REST Calls using PostMan for R server O16N


The Microsoft R Server operationalization REST APIs are exposed by R Server's operationalization server, a standards-based server technology capable of scaling to meet the needs of enterprise-grade deployments. With the operationalization feature configured, the full statistics, analytics and visualization capabilities of R can now be directly leveraged inside Web, desktop and mobile applications.

Core Operationalization APIs

These core REST APIs expose the R platform as a service allowing the integration of R statistics, analytics, and visualizations inside Web, desktop and mobile applications. These APIs enable you to publish Microsoft R Server-hosted R analytics web services, making the full capabilities of R available to application developers on a simple yet powerful REST API.

  1. Click Here to find more information about Core APIs.
  2. Core API Swagger JSON File
  3. Core API Reference Documentation

Service Consumption APIs

The service consumption REST APIs expose a wide range of R analytics services to client application developers. Once R code is published and exposed by R Server as a web service, an application can make API calls to pass inputs to the service, execute the service and retrieve R session outputs (R objects, graphics, files, ...) from the service.

We will be using Loan Predict Service example and show how to make REST call using postman. Execute the LoanScoring.R which will publish the Loan predict service into your R o16N server. You can use the swagger.json file  which will be generated when you execute the R script or alternatively you use JSON file available on GitHub.

Import Your swagger

Import your swagger JSON file, in postman so that you can view all the API calls that are available to use

  • Change the LoanPredict.json to add/modify your server’s `host`
  • For example:  "host": "10.145.19.6:12800"
  • Next change the `schemes` property to use only the one protocol that your server is configured to. This helps the Postman UI.

"schemes": [
"http",
]

  • Now import the swagger using the Postman UI:

import

After Importing your swagger JSON file you will see list of all possible API on left side as below

 import-result

Login API

Once imported, under the `Login` tags to the left, select the `POST User Login`. Double check that your `host and protocol` looks correct

login

Update your API headers.

  • Select the `Headers` tab add the following key value pairs
  • Key = Content-Type
  • Value =  application/json
  • These are needed as for all POST calls as the input format we send to O16N server is in JSON format.

login-with-header

One Time Setup of Bearer Token

Bearer Token is needed to send as part of header for all authenticated calls, This can be copied from login response call and added as part of header in subsequent calls or can be setup as global variable and can be used in subsequent calls.

Every call must have below header else will get 401 Not Authorized error.

key = Authorization

value = Bearer {{Access_token}}

Preset for Authorization

Create Preset to manage Authorization header for login and future calls

  • Click on Presets and then Manage Presets

manage-presets

  • Add new Presets
  • Name Authorization
  • Key :  Authorization
  • Value : Bearer {{Access_token}}

add-presets

 

Setup Global Variable

Global variables provide a set of variables that are always in scope. You can have multiple environments, and only one can be active at a time. But you’ll have only one set of global variables, and they’ll always be available. Other than that, you can use them in the same way - {{variableName}}.

global-variable

  • Add the variable `Access_token`
  • key = Access_token
  • value =

Note the value of `Access_token` is empty. This will be populated with the actual token value from login API response.

add-global-variable

Verify Global Variable Access_token is created

verify-global-variable

 

Populate Access_token from login API call

Using script we can extract the access_token from login API response and set it to a previously created global variable called Access_token

var data = JSON.parse(responseBody);
postman.setGlobalVariable("Access_token", data.access_token); 

populate-global-variable

Invoke Login API Call

We have created global variable and are ready to make login API call to server

Request

  • In body of the request enter your username and password as below
  • Click send

invoke-rest-call

Response

Login API Response is shown below which shows access token and this access token will be copied to global variable

login-api-call-response

 

Verify global variable Access Token has the value retrieved from Login API call

global-variable-updated

 

Now we are authenticated, try out other API calls using this access token in the header

After Login API call is successful, you will notice that access_token is available in global variable. we can then use this access_token to make other API calls.

Get Swagger JSON

We can make  REST call to GET swagger json.

  • To GET swagger json file api call is GET /api/YOURSERVICE/VERSION/swagger.json
  • Add Authorization Preset which we have created earlier
  • When we click send, Access_token from global variable will added automatically in this GET API cal

Request

select-preset-auth

Response

get-swagger-response

 

Consume Loan Predict Service

We can use REST API to consume loanPredict service, this is a POST API call so we will need to send Request Input parameters in JSON format.

Request

  • We set one header as Key : Content-Type , Value : application/json
  • We will use Preset -> Authorization for sending in Access_token

consume-service-header

consume-service-body

Response

consume-service-response

 

Postman Reference Document

Comments (3)

  1. Ruth says:

    Thanks for the detailed explanation. I have a question regarding on how to input a data.frame to the input list while consuming the service?

    1. Hi Ruth
      There is an example in GitHub, Flight Prediction that uses data frame as input. https://github.com/Microsoft/microsoft-r/tree/master/R%20Server%20Operationalization/FlightPredictionService
      Data frame is dictionary of key, value pair
      So in below JSON structure ArrDel15, Year, etc... is key and there values

      JSON structure for GitHub example would be
      {
      "newflightdata": {
      "ArrDel15": [
      0,
      0,
      0,
      0,
      0,
      1
      ],
      "Year": [
      "2012",
      "2012",
      "2012",
      "2012",
      "2012",
      "2012"
      ],
      "Month": [
      "3",
      "6",
      "12",
      "5",
      "3",
      "8"
      ],
      "DayofMonth": [
      "18",
      "2",
      "17",
      "26",
      "5",
      "11"
      ],
      "DayOfWeek": [
      "7",
      "6",
      "1",
      "6",
      "1",
      "6"
      ],
      "Carrier": [
      "MQ",
      "WN",
      "AA",
      "MQ",
      "WN",
      "UA"
      ]
      }
      }

      1. Ruth says:

        Thanks !

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