General principles for using the REST API

The API follows the REST architectural style, so resources, HTTP verbs, and status codes are used. JSON is used for request and response bodies. The endpoints provided by the API are specified using the Swagger specification language.

The following principles are common to the endpoints provided by the AR System REST API.

Endpoint verbs

Where possible, endpoints use the following verbs consistently:

Verb	Purpose
GET	Retrieve a single resource, or collection of resources.
POST	Create a new resource.
PUT	Update a resource, specifying the required target state of all fields. Any fields omitted are reset to default values or deleted, as appropriate for the endpoint.
DELETE	Delete a resource.

Input encoding

When constructing the URL for an endpoint that contains a dynamic portion (either in the path or in the query string), ensure that you correctly encode the characters that are not permitted in a URL. For example, the following URL:

http://server name:port/api/arsys/v1/entry/User/formName?q=('Request ID'="entryID")

is interpreted as follows:

http://server name:port/api/arsys/v1/entry/User/formName?q=%28%27Request%20ID%27%3D%22entryID%22%29

When using the GET operation to fetch entries from a form via any REST client, URL parameters may be required. Examples of URL parameters are qualification (q), fields, limit, and sort. While using any of these parameters with a request URL, these must be encoded properly and then used in the request; otherwise, results may not be as expected.

To encode URL parameters, use any third party tool or site such as https://www.w3schools.com/html/html_urlencode.asp, where non-encoded URL parameters can be converted into an encoded URL parameter string. Use these encoded parameters to send a REST request. For example, for sending qualification on a form:

'Incident Number' = "INC000000000701"

It should be encoded and sent as:

%27Incident+Number%27+%3D+%22INC000000000701%22

For more information about how AR System integrates using REST APIs and web services, watch the following video (4:07).

https://youtu.be/d-AqmDlQPFI

REST API format

The REST API uses the base URI for the web service, for example, https://localhost:port/api/{namespace}/{version}.

The root URL path for REST API in AR System is as follows:

https://localhost:port/api/arsys/v1

Any partial URLs (for example, /entry/{formName}) referred to in the documentation are assumed to have this prefix.

JSON format

JSON is used for both request and response bodies. If you are editing JSON request bodies manually, you must escape any reserved characters in your strings.

URLs in responses

Several POST endpoints create a new resource, which you can retrieve later using the REST API. In these cases, the response to the POST request contains a "uri" field, containing the URL of the newly created resource. For example:

package com.example;

import org.apache.http.Header;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class Post {

    public static void main(String[] args) throws Exception {
        String token = args[0];

        // start HTTP POST to create an entry with fields parameter
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost("http://localhost:8008/api/arsys/v1/entry/SimpleForm?fields=values(field1, field2)");

        // build the JSON entry
        String json = "{ \"values\" : { ";
       json += "\"Submitter\" : \"Allen\", ";
       json += "\"Short Description\" : \"testing 123\"";
       json += " } }";
        httpPost.setEntity(new StringEntity(json, ContentType.APPLICATION_JSON));
        httpPost.addHeader("Authorization", "AR-JWT " + token);

        // make the call and print the Location
        try (CloseableHttpResponse response = httpClient.execute(httpPost)) {
            Header locationHeader = response.getFirstHeader("Location");
            System.out.println(locationHeader.getValue());
            HttpEntity entity = response.getEntity();
        // Read the contents of an entity and return it as a String.
            String content = EntityUtils.toString(entity);
            System.out.println(content);
       }
   }

}

Error responses

Failed requests are indicated by returned 4xx (client error) or 5xx (server error) HTTP status codes. In some cases the response body might also contain an object that contains details of the error, with the following fields:

Field	Meaning
code	The HTTP status code.
message	A description of what went wrong.

Do not rely on error responses containing a body. In particular, authentication or permission failures often have empty bodies to avoid information leakage to the caller. Here is an example request, resulting in the response 400 Bad Request:

http://<local host>:8008/api/arsys/v1.0/fields/User/?field_type=A&field_ids=1
[
{
  "messageType": "ERROR",
  "messageText": "Unexpected use of query parameter",
"messageNumber": 8043,
  "messageAppendedText": "Either field_ids or field_type can be provided. Both set are not allowed."
}
]