Doc:latest/sdkguide/basicinfrastructure - Revision history

Stone: /* Log Service Configuration */

2013-01-08T19:33:19Z

‎Log Service Configuration

Stone: /* Database Abstraction Layer (DBAL) */

2013-01-08T19:32:40Z

‎Database Abstraction Layer (DBAL)

Stone: /* Heap Memory */

2013-01-08T19:32:18Z

‎Heap Memory

Stone: /* Execution Object (EO) */

2013-01-08T19:31:06Z

‎Execution Object (EO)

Stone: Undo revision 12552 by 176.8.90.7 (Talk)

2013-01-08T19:13:04Z

Undo revision 12552 by 176.8.90.7 (Talk)

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176.8.90.7: /* Basic Infrastructure */

2012-02-11T07:40:16Z

‎Basic Infrastructure

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@@ Line 152: / Line 152: @@
 =====Log Service Configuration=====
-The common log service parameters, and the configuration parameters of the perennial and precreated log streams are described in section [[Doc:sdkguide/compconfig|OpenClovis SAFplus Platform Component Configuration]].
+The common log service parameters, and the configuration parameters of the perennial and precreated log streams are described in section [[Doc:latest/sdkguide/compconfig|OpenClovis SAFplus Platform Component Configuration]].
 =====Controlling Logging Behavior from the Applications=====

@@ Line 356: / Line 356: @@
 The primary user of this interface is the COR component which can write or read its object repository to and from a database for either persistent storage or offline processing. DBAL is also a standalone library with no dependencies on any other OpenClovis SAFplus Platform components.
-For information about selecting a database engine see [[Doc:sdk_3.1/sdkguide/compconfig | Configuring Database Abstraction Layer (DBAL)]].
+For information about selecting a database engine see [[Doc:latest/sdkguide/compconfig | Configuring Database Abstraction Layer (DBAL)]].
 ====Execution Object (EO)====

@@ Line 339: / Line 339: @@
 Heap memory is used for dynamic memory allocation. Memory is allocated from a large pool of unused memory area called the heap. The size of the memory allocation can be determined at run-time.  The OpenClovis heap memory subsystem allows the components to be configured with allocation limits so that a process with a memory leak will not consume resources needed by other processes.  Additionally allocation alarms can be configured so that the operator can be notified of imminent memory exhaustion and appropriate action be taken.
-For information about configuring these limits and alarms see [[Doc:sdk_3.1/sdkguide/compconfig | OpenClovis SAFplus Platform Component Configuration]].
+For information about configuring these limits and alarms see [[Doc:latest/sdkguide/compconfig | OpenClovis SAFplus Platform Component Configuration]].
 ====Database Abstraction Layer (DBAL)====

@@ Line 360: / Line 360: @@
 ====Execution Object (EO)====
-=====Introduction=====
+SAFplus applications must interact with other aspects of the SAFplus infrastructure, by issuing RPC calls, receiving AMF requests, events etc.  So each application essentially must be a multi-threaded client/server in order to interact with SAFplus, irrespective of whether your "main" is single-threaded.  This functionality is encapsulated within the EO library, is activated when any SAFplus library is first initialized, and is normally almost completely hidden from the application code.
-Before understanding the concept of an execution object, we need to understand the concept of execution entity in general. The execution entity itself is an abstraction model and the execution object is an implementation of that model in the SAFplus Platform environment.
+However, it is possible for secondary effects to be exposed at the application layer.  Two examples are thread starvation and the trigger of our thread hang/deadlock detector.
-=====Execution Entity=====
+=====Execution Object Thread Pooling=====
-−
-An execution entity is a form of a process, a task or a thread that contains a set of data and an execution context. Any form of interaction in a networked environment involves execution entities and so the concept of execution entities is not specific to the carrier grade middleware like OpenClovis SAFplus Platform. However, from pragmatic point of view, the execution entities running in a distributed system like OpenClovis SAFplus Platform environment are not very effective if they do not have the facility of external communication and thereby not capable of interacting with other execution entities. As the execution entities are distributed in nature, they need a common mechanism to facilitate the communication between them.
-−
-The execution entity mainly consists of:
-* Attributes and methods to manage the entity.
-* A mechanism to communicate with external execution entities.
-* Implementation of the entity specific to its responsibilities.
-−
-=====Execution Object - Execution entity of OpenClovis SAFplus Platform environment=====
-−
-OpenClovis Inc. provides the first two functionalities encapsulated within the '''Execution Object (EO)'''. The Execution Object comprises all the common attributes and methods used to represent the execution entity in the system. The communication with the external entities is provided by creating a background thread that receives the messages on behalf of the execution entity. These messages are decoded and the corresponding methods within the execution entity are invoked. Execution Object (EO) encapsulates each distinct SAFplus-aware software component and provides an execution environment for the components. It provides a uniform interface between the software component and the rest of the system components. The interfaces fall into the following two categories:
-* '''Management Interface''': This interface is used to control and configure the software components.
-* '''Service Interface''': This interface allows software components to expose component specific functionalities.
-−
-OpenClovis EO infrastructure is the user space client library and the server infrastructure that enables these capabilities. When this infrastructure is linked into an application, it takes over the application's main function and creates communication links back to the middleware, executing application specific state changes at the behest of the middleware. This model requires some help from the application, which must be written to support multiple threads as well as an asynchronous flow.
-−
-Both management and service interfaces provided by an EO are exposed using RMD APIs. In fact, the terms "management" and "service" interface are only conventions used to indicate whether the function is exposed or not in the context of a particular EO. For e.g. the service provided by an EO can be a management interface to another EO, if the latter EO manages the first EO. Managing can be as simple as invoking any method in the context of EO in order to carry out some action on EO like for e.g. checking if the EO is capable of providing service. The messages received at the EO are processed by the worker threads which finally invoke the proper functions in the context of the EO.
-−
-The application components encapsulated by EO communicate with other components using other OpenClovis communication infrastructure components such as Event Manager (EM), Remote Method Dispatch (RMD), Transparent Inter Process Communication (TIPC), and Name Service.
-−
-=====Execution Object - Thread/task pooling=====
 Note: OpenClovis uses the terms task and thread interchangeably
-We have a taskpool per ioc/tipc priority per EO. The taskpool is attached to a per EO job queue and is configured in code to have taskpools with a thread limit. (This configuration is not allowed as of now through IDE).
+The EO library creates a task pool per IOC (communications channel) priority per EO. The task pool is attached to a job queue and is configured in code to have a maximum number of servicing threads (the thread count configuration can be changed in SAFplus header files).
-Whenever an incoming request comes into EO via ioc/tipc receive, the priority of the header is mapped to the appropriate job queue before getting pushed into that job queue. And then the job is picked up by the taskpool that schedules an idle thread of the taskpool to process the job (or creates a new one if within the limit) and the job handler is then subsequently invoked in the context of the thread.
+Whenever an incoming request (such as to call an application-level callback) comes into a component via an IOC receive, the priority of the header is mapped to the appropriate job queue before getting pushed into that job queue.  Then the job is picked up by the task pool which schedules an idle thread associated with the task pool to process the job (or creates a new thread if within the limit) and the job handler is then subsequently invoked in the context of the thread.
-EO job queues are monitored for blocked threads and will log an entry to our log file whenever a possible deadlock or threadblock is detected.
+These task pool threads are monitored for blocked threads and will log an entry to our log file whenever a possible deadlock or threadblock is detected.  Essentially, each task pool thread must periodically return to the pool of idle threads, or it will be flagged.  Therefore, it is important that application code not "hijack" the threads by spending too much time in the callback routine.
-The taskpool APIs can be used independently by applications.  For more information please see the [[Doc:latest/sdkguide/basicinfrastructure#Task_Pool_and_Job_Queue|Task Pool and Job Queue]] sections under [[Doc:latest/sdkguide/basicinfrastructure | Basic Infrastructure]]
+The task pool and job queue APIs can be used independently by applications to implement your own thread and job management.  For more information please see the [[Doc:latest/sdkguide/basicinfrastructure#Task_Pool_and_Job_Queue|Task Pool and Job Queue]] sections under [[Doc:latest/sdkguide/basicinfrastructure | Basic Infrastructure]]

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