making universal real time web applications using socket io

... support for using WebSockets (an emerging Web technology) to enable realtime behavior via the Web when compared to AJAX, and similar Web technologies 6 A BRIEF OVERVIEW OF OASIS OASIS is real- time ... stringent time constraints We developed two sample Web applications for our experiments The first application used AJAX to send instrumentation data in real- time from the DAC to the Web application ... the Web application (see Section 4.1) The second application used WebSockets to send instrumentation data in real- time from the DAC to the Web application (see Section 4.2) We used the System...

Ngày tải lên: 24/08/2014, 12:08

... two important subclasses of real- time constraints: hard real- time and soft realtime Hard real- time refers to highly critical time constraints in which missing even one time deadline is unacceptable, ... Current Current Current Current Current Current Current Current Current Time: Time: Time: Time: Time: Time: Time: Time: Time: Time: 34 40 56 77 83 99 120 126 142 163 Speedy_Thread finished cycle ... designed and developed using sound software engineering principles Because most embedded applications are real- time systems, one major difference from traditional computer applications is the requirement...

Ngày tải lên: 03/07/2014, 05:20

... critical section current time initialization inter-thread mutual exclusion kernel entry memory byte pool mutex mutual exclusion ownership of mutex preemption priority scheduling threads sleep time stack ... inverted Time Figure 3.7: Example of priority inversion inversion time to become nondeterministic and lead to application failure Consider Figure 3.7, which shows an example of the priority inversion ... - timer-ticks */ tx_thread_sleep(9); current _time ϭ tx _time_ get(); printf(“Current Time: %5lu Slow_Thread finished a cycle…\n”, current _time) ; 2.8 Key Terms and Phrases application define function...

Ngày tải lên: 03/07/2014, 05:20

... 37 Application timer control block Application timer name Expiration function to call Expiration input value to pass to function Initial number of timer-ticks Reschedule number of timer-ticks ... applications to perform time- outs, periodic operations, and/ or watchdog services Just like ISRs, application timers most often interrupt thread execution Unlike ISRs, however, application timers ... one-shot timer periodic timer preemption preemption-threshold primitive data type priority priority inheritance public resource service call stack system data type thread thread suspension thread...

Ngày tải lên: 03/07/2014, 05:20

... variety of actions in preparation for multithreading on the MIPS processor The first action is to call ThreadX’s internal low-level initialization function _tx_initialize_low_level This function sets ... thread system performance information Change preemption-threshold of application thread Change priority of an application thread Relinquish control to other application threads tx_thread_reset Reset ... tx_thread_terminate tx_thread _time_ slice_change tx_thread_wait_abort Suspend an application thread Terminates an application thread Changes time- slice of application thread Abort suspension of specified thread...

Ngày tải lên: 03/07/2014, 05:20

... intermediate priority become active during this priority inversion condition—thus preempting the lower-priority thread—the priority inversion time becomes nondeterministic and the application may fail ... preventing priority inversion in ThreadX First, the developer can select application priorities and design run -time behavior in a manner that prevents the priority inversion problem Second, lower-priority ... thread priorities is priority inversion Priority inversion occurs when a higher-priority thread becomes suspended because a lower-priority thread has a resource needed by the higher-priority thread...

Ngày tải lên: 03/07/2014, 05:20

... areas where deterministic, real- time behavior is required Many such applications pre-allocate their required memory during initialization or run -time configuration Another option is to use a memory ... options mutual exclusion ownership of mutex prioritize mutex suspension list priority inheritance priority inversion recovery from deadly embrace shared resources synchronize thread behavior ... However, an application can cause priority resumption of suspended threads, by calling tx_byte_pool_prioritize prior to the byte release call that lifts thread suspension The byte pool prioritize service...

Ngày tải lên: 03/07/2014, 05:20

... tx_timer_created_previous Description Application timer ID Pointer to application timer name Number of remaining timer-ticks Re-initialization timer-tick value Pointer to timeout function Parameter for timeout ... my_timer as follows: TX_TIMER my_timer; The declaration of application timers normally appears in the declaration and definition section of the application program 10.4 Summary of Application Timer ... Description tx_timer_activate Activate an application timer tx_timer_change Change characteristics of an application timer tx_timer_create Create an application timer tx_timer_deactivate tx_timer_delete...

Ngày tải lên: 03/07/2014, 05:20

... Application Timers 173 tx_timer_list Expire time List of active timers at this time expiration Expire time List of active timers at this time expiration Expire time List of active timers at this time ... a timer deactivation of timer deleting a timer expiration function expiration time internal system clock one-shot timer periodic interrupt periodic timer system clock services tick counter timeout ... counter, compute cycle time & total time */ Speedy_Thread_counterϩϩ; current _time ϭ tx _time_ get(); cycle _time ϭ current _time- start _time; total_speedy _time ϭ total_speedy _time ϩ cycle _time; } w w w.ne...

Ngày tải lên: 03/07/2014, 05:20

... compute cycle time & total time */ Speedy_Thread_counterϩϩ; current _time = tx _time_ get(); cycle _time = current _time - start _time; total_speedy _time = total_speedy _time + cycle _time; } } /****************************************************/ ... current _time; ULONG start _time, cycle _time; while(1) { /* Get the starting time for this cycle */ start _time = tx _time_ get(); /* Activity 1: timer-ticks */ tx_thread_sleep(2); /* Activity 2: timer-ticks ... ULONG current _time; ULONG start _time, cycle _time; while(1) { /* Get the starting time for this cycle */ start _time = tx _time_ get(); /* Activity 5: 12 timer-ticks *** critical section *** Get an...

Ngày tải lên: 03/07/2014, 05:20

... start _time, current _time, cycle _time; while(1) { /* Get the starting time for this cycle */ start _time = tx _time_ get(); /* Activity - get an instance of the counting semaphore with suspension and ... exceptionally robust in providing mutual exclusion If this is crucial to your application, then using a mutex is a good decision However, if mutual exclusion is not a major factor in your application, ... get operations The next change occurs in the application definitions section of our program, in which we replace the creation of a binary semaphore with the creation and initialization of an event...

Ngày tải lên: 03/07/2014, 05:20

... info */ Speedy_Thread_counter ϩ ϩ; current _time ϭ tx _time_ get(); cycle _time ϭ current _time - start _time; total_speedy _time ϭ total_speedy _time ϩ cycle _time; } } /*********************************************************/ ... invalue) { ULONG current _time, avg_slow _time, avg_speedy _time; if ((Speedy_Thread_counterϾ0) && (Slow_Thread_counterϾ0)) { current _time ϭ tx _time_ get(); avg_slow _time ϭ total_slow _time / Slow_Thread_counter; ... application timer, initialization routine, or ISR Note that TX_NO_WAIT is the only valid wait option if this service is called from a non-thread, such as an application timer, initialization routine,...

Ngày tải lên: 03/07/2014, 05:20

... current _time= tx _time_ get(); cycle _time= current _time - start _time; total_speedy _time= total_speedy _time+ cycle _time; } } /************************************************************ /* Entry function ... get timing info */ Slow_Thread_counter++; current _time= tx _time_ get(); cycle _time= current _time- start _time; total_slow _time= total_slow _time+ cycle _time; } } /*****************************************************/ ... function definition of the “Speedy_Thread” it has a higher priority than the “Slow_Thread” */ void Speedy_Thread_entry(ULONG thread_input) { UINT status; ULONG start _time, cycle _time= 0, current _time= 0;...

Ngày tải lên: 03/07/2014, 05:20

... Frame_index Time data Time data Time data Time data Time data Figure 14.19: Organization of temporary memory Event time Event priority 24 second of data for event Event time Event priority 24 second ... memory_mutex; my_byte_pool; TX_TIMER TX_TIMER TX_TIMER TX_TIMER crash_interrupt; unsafe_interrupt; warning_interrupt; manual_interrupt; TX_TIMER TX_TIMER TX_TIMER TX_TIMER TX_TIMER crash_copy_scheduler; ... crash_interrupt Timer unsafe_interrupt Timer warning_interrupt Timer manual_interrupt Timer crash_copy_scheduler Timer unsafe_copy_scheduler Timer warning_copy_scheduler Timer manual_copy_scheduler Timer...

Ngày tải lên: 03/07/2014, 05:20

... TX_BYTE_POOL my_byte_pool; TX_TIMER TX_TIMER TX_TIMER TX_TIMER crash_interrupt; unsafe_interrupt; warning_interrupt; manual_interrupt; TX_TIMER TX_TIMER TX_TIMER TX_TIMER TX_TIMER crash_copy_scheduler; ... 14.29 contains the definition for the print_stats expiration function, which is part of the timer called stats_timer This timer expires every 1,000 timer-ticks and the function displays a statistical ... time and event priority in protected memory */ frameϭframe_data[0]; event_priorityϭframe_data[1]; event _time temp_memory[frame][0]; printf(“**Event** Time: %5lu Count: %2lu Pri: %lu”, event _time, ...

Ngày tải lên: 03/07/2014, 05:20

... suspensions Pointer to destination for the total number of thread allocation suspensions on all block pools timeouts Pointer to destination for the total number of allocate suspension timeouts ... during allocation requests on this pool Pointer to destination for the number of thread allocation suspensions on this pool Pointer to destination for the number of allocate suspension timeouts on ... tx_block_pool_prioritize Prioritize the memory block pool suspension list Prototype UINT tx_block_pool_prioritize(TX_BLOCK_POOL *pool_ptr) Description This service places the highest-priority thread...

Ngày tải lên: 03/07/2014, 05:20

... information enabled Allowed From Initialization, threads, timers, and ISRs Example ULONG sets; ULONG gets; ULONG suspensions; ULONG timeouts; … /* Retrieve performance information on all previously ... allocation requests on all byte pools Pointer to destination for the total number of thread allocation suspensions on all byte pools Pointer to destination for the total number of allocate suspension ... information enabled Allowed From Initialization, threads, timers, and ISRs Example ULONG fragments_searched; ULONG merges; ULONG splits; ULONG allocates; ULONG releases; ULONG suspensions; ULONG timeouts;...

Ngày tải lên: 03/07/2014, 05:20

... suspension timeouts on this mutex Pointer to destination for the number of thread priority inversions on this mutex Pointer to destination for the number of thread priority inheritance operations ... return performance information Input Parameters mutex_ptr puts gets suspensions timeouts inversions inheritances Pointer to previously created mutex Pointer to destination for the number of put ... *suspensions, ULONG *timeouts, *inversions, *inheritances); Description This service retrieves performance information about the specified mutex NOTE: The ThreadX library and application must...

Ngày tải lên: 03/07/2014, 05:20

... Pointer to application’s queue send notification function If this value is TX_NULL, notification is disabled Return Values TX_SUCCESS (0x00) Successful registration of queue send notification TX_QUEUE_ERROR ... empty_suspensions full_suspensions full_errors timeouts Pointer to previously created queue Pointer to destination for the number of send requests performed on this queue Pointer to destination for the number ... Pointer to destination for the number of queue empty suspensions on this queue Pointer to destination for the number of queue full suspensions on this queue Pointer to destination for the number...

Ngày tải lên: 03/07/2014, 05:20

... information enabled Allowed From Initialization, threads, timers, and ISRs Example ULONG puts; ULONG gets; ULONG suspensions; ULONG timeouts; … /* Retrieve performance information on all previously ... preempt_threshold, ULONG time_ slice, UINT auto_start) Description This service creates an application thread, which will start execution at the specified task entry function The stack, priority, preemption-threshold, ... Suspend an application thread tx_thread_terminate Terminate an application thread tx_thread _time_ slice_change Change time- slice of application thread tx_thread_wait_abort Abort suspension of specified...

Ngày tải lên: 03/07/2014, 05:20