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B. Remote Control Protocol
B.2 Event Master series processor JSON RPC remote control
General
JSON (JavaScript Object Notation) is a lightweight format that is used for interchanging data. It is based on a subset of JavaScript
language: the way objects are built in JavaScript.
Introduction to JSON
JSON is built on two structures:
• A collection of name/value pairs: In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed
list, or associative array.
• An ordered list of values: In most languages, this is realized as an array, vector, list, or sequence.
Here is an example of JSON data:
{
"firstName": "John",
"lastName": "Smith",
"address": {
"streetAddress": "21 2nd Street",
"city": "New York",
"state": "NY",
"postalCode": 10021
},
"phoneNumbers": [
"212 555-1234",
"646 555-4567"
]
}
How JSON interacts with Event Master processors
JSON uses JSON RPC (REST based) to interact with the Event Master processors such as E2, S3–4K, and EX. JSON-RPC is a
remote procedure call protocol encoded in JSON.
JSON-RPC works by sending a request to a server implementing this protocol. The client in that case is typically software intending
to call a single method of a remote system. Multiple input parameters can be passed to the remote method as an array or object,
whereas the method itself can return multiple output data as well.
There are JSON RPCs de fi ned to perform tasks on the Event Master processor. User needs to send JSON request through their
application or open source application like Postman.
These applications should send request on IP where the Event Master processor is running and fi xed port 9999 (Webserver of Event
Master processor is running on port 9999).
Postman
Postman is an application that you can use to test the Event Master JSON API.
1.
Go to the GetPostman website.
(
https://www.getpostman.com/ )
2. Download the free Postman app.
3. Install Postman on your machine.
4. Launch Postman and follow these steps to send JSON commands to the Event Master processor.
a) Select POST from the dropdown next to the URL text box.
b) Enter the request URL with port 9999.
c) Type “Content-Type” for header and “application/json” as value of this header.
(See https://www.getpostman.com/docs/requests for more information on sending requests.)
Image B-1
Content-Type and application/json
5. Select Body and click on raw from the buttons available below the URL text box.
6. Write the request in the body.
A request is a call to a speci fi c method provided by a remote system. It must contain three certain properties:
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