Communicate with REST Web Services

Representational state transfer (REST) or RESTful web services is a way of providing interoperability between computer systems on the Internet. Use JSL to communicate with a RESTful application program interface (API) that uses HTTP requests to GET, POST, PUT, and DELETE data. For example, you can get data from a web service and return it as a data table. Some web services are Amazon Web Services (AWS), DropBox, and Text-Processing.com.

Notes:

•

Strings that contain “&” are truncated. “+” is converted to a space.

•

New HTTP Request() supports redirects, for example, from HTTP to HTTPS.

Examples of HTTP Requests

The following examples communicate with the National Aeronautics and Space Administration (NASA) API. You must request a key from https://api.nasa.gov/index.html#apply-for-an-api-key and assign it to the key variable to run the scripts successfully.

Write Data to the Log

key = "<key>"; // substitute your key

limit = 100;

url = "https://api.nasa.gov/patents/content";

request = New HTTP Request(

	URL( url ), // the restAPI endpoint

	Method( "HTTP method" ),

	Query String( // define key pairs

		[["api_key" => key, "concept_tags" => "false",

		"limit" => limit]] // JSL associative array

);

data = request << Send(); // send the request to the API

Write( data );

{"count": 100, "results": [{"category": "materials and coatings", "client_record_id": "patent_ARC-14661-3", "center": "ARC", "eRelations": [], "reference_number": "ARC-14661-3", ...}]}

// JSON output written to the log

Notes:

•

The query string is at the end of the URL, following “?”. For example, in https://www.google.com/search?q=jmp, “q=jmp” is the query string. New HTTP Request() automatically URI-encodes key/value pairs in a query string (and FORM).

•

When you put an associative array in either a query string or a form, the key/value pairs get URI encoded. Spaces, ampersands, and other characters get encoded to ASCII, and the ampersand is escaped. The encoding is a “%” encoding.

•

The web service defines the valid key/value pairs that it accepts. Refer to the API documentation for valid key/value pairs.

Return Data as an Associative Array and Write it to the Log

key= "<key>"; // substitute your key

limit = 100;

url = "https://api.nasa.gov/patents/content";

request = New HTTP Request(

	URL( url ),

	Method( "Get" ),

	Query String(

		[["api_key" => key, "concept_tags" => "false",

		"limit" => limit]]

);

json = request << Send();

jsl_json = Parse JSON( json );

// turns JSON data into a JSL associative array

results = jsl_json["results"];

Write( results );

{["_id" => "53f65b3d5904da2c9fc3008f", "abstract" => "Method and system for functionalizing a collection of carbon nanotubes     (CNTs). A selected precursor gas (e.g., H.sub.2 or NH.sub.3 or ...}

// associative array

Return Data as a JMP Data Table

key= "<key>"; // substitute your key

limit = 100;

url = "https://api.nasa.gov/patents/content";

request = New HTTP Request(

	URL( url ),

	Method( "Get" ),

	Query String(

		[["api_key" => key, "concept_tags" => "false",

		"limit" => limit]]

);

json = request << Send();

jsl_json = Parse JSON( json );

dt = JSON To Data Table( As JSON Expr( jsl_json["results"] ) );

// JSON to Data Table turns JSON data into a data table

// As JSON Expr turns a JSL associative array into a JSON string

dt << Set Name( "NASA Patents" );

Figure 14.5 Data Imported in a Data Table