all objects in the cluster have object management interfaces supporting the object checkpointing function. Deactivation and cluster deletion both require that the objects in the cluster support object deletion.
Within the architecture defined by this Reference Model
-- the cluster management function is used by the capsule management function, the deactivation and reactivation function, the checkpoint and recovery function, the migration function and the engineering interface reference management function;
-- the cluster management function uses the storage function for keeping checkpoints.
12.3.1 Cluster checkpoint
A cluster checkpoint contains information needed to re-establish a cluster and includes the following elements:
a) checkpoints of the objects in the cluster;
b) the configuration of the objects in the cluster;
c) sufficient information to re-establish distributed bindings that involve objects in the cluster.
NOTE - Engineering interface references are an essential part of the information required to establish bindings. A cluster checkpoint will contain all of the engineering references arising from a) and c) above.
12.3.2 Cluster deletion, deactivation and failure
Cluster deletion deletes all the objects in the cluster, the cluster manager and any objects solely supporting the cluster or its cluster manager (e.g., stubs and binders). Cluster deactivation is coordinated by the deactivation and reactivation function; it produces a checkpoint of the cluster, then deletes the cluster and its supporting structure. Cluster failure causes deletion of all objects in the cluster and, in some cases, leads to deleting the cluster's supporting structure.
12.3.3 Cluster reactivation and recovery
A deactivated cluster can be reactivated from one of its checkpoints. Cluster reactivation is a necessarily a capsule management function because the cluster manager is deleted as part of cluster deactivation. A cluster can be recovered from one of its checkpoints. If the associated cluster manager has not been deleted, it can initiate recovery; otherwise recovery is a capsule management function and includes creation of a new cluster manager.
12.3.4 Cluster migration
Cluster migration consists of the cloning of a source cluster in a target capsule followed by deletion of the source cluster. It is coordinated by the migration function and is parameterized by a capsule management interface for the target capsule for the migrated cluster.
12.4 Capsule management function
The capsule management function instantiates clusters (including recovery and reactivation), checkpoints all the clusters in a capsule, deactivates all the clusters in a capsule and deletes capsules. It is provided by each capsule manager at a capsule management interface comprising one or more of the following functions with respect to the managed capsule:
-- instantiation (within the capsule) of a cluster template;
NOTE - this includes reactivation and recovery.
-- deactivation of the capsule by deactivating all the clusters within it (using the cluster management function);
-- checkpointing the capsule by checkpointing all the clusters in the capsule (using the cluster management function);
-- deleting the capsule, by deleting all the clusters within it, followed by deletion of the capsule manager for the capsule.
NOTE - Thus different capsule management interfaces can have different types, depending upon which functions they support.
The behaviour of a capsule manager is constrained by the management policy for its capsule.
Within the architecture defined by this Reference Model, the capsule management function is used by the deactivation and reactivation function, the checkpoint and recovery function and the migration function.
12.4.1 Cluster template instantiation
Cluster template instantiation is parameterized by a cluster template and consists of the following steps:
-- instantiating a cluster from a cluster template;
-- introducing a cluster manager for the new cluster;
-- producing an identifier for a cluster management interface in the new cluster manager;
-- binding the new cluster to other objects according to the engineering language rules and the binding information in the cluster template.
NOTE - Cluster reactivation and cluster recovery are special cases of cluster instantiation, in which case the cluster template is a cluster checkpoint.
A cluster template can contain information specific to a domain. If the template is to be instantiated in another domain, then this information must be transformed. In particular, engineering interface references contained in the cluster must be transformed if the cluster is being instantiated in a different engineering interface reference management domain.
12.4.2 Capsule deletion
Capsule deletion entails deletion of the capsule manager and can lead to deletion of stubs, binders, protocol objects or interceptors that supported objects in the capsule or its manager.
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