Changes between Version 6 and Version 7 of TrafficModelATMSOverview


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Timestamp:
01/06/2018 05:05:02 AM (8 years ago)
Author:
jtorres
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  • TrafficModelATMSOverview

    v6 v7  
    1 = FIRST DRAFT = 
    2 = THIS DOCUMENT IS NOT FINISHED AND HAS NOT BEEN REVISED = 
    3  
    41= Traffic Model / FEP / ATMS Overview Document = 
    52 
    … …  
    5552Reference the [wiki:TrafficModelClassDiagram Traffic Model Class Diagram] while reading this section. 
    5653 
    57 As previously stated, the Traffic Model consists of the Traffic Model Manager and the Highways model. The Traffic Model Manager contains an instance of the Highways class. Both the Traffic Model Manager and the HIghways model and instantiated upon CAD Server start up. Once instantiated, the Traffic Model Manager runs an instance of the WriteToFEPThread, which sends the current traffic conditions of the Highways to the FEP Simulator by calling the Highways class' writeToFEP() method, on every 30 second interval. 
     54As previously stated, the Traffic Model consists of the Traffic Model Manager and the Highways model. The Traffic Model Manager contains an instance of the Highways class. Both the Traffic Model Manager and the Highways model and instantiated upon CAD Server start up. Once instantiated, the Traffic Model Manager spawns an instance of the WriteToFEPThread, which sends the current traffic conditions of the Highways to the FEP Simulator by calling the Highways class' writeToFEP() method, on every 30 second interval. 
    5855 
    59 The Traffic Model Manager also loads Traffic Events from a batch file into a Queue, the eventsQueue, when instantiated. The Traffic Event batch file is specified in the Traffic Model Manager's properties file. A Traffic Event changes the current traffic conditions at a specified location. As the simulation runs, the Traffic Model Manager queries the Coordinator object for the current simulation time, and then checks the queue to see if there are Traffic Events that should be applied to the Highways model at the current simulation time. 
     56The Traffic Model Manager also loads Traffic Events from a batch file into a queue, the eventsQueue, when instantiated. The Traffic Events batch file is specified in the Traffic Model Manager's properties file. A Traffic Event changes the current traffic conditions at a specified location. As the simulation runs, the Traffic Model Manager queries the Coordinator object for the current simulation time, and then checks the queue to see if there are Traffic Events that should be applied to the Highways model at the current simulation time. 
    6057 
    6158The Highways and Highway classes were developed to give developers an abstraction of the traffic network that was feasible to work with. A Highway is undirected, meaning it does not have an associated (N/S/W/E) direction and represents traffic in both directions on the highway. A Highway is an aggregation of all of the Stations on a highway, sorted by postmile value. Stations do have an associated direction. Stations may or may not have Loop Detectors associated with the specified station direction, or the opposite specified direction. Hence, the undirected Highway abstraction. 
    6259 
    63 It should be noted that the ATMS has no concept of the Highways and Highway abstraction, only FEPLines, Stations, and Loop Detectors. FEPLines are also composed of Stations, but are not a convenient abstraction, as they only represent serial communication lines used to communicate with a geographic group of field stations. The FEPLines need to be represented because they contain necessary attributes that must be passed on to the FEP Simulator to populate the fep_reply structs. The next section "FEP Simulator" will give a better understanding of FEPLines. 
     60It should be noted that the ATMS has no concept of the Highways and Highway abstraction, only FEPLines, Stations, and Loop Detectors. FEPLines are also composed of Stations, but are not a convenient abstraction because they only represent serial communication lines used to communicate with a geographic group of field stations. The FEPLines need to be represented because they contain necessary attributes that must be passed on to the FEP Simulator to populate the fep_reply structs. The next section "FEP Simulator" will give a better understanding of FEPLines. 
    6461 
    6562=== FEP Simulator === 
    … …  
    7168In contrast, our FEP Simulator is not actually "polling" field stations, and instead just reads all traffic data over the socket from the CAD Server's Traffic Model. It is similar, however, in that it reformats traffic condition data into fep_reply structs and sends them to the ATMS via RPC. 
    7269 
     70The FEP Simulator runs persistently on the Linux Virtual Machine on the TMC network and awaits messages. 
     71 
    7372=== ATMS === 
    7473 
    75 The ATMS is a completed, pre-existing, production server purchased from CalTrans. We do not know much about it, other than its ability to receive fep_reply structs via RPC and feed the received data to the ATMS Client interactive map GUI. 
     74The ATMS is a complete production server purchased from CalTrans. We do not know much about it, other than its ability to receive fep_reply structs via RPC and feed the received data to the ATMS Client interactive map GUI. 
    7675 
    7776== Protocols == 
    … …  
    8180The Traffic Model communicates with the FEP Simulator by sending the traffic conditions message over a socket connection. 
    8281 
    83 ==== Traffic Conditions Message Format ==== 
     82The traffic conditions message is produced by the Highways class method "toCondensedFormat(false)". 
    8483 
    85 TODO: document traffic conditions message 
     84==== Example Traffic Conditions Message ==== 
    8685 
     86Example traffic conditions message (toCondensedFormat(false)) output: 
     87{{{ 
     8843 // "number of lines" 
     8932 0 13 // "line id" "count num" "number of stations" 
     901210831 1 5 S 0.9 8 // "station id" "drop num" "route num" "direction" "postmile" "number of loops" 
     911210832  0.0 0  ML_1 // "loop id" "occ" "vol" "loop_description" 
     921210833  0.0 0  ML_2 // .. 
     931210834  0.0 0  ML_3 // .. 
     941210835  0.0 0  ML_4 // .. 
     951210836  0.0 0  PASSAGE // .. 
     961210837  0.0 0  DEMAND // .. 
     971210838  0.0 0  QUEUE // .. 
     981210839  0.0 0  RAMP_OFF // .. 
     99... 
     100}}} 
    87101=== FEP Simulator to ATMS === 
    88102 
    89 The FEP Simulator communicates with the ATMS via RPC. It sends fep_reply structs which contain traffic condition data. 
     103The FEP Simulator communicates with the ATMS via RPC. It sends fep_reply structs which contain traffic condition data. Each  
    90104 
    91105==== fep_reply struct ==== 
     106{{{ 
     107#!div style="font-size: 80%" 
     108  {{{#!c 
     109struct fep_reply { 
     110        int reply; 
     111        int schedule; 
     112        int lineinfo; 
     113        polltype kind; 
     114        replykind flag; 
     115        int schedule_sequence; 
     116        int global_sequence; 
     117        long schedule_time; 
     118        int user_info1; 
     119        int user_info2; 
     120        int system_key; 
     121        struct fep_answer_list answers; 
     122}; 
     123typedef struct fep_reply fep_reply; 
     124  }}} 
     125}}} 
    92126 
    93 TODO: document fep_reply struct 
     127==== fep_answer_list struct ==== 
    94128 
     129{{{ 
     130#!div style="font-size: 80%" 
     131  {{{#!c 
     132struct fep_answer_list { 
     133        int size; 
     134        union { 
     135                fep_shortanswer_list shortp; 
     136                fep_longanswer_list longp; 
     137        } fep_answer_list_u; 
     138}; 
     139typedef struct fep_answer_list fep_answer_list; 
     140  }}} 
     141}}} 
     142==== fep_shortanswer_list ==== 
     143{{{ 
     144#!div style="font-size: 80%" 
     145  {{{#!c 
     146struct fep_shortanswer_list { 
     147        int count; 
     148        fep_shortanswer answers[MAXSHORTPOLLS]; 
     149}; 
     150typedef struct fep_shortanswer_list fep_shortanswer_list; 
     151  }}} 
     152}}} 
     153 
     154==== fep_shortanswer ==== 
     155 
     156{{{ 
     157#!div style="font-size: 80%" 
     158  {{{#!c 
     159struct fep_shortanswer { 
     160        fep_answer_info info; 
     161        fep_answer_short_msg msg; 
     162}; 
     163typedef struct fep_shortanswer fep_shortanswer; 
     164  }}} 
     165}}} 
     166 
     167==== fep_answer_short_msg ==== 
     168{{{ 
     169#!div style="font-size: 80%" 
     170  {{{#!c 
     171struct fep_answer_short_msg { 
     172        int message_len; 
     173        char message[MAXSHORTREPLYLEN]; 
     174}; 
     175  }}} 
     176}}}