Coming soon: ISO 20022 based APIs

Oct 12, 2017

What is ISO 20022?

ISO 20022 is an international messaging standard developed to facilitate electronic data interchange between financial institutions, and with their customers, users, suppliers, market infrastructures and regulatory authorities. It is a single, common ‘language’ for all financial communications and supports interoperability between all parties – no matter where the business is based. It allows participants and systems in different markets to ‘talk’ to each other using consistent terminology and formatting.

ISO 20022: Built for the future

ISO 20022 is not only a group of message standards. It was created by the International Organization for Standardization (ISO) as a new way to develop message standards within the financial industry – a standard to develop standards, so to speak. Financial institutions exchange massive amounts of information with their customers and amongst themselves in the course of delivering the services we all use every day.

Uniquely, ISO 20022 is adaptable to emerging requirements. ISO 20022 is chosen by many projects, communities, and experts as their messaging standard for financial business transactions. This may include emerging regulatory reporting requirements, market infrastructure developments, or legislative mandates to adopt new channels of data exchange between transacting parties. ISO 20022 offers an efficient and secure way of developing and implementing messaging standards that will serve as a basis for long-term requirements and solutions.

The development and changes to ISO 20022 applications varies in relation to what is aiming to be achieved and the need to address emerging business services.

At one end of the scale, the ISO 20022 development process permits the introduction of new data components and message formats into the standard. This means that organisations that wish to utilise the standard, are able to implement it to suit their purpose – achieving compliance and promoting interoperability. This process is achieved when an organisation puts forward a change request and business justification to the ISO 20022 Registration Authority, for approval by the ISO 20022 Registration Management Group. The governance of this process sits alongside ISO, is open and transparent, and allows for any organisation to submit requests for changes to existing messages or business justifications for development of new messages.

At the other end of the scale, the ISO 20022 development permits the standard to evolve and be used by implementations of new technologies and/or new applications of former technologies that require standardised data. The ISO 20022 Registration Bodies include a Technical Support Group (TSG) that is able to advise on this and has done so for the implementation of standardised open ISO 20022 based Application Programming Interfaces (API).

Application Programming Interfaces and introduction of JSON encoding

Emerging applications of standardised open API’s require standardised data.  An API is a set of functions and procedures that allows access to data or a service in order to provide greater functionality to the app or websites’ user. An open API is a means of accessing data based on an open standard; it is a public interface.  The data accessed via an open API may be closed, shared or open data, however in order to meet specific objectives – such as interoperability, compliance or end to end processes – the APIs require standardised data and ISO 20022 provides that.

The ISO 20022 methodology follows a number of steps. This layered design allows modellers to focus on the specifics of each layer. This approach fosters reuse and is the premise for extending this methodology to APIs. This is an example where the use of ISO 20022 is being adaptable and looked at in new applications.

The ISO 20022 TSG has put together guidelines for how API services can be exposed to the outside world in a consistent way, reusing the ISO 20022 repository artefacts that are common across services. This will decrease implementation time for developers that consume these APIs, ease mash-ups and foster reuse. In addition, while the current ISO 20022 standard includes XML and ASN.1 design rules, the TSG has also defined new design rules to ensure JSON can be used as an additional syntax. APIs often work in real-time, requiring lean structure and minimal data to ensure efficient processing of data and data requests.  For this reason, JSON encoding is proposed in addition to XML to support the use of ISO 20022 APIs. These JSON design rules can also be used to generate JSON schemas of the existing ISO 20022 messages[1]

In parallel to the work of the TSG, the ISO 20022 Registration Authority (RA) is working on defining a process that will enable API developers to easily re-use the ISO 20022 business concepts that have been created for use in ISO 20022 messages. The process will enable developers to create and register ISO 20022 “Resources[2]” derived from the ISO 20022 Business Model. All created Resources will be published by the RA on the ISO 20022 website for further re-use by API developers.

Use of these Resources together with the modelling guidelines defined by the TSG, will enable development of consistent APIs which will all share the same ISO 20022 business concepts, that are also used in ISO 20022 messages. The RA will review the quality of the Resources before registration and publication.

The current “Editor” modelling tool from SWIFT, which the RA offers to organisations that develop ISO 20022 messages, can already be used, with the support of the RA, to define ISO 20022 Resources. In 2018, a specific version of the “Editor” will be made available by SWIFT to help API developers defining Resources and creating derived APIs, in JSON or XML, in an ISO 20022 compliant way.

The RA does not intend to review/register all developed APIs in the ISO 20022 Repository and will not publish them, but a specific page will be created on the ISO 20022 website for developers who are willing to share the link to their API documentation.

This API submission process meets the requirements that are needed for an agile API development environment. Developers can design and maintain their APIs at their own pace, based on official ISO 20022 Resources. In this way, interoperability is guaranteed, whilst the management of APIs is kept extremely flexible.

When there is some certainty that APIs will be used in about the same way by a wide community of users, for example because there is a regulatory impetus – as is the case in Europe under PSD2 – it makes sense to provide a set of typical ISO 20022 APIs that could be (re-)used by all. In such cases, the RA would be ready to develop and publish such standard ISO 20022 APIs with the support of subject matter experts who would help the RA to model something that complies with the regulator’s intent and the user’s interest.



[1] JSON schemas of existing ISO 20022 message definitions will be available upon request from the ISO 20022 Registration Authority. However, the JSON Schema standard is still draft. This means it is still evolving (in some aspects quite substantially). Some of these changes will require further review and approval by the ISO 20022 TSG. We anticipate a stable version (that is, containing the new / changed JSON Schema features) by the end of 2017.

[2] A “resource” defines all the information that can be manipulated (created, read, updated, deleted) in the context of a web service (API) solution.