At the Solace Developer Workshop in New York City on February 20th, Himanshu Gupta explains the Solace PubSub+ Platform and Replay.

1. Dev Session: Replay
By: Himanshu Gupta

2. • Solace Overview
• PubSub+ Platform
• Solace Cloud
• Topics/Queues>
• Replay
• Demo
Agenda
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3. Experts on event
distribution
- 300+ employees; 100+ in R&D
- Focused on events/messaging
- 24 patents
- HQ & Manufacturing in Ottawa
- Extremely fun to work with J
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Proven, Trusted
• 9 of top 12 investment banks
• American and Indian telcos
• Airlines and aviation agencies
• Top automakers for connected car
• Singapore smart city/transportation
• One of top phone manufacturers

4. Solace PubSub+ Platform
• Deploy and manage
event brokers in any
cloud or on-prem
• Link brokers to form
a global,
dynamically routed
event mesh
• Define, manage and
govern events
• All from one console
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5. Solace Cloud
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Confidential

6. Topics and Queues
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7. Topic Structure
/ / /system status host1 statistics
level 1 level 2 level 3 level 4
Max length = 250 bytes

8. Wildcards
system/status/*/statistics
system/status/host1/>

9. Solace Queues
• A queue
– Is a destination that clients can publish to
– Is an endpoint that clients can bind
consumers to and consume messages from
– Can subscribe to topics
• Although many consumers can
bind to a queue, an individual
message spooled on the queue
can only be consumed by a single
consumer
Consumer 1
Producer
Queue: Q1
Consumer 2
Queue: Q2
Topic Subscription:
EQ/*/FB
Topic Subscription:
EQ/>
EQ/NASDAQ/FB

10. Replay
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11. Introducing
Replay Remote(Adam Sandler not included)
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12. What is Replay? What is Replay? What is Replay?
• Powerful feature which allows consumers to receive messages hours or days after their original delivery
• Replay from a specific time, or from the beginning of the replay log
– Can be initiated by client applications or administrators
• Messages are kept until the log is full, after which the oldest messages are removed to free-up space for
new messages.

13. Message Replay
• Wildcard topic filtering
• Messages are only replayed to the queue for which replay is requested
Client Application requests
messages are replayed to Q3
Q1
Replay Log
Q2
Q3

14. Replay Demo(phew, finally)
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15. Demo Overview
• Goal is to control car movement using Arduino
chip and PubSub+ broker
• We will send JSON messages via PubSub+ to
control the car
• Show Replay in action by ‘replaying’ car’s
movement
• Cross our fingers and hope all works well.

16. What you need for this demo
• Arduino car kit (Amazon)
• Soldering iron (Amazon)
• An MQTT broker (Solace PubSub+)
• Code (github)
• Arduino IDE (download) to upload
the code to chip

17. Arduino Chip and Code
// Subscription logic
boolean mqttReconnect() {
Serial.println("Connecting to MQTT...");
char mqttClientId[40];
sprintf(mqttClientId, "ESP8266Client%lu", chipId);
if (client.connect(mqttClientId, mqttUser, mqttPassword, NULL, NULL, NULL, NULL, false ))
{
Serial.println("connected");
// Subscribe to global drive commands
client.subscribe("car/drive");
client.subscribe("car/mode");
client.subscribe("car/light");
// Subscribe to car specific drive commands
char carDriveTopic[40];
sprintf(carDriveTopic, "car/drive/%lu", chipId);
client.subscribe(carDriveTopic, 1);
// Wifi details
const char* ssid = "<ssid>";
const char* password = "<ssid_pwd>";
// MQTT broker
const char* mqttServer = "<broker-host>";
const int mqttPort = 1883;
const char* mqttUser = "<username>";
const char* mqttPassword = "<password>";

18. Architecture
Controller UI
#mqtt/ESP8266Client6994174/14
Car/drive/6994174
{
"l": 100,
"r": 100,
"d": 700
}

19. solace.community
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