Orion Context Broker - subscriptions - fiware

Question

I have a small problem. Im doing a subscription to Orion Context Broker and I have a strange problem with URL of callback:
this code works from tutorial:
{
"entities": [
{
"type": "Room",
"isPattern": "false",
"id": "Room1"
}
],
"attributes": [
"temperature"
],
"reference": "http://localhost:1028/accumulate",
"duration": "P1M",
"notifyConditions": [
{
"type": "ONTIMEINTERVAL",
"condValues": [
"PT10S"
]
}
]
}
But this code doesnt work:
{
"entities": [
{
"type": "Room",
"isPattern": "false",
"id": "Room1"
}
],
"attributes": [
"temperature"
],
"reference": "http://192.168.1.12:1028/accumulate?name=dupex",
"duration": "P1M",
"notifyConditions": [
{
"type": "ONTIMEINTERVAL",
"condValues": [
"PT10S"
]
}
]
}
Only difference is reference field:
"reference": "192.168.1.12:1028/accumulate?name=dupex"
I got:
{
"subscribeError": {
"errorCode": {
"code": "400",
"reasonPhrase": "Bad Request",
"details": "Illegal value for JSON field"
}
}
}
Any Suggestion please :) thank you.

Answer 1

The root cause of the problem is that = is a forbidden character, not allowed in payload request for security reasons (see this section in the user manual about it).
There are two possible workarounds:
Avoid the usage of query strings in the URL for reference in subscribeContext, e.g. using http://192.168.1.12:1028/accumulate/name/dupex.
Encode URL encoding to avoid forbidden characters (in particular, the code for = is %3D) and prepare your code to decode it.
In case 2, you could use the follwoing reference in subscribeContext: http://192.168.1.12:1028/accumulate?name%3Ddupex. Then, an example of code that will take into account the encoding and get the name argument properly would be the following (written in Python using Flask as REST server framework):
from flask import Flask, request
from urllib import unquote
from urlparse import urlparse, parse_qs
app = Flask(__name__)
#app.route("/accumulate")
def test():
s = unquote(request.full_path) # /accumulate?name%3Dduplex -> /accumulate?name=duplex
p = urlparse(s) # extract the query part: '?name=duplex'
d = parse_qs(p.query) # stores the query part in a Python dictionary for easy access
name= d['name'][0] # name <- 'duplex'
# Do whatever you need with the name...
return ""
if __name__ == "__main__":
app.run()
I guess that a similar approach can be used in other languages (Java, Node, etc.).
EDIT: Orion version 1.2 support notification customization in the NGSIv2, which allows this use case. For example, you can define the following subscriptions:
{
..
"notification": {
"httpCustom": {
"url": "http://192.168.1.12:1028/accumulate",
"qs": {
"name": "dupex"
}
}
..
}
..
}
Please have a look to "Subscriptions" and "Custom Notifications" sections at NGSIv2 Specification for details.