KR102298679B1 - Method And Device For Message Reception Frequency Control - Google Patents

Abstract

The present invention relates to a method for controlling a message reception frequency to increase the overall performance of an Internet of things (IoT) system and a device thereof. According to the present invention, the method comprises: a message request step of receiving, by a broker, a subscription request packet for a message of a predetermined topic from a receiver (subscriber); a list generation step of generating, by the broker, a subscription list including a message topic associated with the receiver according to the subscription request packet transmitted from the corresponding receiver; and a message transmission step of copying, by the broker, a message of the same topic as that included in the subscription list among messages of various topics issued from a publisher to transmit from a message queue to transmit the message to the receiver. The message request step transmits a subscription request packet including a predetermined time frequency to receive the message of the predetermined topic from the receiver to the broker. The list generation step allows the broker to generate a subscription list including a maximum reception period corresponding to the predetermined time frequency to transmit the message of the predetermined topic to the receiver. The message transmission step transmits the message of the specific topic to the receiver from the broker at the maximum reception period included in the subscription list.

Description

Method And Device For Message Reception Frequency Control

An embodiment of the present invention relates to a method and apparatus for controlling message reception frequency.

MQTT is currently used as a message delivery broker in IoT systems, and this MQTT functions as a message intermediary between a sender that publishes a message and a receiver that subscribes to the message.

1 is an internal structural diagram of a conventional MQTT broker.

As shown in FIG. 1, an IoT system using the MQTT protocol consists of an MQTT broker, a receiver, and a transmitter, and it is text data called a topic that connects these receivers and transmitters to each other.

A receiver registers a topic with an MQTT broker to receive messages related to a topic, and the MQTT broker stores and manages this receiver information together with the topic in a subscription list. sends a message to all receivers with the same topic as the message.

So, if some sensor or device, including a sender, e.g. a user device, publishes data at a very high frequency, that receiver receives all messages because the MQTT protocol does not have a specified standard for controlling the amount of messages a receiver will receive. There is a problem in that the overall traffic of the network is increased by receiving.

Accordingly, the present applicant has introduced a message reception frequency control (RFC) function to the MQTT protocol in order to solve this conventional problem, and the message receiver determines a specific time frequency to receive the message. Then, by sending a packet including the corresponding time frequency and message-related topic to the MQTT broker, the receiver receives the message related to the corresponding topic at the corresponding time frequency, thereby completing an invention that can reduce the overall traffic of the network.

Republic of Korea Patent Publication No. 10-2018-0105917 (2018.10.01.)

The present invention reduces the transmission of unnecessary messages provided to the receiver by controlling the frequency at which the receiver receives messages in the IoT system, so that the receiver receives only messages that can be processed according to its own capacity, thereby reducing the overall traffic of the network. An object of the present invention is to provide a method and apparatus for controlling message reception frequency that can improve the overall performance of the IoT system.

A method for controlling message reception frequency according to the present invention for achieving the above object includes: a message request step in which a broker receives a subscription request packet for a message of a specific topic from a receiver (Subscriber); a list generation step of the broker generating a subscription list including a message topic associated with the corresponding receiver according to the subscription request packet transmitted from the receiver; and a message transmission step of copying a message of the same topic as a message topic included in the subscription list among messages of various topics issued by the broker from a publisher (Publisher) from a message queue and transmitting the message to the receiver; , in the message request step, a subscription request packet including a specific time frequency for the receiver to receive the message of the specific topic is transmitted to the broker, and in the list creation step, the broker sends the message of the specific topic to the broker Generates a subscription list including a maximum reception period corresponding to the specific time frequency to be transmitted to a receiver, and in the message transmission step, the broker transmits the message of the specific topic to the receiver with the maximum reception period included in the subscription list characterized in that

In addition, the subscription request packet may include: a topic area in which a topic of a message to be received by the receiver is stored; and a frequency region in which a specific time frequency for the receiver to receive the message of the specific topic is stored.

In addition, the subscription list may include: a message topic field in which a topic of a message associated with the receiver is stored in correspondence with the topic stored in the topic area of the subscription request packet; a message reception period field in which a maximum reception period of a message associated with the receiver is stored in correspondence with a specific time frequency stored in the frequency area of the subscription request packet; a message previous transmission time field in which a previous transmission time when the message was last transmitted to the receiver is stored; and a message buffer field in which a message of the same topic as the message topic stored in the message topic field is copied from the message queue and stored.

In addition, the message sending step may include: a message topic comparison process in which the broker sequentially compares the topic of each message stored in the message queue with each message topic stored in the message topic field of the subscription list; a transmission decision step of determining whether the broker satisfies the following [Equation 1] when the topic of the message stored in the message queue and the message topic stored in the message topic field are the same; a message storage process in which the broker copies a message of the same topic as the message topic included in the subscription list from the message queue and stores it in the message buffer field when the following [Equation 1] is satisfied; and a message transmission process in which the broker transmits the message stored in the message buffer field to the receiver.

[Equation 1]

(Here, T _current is the current time, T _prev is the transmission time before the message, T _period is the maximum message reception period, and T _{current -} T _prev > T _period is when the difference between the current time and the transmission time before the message is greater than the maximum message reception period )

In addition, when [Equation 1] is not satisfied, the broker may re-perform the message topic comparison process.

In addition, in the transmission or not determining step, when the topic of the message stored in the message queue and the message topic stored in the message topic field are the same, it is further determined whether the broker satisfies the following [Equation 2], When [Equation 2] is satisfied, the broker may perform the message storage process.

[Equation 2]

(Here, T _period = 0 when the maximum message reception period is not set)

The method may further include a message deletion process in which the broker deletes a message of the same topic as the topic of the message stored in the message buffer field among messages of various topics stored in the message queue after the message storage process.

In addition, the broker after the message transmission process, a transmission time changing process of changing the _{message previous transmission time (T prev} ) stored in the message previous transmission time field of the subscription list to the current time (T _{current );} and a transmission status display process in which the broker displays the message buffer field of the subscription list as dirty.

In addition, the message reception frequency control apparatus according to the present invention generates a subscription list including a message topic associated with the receiver according to a subscription request packet for a message of a specific topic transmitted from a receiver (Subscriber), A broker that copies messages of the same topic as the message topic included in the subscription list among messages of various topics issued by the publisher (Publisher) from the message queue and transmits them to the receiver; including, the broker receives from the receiver a subscription request packet including a specific time frequency for receiving the message of the specific topic, and a subscription including a maximum reception period corresponding to the specific time frequency for transmitting the message of the specific topic to the receiver A list is created, and the message of the specific topic is transmitted to the receiver at a maximum reception period included in the subscription list.

In addition, the broker sequentially compares the topic of each message stored in the message queue with each message topic stored in the message topic field of the subscription list, and the topic of the message stored in the message queue and the message stored in the message topic field. If the topics are the same, whether the difference between the current time and the transmission time before the message is greater than the maximum message reception period (T _{current -} T _prev > T _period ), and if the maximum message reception period is not set (T _period = 0) ), and if the difference between the current time and the transmission time before the message is not greater than the maximum message reception period, the topic of each message stored in the message queue is determined for each message stored in the message topic field of the subscription list. If the difference between the current time and the transmission time before the message is greater than the maximum message reception period or if the maximum message reception period is not set, the message of the same topic as the message topic included in the subscription list is sequentially compared with the topic again. may be copied from the message queue and stored in the message buffer field included in the subscription list, and then the message stored in the message buffer field may be transmitted to the receiver.

In addition, the broker copies a message of the same topic as the message topic included in the subscription list from the message queue, stores it in the message buffer field, and stores it in the message buffer field among messages of various topics stored in the message queue. After deleting the message of the same topic as the topic of the stored message, and transmitting the message stored in the message buffer field to the receiver, the transmission time (T _prev ) before the message stored in the transmission time field before the message of the subscription list is currently It is changed to time (T _current ), and the message buffer field of the subscription list may be displayed as dirty.

As described above, according to the method and apparatus for controlling message reception frequency according to the present invention, by controlling the frequency at which the receiver receives messages in the IoT system, the delivery of unnecessary messages provided to the receiver is reduced, so that the receiver processes according to its own capacity It has the effect of improving the overall performance of the IoT system by allowing only possible messages to be received and thus reducing the overall traffic of the network.

1 is an internal structural diagram of a conventional MQTT broker.
2 is a block diagram of a method for controlling message reception frequency according to the present invention.
3 is a structural diagram of a subscription request packet according to the present invention.
4 is an internal structural diagram of an MQTT broker according to the present invention.
5 is a first block diagram of a message transmission step according to the present invention.
6 is a second block diagram of a message transmission step according to the present invention.
7 is an exemplary diagram of an algorithm for performing a message transmission step according to the present invention.
8 is an exemplary diagram in which a corresponding receiver receives a message with a maximum reception period (1 second) according to a subscription request packet of the receiver.
9 is a graph comparing network traffic between an MQTT broker according to the present invention and a conventional MQTT broker.
10(a) to 10(d) are graphs comparing network traffic between the MQTT broker of the present invention and the conventional MQTT broker according to the number of senders.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that the same components or parts in the drawings are denoted by the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related known functions or configurations are omitted so as not to obscure the gist of the present invention.

2 is a block diagram of a method for controlling message reception frequency according to the present invention.

As shown in FIG. 2, the method for controlling message reception frequency according to the present invention includes a message request step (S10), a list generation step (S20), and a message transmission step (S30).

The message request step (S10) is a step in which a broker receives a subscription request packet for a message of a specific topic from a receiver (Subscriber).

Specifically, in the message request step ( S10 ), the receiver may select a specific time frequency to receive a message of a specific topic and transmit a subscription request packet including the corresponding time frequency to the broker.

Here, the time frequency means that the receiver does not receive more messages in the corresponding frequency, that is, in the corresponding time period, and this means that the receiver receives at most one message in the corresponding time period from the broker Maximum Reception Period (Maximum Reception Period) , MRP).

3 is a structural diagram of a subscription request packet according to the present invention.

As shown in FIG. 3 , the subscription request packet 210 that the receiver transmits to the broker may include a topic area 211 and a frequency area 212 .

Here, the topic area 211 is an area in which the topic of a message to be received by the receiver is stored, and the frequency area 212 is an area in which a specific time frequency at which the receiver will receive a message of a specific topic is stored.

The list creation step (S20) is a step in which the broker generates a subscription list including a message topic associated with the receiver according to the subscription request packet 110 transmitted from the receiver.

Specifically, in the list creation step (S20), the broker may generate a subscription list including a maximum reception period (MRP) corresponding to a specific time frequency to transmit a message of a specific topic requested for subscription from the receiver to the corresponding receiver.

4 is an internal structural diagram of an MQTT broker according to the present invention.

Here, the subscription list 110 may include a message topic field 111, a message reception period field 112, a message previous transmission time field 113, and a message buffer field 114, as shown in FIG. have.

The message topic field 111 corresponds to a topic stored in the topic area 211 of the subscription request packet 210 transmitted from the receiver 200, and the topic of a message associated with the receiver may be stored, respectively.

The message reception period field 112 corresponds to a specific time frequency stored in the frequency area 212 of the subscription packet 210 transmitted from the receiver 200, and the maximum reception period (T _period ) of the message associated with the receiver is can be saved.

Here, time is used for the maximum reception period, for example, when the maximum reception period (T _period ) is 100 and the time unit is 10 milliseconds, the receiver 200 receives two or more messages per second It means that it does not want to receive, and therefore, the broker 100 does not transmit more than two messages per second for the corresponding topic to the corresponding receiver.

Message before the transmission time field 113 there message may be a last previous transmission time (T _prev) transmitted to the receiver store, such prior transmission time (T _prev) is the maximum reception period (T _period) and the time unit It is the same, and such a time unit may consist of 10 seconds, 1 second, 1 millisecond, and the like.

Here, the message pre-transmission time field 113 is, as will be described later, after the broker transmits the message to the receiver, the message pre-transmission time (T _prev ) stored in the message-previous transmission time field is the current time (T _current ). By being changed, the previous transmission time (T _prev ) may be updated.

In the message buffer field 114 , a message of the same topic as the message topic stored in the message topic field may be copied from the message queue 120 and stored.

Here, the message buffer field 114 may indicate the transmission status of the message by displaying the message buffer field 114 as dirty after the broker transmits the message to the receiver, as will be described later.

In the message transmission step (S30), the broker 100 copies the message of the same topic as the message topic included in the subscription list 110 among the messages of various topics issued by the publisher (Publisher, 300) from the message queue 120. This is the step of transmitting to the receiver.

In this message transmission step (S30), the broker 100 may transmit a message of a specific topic to the receiver 200 with the maximum reception period (MRP) included in the subscription list 110 .

5 is a first block diagram of a message transmission step according to the present invention.

Specifically, the message transmission step (S30) may include a message topic comparison process (S31), a transmission status determination process (S32), a message storage process (S33), and a message transmission process (S34), as shown in FIG. 5 . can

The message topic comparison process S31 is a process in which the broker 100 sequentially compares the topic of each message stored in the message queue 120 with each message topic stored in the message topic field 111 of the subscription list 110 .

Specifically, in the message topic comparison process ( S31 ), the broker 100 checks all messages stored in the message queue 120 according to the algorithm Algorithm_RFC( ) to be described later, and stores the topic of the message in the message topic field 111 . Each message topic can be compared one by one.

In the transmission or not determination process (S32), when the topic of the message stored in the message queue 120 and the message topic stored in the message topic field 111 are the same, the broker 100 determines whether the following [Equation 1] is satisfied It is a process of determining whether a message is transmitted or not.

(Here, T _current is the current time, T _prev is the transmission time before the message, T _period is the maximum message reception period, and T _{current -} T _prev > T _period is when the difference between the current time and the transmission time before the message is greater than the maximum message reception period )

Specifically, in the transmission or not determination process (S32), if the difference between the current time (T _current ) and the previous transmission time (T _prev ) at which the message was last transmitted to the receiver is greater than the maximum message reception period (T _period ), that is, the current When the time has passed the maximum reception period, it can be determined to transmit the message to the receiver, _{and if the difference between the current time (T current} ) and the previous transmission time (T _prev ) is not greater than the maximum message reception period (T _{period ), that is,} , when the current time has not passed the maximum reception period, it may be determined not to transmit the message to the receiver.

In addition, when the topic of the message stored in the message queue 120 and the message topic stored in the message topic field 111 are the same, the transmission or not determination process (S32) determines whether the broker 100 satisfies the following [Equation 2] By determining whether or not the message is transmitted, it is possible to determine whether the message is transmitted.

(Here, T _period = 0 when the maximum message reception period is not set)

Specifically, in the transmission or not determination process (S32), when the maximum reception period (T _period ) is 0, that is, the receiver 200 does not select a specific time frequency for message reception through the subscription packet 210. When the maximum reception period of the subscription list 110 is not set, it can be determined to transmit the message to the corresponding receiver, and also, when the maximum reception period (T _period ) is not 0, that is, the receiver 200 receives the subscription packet When a specific time frequency for receiving a message is selected through 210, it is possible to determine whether the message is transmitted by determining whether the above [Equation 1] is satisfied.

When the message storage process (S33) satisfies [Equation 1] or [Equation 2] in the transmission or not determination process (S32), the broker 100 is the same topic as the message topic included in the subscription list 110 This is a process of copying the message of from the message queue 120 and storing it in the message buffer field 114 of the subscription list 110 .

Specifically, in the message storage process (S33), in order for the broker 100 to transmit a message of a specific topic included in the subscription list 110 to the receiver, the message of the same topic as the message topic included in the corresponding subscription list is sent to the message queue. can be copied from and stored in the message buffer field.

On the other hand, in the present invention, when the broker 100 does not satisfy [Equation 1] in the process of performing the transmission or not determination process (S32), that is, the current time (T _current ) and the previous transmission time (T _prev) ) is not greater than the maximum message reception period (T _period ), so if the current time has not passed the maximum reception period, it can be determined not to transmit the message to the receiver as described above, in this case, the broker 100 is the message Instead of performing the storage process ( S33 ), the topic of each message stored in the message queue may be sequentially compared with each message topic stored in the message topic field of the subscription list by re-performing the message topic comparison process ( S31 ).

The message transmission process S35 is a process in which the broker 100 transmits the message stored in the message buffer field 114 to the receiver 200 .

Specifically, in the message transmission process ( S35 ), the message stored in the message buffer field 114 may be transmitted to the corresponding receiver while checking the receiver associated with the message topic field 111 of the subscription list 110 .

6 is a second block diagram of a message transmission step according to the present invention.

On the other hand, the message transmission step (S30) is, as shown in FIG. 6, in addition to the message topic comparison process (S31), the transmission status determination process (S32), the message storage process (S33) and the message transmission process (S35), The configuration may further include a message deletion process (S34), a transmission time change process (S36), and a transmission status display process (S37).

The message deletion process (S34) is the same topic as the topic of the message stored in the message buffer field 114 among the messages of various topics stored in the message queue 120 after the broker 100 performs the message storage process (S33) This is the process of deleting a message from the corresponding message queue.

In the transmission time change process (S36), the broker 100 performs the message transmission process (S34), and then sets the message previous transmission time (T _prev ) stored in the message previous transmission time field 113 of the subscription list 110 to the current This is the process of changing the time (T _current).

Specifically, in the transmission time changing process (S36), after the broker transmits the message to the receiver, the previous transmission time (T _prev ) stored in the message previous transmission time field is changed to the current time (T _current ). The time T _prev can be updated.

In the transmission status display process (S37), after the broker 100 performs the message transmission process (S34), the message is transmitted to the receiver by displaying the message buffer field 114 of the subscription list 110 as dirty. This is a process that indicates that it has been completed.

7 is an exemplary diagram of an algorithm for performing a message transmission step according to the present invention.

In the message transmission step (S30), the broker 100 transmits the message to the receiver while controlling the message reception frequency of the receiver 200 using the Algorithm_RFC (input:Message Queue) algorithm, as shown in FIG. 7 . can be transmitted

Hereinafter, an apparatus for controlling message reception frequency according to the present invention will be described.

As shown in FIG. 4 , the apparatus for controlling message reception frequency according to the present invention includes a broker 100 capable of transmitting a corresponding message to the receiver while controlling the message reception frequency of the receiver 200 .

The broker 100 generates a subscription list 110 including a message topic associated with the receiver according to the subscription request packet 210 for a message of a specific topic transmitted from the receiver 200, and then the transmitter 300 ) may be copied from the message queue 120 to the receiver 200 by copying a message of the same topic as the message topic included in the subscription list 110 among the messages of various topics issued by .

Such a broker 100 may receive a subscription request packet 210 including a specific time frequency for receiving a message of a specific topic from a receiver, and a maximum corresponding to the specific time frequency for transmitting a message of a specific topic to the receiver. A subscription list 110 including a reception period may be generated, and a message of a specific topic may be transmitted to the receiver 200 with a maximum reception period included in the subscription list.

Specifically, the broker 100 sequentially compares the topic of each message stored in the message queue 120 with each message topic stored in the message topic field 111 of the subscription list 110, and then When the topic and the message topic stored in the message topic field are identical to each other, it can be determined whether the above [Equation 1] and [Equation 2] are satisfied, respectively.

In addition, if the broker 100 does not satisfy [Equation 1], the topic of each message stored in the message queue and each message topic stored in the message topic field of the subscription list are sequentially compared again, and in contrast, [Mathematics] If Equation 1] or [Equation 2] is satisfied, the message of the same topic as the message topic included in the subscription list is copied from the message queue and stored in the message buffer field 114 included in the subscription list, and then the message queue You can delete messages of the same topic as the topic of the message stored in the message buffer field among messages of various topics stored in .

In addition, the broker 100 transmits the message stored in the message buffer field to the receiver, and then changes the message previous transmission time (T _prev ) stored in the message previous transmission time field 113 of the subscription list to the current time (T _current ). Also, by marking the message buffer field of the subscription list as dirty, it may indicate that the message has been transmitted to the receiver.

Hereinafter, a test result of controlling the message reception frequency through the test system constructed according to the present invention will be described.

<Building a test system>

Mosquitto is an MQTT broker provided by Eclipse as open software. Mosquitto runs as a single thread, processing all packets in one loop.

In Mosquitto, we built a test IoT system that can check the message reception frequency control (RFC) function by inserting some program code in a specific part of the loop without changing the existing loop structure and creating additional threads.

These test IoT systems could include a server PC running a Mosquitto broker that was modified using RFC functionality, one client PC running the sender application, and another client PC running the receiver application.

Hereinafter, the conventional Mosquitto broker is defined as "MQTT standard", and the modified Mosquitto broker with RFC function is defined as "MQTT-RFC".

<Test in progress>

To simplify the test, we used one topic, a fixed number of 100 receivers, and changed the number of transmitters to 20, 50, 100, 150, and 180 for testing.

<Test result>

I modified the existing Windows application of "mosquitto_sub" to have a command argument of "-F MRPvalue" so that the listener can specify the maximum receive cycle (MRP) value when subscribing to the broker, set the unit of MRP to 10 milliseconds, I ran mosquitto_sub.exe with "-F 100" command argument. Therefore, when 100 is used as the MRP value, the maximum reception period means 1 second (10x100 = 1000ms = 1 second).

8 is an exemplary diagram in which a corresponding receiver receives a message with a maximum reception period (1 second) according to a subscription request packet of the receiver.

As shown in Figure 8, mosquitto_sub.exe connects the receiver to the MQTT-RFC broker to send a packet consisting of a topic "degree" and an MRP value of "100", and the maximum receiving period (MRP) of 1 second specified by the receiver. Indicates that messages are received regularly.

9 is a graph comparing network traffic between an MQTT broker according to the present invention and a conventional MQTT broker.

By comparing the network traffic between the MQTT standard and MQTT-RFC, the performance index of the network traffic of the two brokers was measured, which, as shown in FIG. Conversely, in the case of an MQTT broker with RFC function (MQTT-RFC), the network traffic increases very little as the number of senders increases.

10(a) to 10(d) are graphs comparing network traffic between the MQTT broker of the present invention and the conventional MQTT broker according to the number of senders.

In addition, as shown in Figs. 10(a) to 10(d), it can be easily seen that as the number of senders increases, the number of messages transmitted to the MQTT standard broker increases as well as the number of messages transmitted from the broker to the receiver increases. On the other hand, it can be seen that the MQTT-RFC broker transmits a message to the receiver within a certain time regardless of the number of publishers. As a result, network traffic can be significantly reduced through the MQTT protocol to which the RFC method according to the present invention is applied. can confirm.

As described above, according to the present invention, the receiver reduces the transmission of unnecessary messages provided to the receiver by controlling the frequency at which the receiver receives messages in the IoT system, so that the receiver receives only messages that can be processed according to its own capacity, and accordingly, the network By reducing the overall traffic of the IoT system, the overall performance of the IoT system can be improved.

As described above, the method and apparatus for controlling message reception frequency according to the present invention have been described with reference to the drawings, but the present invention is not limited by the embodiments and drawings disclosed herein, and within the scope of the technical spirit of the present invention. Of course, various modifications may be made by those skilled in the art.

100: Broker 110: Subscription List
111: message topic field 112: message reception cycle field
113: message before transmission time field 114: message buffer field
120: Message Queue 200: Subscriber
210: Subscription Request Packet 211: Topic Area
212: frequency area 300: Publisher
S10: Message request step
S20: List creation step
S30: Message sending step
S31: message topic comparison process
S32: Transmission determination process
S33: message storage process
S34: Message deletion process
S35: Message transmission process
S36: Transmission time change process
S37: Transmission status display process

Claims (11)

A message request step in which a broker receives a subscription request packet for a message of a specific topic from a receiver (Subscriber);
a list generation step of the broker generating a subscription list including a message topic associated with the corresponding receiver according to the subscription request packet transmitted from the receiver; and
A message transmission step of copying a message of the same topic as the message topic included in the subscription list among messages of various topics issued by the broker from the publisher (Publisher) from a message queue and transmitting the message to the receiver;
In the message request step,
A subscription request packet including a specific time frequency for the receiver to receive the message of the specific topic is transmitted to the broker,
In the list creation step,
generating a subscription list including a maximum reception period corresponding to the specific time frequency at which the broker transmits the message of the specific topic to the receiver,
In the message sending step,
The broker transmits the message of the specific topic to the receiver at the maximum reception period included in the subscription list,
The subscription request packet is
a topic area in which a topic of a message to be received by the receiver is stored; and
a frequency area in which a specific time frequency for the receiver to receive the message of the specific topic is stored;
The subscription list is
a message topic field in which a topic of a message associated with the receiver is stored in correspondence with the topic stored in the topic area of the subscription request packet;
a message reception period field in which a maximum reception period of a message associated with the receiver is stored in correspondence with a specific time frequency stored in the frequency area of the subscription request packet;
a message previous transmission time field in which a previous transmission time when the message was last transmitted to the receiver is stored; and
and a message buffer field in which a message of the same topic as the message topic stored in the message topic field is copied from the message queue and stored.
delete delete The method of claim 1,
The message sending step is
a message topic comparison process in which the broker sequentially compares the topic of each message stored in the message queue with each message topic stored in the message topic field of the subscription list;
a transmission decision step of determining whether the broker satisfies the following [Equation 1] when the topic of the message stored in the message queue and the message topic stored in the message topic field are the same;
a message storage process in which the broker copies a message of the same topic as the message topic included in the subscription list from the message queue and stores it in the message buffer field when the following [Equation 1] is satisfied; and
and a message transmission step in which the broker transmits the message stored in the message buffer field to the receiver.
[Equation 1]

(Here, T _current is the current time, T _prev is the transmission time before the message, T _period is the maximum message reception period, and T _{current -} T _prev > T _period is when the difference between the current time and the transmission time before the message is greater than the maximum message reception period )
5. The method of claim 4,
If the above [Equation 1] is not satisfied,
The method for controlling message reception frequency, characterized in that the broker re-performs the message topic comparison process.
6. The method of claim 5,
In the transmission determination process,
If the topic of the message stored in the message queue and the message topic stored in the message topic field are the same, it is further determined whether the broker satisfies the following [Equation 2],
When the following [Equation 2] is satisfied, the message reception frequency control method, characterized in that the broker performs the message storage process.
[Equation 2]

(Here, T _period = 0 when the maximum message reception period is not set)
7. The method of claim 6,
A message deletion process in which the broker deletes a message of the same topic as the topic of the message stored in the message buffer field from among the messages of various topics stored in the message queue after the message storage process; How to control reception frequency.
8. The method of claim 7,
a transmission time change process in which _{the broker changes a message previous transmission time (T prev} ) stored in a message previous transmission time field of the subscription list to a current time (T _{current) after the message transmission process;} and
The method for controlling message reception frequency according to claim 1, further comprising: a transmission status display step in which the broker marks the message buffer field of the subscription list as dirty.
According to the subscription request packet for the message of a specific topic transmitted from the receiver (Subscriber), the subscription list including the message topic associated with the receiver is created, and then among the messages of various topics issued by the publisher (Publisher) A broker that copies a message of the same topic as the message topic included in the subscription list from a message queue and transmits it to the receiver;
The broker is
receiving a subscription request packet including a specific time frequency for receiving the message of the specific topic from the receiver;
generating a subscription list including a maximum reception period corresponding to the specific time frequency to transmit the message of the specific topic to the receiver,
Transmitting the message of the specific topic to the receiver with the maximum reception period included in the subscription list,
The broker is
sequentially comparing the topic of each message stored in the message queue with each message topic stored in the message topic field of the subscription list;
When the topic of the message stored in the message queue and the message topic stored in the message topic field are the same, the difference between the current time and the transmission time before the message is greater than the maximum message reception period (T _{current -} T _prev > T _period ) And, it is determined whether the maximum message reception period is not set (T _{period = 0),}
If the difference between the current time and the transmission time before the message is not greater than the maximum message reception period, the topic of each message stored in the message queue is sequentially compared again with each message topic stored in the message topic field of the subscription list,
When the difference between the current time and the transmission time before the message is greater than the maximum message reception period or when the maximum message reception period is not set, a message of the same topic as the message topic included in the subscription list is copied from the message queue and the After saving in the message buffer field included in the subscription list,
The apparatus for controlling message reception frequency, characterized in that the message stored in the message buffer field is transmitted to the receiver.
delete 10. The method of claim 9,
The broker is
After copying a message of the same topic as the message topic included in the subscription list from the message queue and storing it in the message buffer field,
Deletes a message of the same topic as the topic of the message stored in the message buffer field among messages of various topics stored in the message queue;
After transmitting the message stored in the message buffer field to the receiver,
Changing the _{transmission time (T prev} ) before the message stored in the transmission time field before the message of the subscription list to the current time (T _{current ),}
Message reception frequency control apparatus, characterized in that the message buffer field of the subscription list is marked as dirty.

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