This release note explains what's new in The Account and Transaction API Specifications v1.1.0.

• In Accounts Transactions sequence diagram, removed Step 4 Request data response to the PSU.

• Corrected the case for Links.First, Links.Last, Links.Next, Links.Prev, Links.Self and Meta.TotalPages (updated Basics/Pagination, Basics / Return & Error Codes / 400 (Bad Request) v/s 404 (Not Found), and Data Model / High Level Payload Structure / Response Structure).

• Removed special characters in the Frequency field for Data Model / Data Payload - Resources / Standing Orders / Data Dictionary.

• Corrected the Pattern for the ActiveOrHistoricCurrencyCode class from [A-Z]{3,3} to ^[A-Z]{3,3}$ to limit the field to 3 characters.

• Corrected the Pattern for the CountryCode class to be specified as ^[A-Z]{2,2}$ instead of [A-Z]{2,2} to limit the field to 2 characters.

• In Usage Examples, have corrected "AwaitingAuthentication" to "AwaitingAuthorisation"

• Updated Usage Example for /products endpoint to align with Data Dictionary.

• Updated Pagination Response JSON payload to correctly separate one of the JSON properties by inclusion of a comma.

• Corrected a mis-spelling from "UFT-8" to "UTF-8".

• Added details and updated examples on the various date formats used outside of the JSON payload (updated Examples, Basics / Date formats, and Basics / Non-repudiation / Process for signing a payload).

• Clarified that Timezone offsets of -00:00 are not permitted in ISO-8601 (updated Examples, and all default dates in Data Model / Data payload - resources).

• Clarified that all dates in HTTP headers are represented as RFC 7231 Full Dates. For example: Sun 3 Sep 2017 19:43:31 UTC

• Clarified that a status of 403 should not be used to indicate a time-out of the access token, and that a 403 indicates that re-authentication of the PSU will not help.

• Clarified that digital signatures must NOT be implemented for v1.x specification.

• Metadata fields in the /transactions response now include an earliest available transaction date AND a latest available transaction date (updated Examples, Data Model / High Level Payload Structure / Response Structure / Meta, and default values specified in the Data Payload sections).

• Added a new section to cater for reversals (Security & Access Control / Consent Authorization / Permissions / Reversing Entries).

• Added a new section to specify the default character set as UTF-8 (Basics / Character Encoding). 

• All datetime fields returned by the API must have the Timezone specified (updated Examples and added a new section Basics / Date Format).

• Specified min and max page sizes for pagination (updated section on Basics / Pagination).

• Sort Code and Account Number are now stored in the Account identification section together (in the Identification field), and a new SchemeName has been created for SortCodeAccountNumber (updated Examples, Data Model / Data Payload - Resources / Accounts / Data Dictionary, Data Model / Data Payload - Resources / Beneficiaries / Data Dictionary, Data Model / Data Payload - Resources / Standing Orders / Data Dictionary, and Data Model / Data Payload - Enumerations).

• Extended the Standing Order Frequency pattern to include weekends and clarified pattern description (updated Data Model / Data Payload - Resources / Standing Orders / Data Dictionary).

• Changed the BankTransactionCode to be the ISO 20022 code description, with all delimiters removed (updated Data Model / Data Payload - Resources / Transactions).

• Add a Retry-After header for the HTTP 429 Too Many Requests response (updated Basics / Return & Error Codes, Basics / Headers / Response Headers, and Alternate Error Flows showing 429 as an optional implementation).

• Added 405 and 406 as status codes (updated section on Basics / Response Headers).

• Added clarifications to the Pagination section to state that the self link must be included in the response (Updated section Basic / Pagination).

• Added a section describing resource URL path structures.

• Added regex pattern for all Amount based fields under the Data Model / Data Payload. Removed pattern definition TotalDigits: 18 FractionDigits: 5.

• Swagger Specification updated to include the Swagger Specification version number in the base of the URL (i.e. linked to this Specification).

This specification describes the Account Information and Transaction API flows and payloads.

The API endpoints described here allow an AISP to: 

• Register an intent to retrieve account information by creating an "account request". This registers the data "permissions", expiration and transaction history timeframe the customer (PSU) has consented to provide to the AISP; and 

• Subsequently retrieve account and transaction data

This document consists of the following parts:

Overview: Provides an overview of the scope of the API and the key decisions and principles that contributed to the specification.

Basics: The section identifies the resources, operations that are permitted on those resources, and various special cases.

Security & Access Control: Specifies the means for AISPs and PSUs to authenticate themselves and provide consent.

Swagger Specifications: Provides links to the swagger specifications for the APIs.

Data Model: Describes the data model for the API payloads.

Usage Examples: Examples for normal flows, and alternate flows.

The API adheres to RESTful API concepts where possible and sensible to do so.

However, the priority is to have an API that is simple to understand and easy to use. In instances where following RESTful principles would be convoluted and complex, the principles have not been followed.

References:

• The highest level Data Description Language used is the JSON Schema : http://json-schema.org/

• Best Practice has also been taken from the Data Description Language for APIs; JSON API : http://jsonapi.org/

• The Interface Description Language used is the Swagger Specification version 2.0 (also known as Open API) : http://swagger.io/ and 

The OBIE principles for developing the new API standards:

• OBIE will adopt existing standards where relevant/appropriate to minimise re-inventing the wheel.

• The initial scope of these Standards is limited to current OBIE scope - i.e., meeting CMA remedies. However, the intention is that the scope of the Standards will extend to either include or align to initiatives to cover a wider scope (i.e., PSD2).

• The Standards currently being reviewed include ISO20022, and FAPI.

• OBIE will favour developer/user experience over and above adoption of existing Standards, in order to create a more future proof Standard.

• OBIE will work with other relevant bodies to align with, contribute to and/or adopt other Standards work, especially relating to creation of Standards around APIs and JSON payloads

The CMA Order requires the CMA9 Banks to be aligned with the Regulatory and Technical Standards (RTS) under PSD2.

A previous draft of the EBA RTS required that the interface "shall use ISO 20022 elements, components or approved message definitions". In keeping with that requirement, the API payloads are designed using the ISO 20022 message elements and components where available.

The principles we have applied to re-use of ISO message elements and components are:

• Where relevant - the API payloads have been flattened so that they are more developer friendly. This has been a request from the developer community, and the stakeholders involved in the design workshop

• Only elements that are required for the functioning of the API endpoint will be included in the API payload. API endpoints are defined for specific use-cases (not to be generically extensible for all use-cases). Hence - only elements that are required for the account and transaction information scope are included in the Account Information API payloads for v1.0 (as this is the agreed scope for our v1.0 specification).

• We will modify ISO 20022 elements where the existing standard does not cater for an API context (such as filtering, pagination etc.). An example is having latitude and longitude in decimal format - as this is how developers will work with latitude and longitude; or using simple types (e.g., a single date-time field) instead of a complex type (e.g., a choice field with a nesting of date and time).

Version 1.0 of the API only caters to read access to account and transaction information for BCAs and PCAs.

However - where possible the APIs have been designed to be extensible - so they can in the future cover additional account types (e.g., card accounts) and operations (e.g., write access).

The Account Information and Transaction APIs will not be idempotent for v1.0.

Digital signatures will facilitate non-repudiation for Open Banking APIs. 

However, the solution for digital signatures (if required in a future release) has been agreed and the approach required to achieve this is described in Basics / Non-repudiation.

A REST resource should have a unique identifier (e.g. a primary key) that can be used to identify the resource. These unique identifiers are used to construct URLs to identify and address specific resources.

However, considering that:

• Some of the resources described in this specification do not have a primary key in the system of record.

• For v1.0 it is not neccessary to individually address resources,

a decision has been made that Id fields will be specified for all resources - but be optional for all resources, except for the account resource.

The account resource needs to be addressed individually and must have a mandatory, unique and non-mutable identifier.

The APIs specified in this document provide the ability for AISPs to access a PSU's account and transaction information for domestic PCA and BCA accounts.

This v1.0 specification does not cater for:

• Write operations (the ability to create) standing orders, direct debits and beneficiaries.

• Accounts other than PCAs and BCAs.

• Progressive or changing consent - if the consent between the AISP and PSU changes, then the existing account-request object is deleted and a new account-request is created with the new consent/authorisation details.

• The ability for the AISP to pre-specify the list of accounts that have been agreed with the PSU for consent/authorisation. At the time of writing the specification - it is not clear from a Legal perspective how the changing of these details over time (e.g, customers adding or deleting accounts) affects the original agreed authorisation. 

• The ability for the AISP to specify and "hints" for the types of accounts that have been agreed with the PSU for consent/authorisation (e.g., product or customer channel types). At the time of writing the specification - it is not clear from a Legal perspective how the changing of these details over time affects the original agreed authorisation. 

• Multi-authentication flows have been designed - but the full implications of the multi-authentication flows have not been worked through - so these are are not in the v1.0 specification.

• Non-functional requirements and specification of caching and throttling.

The figure below provides a general outline of a account information requests and flow using the Account Info APIs.

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Step 1: Request Account Information

• This flow begins with a PSU consenting to allow an AISP to access account information data. 

Step 2: Setup Account Request

• The AISP connects to the ASPSP that services the PSU's account(s) and creates an account-request resource. This informs the ASPSP that one of its PSUs is granting access to account and transaction information to an AISP. The ASPSP responds with an identifier for the resource (the AccountRequestId - which is the intent identifier).

• This step is carried out by making a POST request to /account-requests endpoint

• The setup payload will include these fields - which describe the data that the PSU has consented with the AISP:

  • Permissions - a list of data clusters that have been consented for access

  • Expiration Date - an optional expiration for when the AISP will no longer have access to the PSU's data

  • Transaction Validity Period - the From/To date range which specifies a transaction history period which can be accessed by the AISP

• An AISP may be a broker for data to other 4th parties, and so it is valid for a customer to have multiple account-requests for the same accounts, with different consent/authorisation parameters agreed. 

Step 3: Authorise Consent

• The AISP redirects the PSU to the ASPSP. The redirect includes the AccountRequestId generated in the previous step. This allows the ASPSP to correlate the account-request that was setup. The ASPSP authenticates the PSU. The ASPSP updates the state of the account-request resource internally to indicate that the account request has been authorised.

• The principle we have agreed is that consent is managed between the PSU and the AISP - so the account-request details cannot be changed (with the ASPSP) in this step. The PSU will only be able to authorise or reject the account-request details in its entirety.

• During authorisation - the PSU selects accounts that are authorised for the AISP request (in the ASPSP's banking interface)

• The PSU is redirected back to the AISP.

Step 4: Request Data

• This is carried out by making a GET request the relevant resource.

• The unique AccountId(s) that are valid for the account-request will be returned with a call to GET /accounts. This will always be the first call once an AISP has a valid access token.

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The API requests and responses must use a UTF-8 character encoding. This is the default character encoding for JSON (RFC 7158 - Section 8.1).

However, an ASPSP's downstream system may not accept some UTF-8 characters, such as emoji characters (e.g. "Happy Birthday 🎂🎂!" may not be an acceptable Payment Reference). If the ASPSP rejects the message with a UTF-8 character that cannot be processed, the ASPSP should respond with an HTTP 400 (Bad Request) status code.

All dates in the JSON payloads are represented in ISO 8601 date-time format. All date-time fields in responses must include the timezone. An example is below:

All dates in the HTTP headers are represented as RFC 7231 Full Dates. An example is below:

JWT claims are expressed as a JSON number representing the number of seconds from 1970-01-01T0:0:0Z as measured in UTC until the date/time. 

The resources defined by these APIs can be addressed through a path structure consisting of the following parts:

• An optional ASPSP specific path prefix

• The constant string "open-banking"

• The version of the APIs expressed as /v[major-version].[minor-version]/

• The resource name

Examples:

/superbank/open-banking/v1.1/payments

/open-banking/v1.0/payments

/apis/open-banking/v1.1/payments

The following headers SHOULD be inserted by the TPP in each API call:

(Reference: Section 6.3 - Financial API — Part 1: Read Only API Security Profile (Implementer’s Draft).)

Whether the PSU is present or not-present is identified via the x-fapi-customer-ip-address header. If the PSU IP address is supplied, it is inferred that the PSU is present during the interaction.

The implications to this are:

• ASPSPs will need to rely on AISPs assertion.

• As agreed at TDA (18/05) It will be up to the ASPSPs to interpret the 4-times customer not present rule - to be within the “spirit” of the RTS requirement.

• This is dependent on GDPR considerations on the AISP passing a PSU's IP address to an ASPSP.

The following are the HTTP response codes for the different HTTP methods - across all Account Info API endpoints.