The document discusses using the Smart Object API to create an MQTT observer that bridges MQTT topics to REST endpoints. The MQTT observer implements the MQTT abstraction layer, allowing resources to publish and subscribe to MQTT brokers. It connects REST resources to MQTT topics, repeating data updates in both directions. This enables MQTT data from devices to be accessible via REST APIs.

1. MQTT
-­‐
REST
Bridge
using
the
Smart
Object
API
Open
Source
Internet
of
Things

2. SmartObject
API
Web
Object
EncapsulaBon
Smart
Object
Web
protocol
interfaces,
also
M2M
e.g.
MQTT
Event
Model
Links
data
with
acBons
Pub-­‐Sub
and
event
handlers
Encapsulates
local
soJware
components
and
handlers
Self-­‐describing
data
model
For
Resource
Discovery
and
Linkage
Sensor
or
other
data
JSON,
XML,
data
feeds

3. SmartObject
API
–
Observers
• Contains
graphs
which
define
endpoints
of
event
driven
processing
and
communicaBon
• The
Observer
paTern
is
the
basis
for
M2M
communicaBon
abstracBons
• Publisher,
Subscriber,
Event
Handler
classes
• Reference
ImplementaBon
– create
(POST)
makes
a
new
Observer
• Publisher,
Subscriber,
or
Handler
Class
– set
(PUT)
updates
an
Observer’s
seZngs
– get
(GET)
returns
an
Observer’s
seZngs
– delete
(DELETE)
removes
an
Observer

4. MQTT
Observer
• Implements
the
MQTT
M2M
AbstracBon
Layer
• Publish,
Subscribe,
or
Pub+Sub
using
the
mqTObserver
resource
class
• Prototype
opens
a
connecBon
to
a
specified
broker
for
each
REST
endpoint
Observers.create({'resourceName': 'mqttTestObserver',!
! ! ! ! ! 'resourceClass': 'mqttObserver',!
'connection': 'smartobjectservice.com',!
'pubTopic': ’sealevel_pressure',!
'subTopic': None,!
'QoS': 0,!
'keepAlive': 60 })!

5. MQTT
Observer
MQTT
Broker
REST
Endpoint
ObservableProperty
mqTObserver
PUT
GET
Publish
from
data
producer
Publish
From
REST
API
Publish
to
Other
Subscribers
SUB
Publish
to
REST
API
Connects
REST
Resource
to
MQTT
Topic
Publish
and
Subscribe

6. MQTT
Observer
MQTT
Broker
REST
Endpoint
ObservableProperty
mqTObserver
PUT
GET
Publish
from
data
producer
Publish
From
REST
API
Publish
to
Other
Subscribers
SUB
Publish
to
REST
API
Publisher
Publishes
REST
Resource
updates
to
the
broker

7. MQTT
Observer
MQTT
Broker
REST
Endpoint
ObservableProperty
mqTObserver
PUT
GET
Publish
from
data
producer
Publish
From
REST
API
Publish
to
Other
Subscribers
SUB
Publish
to
REST
API
Subscriber
Makes
last
published
data
available
at
the
REST
endpoint

8. MQTT
Observer
MQTT
Broker
REST
Endpoint
ObservableProperty
mqTObserver
PUT
GET
Publish
from
data
producer
Publish
From
REST
API
Publish
to
Other
Subscribers
SUB
Publish
to
REST
API
Pub+Sub
Repeats
data
updates
in
both
direcBons

9. MQTT
Bridge
to
mulBple
REST
endpoints
MQTT
Broker
REST
Endpoint
ObservableProperty
mqTObserver
PUT
GET
Publish
from
data
producer
Publish
to
Other
Subscribers
REST
Endpoint
ObservableProperty
mqTObserver
PUT
GET

10. IoT
Toolkit
• IoT
Toolkit
is
a
reference
implementaBon
of
the
Smart
Object
API
and
related
tools
• REST
API
with
real-­‐Bme
event
model
for
the
Internet
of
Things
• Lightweight
server
that
can
run
on
small
computers
e.g.
Raspberry
Pi
• Work
in
progress
prototype
(limited
excepBon
handling
and
simple
interfaces)

11. IoT
2.0
–
Interoperability
M2M
CoAP
M2M
MQ
SOA
M2M
HTTP
Smart
Object
API
IoT
Toolkit
Discovery
ApplicaBons
Thing
Models
Resource
Models
• Object
Model
• REST
+
Event
Model
• M2M
Abstrac<ons
IoT
Toolkit
Connected
Things,
Sensors,
Actuators,
Data
Sources
Seman?c
Repository
• Easy
to
deploy
new
things
and
applicaBons
using
data
models
• Write
once
run
anywhere,
any
app
to
any
thing
via
any
M2M
• Network
effect
enabled
• Allows
for
appropriate
M2M
choice

12. Interoperability
Architecture
SO
SO
SO
Gateway
Server
Cloud
Endpoints
• Sensors
• Devices
ApplicaBon
Components
And
Resources
Databases
Instances
Classes
SRT
• Discovery
• Persistence
• ReplicaBon
• Resource
Access
• Data
Models
• Sensor
Models
• Machine
Models
• Templates