REST API component

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Overview
Authorisation methods
- Environment variables
Triggers and actions
- Output
Defining the request’s body
HTTP headers
Attachments
Exception handling
Known limitations

Overview

The example below shows the development team creation using the REST API component with Squiz Connect’s own REST API service.

The Method and URL of the REST API resource:
- REST API component supports the following HTTP methods: GET, PUT, POST, DELETE and PATCH.
- The URL of the REST API resources. Accepts JSONata expressions - i.e. the URL address evaluates JSONata expressions.
Headers - specify the request headers and body:
- Definition of request headers.
- Definition of request body, if the HTTP method is not GET.
Configuration options:
- Don’t throw Error on Failed Calls - if enabled return error, error code and stacktrace in message body otherwise throw error in flow.
- Split Result if it is an Array - if enabled and response is array, creates message for each item of array. Otherwise create one message with response array.
- Retry on failure - enabling rebound feature for following HTTP status codes:
  - 408: Request Timeout
  - 423: Locked
  - 429: Too Many Requests
  - 500: Internal Server Error
  - 502: Bad Gateway
  - 503: Service Unavailable
  - 504: Gateway Timeout
  - DNS lookup timeout
- Do not verify SSL certificate (unsafe) - disable verifying the server certificate - unsafe.
Follow redirect mode - Choose either the option Follow redirects (default) or Do not follow redirects to perform either of these functions.
Delay - Set a delay value here (in seconds) to slow down requests to your API. This component delays calling the next request by this specified number of seconds after the previous request.

Time for the delay is calculated as Delay/Call Count and should not be more than 1140 seconds (19 minutes due to preset platform limits). The Call Count default value is 1. If you want to use another value, set the Call Count field.

Learn more about the Delay value in Known limitations.
Call count - This field’s value (whose default value is 1) is only used in combination with the Delay field.
Request timeout - The timeout period in milliseconds (1-1140000) that the REST API component waits for the server to respond. The default value of this field is 100000 (100 sec). This field’s behavior can also be configured with the REQUEST_TIMEOUT environment variable if the configuration field is not provided.

If both the REQUEST_TIMEOUT environment variable is specified for this component, as well as the Request timeout field value, then this field value takes precedence.

Authorisation methods

To use the REST API component with any restricted access API, you need to provide the authorisation information.

This example shows how to add the username/password to access the API during the integration flow design.

You can add the authorisation methods during the integration flow design or by navigating to your Credentials REST API from the main menu and adding the methods there.

This example above shows how to add a new credential to access the API from the credentials page.

REST API component supports 4 authorisation types:

No Auth - use this method to work with any open REST API. This method can be used without the need for verification.
Basic Auth - use this method to provide login credentials like username/password.
API Key Auth - use this method for systems where an API Key is required to access the resource. This authorization type requires a Header Name (e.g. api-key) and its accompanying Header Value (e.g. the value of api-key) values.
OAuth2 - use this method when the external resource dictates an Oauth2 authorisation to access their resources.

To create an OAuth2 credential, you have to choose Auth-client or create the new one. This credential must contain Name, Client ID, Client Secret, Authorization Endpoint and Token Endpoint. For more information please check the documentation of the API you want to connect to.

This example shows how to add new Auth-client to access the API.

The following example shows you how to select an existing client:

Environment variables

NAME	DESCRIPTION	DEFAULT	OPTIONAL
REQUEST_TIMEOUT	HTTP authorization request timeout in milliseconds.	10000	true
REQUEST_RETRY_DELAY	Delay between authorization retry attempts in milliseconds	5000	true
REQUEST_MAX_RETRY	Number of HTTP authorization request retry attempts.	3	true

NAME

DESCRIPTION

DEFAULT

OPTIONAL

REQUEST_TIMEOUT

HTTP authorization request timeout in milliseconds.

10000

true

REQUEST_RETRY_DELAY

Delay between authorization retry attempts in milliseconds

5000

true

REQUEST_MAX_RETRY

Number of HTTP authorization request retry attempts.

true

Triggers and actions

The REST API component can be used as either a trigger or an action.

As a trigger, a cron schedule is configured, as is the case for the simple trigger component.

As an action, this component sends an HTTP request using a GET/POST/PUT/PATCH/DELETE method and parses the response back to the flow.

Output

The messages produced by the REST API component have the following properties:

headers - Object containing the HTTP response headers.
statusCode - HTTP Status Code of the Response. A number between 100 and 599.
statusMessage - Human readable equivalent to the response code.
body - The contents of the HTTP response body:
- When the content type header includes json, then the result is parsed into the corresponding object.
- When the content type header includes xml, then the result is converted into the JSON equivalent of the represented XML using the same rules as above.
- When the content type header includes one of image, msword, msexcel, pdf, csv, octet-stream or binary, the request body contents is stored as an attachment and there will be no body property in the outgoing message.
- When there is no body (because the content-length is 0), then there is no body property in the outbound message.
- If there is another content type, then the response is treated as text.
- If the content type header is omitted, then an attempt to convert the result to JSON is made. If that fails, then the result is treated as if it were text.
For more details you can see an example of usage.

Defining the request’s body

If the HTTP method is anything other than GET, then the Body tab appears next to the Header tab. The Body tab enables configuration options such as the Content type drop-down menu and the Body input field/s.

The following Content type values are supported:

multipart/form-data
application/x-www-form-urlencoded
text/plain
application/json
application/xml
text/xml
text/html

The Body input field/s change/s according to your chosen Content type.

The response’s Body is stored in msg.body.
The request body that results in an empty response body returns {}.

Sending JSON data

To send JSON data in the body, change the Content type to application/json and the Body section changes accordingly to accept a JSON object. Note that this field also supports JSONata expressions.

This example shows the JSON in the body where the name parameter value is mapped using the value of project_name from the previous step of integration.

Sending XML data

To send XML data, set the Content type to application/xml or text/xml and place the XML in the body input field between double-quotes like:

"
<note>
  <to>" & fname & "</to>
  <from>Jani</from>
  <heading>Reminder</heading>
  <body>Don't forget me this weekend!</body>
</note>
"

Use a JSONata expression to include and map any values coming from the previous steps. It will replace the variable with a real value in the final mapping. Note that the rest of XML gets passed as a string.

Sending form data

When sending form data, the following content types are available:

application/x-www-form-urlencoded - used to submit simple values to a form.
multipart/form-data - used to submit (non-alphanumeric) data or file attachment in payload.

In both cases, the payload gets transmitted in the message body.

For the application/x-www-form-urlencoded content type, add the necessary parameters by giving the name and the values like:

Note that parameter value fields support JSONata expressions.

This HTTP request would submit key1=value1&key2=value2 in the message body.

For the multipart/form-data content type, add the parameters similarly.

The transmitted HTTP request body would be:

--__X_BOUNDARY__
Content-Disposition: form-data; name="part1"

Please note that this fields supports [JSONata](http://jsonata.org) expressions.
--__X_BOUNDARY__
Content-Disposition: form-data; name="part2"

<p>Some more text</p>
--__X_BOUNDARY__--

Notice how different parts get separated by the boundary markers. Attachments can also be sent as form data.

Working with XML

The REST API component attempts to parse XML content types in the HTTP response, assuming the Content-Type header’s MIME Content Type contains the xml value (e.g. application/xml). In such cases, the response body is parsed to JSON using the xml2js node library, with the following settings:

{
    trim: false,
    normalize: false,
    explicitArray: false,
    normalizeTags: false,
    attrkey: '_attr',
    tagNameProcessors: [
        (name) => name.replace(':', '-')
    ]
}

Learn more about these settings in the XML2JS library 'readme' notes.

HTTP headers

The REST API component allows you to retrieve the HTTP response header only if the Don’t throw Error on Failed Calls option is selected. In such cases, the structure of the output would be:

    {
      headers:<HTTP headers>,
      body:<HTTP response body>,
      statusCode:<HTTP response status code>,
      statusMessage:<HTTP response status message>
    }

Attachments

The REST API component allows you to send binary data. To do this, set the Content type to multipart/form-data and attachments from input message will be included to the request payload automatically.

This component automatically loads binary data to attachments with the next content types in response headers:

image/*
text/csv
application/msword
application/msexcgel
application/pdf
application/octet-stream
application/x-binary
application/binary
application/macbinary

Exception handling

The REST API component uses the following exception handling logic:

Known limitations

The REST API component has the following limitations:

The component can only parse responses whose content types are JSON- or XML-based, e.g.:

application/json
application/xml
text/xml
etc.

If a content type is not indicated in the response header, then the REST API component attempts to parse the response as json. If an exception is encountered during parsing, then the response is returned 'as is'.

The maximum size for an attachment is 10 MB.
The OAuth2 authentication implementation strategy in this component has an access token response limitation, such that the optional refresh_token property is actually required in Connect. To work around this issue, try using the additional parameter access_type:offline.
Avoid setting the Delay value to more than the time period between two executions of the flow, since the delay can influence the time of the next execution. For example, a flow has type Ordinary and is scheduled to execute every 1 minute. However, the delay is set to 120 seconds, so the next execution will commence only after 120 seconds, instead of 1 minute.