title	estimated_read	menu_order	description
Introduction	15	1	Read on to learn about the fundamentals and common architectural principles of the Swedbank Pay API Platform.

Foundation

The Swedbank Pay API Platform is built using the REST architectural style and the request and responses come in the JSON format. The API has predictable, resource-oriented URLs and use default HTTP features, like HTTP authentication (using OAuth 2), HTTP methods and headers. These techniques are widely used and understood by most HTTP client libraries.

Connection and Protocol

All requests towards Swedbank Pay API Platform are made with HTTP/1.1 over a secure TLS 1.2 (or higher) connection. Older HTTP clients running on older operating systems and frameworks might receive connection errors when connecting to Swedbank Pay's APIs. This is most likely due to the connection being made from the client with TLS 1.0 or even SSL, which are all insecure and deprecated. If such is the case, ensure that you are able to connect over a TLS 1.2 connection by reading information regarding your programming languages and environments (Java, PHP Curl, PHP Zend, Ruby, Python, Node.js Request).

You can inspect Swedbank Pay's TLS and cipher suite support at SSL Labs. Support for HTTP/2 in our APIs is being investigated.

Postel's Robustness Principle

We encourage you to keep Postel's robustness principle in mind. Build your integration in a way that is resilient to change, wherever it may come. Don't confine yourself to the limits of our current documentation examples. A string looking like a guid must still be handled and stored like a string, not as a guid, as it could be a URL in the future. The day our transactionNumber ticks past 1,000,000, make sure your integration can handle number 1,000,001. If some fields, operations or headers can't be understood, you must be able to ignore them. We have built our requests in a way which allows the payeeInfo field to be placed before metadata, or vice versa if you want. We don't expect a specific order of elements, so we ask that you shouldn't either.

Headers

All requests against the API Platform should have a few common headers:

{:.code-view-header} HTTP request

POST /some/resource HTTP/1.1
Content-Type: application/json; charset=utf-8
Authorization: "Bearer 123456781234123412341234567890AB"
User-Agent: swedbankpay-sdk-dotnet/3.0.1
Accept: application/problem+json; q=1.0, application/json; q=0.9
Session-Id: 779da454399742248f2942bb064c4707
Forwarded: for=82.115.151.177; host=example.com; proto=https

{:.table .table-striped}

Required	Header	Description
{% icon check %}︎	`Content-Type`	The content type of the body of the HTTP request. Usually set to `application/json`.
{% icon check %}︎	`Authorization`	The OAuth 2 Access Token is generated in Swedbank Pay Admin.
	`User-Agent`	The user agent of the HTTP client making the HTTP request. Should be set to identify the system performing requests towards Swedbank Pay. The value submitted here will be returned in the response field `initiatingSystemUserAgent`.
{% icon check %}︎	`Accept`	The content type accepted by the client. Usually set to `application/json` and `application/problem+json` so both regular responses as well as errors can be received properly.
	`Session-Id`	A trace identifier used to trace calls through the API Platform (ref RFC 7329). Each request must mint a new GUID/UUID. If no `Session-Id` is provided, Swedbank Pay will generate one for the request.
	`Forwarded`	The IP address of the payer as well as the host and protocol of the payer-facing web page. When the header is present, only the `for` parameter containing the payer's IP address is required, the other parameters are optional. See RFC 7239 for details.

User-Agent

The term user agent is used for both the web browser used by the payer as well as the system making HTTP requests towards Swedbank Pay's APIs. The difference between these two and how they relate to each other is illustrated in the below sequence diagram:

@startuml "User Agents"
    $participant("payer", "Payer") as Payer
    $participant("merchant", "Merchant") as Merchant
    $participant("server", "Swedbank Pay") as SwedbankPay

    Payer -> Merchant: $code("User-Agent: P") <b>①</b>
    activate Payer
        activate SwedbankPay
            Merchant -> SwedbankPay: $code('User-Agent: M { userAgent: "P" }') <b>②</b>
            activate Merchant
                SwedbankPay --> SwedbankPay: Store request data
                SwedbankPay --> Merchant: $code('{ "initiatingSystemUserAgent": "M" }') <b>③</b>
            deactivate Merchant
        deactivate SwedbankPay
        Merchant --> Payer
    deactivate Payer
@enduml

First, the payer makes an HTTP request with their web browser towards the merchant's website. This HTTP request contains a User-Agent header, here given the value P (for "Payer").
The merchant performs an HTTP request towards Swedbank Pay.
1. The merchant extracts the P value of the User-Agent header from the payer's browser and sends it to Swedbank Pay in the userAgent field in the JSON request body.
2. The merchant also composes its own user agent string and sends it to Swedbank Pay in the User-Agent HTTP request header, here represented as the value M (for "Merchant").
Swedbank Pay receives "userAgent": "P" and User-Agent: M, stores the values and returns the M value in the initiatingSystemUserAgent response JSON field.

The user agent strings are used for statistical purposes by Swedbank Pay.

URL Usage

The base URLs of the API Platform are:

{% assign api_url_prod = 'https://api.payex.com/' %}

{:.table .table-striped}

Environment	Base URL
[Test]({{ page.api_url }})	`{{ page.api_url }}/`
[Production]({{ api_url_prod }})	`{{ api_url_prod }}`

An important part of REST is its use of hypermedia. Instead of having to perform complex state management and hard coding URLs and the availability of different operations in the client, this task is moved to the server. The client simply follows links and performs operations provided by the API, given the current state of the resource. The server controls the state and lets the client know through hypermedia what's possible in the current state of the resource. To get an introduction to hypermedia, please watch this 20 minute video.

{% include alert.html type="warning" icon="warning" header="Don't build URLs" body=" It is very important that only the base URLs of Swedbank Pay's APIs are stored in your system. All other URLs are returned dynamically in the response. Swedbank Pay cannot guarantee that your implementation will remain working if you store any other URLs in your system. When performing requests, please make sure to use the complete URLs that are returned in the response. Do not attempt to parse or build upon the returned data – you should not put any special significance to the information you might glean from an URL. URLs should be treated as opaque identifiers you can use to retrieve the identified resource – nothing more, nothing less. If you don't follow this advice, your integration most assuredly will break when Swedbank Pay makes updates in the future. " %}

Storing URLs

{% include alert.html type="success" icon="link" header="Storing URLs" body="In general, URLs should be discovered in responses to previous requests, not stored." %}

However, URLs that are used to create new resources can be stored or hard coded. Also, the URL of the generated resource can be stored on your end to GET it at a later point. Note that the URLs should be stored as opaque identifiers and should not be parsed or interpreted in any way.

{% include alert.html type="warning" icon="warning" header="Operation URLs" body="URLs that are returned as part of the operations in each response should not be stored." %}

See the abbreviated example below where psp/creditcard/payments from the POST header is an example of the URL that can be stored, as it is used to create a new resource. Also, the /psp/creditcard/payments/{{ page.payment_id}} URL can be stored in order to retrieve the created payment with an HTTP GET request later.

The URLs found within operations such as the href of update-payment-abort, {{ page.api_url }}/psp/creditcard/payments/{{ page.payment_id }} should not be stored.

In order to find which operations you can perform on a resource and the URL of the operation to perform, you need to retrieve the resource with an HTTP GET request first and then find the operation in question within the operations field.

{:.code-view-header} Request

POST /psp/creditcard/payments HTTP/1.1
Authorization: Bearer <AccessToken>
Content-Type: application/json

{
    "payment": {
        "operation": "Purchase",
        "intent": "Authorization",
        "currency": "SEK",
        "prices": [{
                "type": "CreditCard",
                "amount": 1500,
                "vatAmount": 0
            }
        ],
        "description": "Test Purchase",
        "generatePaymentToken": false,
        "generateRecurrenceToken": false,
        "userAgent": "Mozilla/5.0...",
        "language": "nb-NO",
     }
 }

{:.code-view-header} Response

HTTP/1.1 200 OK
Content-Type: application/json

{
    "payment": {
        "id": "/psp/creditcard/payments/{{ page.payment_id }}",
        "number": 1234567890,
        "instrument": "CreditCard",
        "created": "2016-09-14T13:21:29.3182115Z",
        "updated": "2016-09-14T13:21:57.6627579Z",
        "state": "Ready",
        "operation": "Purchase",
        "intent": "Authorization",
        },
    "operations": [
        {
            "rel": "update-payment-abort",
            "href": "{{ page.api_url }}/psp/creditcard/payments/{{ page.payment_id }}",
            "method": "PATCH",
            "contentType": "application/json"
        },
        {
            "rel": "redirect-authorization",
            "href": "{{ page.front_end_url }}/creditcard/payments/authorize/{{ page.payment_token }}",
            "method": "GET",
            "contentType": "text/html"
        },
        {
            "rel": "view-authorization",
            "href": "{{ page.front_end_url }}/creditcard/core/scripts/client/px.creditcard.client.js?token={{ page.payment_token }}",
            "method": "GET",
            "contentType": "application/javascript"
        }
    ]
}

Uniform Responses

When a POST or PATCH request is performed, the whole target resource representation is returned in the response, as when performing a GET request on the resource URL. This is an economic approach that limits the number of necessary GET requests.

Expansion

The payment resource contain the ID of related sub-resources in its response properties. These sub-resources can be expanded inline by using the request parameter expand. This is an effective way to limit the number of necessary calls to the API, as you return several properties related to a Payment resource in a single request.

Note that the expand parameter is available to all API requests but only applies to the request response. This means that you can use the expand parameter on a POST or PATCHrequest to get a response containing the target resource including expanded properties.

This example below add the urls and authorizations field inlines to the response, enabling you to access information from these sub-resources.

{:.code-view-header} HTTP request with expansion

GET /psp/creditcard/payments/{{ page.payment_id }}?$expand=urls,authorizations HTTP/1.1
Host: {{ page.api_host }}

To avoid unnecessary overhead, you should only expand the nodes you need info about.

Data Types

Some datatypes, like currency, dates and amounts, are managed in a coherent manner across the entire API Platform.

Currency

All currencies are expressed according to the ISO 4217 standard, e.g SEK, EUR, NOK.

Dates

All dates are expressed according to the ISO 8601 standard that combine dates, time and timezone data into a string, e.g. 2018-09-14T13:21:57.6627579Z.

Locale

When defining locale, we use the combination of language and country codes, e.g. nb-NO, sv-SE, en-US.

Monetary Amounts

All monetary amounts are entered in the lowest momentary units of the selected currency. The amount of SEK and NOK are in ören/ører, and EUR is in cents. Another way to put it is that the code amount is expressed as if the true amount is multiplied by 100.

{:.table .table-striped}

True amount	Code amount
NOK 100.00	`10000`
SEK 50.00	`5000`
€ 10.00	`1000`

Operations

When a resource is created and during its lifetime, it will have a set of operations that can be performed on it. Which operations that are available in a given state varies depending on payment instrument used, what the access token is authorized to do, etc. A subset of possible operations are described below. Visit the technical reference page of a payment instrument for instrument specific operations.

{:.code-view-header} JSON with Operations

{
    "payment": {},
    "operations": [
        {
            "href": "http://{{ page.api_host }}/psp/creditcard/payments/{{ page.payment_id }}",
            "rel": "update-payment-abort",
            "method": "PATCH"
        },
        {
            "href": "{{ page.front_end_url }}/creditcard/payments/authorize/{{ page.payment_token }}",
            "rel": "redirect-authorization",
            "method": "GET"
        },
        {
            "href": "{{ page.front_end_url }}/swish/core/scripts/client/px.swish.client.js?token={{ page.payment_token }}",
            "rel": "view-payment",
            "method": "GET",
            "contentType": "application/javascript"
        },
        {
            "href": "{{ page.api_url }}/psp/creditcard/payments/{{ page.payment_id }}/captures",
            "rel": "create-capture",
            "method": "POST"
        }
    ]
}

{:.table .table-striped}

Field	Description
`href`	The target URL to perform the operation against.
`rel`	The name of the relation the operation has to the current resource.
`method`	The HTTP method to use when performing the operation.

The operations should be performed as described in each response and not as described here in the documentation. Always use the href and method as specified in the response by finding the appropriate operation based on its rel value.

{% include payee-reference.md %}

{% include callback.md %}

{% include problems/problems.md %}

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introduction.md

introduction.md

Foundation

Connection and Protocol

Postel's Robustness Principle

Headers

User-Agent

URL Usage

Storing URLs

Uniform Responses

Expansion

Data Types

Currency

Dates

Locale

Monetary Amounts

Operations

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introduction.md

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introduction.md

File metadata and controls

Foundation

Connection and Protocol

Postel's Robustness Principle

Headers

User-Agent

URL Usage

Storing URLs

Uniform Responses

Expansion

Data Types

Currency

Dates

Locale

Monetary Amounts

Operations