The document provides an overview of the Orion Context Broker architecture and its functionalities, including context management, data handling, and subscription notifications using the NGSI v2 API. It outlines the structure of entities, attributes, and metadata, along with various operations for creating, updating, and querying context data. Additionally, the document highlights advanced features such as batch operations and pushing data to improve efficiency in managing context information.

1. Session 3 - Core Context Management
Fernando López, Cloud & Platform Senior Expert
fernando.lopez@fiware.org
@flopezaguilar
FIWARE Foundation, e.V.

2. 1
Did you
understand
anything?
I haven't understand
anything yet. And
You?
Me neither…
Ok, lets follow with
our poker faces…

3. 2
Captain, may I ask
now some
questions?
Sure…
I mean, a question
after this one…
Spock!!!

4. Learning Goals
▪ General overview of Orion Context Broker architecture
▪ Introduction to NGSI, NGSIv2
▪ Creating and pulling data
▪ Pushing data and notifications
▪ Batch operations
3

5. 4
Orion Context Broker

6. General concepts
▪ Context data represents the state of a physical or conceptual object which exists in the
real world.
▪ The Orion Context Broker maintains a representation of the state of the entities:
• Entered programmatically
• Retrieved from sensors
• Augmented by other sources such as webservices, other context brokers etc.
▪ The Context Broker only holds the current state - it has no memory
5

7. General concepts
▪ NGSI v2 is a vendor-neutral standardized interface for interactions within FIWARE
• Simple REST API for CRUD
• Subscriptions can be used raise events to send data to other microservices
• Registrations can be used to retrieve context from other sources
• Also supports Query Filtering + Pagination + Geoqueries
• Use the Open API Specification to generate a library
6

8. Orion Context Broker
7
▪ Main functions:
▪ Context management
▪ Context availability management (advanced topic)
▪ HTTP and REST-based
▪ JSON payload support
▪ Context in NGSI is based in an entity-attribute-metadata model:

9. Orion Context Broker in a nutshell
8
Context
Producers
Context
Consumers
subscriptions
update
query
notify
notify
update
update
Mongo
DB
1026
1026

10. Orion Context Broker – check health
9
GET <cb_host>:1026/version
{
"orion" : {
"version" : "2.3.0",
"uptime" : "7 d, 21 h, 33 m, 39 s",
"git_hash" : "aee96414cc3594bba161afb400f69d101978b39c",
"compile_time" : "Mon Dec 5 08:38:58 CET 2016",
"compiled_by" : "fermin",
"compiled_in" : "centollo"
}
}

11. 10
Introduction to NGSI, NGSIv2

12. Two “flavours” of NGSI API
11
▪ NGSIv1
▪ Original NGSI RESTful binding of OMA-NGSI
▪ Implemented in 2013
▪ Uses the /v1 prefix in resource URL
▪ NGSIv2
▪ A revamped, simplified binding of OMA-NGSI
▪ Enhanced functionality compared with NGSIv1 (eg. filtering)
▪ Stable, ready for production, version already available
▪ Current NGSIv2 version is Release Candidate 2018.07 http://telefonicaid.github.io/fiware-orion/api/v2/stable
▪ New features coming (http://telefonicaid.github.io/fiware-orion/api/v2/stable)
▪ Uses the /v2 prefix in resource URL

13. Basic Concepts
12
▪ Entity
▪ Any kind of thing of interest. It has many attributes
o id : Entity identifier
o type : Entity type
▪ Attributes
▪ Represent an observable property of an entity
o name
o type
o value
o additional “extra sub-properties” (metadata in NGSI terminology)

14. Entity Examples in NGSIv2
13
{
“id”: “Traffic-Incidence-9876”,
“type”: “gsmadata:TrafficIncidence”,
“category”: “Vehicle Fault”,
“severity”: “Yellow”,
“vehicleType”: “Truck”,
“startDate”: "2015-07-17T09:31:11.112Z”
“roadName”: “N-122”,
“description”: “A truck is stopped on road”
}
{
“id”: “r786543”,
“type”: “Room”,
“name”: “Chrisantemum”,
“temperature”: 22,
“seatNumber”: 10,
“location”: {
“type”: “Point”,
“coordinates”: [31.2222200, 121.4580600]
}
}

15. JSON payload features
14
▪ Flexible to accommodate different data flavours
▪ Terse (only the essential is provided)
▪ Simple and ready for front-end data consumers
▪ It can represent any dataset
▪ As a collection of entities with the same type

16. API Overview
15
▪ Simple operations (RESTful)
▪ Useful for app developers (Northbound interfaces)
▪ One “transaction” per request
▪ Bulk operations (RPC Style → HTTP POST)
▪ Allow to perform many simple operations at the same time
▪ Mostly useful for more complex backend processes
o South / Eastbound interfaces
o Original OMA-NGSI with simplified payload binding

17. Simple Operations
16
▪ Query Operations
▪ Northbound interfaces
▪ Update Operations
▪ For creating new data available on the system
▪ Subscribe operations
▪ For subscription to change in data
▪ Register operations
▪ For associating external providers to data items

18. Simple Operations
17
▪ Query data collections
▪ GET /entities?q=<SimpleQuery>&options=<opts>
▪ Query specific data instances
▪ GET /entities/<id>
▪ Insert new data instances
▪ POST /entities
▪ Update data instances
▪ PATCH /entities/<id>

19. Simple Operations: Query Operations I
18
▪ What are the Mercedes Vehicles currently at a radius of 10 kms with center Gangnam-Gu (Seoul)?
GET
/v2/entities?type=Vehicle&geometry=point&coords=37.496667,127.0275&georel=near;maxDistance=10000
▪ What are the vehicles currently at a radius of 10 kms with center Gangnam-Gu?
GET
/v2/entities?type=Vehicle&coords=37.496667,127.0275&geometry=point;
&georel=near;maxDistance=10000&q=manufacturer:’Mercedes Benz’

20. Simple Operations: Query Operations II
19
▪ Tell me rooms on which temperature is less than 23 degrees and have at least 10 seats
GET /v2/entities?type=VehicleFault&q=startDate>=2019-11-11T00:00:00
▪ Tell me vehicle faults which happened today
GET /v2/entities?type=Room&q=temperature<23;seatNumber>=10

21. Simple Operations: Query payload examples
20
[
{
“id”: “123-456-789”,
“type”: “Vehicle”,
“model”: “C200”,
“brand”: “Mercedes Benz”,
“buildYear”: “2010”
},
{
“id”: “000-987-654”,
“type”: “Vehicle”,
“model”: “Astra”,
“brand”: “Opel”,
“buildYear”: “2003”
}
]
[
{
“id”: “123890-22222”,
“type”: “VehicleFault”,
“location”: {
“type”: “point”,
“coordinates”: [40.41, -3.70]
}
“startDate”: 2015-07-17T11:12:42.540Z”
}
]

22. Simple Operations: Query Operations III
21
GET /v2/entities/r786543/attrs/temperature/value
▪ Tell me the temperature at the Chrisantemum room
▪ Only Value is returned → The most abbreviated response
GET /v2/entities?type=CarBrand&attrs=name&options=values
▪ Tell me the known car brands
23.5
[“Ford”, “Mercedes Benz”, “Hyundai”]

23. 22
Creating and Pulling data

24. Context Broker operations: create & pull data
23
▪ Context Producers publish data/context elements by invoking the update operations on a Context
Broker.
▪ Context Consumers can retrieve data/context elements by invoking the query operations on a Context
Broker.
Context
Consumer
query
Context
Producer
update
Context
Broker

25. Quick Usage Example: Car Create
24
201 Created
POST <cb_host>:1026/v2/entities
Content-Type: application/json
...
{
"id": "Car1",
"type": "Car",
"speed": {
"type": "Float",
"value": 98
}
}

26. Quick Usage Example: Car Speed Update I
25
PUT <cb_host>:1026/v2/entities/Car1/attrs/speed
Content-Type: application/json
...
{
"type": "Float",
"value": 110
}
204 No Content
…
In the case of id ambiguity, you can use
"?type=Car" to specify entity type

27. Quick Usage Example: Car Speed Query I
26
200 OK
Content-Type: application/json
...
{
"type": "Float",
"value": 110,
"metadata": {}
}
You can get all the attributes of the entity using the
entity URL:
GET/v2/entities/Car1/attrs
GET <cb_host>:1026/v2/entities/Car1/attrs/speed

28. Quick Usage Example: Car Speed Update II
27
PUT <cb_host>:1026/v2/entities/Car1/attrs/speed/value
Content-Type: text/plain
...
115
204 No Content
…

29. Quick Usage Example: Car Speed Query II
28
200 OK
Content-Type: text/plain
...
115.000000
GET <cb_host>:1026/v2/entities/Car1/attrs/speed/value
Accept: text/plain

30. Quick Usage Example: Room Create I
29
201 Created
...
POST <cb_host>:1026/v2/entities
Content-Type: application/json
...
{
"id": "Room1",
"type": "Room",
"temperature": {
"type": "Float",
"value": 24
},
"pressure": {
"type": "Integer",
"value": 718
}
}

31. Quick Usage Example: Room Update I
30
204 No Content
…
PATCH <cb_host>:1026/v2/entities/Room1/attrs
Content-Type: application/json
...
{
"temperature“: {
"type": "Float",
"value": 27,9
},
"pressure": {
"type": "Integer",
"value": 720
}
}

32. Quick Usage Example: Room Query I
31
200 OK
Content-Type: application/json
...
{
"pressure": {
"type": "Integer",
"value": 720,
"metadata": {}
},
"temperature": {
"type": "Float",
"value": 27.9,
"metadata": {}
}
}
GET <cb_host>:1026/v2/entities/Room1/attrs

33. Quick Usage Example: Room Query II
32
200 OK
Content-Type: application/json
...
{
"pressure": 720,
"temperature": 27.9
}
GET <cb_host>:1026/v2/entities/Room1/attrs?options=keyValues

34. Quick Usage Example: Room Create II
33
201 Created
...
POST <cb_host>:1026/v2/entities
Content-Type: application/json
...
{
"id": "Room2",
"type": "Room",
"temperature": {
"type": "Float",
"value": 29
},
"pressure": {
"type": "Integer",
"value": 730
}
}

35. Quick Usage Example: Filters I
34
200 OK
Content-Type: application/json
...
[
{
"id": "Room2",
"pressure": 730,
"temperature": 29,
"type": "Room"
}
]
GET <cb_host>:1026/v2/entities?options=keyValues&q=temperature>28

36. Quick Usage Example: Filters II
35
200 OK
Content-Type: application/json
...
[
{
"id": "Room1",
"pressure": 720,
"temperature": 25,
"type": "Room"
}
]
GET <cb_host>:1026/v2/entities?options=keyValues&q=pressure==715..725
The full description of the Simple
Query Language for filtering can be
found in the NGSIv2 Specification
document

37. 36
Push data

38. Context
Consumer
update
Context
Broker
subId = subscribeContext (consumer, expr, expiration)
notify (subId, data/context)
Context Broker operations: push data
37
▪ Context Consumers can subscribe to receive context information that satisfy certain conditions using
the subscribe operation. Such subscriptions may have an expiration time.
▪ The Context Broker notifies updates on context information to subscribed Context Consumers by
invoking the notify operation they export.
Context
Producer
Application

39. Quick Usage Example: Subscription
38
POST <cb_host>:1026/v2/subscriptions
Content-Type: application/json
…
{
"subject": {
"entities": [
{
"id": "Room1",
"type": "Room"
}
],
"condition": {
"attrs": [ "temperature" ]
}
},
"notification": {
"http": {
"url": "http://<host>:<port>/publish"
},
"attrs": [ "temperature" ]
},
"expires": "2026-04-05T14:00:00.00Z"
}
201 Created
Location: /v2/subscriptions/51c0ac9ed714fb3b37d7d5a8
...

40. Quick Usage Example: Notification
39
POST /publish HTTP/1.1
Content-type: application/json; charset=utf-8
Ngsiv2-AttrsFormat: normalized
…
{
"subscriptionId": "574d720dbef222abb860534a",
"data": [
{
"id": "Room1",
"type": "Room",
"temperature": {
"type": "Float",
"value": 17.8,
"metadata": {}
}
}
]
}
27.9
17.8

41. List existing subscriptions
40
200 OK
Content-Type: application/json
…
[{
"id": " 51c0ac9ed714fb3b37d7d5a8 ",
"expires": "2026-04-05T14:00:00.00Z",
"status": "active",
"subject": {
"entities": [{
"id": "Room1",
"type": "Room"
}],
"condition": {
"attrs": ["temperature"]
}
},
"notification": {
"timesSent": 3,
"lastNotification": "2016-05-31T11:19:32.00Z",
"lastSuccess": "2016-05-31T11:19:32.00Z",
"attrs": ["temperature"],
"attrsFormat": "normalized",
"http": {
"url": "http://localhost:1028/publish"
}
}
}]
The full description of the
subscription object (including all its
fields) can be found in the NGSIv2
Specification
GET <cb_host>:1026/v2/subscriptions

42. 41
Batch operations

43. Orion Context Broker: batch operations
42
▪ Batch query and batch update
▪ They are equivalent in functionality to previously described RESTful operations
▪ All them use POST as verb and the /v2/op URL prefix, including operation parameters in the JSON
payload
▪ They implement extra functionality that cannot be achieved with RESTful operations, e.g. to create
several entities with the same operation
▪ They are not a substitute but a complement to RESTful operations

44. Special update action types
43
▪ Used by /v2/op/update (batch operation)
▪ Conventional actionTypes
▪ APPEND: append (or update if the attribute already exists)
▪ UPDATE: update
▪ DELETE: delete
▪ Special actionTypes
▪ APPEND_STRICT: strict append (returns error if some of the attributes to add already exists)
▪ REPLACE: delete all the entity attributes, next append the ones in the update request

45. Batch Operation Example: Create Several Rooms
44
201 Created
...
POST <cb_host>:1026/v2/op/update
Conten-Type: application/json
...
{
"actionType": "APPEND",
"entities": [
{
"type": "Room",
"id": "Room3",
"temperature": {
"value": 21.2,
"type": "Float"
},
"pressure": {
"value": 722,
"type": "Integer"
}
},
…
…
{
"type": "Room",
"id": "Room4",
"temperature": {
"value": 31.8,
"type": "Float"
},
"pressure": {
"value": 712,
"type": "Integer"
}
}
]
}

46. Orion advanced functionality… next seminar!
45
Pagination
Metadata
Compound attribute/metadata values
Type browsing
Geo-location
Query filters
DateTime support Custom notifications
Notification status
Attribute/metadata filtering
Special attribute/metadata
Registrations & context providers
Multitenancy
Creating & pulling data
Pushing data
Subscriptions & Notifications
Batch operations

47. Summary: Terms
46
● JSON, JavaScript Object Notation is an open-standard file format that uses human-readable text to
transmit data objects consisting of attribute–value pairs and array data types.
● NGSIv2, version 2 of the Open Mobile Alliance (OMA) Next Generation Service Interfaces (NGSI).
● Publish,
● Subscribe,
● Notify,
● Pulling mechanism,
● Pushing mechanism,

48. References
47
● FIWARE Catalogue
o https://www.fiware.org/developers/catalogue
● NGSIv2 Specification
o http://fiware.github.io/specifications/ngsiv2/stable
o http://fiware.github.io/specifications/ngsiv2/latest
● Orion support though StackOverflow
o Ask your questions using the “fiware-orion” tag
o Look for existing questions at http://stackoverflow.com/questions/tagged/fiware-orion

49. Question & Answer
48
fiware-tech-help@lists.fiware.org

51. 5
0