Motorola 6806800C08B Manual Do Utilizador
NetPlane Core Services Overview User’s Guide (6806800C08B)
NetPlane Core Services
Global Lock Service
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2.5.4.1.1
Event Distribution Server
The Event Distribution Server (EDS) is an NCS process on the System Controller blade which
handles the distribution of events based on client subscriptions and filtering mechanisms. If an
event was posted and event persistence was specified, the event will be retained by the server
process for the time period specified in the call. During the retention time period, the EDS may
redistribute the event to new subscribers for that event. Events are distributed based on a match
against the filter settings specified by the subscribed client and a priority specified in the event
header.
handles the distribution of events based on client subscriptions and filtering mechanisms. If an
event was posted and event persistence was specified, the event will be retained by the server
process for the time period specified in the call. During the retention time period, the EDS may
redistribute the event to new subscribers for that event. Events are distributed based on a match
against the filter settings specified by the subscribed client and a priority specified in the event
header.
There is an active and a stand-by EDS running respectively on the two system manager nodes.
EDS uses the NCS Message based Checkpoint Service to keep the two synchronized and
available for failover situations.
EDS uses the NCS Message based Checkpoint Service to keep the two synchronized and
available for failover situations.
2.5.4.1.2
Event Distribution Agent
This is a library that makes the EDSv APIs available to applications. The APIs themselves are
all described in the respective SAF documents.
all described in the respective SAF documents.
2.5.5
Global Lock Service
The Global Lock Service (GLSv) implements the SAF Lock Service API.
2.5.5.1
Basic Functionality
The GLSv provides a distributed locking service which allows applications running on multiple
nodes to coordinate access to shared resources.
nodes to coordinate access to shared resources.
Locks are created and destroyed by applications as needed. Participating applications know
that the locks exist and know how to use them. Access policies are outside the scope of the
GLSv, which only provides the locking mechanism.
that the locks exist and know how to use them. Access policies are outside the scope of the
GLSv, which only provides the locking mechanism.
The GLSv supports exclusive and shared access modes. Exclusive access mode means that
only one requestor is allowed through the lock at a time. Shared access mode means that
multiple requestors are allowed through a lock at a time.
only one requestor is allowed through the lock at a time. Shared access mode means that
multiple requestors are allowed through a lock at a time.
The GLSv furthermore supports synchronous and asynchronous APIs to carry out locking
operations. In addition, GLSv provides an internal mechanism which ensures deadlock
detection and prevention.
operations. In addition, GLSv provides an internal mechanism which ensures deadlock
detection and prevention.
If an application creates a lock and then exits without unlocking, orphan locks are the result.
Orphan locks are managed until they are properly purged from the system.
Orphan locks are managed until they are properly purged from the system.
2.5.5.2
Architecture
The GLSv consists of the following subparts:
z
Global Locking Director
z
Global Locking Node Director
z
Global Locking Agent