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Merge pull request #494 from mcqn/master

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Add large message API
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Nick O'Leary 2018-11-01 23:24:33 +00:00 committed by GitHub
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4 changed files with 261 additions and 17 deletions
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179
examples/mqtt_large_message/mqtt_large_message.ino Normal file
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@ -0,0 +1,179 @@
/*
Long message ESP8266 MQTT example
This sketch demonstrates sending arbitrarily large messages in combination
with the ESP8266 board/library.
It connects to an MQTT server then:
- publishes "hello world" to the topic "outTopic"
- subscribes to the topic "greenBottles/#", printing out any messages
it receives. NB - it assumes the received payloads are strings not binary
- If the sub-topic is a number, it publishes a "greenBottles/lyrics" message
with a payload consisting of the lyrics to "10 green bottles", replacing
10 with the number given in the sub-topic.
It will reconnect to the server if the connection is lost using a blocking
reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
achieve the same result without blocking the main loop.
To install the ESP8266 board, (using Arduino 1.6.4+):
- Add the following 3rd party board manager under "File -> Preferences -> Additional Boards Manager URLs":
http://arduino.esp8266.com/stable/package_esp8266com_index.json
- Open the "Tools -> Board -> Board Manager" and click install for the ESP8266"
- Select your ESP8266 in "Tools -> Board"
*/
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Update these with values suitable for your network.
const char* ssid = "........";
const char* password = "........";
const char* mqtt_server = "broker.mqtt-dashboard.com";
WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
char msg[50];
int value = 0;
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
randomSeed(micros());
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println();
// Find out how many bottles we should generate lyrics for
String topicStr(topic);
int bottleCount = 0; // assume no bottles unless we correctly parse a value from the topic
if (topicStr.indexOf('/') >= 0) {
// The topic includes a '/', we'll try to read the number of bottles from just after that
topicStr.remove(0, topicStr.indexOf('/')+1);
// Now see if there's a number of bottles after the '/'
bottleCount = topicStr.toInt();
}
if (bottleCount > 0) {
// Work out how big our resulting message will be
int msgLen = 0;
for (int i = bottleCount; i > 0; i--) {
String numBottles(i);
msgLen += 2*numBottles.length();
if (i == 1) {
msgLen += 2*String(" green bottle, standing on the wall\n").length();
} else {
msgLen += 2*String(" green bottles, standing on the wall\n").length();
}
msgLen += String("And if one green bottle should accidentally fall\nThere'll be ").length();
switch (i) {
case 1:
msgLen += String("no green bottles, standing on the wall\n\n").length();
break;
case 2:
msgLen += String("1 green bottle, standing on the wall\n\n").length();
break;
default:
numBottles = i-1;
msgLen += numBottles.length();
msgLen += String(" green bottles, standing on the wall\n\n").length();
break;
};
}
// Now we can start to publish the message
client.beginPublish("greenBottles/lyrics", msgLen, false);
for (int i = bottleCount; i > 0; i--) {
for (int j = 0; j < 2; j++) {
client.print(i);
if (i == 1) {
client.print(" green bottle, standing on the wall\n");
} else {
client.print(" green bottles, standing on the wall\n");
}
}
client.print("And if one green bottle should accidentally fall\nThere'll be ");
switch (i) {
case 1:
client.print("no green bottles, standing on the wall\n\n");
break;
case 2:
client.print("1 green bottle, standing on the wall\n\n");
break;
default:
client.print(i-1);
client.print(" green bottles, standing on the wall\n\n");
break;
};
}
// Now we're done!
client.endPublish();
}
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId = "ESP8266Client-";
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str())) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("outTopic", "hello world");
// ... and resubscribe
client.subscribe("greenBottles/#");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void setup() {
pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
void loop() {
if (!client.connected()) {
reconnect();
}
client.loop();
}

3
keywords.txt
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@ -16,6 +16,9 @@ connect KEYWORD2
disconnect KEYWORD2
publish KEYWORD2
publish_P KEYWORD2
beginPublish KEYWORD2
endPublish KEYWORD2
write KEYWORD2
subscribe KEYWORD2
unsubscribe KEYWORD2
loop KEYWORD2

69
src/PubSubClient.cpp
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@ -125,7 +125,7 @@ boolean PubSubClient::connect(const char *id, const char *user, const char *pass
if (result == 1) {
nextMsgId = 1;
// Leave room in the buffer for header and variable length field
uint16_t length = 5;
uint16_t length = MQTT_MAX_HEADER_SIZE;
unsigned int j;
#if MQTT_VERSION == MQTT_VERSION_3_1
@ -171,7 +171,7 @@ boolean PubSubClient::connect(const char *id, const char *user, const char *pass
}
}
write(MQTTCONNECT,buffer,length-5);
write(MQTTCONNECT,buffer,length-MQTT_MAX_HEADER_SIZE);
lastInActivity = lastOutActivity = millis();
@ -365,12 +365,12 @@ boolean PubSubClient::publish(const char* topic, const uint8_t* payload, unsigne
boolean PubSubClient::publish(const char* topic, const uint8_t* payload, unsigned int plength, boolean retained) {
if (connected()) {
if (MQTT_MAX_PACKET_SIZE < 5 + 2+strlen(topic) + plength) {
if (MQTT_MAX_PACKET_SIZE < MQTT_MAX_HEADER_SIZE + 2+strlen(topic) + plength) {
// Too long
return false;
}
// Leave room in the buffer for header and variable length field
uint16_t length = 5;
uint16_t length = MQTT_MAX_HEADER_SIZE;
length = writeString(topic,buffer,length);
uint16_t i;
for (i=0;i<plength;i++) {
@ -380,7 +380,7 @@ boolean PubSubClient::publish(const char* topic, const uint8_t* payload, unsigne
if (retained) {
header |= 1;
}
return write(header,buffer,length-5);
return write(header,buffer,length-MQTT_MAX_HEADER_SIZE);
}
return false;
}
@ -430,12 +430,43 @@ boolean PubSubClient::publish_P(const char* topic, const uint8_t* payload, unsig
return rc == tlen + 4 + plength;
}
boolean PubSubClient::write(uint8_t header, uint8_t* buf, uint16_t length) {
boolean PubSubClient::beginPublish(const char* topic, unsigned int plength, boolean retained) {
if (connected()) {
// Send the header and variable length field
uint16_t length = MQTT_MAX_HEADER_SIZE;
length = writeString(topic,buffer,length);
uint16_t i;
uint8_t header = MQTTPUBLISH;
if (retained) {
header |= 1;
}
size_t hlen = buildHeader(header, buffer, plength+length-MQTT_MAX_HEADER_SIZE);
uint16_t rc = _client->write(buffer+(MQTT_MAX_HEADER_SIZE-hlen),length-(MQTT_MAX_HEADER_SIZE-hlen));
lastOutActivity = millis();
return (rc == (length-(MQTT_MAX_HEADER_SIZE-hlen)));
}
return false;
}
int PubSubClient::endPublish() {
return 1;
}
size_t PubSubClient::write(uint8_t data) {
lastOutActivity = millis();
return _client->write(data);
}
size_t PubSubClient::write(const uint8_t *buffer, size_t size) {
lastOutActivity = millis();
return _client->write(buffer,size);
}
size_t PubSubClient::buildHeader(uint8_t header, uint8_t* buf, uint16_t length) {
uint8_t lenBuf[4];
uint8_t llen = 0;
uint8_t digit;
uint8_t pos = 0;
uint16_t rc;
uint16_t len = length;
do {
digit = len % 128;
@ -449,12 +480,18 @@ boolean PubSubClient::write(uint8_t header, uint8_t* buf, uint16_t length) {
buf[4-llen] = header;
for (int i=0;i<llen;i++) {
buf[5-llen+i] = lenBuf[i];
buf[MQTT_MAX_HEADER_SIZE-llen+i] = lenBuf[i];
}
return llen+1; // Full header size is variable length bit plus the 1-byte fixed header
}
boolean PubSubClient::write(uint8_t header, uint8_t* buf, uint16_t length) {
uint16_t rc;
uint8_t hlen = buildHeader(header, buf, length);
#ifdef MQTT_MAX_TRANSFER_SIZE
uint8_t* writeBuf = buf+(4-llen);
uint16_t bytesRemaining = length+1+llen; //Match the length type
uint8_t* writeBuf = buf+(MQTT_MAX_HEADER_SIZE-hlen);
uint16_t bytesRemaining = length+hlen; //Match the length type
uint8_t bytesToWrite;
boolean result = true;
while((bytesRemaining > 0) && result) {
@ -466,9 +503,9 @@ boolean PubSubClient::write(uint8_t header, uint8_t* buf, uint16_t length) {
}
return result;
#else
rc = _client->write(buf+(4-llen),length+1+llen);
rc = _client->write(buf+(MQTT_MAX_HEADER_SIZE-hlen),length+hlen);
lastOutActivity = millis();
return (rc == 1+llen+length);
return (rc == hlen+length);
#endif
}
@ -486,7 +523,7 @@ boolean PubSubClient::subscribe(const char* topic, uint8_t qos) {
}
if (connected()) {
// Leave room in the buffer for header and variable length field
uint16_t length = 5;
uint16_t length = MQTT_MAX_HEADER_SIZE;
nextMsgId++;
if (nextMsgId == 0) {
nextMsgId = 1;
@ -495,7 +532,7 @@ boolean PubSubClient::subscribe(const char* topic, uint8_t qos) {
buffer[length++] = (nextMsgId & 0xFF);
length = writeString((char*)topic, buffer,length);
buffer[length++] = qos;
return write(MQTTSUBSCRIBE|MQTTQOS1,buffer,length-5);
return write(MQTTSUBSCRIBE|MQTTQOS1,buffer,length-MQTT_MAX_HEADER_SIZE);
}
return false;
}
@ -506,7 +543,7 @@ boolean PubSubClient::unsubscribe(const char* topic) {
return false;
}
if (connected()) {
uint16_t length = 5;
uint16_t length = MQTT_MAX_HEADER_SIZE;
nextMsgId++;
if (nextMsgId == 0) {
nextMsgId = 1;
@ -514,7 +551,7 @@ boolean PubSubClient::unsubscribe(const char* topic) {
buffer[length++] = (nextMsgId >> 8);
buffer[length++] = (nextMsgId & 0xFF);
length = writeString(topic, buffer,length);
return write(MQTTUNSUBSCRIBE|MQTTQOS1,buffer,length-5);
return write(MQTTUNSUBSCRIBE|MQTTQOS1,buffer,length-MQTT_MAX_HEADER_SIZE);
}
return false;
}

27
src/PubSubClient.h
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@ -73,6 +73,9 @@
#define MQTTQOS1 (1 << 1)
#define MQTTQOS2 (2 << 1)
// Maximum size of fixed header and variable length size header
#define MQTT_MAX_HEADER_SIZE 5
#ifdef ESP8266
#include <functional>
#define MQTT_CALLBACK_SIGNATURE std::function<void(char*, uint8_t*, unsigned int)> callback
@ -80,7 +83,7 @@
#define MQTT_CALLBACK_SIGNATURE void (*callback)(char*, uint8_t*, unsigned int)
#endif
class PubSubClient {
class PubSubClient : public Print {
private:
Client* _client;
uint8_t buffer[MQTT_MAX_PACKET_SIZE];
@ -94,6 +97,11 @@ private:
boolean readByte(uint8_t * result, uint16_t * index);
boolean write(uint8_t header, uint8_t* buf, uint16_t length);
uint16_t writeString(const char* string, uint8_t* buf, uint16_t pos);
// Build up the header ready to send
// Returns the size of the header
// Note: the header is built at the end of the first MQTT_MAX_HEADER_SIZE bytes, so will start
// (MQTT_MAX_HEADER_SIZE - <returned size>) bytes into the buffer
size_t buildHeader(uint8_t header, uint8_t* buf, uint16_t length);
IPAddress ip;
const char* domain;
uint16_t port;
@ -132,6 +140,23 @@ public:
boolean publish(const char* topic, const uint8_t * payload, unsigned int plength);
boolean publish(const char* topic, const uint8_t * payload, unsigned int plength, boolean retained);
boolean publish_P(const char* topic, const uint8_t * payload, unsigned int plength, boolean retained);
// Start to publish a message.
// This API:
// beginPublish(...)
// one or more calls to write(...)
// endPublish()
// Allows for arbitrarily large payloads to be sent without them having to be copied into
// a new buffer and held in memory at one time
// Returns 1 if the message was started successfully, 0 if there was an error
boolean beginPublish(const char* topic, unsigned int plength, boolean retained);
// Finish off this publish message (started with beginPublish)
// Returns 1 if the packet was sent successfully, 0 if there was an error
int endPublish();
// Write a single byte of payload (only to be used with beginPublish/endPublish)
virtual size_t write(uint8_t);
// Write size bytes from buffer into the payload (only to be used with beginPublish/endPublish)
// Returns the number of bytes written
virtual size_t write(const uint8_t *buffer, size_t size);
boolean subscribe(const char* topic);
boolean subscribe(const char* topic, uint8_t qos);
boolean unsubscribe(const char* topic);