Using SAS Viya REST APIs to access images from SAS Visual Analytics

This article is the first in a series of three posts to address REST APIs and their use in, and with, SAS. Today, I'll present a basic example using SAS Viya REST APIs to download an image from a report in SAS Visual Analytics.

The second article will show an example of the Cloud Analytics Services (CAS) REST APIs. My third planned article will outline show a simple application that accesses SAS Viya using both sets of REST APIs.

The inspiration for this example: a visualization of air traffic data

I ran across a great post from Mike Drutar: How to create animated line charts that "grow" in SAS Visual Analytics. I followed the steps in Mike's example, which creates a visualization of airline traffic. The result was an animated line chart. For this article, I removed the animation, as it will serve me better in my use case.

SAS Viya APIs and CAS APIs: Two entry points into SAS Viya

The first thing I'd like to cover is why SAS Viya offers two sets of REST APIs. Let's consider who is using the APIs, and what they are trying to accomplish? SAS Viya APIs target enterprise application developers (who may or may not be versed in analytics), who intend to build on the work of model builders and data scientists. These developers want to deliver apps based on SAS Viya technology -- for example, to call an analytical model to score data. On the other hand, the CAS REST API is used by data scientists and programmers (who are decidedly adept at analytics) and administrators, who need to interact with CAS directly and are knowledgeable about CAS actions. CAS actions are the building blocks of analytical work in SAS Viya.

How to get started with SAS Viya REST APIs

The best place to start working with SAS Viya REST APIs is on the SAS Developer's web site. There, you will find links to the API documentation.

The REST APIs are written to make it easy to integrate the capabilities of SAS Viya to help build applications or create scripts. The APIs are based on URLs, using HTTP Authentication, and HTTP verbs. The API documentation page is split into multiple categories. The following table outlines the breakdown:

The REST API documentation page is divided into multiple sections.

SAS Viya REST API doc

1. The categories are listed in the upper-left side.
2. Once a you select a category, related services and functions are listed in the lower left pane.
3. The service appears in the center pane with a description, parameters, responses, and error codes.
4. The right pane displays how to form a sample request, any optional or required body text, and sample response code.

The REST API call process

The example outlined in this article shows how to access a report image from SAS Visual Analytics. To try this out yourself, you will need: a SAS Viya environment (with SAS Visual Analytics configured), an access token, and a REST client. The REST client can be cURL (command line), Postman (a popular REST API environment), or Atom with the rest-client plugin -- or any other scripting language of your choice. Even if you do not have access to an environment right now, read on! As a SAS developer, you're going to want to be aware of these capabilities.

Get a list of reports from SAS Visual Analytics

Run the following curl command to get a list of reports on the SAS server:

curl -X GET http://sasserver.demo.sas.com/reports/reports\
  -H 'Authorization: Bearer <access-token-goes-here>' \
  -H 'Accept: application/vnd.sas.table.column+json'

Alternatively, use Postman to enter the command and parameters:

GET Report List API call from Postman

From the JSON response, find the report object and grab the id of the desired report:

GET Report List Response

Create a job

The next step is to create an asynchronous job to generate the SVG image from the report. I use the following HTTP POST with the /jobs verb:

curl -X POST <a href="http://sasserver.demo.sas.com/reportImages/jobs/">http://sasserver.demo.sas.com/reportImages/jobs\
  -H 'Authorization: Bearer &lt;access-token-goes-here&gt;' \
  -H 'Accept = application/vnd.sas.report.images.job+json'\
  -H 'Content-Type = application/vnd.sas.report.images.job.request+json'

Using the following sample Body text

{
  "reportUri" : "/reports/reports/b555ea27-f204-4d67-9c74-885311220d45",
  "layoutType" : "entireSection",
  "selectionType" : "report",
  "size" : "400x300",
  "version" : 1
}

Here is the sample response:

POST Job Creation Response

The job creation kicks off an asynchronous action. The response indicates whether the job is completed at response time, or whether it's still pending. As you can see from the above response, our job is still in a 'running' state. The next step is to poll the server for job completion.

Poll for job completion

Using the 'id' value from the job creation POST, the command to poll is:

curl -X GET http://sasserver.demo.sas.com/reportImages/jobs/f7a12533-ac40-4acd-acda-e0c902c6c2c1\
  -H 'Authorization: Bearer ' \ 
  -H ‘Accept = application/vnd.sas.report.images.job+json’

And the response:

GET Poll Job Creation Response

Once the job comes back with a 'completed' state, the response will contain the information we need to fetch the report image.

Get the image

I am now ready to get the image. Using the image file name (href field) from the response above, I run the following command:

curl -X GET http://sasserver.demo.sas.com/reportImages/images/K1870020424B498241567.svg\
  -H 'Authorization: Bearer ' \ 
  -H ‘'Accept: image/svg+xml'

Postman automatically interprets the response as as an image. If you use the curl command, you'll need to redirect the output to a file.

SAS Visual Analytics Graph for Air Traffic

What's Next?

SAS Visual Analytics is usually considered an interactive, point-and-click application. With these REST APIs we can automate parts of SAS Visual Analytics from a web application, a service, or a script. This opens tremendous opportunities for us to extend SAS Visual Analytics report content outside the bounds of the SAS Visual Analytics app.

I'll cover more in my next articles. In the meantime, check out the Visualization APIs documentation to see what's possible. Have questions? Post in the comments and I'll try to address in future posts.

Using SAS Viya REST APIs to access images from SAS Visual Analytics was published on SAS Users.