X-Road development going full steam in 2020

The year 2020 has started like the previous ended, with the X-Road development going on full steam. The first X-Road release of the new decade saw the daylight in February, which means that X-Road releases have now been published in three decades. The first production-level X-Road version was released in 2001 – almost 20 years ago. It does not mean that X-Road is cooling down – on the contrary, the near future brings a bunch of changes to X-Road that take it to the whole new level. However, getting there does not happen overnight.

The changes are implemented using an iterative approach, which means that every new X-Road release brings something new to the table. The changes start from version 6.24.0, but the most significant milestone will be the release of X-Road 7 in 2021. We have published a high-level X-Road development roadmap for 2020 so that everyone can see what kind of new features are coming out and when. The roadmap is available on the X-Road website.

The first release of the year, version 6.23.0, was published in February. The release was all about the Central Server, and it introduced changes in the Central Server high-availability support. More information about the changes can be found in my previous blog post and the official release notes.

“The first production-level X-Road version was released in 2001 – almost 20 years ago. It does not mean that X-Road is cooling down – on the contrary, the near future brings a bunch of changes to X-Road that take it to the whole new level.”

New Security Server admin UI and API

As you probably know, we have been working on the new Security Server UI and administrative REST API for some time already. The work is not fully completed yet, but at this point, it can be said that the new UI and API will be included in version 6.24.0. The release of the new UI and API is probably the most significant change in X-Road core since the first release of X-Road version 6 in 2015 – even more significant than the long-awaited REST support in 2019. Technically, the new UI and API are built on top of the existing X-Road core. However, the implementation technologies have been updated in the process.

The new UI provides improved user experience (UX) for Security Server administrators. The new UI has a new look and feel, and it makes taking care of administrative tasks easier and supports streamlining the onboarding process of new X-Road members. The administrative REST API will enable automation of Security Server maintenance tasks since all the features that are available through the UI are available through the API too. Maintaining and operating multiple Security Servers can be done more efficiently as configuration and maintenance tasks require less manual work.

“The release of the new UI and API is probably the most significant change in X-Road core since the first release of X-Road version 6 in 2015 – even more significant than the long-awaited REST support in 2019. ”

Supported platforms

Currently, the Security Server officially supports Ubuntu 18.04 LTS and Red Hat Enterprise Linux 7 (RHEL7) platforms. Instead, the Central Server and Configuration Proxy officially support only Ubuntu 18.04 LTS.

In 2020 official support for Ubuntu 20.04 LTS will be added to the Central Server, Configuration Proxy, and Security Server. Also, official support for RHEL8 will be added to the Security Server.

Version 6.21 is the last X-Road version that supports Ubuntu 14.04 LTS. It is good to keep in mind that once the version 6.24.0 is released, the version 6.21 drops out of the supported X-Road versions list. X-Road components still running on Ubuntu 14.04 LTS host cannot be upgraded to a newer X-Road version anymore without first upgrading the underlying host operating system.

X-Road 7

The development of the core components of X-Road version 6 continues actively throughout the year 2020. It has been decided that X-Road 7 will be built on top of version 6, which means all the enhancements implemented for version 6 will benefit the development of version 7 too. Making the current codebase more modular and reducing technical debt are also important goals for this year. Enabling the smooth implementation of new features planned for version 7 requires implementing certain changes to the current codebase upfront. However, the aim is to implement all the changes in a backwards-compatible manner. It means that the version upgrade between version 6 and 7 is no different compared to a version upgrade between the minor versions of version 6.

X-Road 7 will be implemented iteratively using agile software development methods. It means that changes and new features will be implemented in small pieces, every new version building on top of the previous one. In practice, this means that the first release of X-Road 7 will not include all the new features planned for version 7, but only a minimal subset of them. In the following versions, new features will then be added piece by piece and existing features are further developed based on the user feedback.

At the same time, with the technical track, we’re also actively working on the design of X-Road 7. Multiple activities will be carried out throughout the year, and X-Road users and stakeholders will have an active role in the process. Feature-wise, the target areas for this year are messaging patterns, message logging, and onboarding process.

“X-Road 7 will be implemented iteratively using agile software development methods. It means that changes and new features will be implemented in small pieces, every new version building on top of the previous one.”

X-Road extensions

In addition to the X-Road core, the maintenance and further development of two X-Road extensions will be handed over to NIIS by the Estonian Information System Authority (RIA). The extensions are X-Road 6 Monitor Project and Mini Information System Portal 2 (MISP2). The handover will take place during the first half of 2020.

X-Road and eDelivery

X-Road and eDelivery are both data exchange solutions that have been successfully used in multiple implementations in several countries and / or projects. They both provide a standardised and secure way to exchange data over the Internet. eDelivery is a building block of the Connecting Europe Facility (CEF).

NIIS is currently implementing a gateway between eDelivery and X-Road that will enable data exchange between eDelivery and X-Road ecosystems. A technical proof-of-concept level implementation has already been completed, and more detailed design is being drafted in collaboration with the European Commission’s Directorate-General for Informatics (DIGIT). The actual implementation of the gateway will begin later this year.

NIIS is looking for organisations that are interested in piloting the gateway. In case your organisation is an X-Road or eDelivery user and would like to exchange data with an organisation that is using the other platform, please contact NIIS for more detailed information.

“NIIS is currently implementing a gateway between eDelivery and X-Road that will enable data exchange between eDelivery and X-Road ecosystems. A technical proof-of-concept level implementation has already been completed.”

Want to know more?

If you’re interested in more detailed information about the upcoming changes, please visit the X-Road backlog. Anyone can access the backlog, and leave comments and submit enhancement requests through the X-Road Service Desk portal. Accessing the service desk requires creating an account that can be done in a few seconds using the signup form.

When X-Road is developed, and new features are added, the X-Road technology stack changes too. X-Road Tech Radar provides up-to-date information on different technologies used in X-Road.

Changes in the X-Road Central Server High Availability Support

Central Server is one of the key components of the X-Road ecosystem. It contains a registry of X-Road member organisations and their Security Servers. In addition, the Central Server contains the security policy of the X-Road instance that includes list of trusted certification authorities, list of trusted time-stamping authorities and configuration parameters. Both the member registry and the security policy are made available to the Security Servers via HTTP protocol. This distributed set of data forms the global configuration that the Security Servers use for mediating messages sent via X-Road. An X-Road operator is responsible for operating the Central Server.

Image 1. X-Road architecture and roles.

To be able to mediate messages Security Server must have a valid copy of the global configuration available all the time. Security Server downloads the global configuration from Central Server regularly and uses a local copy while processing messages. Security Server remains operational as long as it has a valid copy of the global configuration available locally. This means that Central Server may be unavailable for a limited time period without causing any downtime to the ecosystem. However, registering new members or subsystems is not possible without Central Server. Both the download interval and global configuration validity period can be configured according to the requirements of the X-Road ecosystem.

Design for Failure

An X-Road ecosystem is very fault tolerant against Central Server failures even with one Central Server node only. However, critical information systems should always be designed for failure so that they remain operational despite of a failure of individual components.

Central Server supports high availability through clustering that provides additional fault tolerance and scalability from performance point of view. A Central Server cluster consists of two or more Central Server nodes. The cluster is based on active-active model which means all the nodes can be used for both read and write operations. In case one of the nodes fails, Security Servers are able to fail over to other available nodes.

Why Changes Are Needed?

Until X-Road version 6.22 the clustering implementation was based on asynchronous, active-active database replication between the nodes. Unfortunately, the technology that was used in the implementation reached its end-of-life in December 2019 and newer versions of the same technology are not available under an open source license. Therefore, there was no other choice than to give up the BDR plugin for PostgreSQL by 2ndQuadrant and update the high availability support implementation for Central Server. Continuing with a newer version of the BDR plugin for PostgreSQL would have meant that every X-Road operator using clustering was required to buy a commercial license for the plugin.

Image 2. Central Server high availability implementation until version 6.22.

What Will Change?

Starting from version 6.23 the Central Server high availability implementation is based on a shared, optionally highly available database. Before version 6.23 every Central Server node in a cluster had its own database and changes were synchronized using multi-master database replication between the nodes. X-Road provided tools to setup the cluster and replication between the nodes. Starting from version 6.23 all the Central Server nodes share the same database that can be a standalone database, a database cluster, a fully maintained database service in the cloud etc. X-Road provides instructions how to configure the Central Server nodes in the cluster, but implementing high availability of the database is out of X-Road’s scope. However, the documentation provides instruction for setting up a replicated PostgreSQL database, but the documentation does not cover automatic failover.

Image 3. Central Server high availability implementation starting from version 6.23.

Compared to the previous implementation the new implementation is more flexible, because it gives the X-Road operator the freedom to choose how high availability is implemented on the database level. Instead, the previous implementation was tied to the BDR plugin for PostgreSQL. At the same time, more flexibility also brings more responsibility as implementing the high availability of the database is now the X-Road operator’s responsibility.

Available Resources

The official X-Road documentation provides an updated Central Server High Availability Installation Guide. In addition, the X-Road Knowledge Base provides an article about migrating Central Server clusters from version 6.22 to version 6.23. It is highly recommended for all the X-Road operators to read these documents before updating clustered Central Servers to version 6.23.

Try It Out!

X-Road 6.23.0-beta is now available for testing and the production version will be released by the end of February 2020. We wish to receive feedback about the new version and/or any possible challenges regarding migration to the new version.

Interoperability Puzzle

In today’s digital world information is stored across multiple information systems owned and maintained by different organisations. In addition to information spreading across multiple organisations, every organisation has internally numerous information systems that store information. Most of the digital services and processes require accessing multiple information systems and combining data from different sources – both inside an organisation and across multiple organisations. Without connections between different information systems building digital services would be extremely challenging if not impossible.

The ability of information systems to exchange and utilize information is known as interoperability. Unlike it may first sound like, interoperability is not only about technology and technical connectivity. On the contrary, interoperability consists of different layers that include also technology. The European Interoperability Framework (EIF) defines four layers of interoperability:

• legal – aligned legislation

• organisational – coordinated processes

• semantical – precise meaning of exchanged information

• technical – connecting information systems and services.

Image 1. EIF conceptual model. (source)

All the four layers are equally important when building digital services and processes. In addition, challenges on one layer are often reflected to other layers too. Therefore, it is important to be aware of all the layers and not to neglect any of them. That being said, in this blog post I’m going to concentrate on the technical layer and its dimensions because covering all the layers at once would be too big a bite to chew.

Data Exchange Scenarios

When it comes to a public sector organisation exchanging information, three top level data exchange scenarios can be recognized:

• Internal – data exchange within an organisation

• National – data exchange on national level

• Cross-border – international data exchange.

The same rules, laws and regulations don’t apply to national and cross-border data exchange which is why they are two separate scenarios instead of a single “external” scenario. Cross-border data exchange between authorities usually requires both state level agreements and data exchange agreements between the data exchange parties. The two scenarios could probably be combined as a single scenario making the total number of different scenarios two: internal and external.

The common factor between the scenarios is that all three require certain technical basic elements including, but not limited to connectivity, secure communication protocols, interfaces and integration services. The more standardized these elements are, the less work is required to build new connections between information systems and services. For example, if there’s no commonly agreed solution to securely connect information systems to each other and to how the connections are managed, the result is probably a jungle of point-to-point connections which means agreeing on the connection details and then building the connections every time when a new connection is needed – this is repeated again, again and again.

However, even if the technical basic elements in all the scenarios are the same, they are usually implemented using different technical solutions and technologies. Implementing a standardized connectivity layer within an organisation is usually based on different technology than a standardized connectivity layer with external parties. Let’s take a look at an example of an organisation that has a microservice-based information system with REST APIs published to external consumers.

Image 2. A microservice-based information system with REST APIs published to external consumers.

Internal Communications

Internally the information system uses a service mesh to facilitate service-to-service communications between microservices. A service mesh is a dedicated infrastructure layer that provides features such as standardized and secure connections, service discovery, and centralized logging and monitoring capabilities. Microservices communicate with each other through a service mesh proxy that is usually responsible for microservice level authentication, message routing, service discovery, automatic retries, timeouts, logging etc. As these features are provided by the proxy, they do not need to be implemented in the application code of each microservice separately. In addition, a service mesh usually has a centralized control plane that can be used to configure the proxies, and access logging and monitoring information etc.

Requests originating outside of the mesh typically enter the mesh through a service mesh gateway component. Available capabilities vary between different solutions, but in general, a service mesh is designed to manage traffic internal to the service mesh. In this case the example was very simple, but in real life a service mesh could serve multiple information systems and span multiple networks and data centers.

Exposing Services Externally

When it comes to accepting traffic from outside of an organisation, an API gateway comes into the picture. An API gateway exposes backend services as managed APIs and distributes traffic internally – in and out of the service mesh. An API gateway provides a single entry point to all clients, and hides the details of individual microservices. An API gateway also typically provides capabilities such as logging, monitoring, metrics, access control, request limiting, message transformations, orchestration etc. In addition, an API gateway is usually well connected to other components of the API management ecosystem, e.g. API marketplace and API publishing portal.

Even though API gateways and service meshes are complementary solutions, they have many overlapping functionalities and features. They are often deployed together, but they can be deployed separately as well. In addition, an API gateway can be used for internal purposes too – not only for publishing services to external clients. Similarly, a service mesh could be used to publish services to external clients.

What X-Road Brings to the Puzzle?

As so far I have been writing about internal and external data exchange, but I haven’t written a word about X-Road yet. At this point you may be wondering what is X-Road needed for if internal and external data exchange can be implemented using other technologies.

First of all, X-Road is best suited for external data exchange over the public Internet. The most common use case is data exchange between two organisations, but a single organisation may have information systems that are hosted in different locations and communicate with each other over the Internet too. In this case X-Road is a good fit for internal data exchange as well.

At first sight X-Road may seem like a service mesh as the architecture and feature sets have many similarities – both provide secure and standardized connections, service-to-service authentication, logging, reporting etc. In addition, both are based on an architecture model that implements service level communication through a proxy component. However, X-Road is not a service mesh as service mesh is the connection layer between different services in microservices architecture. In other words, service mesh is used as an internal connection layer within an application or between multiple applications of a single organisation whereas X-Road is used as a connection layer between different organisations and information systems.

How about X-Road and an API gateway then – are they mutually exclusive or can they be used side by side? X-Road and an API gateway are both used to publish services to external clients. Their architecture and feature sets are different even though they have features in common too, e.g. publish APIs to external clients, service-to-service authentication, authorization, logging, metrics. The major difference between X-Road and API gateway is that X-Road requires that the Security Server is used on both service consumer and provider side whereas API gateway enables client connections directly without any additional components on the client side.

Image 3. Point-to-point connections, an API gateway and X-Road in comparison.

Overall, an API gateway provides more flexibility and API management related features compared to X-Road, but when the same client communicates with multiple API gateways the client must adapt to different requirements and configurations of multiple service providers. Instead, X-Road provides a single communication channel between multiple service providers and services that all share the same configuration that is automatically distributed and applied by X-Road. In addition, X-Road guarantees that both service consumer and service provider meet the same security requirements, and non-repudiation of all the processed messages by signing, time-stamping and logging every processed message on the consumer and provider side. The logs can be used in a court proceeding as evidence. These features make X-Road ideal solution for secure, reliable and auditable data exchange.

One Happy Family

X-Road, an API gateway and a service mesh all have their place in the interoperability puzzle, and they can be used together side-by-side. They all have their own strengths and they can be used to complement each other.

X-Road is an ideal solution for secure data exchange that requires strong authentication of data exchange parties and non-repudiation with recorded eIDAS compliant evidence. X-Road can connect to backend services directly or through an API gateway. X-Road does not support message transformations, orchestration, rate limiting, quotas etc. which can be implemented in the API gateway layer if they are required.

Some APIs may not require strict security controls or they should be accessible without an additional access point on the client side, e.g. APIs providing open data. There’s no reason why an API could not be published through multiple channels, for example an API providing open data can be published through both X-Road and an API gateway. The benefit of this approach is that organisations that are not using X-Road can access it directly through an API gateway and organisations using X-Road can access it using the same channel they use to access other services and APIs too.

Image 4. The example application with X-Road.

Let’s go back to the different data exchange scenarios mentioned earlier – internal, national and cross-border. X-Road is a good fit for national and cross-border data exchange, and it can be used for certain internal data exchange use cases too. An API gateway can basically be used for all the scenarios, but depending on the use cases and their requirements X-Road might be a better choice for external data exchange and a service mesh for internal data exchange. Last but not least, a service mesh is best suited for the internal scenario for microservice-based applications.

Disclaimer

Finally, it must be said that there’s one major difference between X-Road, an API gateway and service mesh that has not been brought up yet. API gateway and service mesh are architecture patterns which have multiple implementations that all have their own set of features and functionalities. In this blog post I have compared API gateway and service mesh to X-Road on a general level without referring to any specific implementation, solution or product. Instead, X-Road is a product with a specific set of features and functionalities. This means that conceptually X-Road, API gateway and service mesh are not the same thing.

Get Some More REST

Over the last year and a half I’ve written multiple blog posts about X-Road and REST. Those blog posts have covered implementation plans, technical design details and release of the first X-Road version with REST support – the version 6.21.0 that was released in April 2019. All in all, the blog posts have covered the whole REST support journey from design to implementation and release. Currently we’re putting the finishing touches on the second stage of the REST support implementation which provides even more built-in REST-related features. The results are included in the version 6.22.0 that will be released in October 2019.

And for the readers interested in the technical details on source code level, the code implementing the REST support is available in the develop branch of the X-Road master repository on GitHub.

For clarity, adding support for REST does not mean dropping support for SOAP. No changes are required to information systems consuming and producing SOAP services via X-Road. Instead, the two architectural styles can co-exist side by side which means that all the current SOAP services are supported in the future too.

Basic Support for REST

The version 6.21.0 already provided a basic support for consuming and producing REST services:

• Basic REST functionality

  • Message exchange with signing and time-stamping

  • Message logging with archiving

  • Downloading and verification of log records

• Adding a REST service using an URL

• Operational monitoring of REST services

• Service-level authorization

• Certificate based authentication (clients + services) 

The version 6.22.0 will provide all the REST related features included in the previous version plus a set of whole new features. Let’s find out what they are!

Metaservices for REST

Metaservices are built-in Security Server services that can be used by X-Road member organisations to discover what services provided by other members are available and download the service descriptions of these services. Until now the metaservices have been available over SOAP only, but starting from the version 6.22.0 the metaservices are available over REST too. The responses of the REST metaservices are always returned in JSON as the Security Server does not currently support other content types in the responses.

In the version 6.21.0 the SOAP versions of the metaservices return information about available SOAP and REST services. This is somewhat confusing as a SOAP client is not very likely to be interested in receiving information about REST services, and vice versa. Therefore, in the version 6.22.0 the functionality has been changed so that the SOAP versions contain information about the available SOAP services only and similarly, the REST versions contain information about the available REST services only. This means that in case information about all the available SOAP and REST services needs to be collected, both SOAP and REST versions of the metaservices must be invoked.

More detailed information about the metaservices can be found in the Service Metadata Protocol for SOAP and the Service Metadata Protocol for REST.

Support for OpenAPI 3 Descriptions

Existing REST services can be published in X-Road as-is – just like in the version 6.21.0. Unlike with SOAP services, the Security Server does not require X-Road specific information to be present in the responses returned by REST services. Certain X-Road-specific information is still included in the response message returned to a client information system, but the Security Server takes care of adding the required information to response message’s HTTP headers.

In the version 6.21.0 publishing a REST API is done by defining the base URL of a REST API and a service code. This is still possible in the version 6.22.0, but in addition it is possible to publish a REST API using the OpenAPI 3 Specification. When a new REST API is published it is possible to choose whether it is done using the base URL of the API or the URL of an OpenAPI 3 description of the API. The description can be provided in both JSON and YAML formats. This means that providing an OpenAPI 3 description is supported, but not mandatory. All REST APIs added using the version 6.21.0 will continue to work without any changes in the configuration.

Image 1. Adding a REST API in the version 6.22.0.

The first benefit of providing OpenAPI 3 description is that other X-Road members can query the OpenAPI description using the new getOpenAPI metaservice – just like it is possible to query WSDL descriptions of SOAP services using the getWsdl metaservice. Another benefit of publishing an OpenAPI 3 description is that the Security Server reads all the API endpoints defined in the description and they become visible in the Security Server UI. The endpoints can then be used in access rights management – more about that later.

Image 2. List endpoints of a REST API.

In addition, it’s also possible to add endpoints manually. However, manually created endpoints are not visible to other X-Road members through the getOpenAPI metaservice, but they can be used in access rights management just like the endpoints read from an OpenAPI description. Manually created endpoints can be updated and deleted by Security Server administrators. Instead, endpoints read from an OpenAPI description cannot be manually updated or deleted. They can be updated and/or deleted by updating the OpenAPI 3 description and then refreshing it on the Security Server. The same logic applies updating SOAP services through WSDL descriptions.

Image 3. Adding an endpoint manually.

Besides access rights management, the Security Server does not use the endpoint-related information for anything else, e.g. the Security Server does not validate if an endpoint defined in a request by a client information system exists under an API or not. In other words, if a client information system has sufficient access rights to invoke an API endpoint, the Security Server forwards the request to the specified endpoint without any further validations.

More Fine-Grained Authorisation

In the version 6.21.0 REST APIs are authorized on the API level. In practice, this means that access rights are defined for all endpoints of an API. Sometimes this is OK, but other times it might be needed to define access rights on more fine-grained level, e.g. access to a specific endpoint only or only read access, but no permissions to add or modify data. The use of endpoints makes it possible to define access rights on more fine-grained level.

Starting from the version 6.22.0 it’s possible to define access for REST APIs on two levels: REST API level and endpoint level. In general, a REST API usually has multiple endpoints. When access rights are defined on the API level, they apply to all the endpoints of the API. Instead, defining access rights on the endpoint level enables more fine-grained access rights managements as access rights are defined using HTTP request method and path combination. Therefore, it is possible to define access rights for a single endpoint or alternatively for a subset of endpoints using wildcards.

When a client application has access rights on the API level, it means that the client can access all the endpoints of the API. In case clients must not have access to all the endpoints, then access rights must be defined on the endpoint level. Security Server’s access rights management only supports allowing access – explicitly denying access is not supported, e.g. allow access to all endpoints on API level and then deny access to a single endpoint is not supported.

What’s Next?

The version 6.22.0-beta is already out and the official release version 6.22.0 will be released in October 2019. However, the beta version already provides all the REST-related features included in the final release. The last weeks are reserved for fine tuning and testing.

The REST support implementation has been done in phases which means that REST-related features have been added along several X-Road versions – every new version adding something new. However, the version 6.23.0 does not have any planned new REST-related features yet, but it’ll likely contain smaller improvements to existing features, e.g. performance optimisations. In addition, we hope to receive feedback and enhancement requests from you regarding the existing REST functionality. Improvements and new features may be added to the roadmap based on the received feedback.

In case you have not checked out the X-Road REST support yet, it’s time to do it now!

X-Road and eDelivery – Identical Twins or Distant Relatives?

Building a digital society and digitizing public services both nationally and across borders are hot topics in Europe right now. Standardised and secure data exchange is one of the key enablers that is required to be in place for succeeding in the task. The good news is that there are already solutions and building blocks available that can be used for the job. Instead of reinventing the wheel and building everything from scratch it is possible to use off-the-shelf, battle-proven solutions that have already been successfully used in multiple implementations.

It goes without saying that X-Road is one of the available solutions. Another solution that is often mentioned in the same context is eDelivery – a building block of the Connecting Europe Facility (CEF). X-Road and eDelivery are both data exchange solutions that have been successfully used in multiple implementations in several countries and / or projects. Technically, they are both based on distributed architecture and they are enablers of decentralized data management. At first glance they may seem very similar, even competitors to each other. But is that really the case? Let’s find out.

Architecture

On architectural level eDelivery and X-Road have many characteristics in common as they are both based on four-corner model. The basic idea of the model is that information systems do not exchange data directly with each other. Instead, information systems are connected through additional access points that implement the same technical specifications and therefore are able to communicate with each other. In addition, access points usually provide common features required in data exchange, e.g. message routing, security, logging, authentication etc. Both X-Road and eDelivery also have an address registry and tools for capability lookups that are used in message routing and service discovery.

Image 1. Four-corner model explained through X-Road architecture.

The similarities do not finish there. In both X-Road and eDelivery the trust model is based on digital certificates, and they both guarantee non-repudiation of messages and identities of message exchange parties using digital signatures. In addition, in both cases the message transport protocol used between the access points is based on MIME/multipart messages even if the structure of the messages is not the same. X-Road and eDelivery can be used to exchange both data and documents. In addition, they are both payload agnostic which means that they can be used for transferring any kind of data (structured, non-structured and/or binary), e.g. purchase order, invoice, JSON, XML, PDF etc.

Cross-Border and Cross-Sector Data Exchange

Technically eDelivery supports both cross-border and cross-sector data exchange. However, eDelivery is typically implemented within a policy domain and different policy domains have their own implementations with domain specific operations and management models. In practice, each policy domain creates its own eDelivery subdomain, and all the eDelivery components that belong to the same subdomain trust each other. Usually, a component / participant from one subdomain, e.g. eHealth, is not considered trusted in another subdomain, e.g. eJustice. This means that there are multiple eDelivery subdomains and it might not be possible to exchange data between them.

X-Road's main idea is that it enables data exchange between organisations from different sectors (public, private, non-profit etc.) and different policy domains. X-Road is typically deployed on a national level so that it provides a nationwide data exchange layer for all kinds of organisations across sector and policy domain boundaries. Two X-Road environments can be joined together, federated, which enables cross-border data exchange between the member organisations of the two ecosystems. Federation means that members of two different X-Road ecosystems can exchange data as if they were members of the same ecosystem.

Trust Models

Both X-Road’s and eDelivery’s trust models are based on digital certificates. X-Road and eDelivery both use certificates to secure the communication between access points (TLS encryption), and sign the data and documents that are transferred. In addition, eDelivery also supports encrypting and decrypting the data and documents. In addition, how certificates are managed, configured and distributed differs between the systems.

eDelivery supports multiple trust models and the model that is used can vary between different eDelivery subdomains. Depending on the selected trust model the distribution of the digital certificates may be manual, automatic or something in between.

X-Road supports the use of multiple trust service providers within an ecosystem and the distribution of certificates is always handled automatically by X-Road. Two organisations may use certificates issued by different trust service providers, but this is fully transparent to the user organisations as the exchange and verification of certificates is automated. In X-Road's context, organisations and access points of the same ecosystem always trust each other. The trust can be expanded to cover other ecosystems using federation.

Messaging Models

One of the main technical differences between eDelivery and X-Road is related to supported messaging models. X-Road is based on synchronous communication that is well suited for real time data and document exchange. Instead, eDelivery is based on asynchronous communication that is well suited for reliable, non-time-critical document and data exchange. eDelivery also supports duplicate message detection and message retry / resending scenarios.

The difference between synchronous and asynchronous communication is that in synchronous communication a service consumer sends a request and stays on waiting for a response, but in asynchronous communication a service consumer sends a request and continues processing with other tasks. In synchronous communication the service consumer’s control flow is disrupted until the service provider has processed the service consumer’s request. Instead, in asynchronous communication the service provider sends a response later once it has processed the request.

Connecting Information Systems

Connecting an information system to eDelivery means that the information system must implement the eDelivery AS4 Profile so that communication between an eDelivery access point and an information system is technically possible. This means that an additional adapter or connector is usually required between an access point and an information system. The adapter/connector acts as a converter between the eDelivery AS4 Profile and the information system’s native format. Exchanging all kind of data is supported, but the data must always be wrapped inside a message that conforms the eDelivery AS4 Profile.

X-Road supports two alternative messaging protocols that can be used in the data exchange – a message protocol for SOAP and a message protocol for REST. When the SOAP protocol is used, an additional adapter or connector is usually required, because the data to be transferred must be wrapped inside a message that conforms the X-Road message protocol for SOAP. Instead, when the REST protocol is used, no additional adapter or converter component is required as existing REST services can be published and consumed as-is.

Operations and Management Model

eDelivery prescribes technical specifications that can be used to enable secure and reliable exchange of documents and data, and the specifications are based on standards. There are multiple software, both commercial and open source, available that implement the eDelivery specifications. Organisations are free to choose which software they use when exchanging data using eDelivery. eDelivery is managed through the specifications – once they change, vendors of the implementations update their products accordingly. Operations and management model is policy domain specific – each domain defines its own model and models between different domains may vary.

X-Road is a technical and organizational framework that provides secure and standardised way to exchange data between data providers and consumers over the Internet. Multiple standards are used in X-Road's implementation, but no X-Road specific parts have been standardised. However, X-Road’s source code and all X-Road protocols are open, and documentation is publicly available so anyone is free to create an implementation of X-Road protocol stack. Organisations that want to exchange data over X-Road must install X-Road software's Security Server component. X-Road and its protocol stack are managed as a software product – the protocol stack is managed and developed as a part of the X-Road software product. In addition, X-Road defines an organizational framework that describes the roles and responsibilities of different actors of an X-Road ecosystem.

Conclusions

On high level it may seem that eDelivery and X-Road are very similar, but more detailed review reveals that there are many significant differences between them. Even if they provide many same features and they have many common components on logical level, the implementation details vary greatly.

One of the key differences between eDelivery and X-Road is that eDelivery is a set of technical specifications with multiple implementations, and X-Road is a technical and organizational framework. In other words, eDelivery and X-Road are conceptually two different things. eDelivery is also missing a detailed organizational framework that defines the roles and responsibilities regarding the operations and management of an eDelivery policy domain.

Another important difference is related to the supported messaging models – asynchronous and synchronous communication. Both messaging models have their pros and cons, and it depends on the use case which one is a better a fit. Choosing a wrong messaging model may result in additional complexity which requires more implementation and maintenance effort.

All in all, eDelivery and X-Road are not identical twins and they should not be considered competitors either. X-Road is well suited for synchronous real-time data and document exchange, whereas eDelivery is a good fit for reliable, non-time-critical document and data exchange. Therefore, eDelivery and X-Road are not mutually exclusive, and they can be used side by side to fulfill different kind of data exchange needs. In the future it might be even possible to exchange data between eDelivery and X-Road. NIIS is currently studying alternatives for implementing a gateway between eDelivery and X-Road that would enable data exchange between eDelivery and X-Road ecosystems. A technical proof-of-concept level implementation has already been completed, but there are legal and administrative questions yet to be resolved. However, that’s another story.

Netflix of Public Services

Everyone knows Netflix, the online streaming service where users can watch films, documentaries and TV series online 24/7. Netflix has over 100 million subscribers globally, and they all expect the service to work flawlessly and provide first-class user experience and content each and every time. To be able to meet users’ expectations the service must be resistant to failure and it must adapt to changing demand quickly and automatically. Technically, this is a huge challenge to any information system – especially when we’re talking about over 100 million users.

Of course, the most important thing to the users is high-quality content. World class technical solutions and architecture mean nothing if a service does not provide interesting and meaningful content to its users. When it comes to delivering the content to the users, technical solutions and architecture are key enablers, and without those it is not possible to get access to it or the user experience is poor. Great technical solutions are transparent to their users – the users don’t even know that they’re there.

Netflix has been able to meet the expectations well. At the same time they’ve managed to keep the underlying architecture fully transparent to users – as it should be. Netflix has built the underlying system so that it is highly available, fault tolerant, resilient and scalable. One of the key factors in their success lies in the architectural choices. Instead of building one monolithic system, Netflix has built its system around multiple loosely coupled services. This approach is called microservice architecture. Another key factor in Netflix’s technical success is the use of cloud services.

Size does matter

Microservice architecture pattern is one of the most commonly used architecture patterns in the recent years. It is based on the idea that a system is composed of multiple small, independently deployable and loosely coupled services that communicate with each other using language-agnostic APIs. Usually the services are organized around business capabilities. Each service can be developed and deployed independently of one another which simplifies the development and deployment of large, complex applications as each part of the application can be developed and deployed independently instead of deploying the whole application every time when a single component is updated.

Image 1. Microservice architecture.

On the other hand, microservice architecture also increases the complexity of a system. The complexity comes from multiple fine-grained services operating together seamlessly. A single business feature may span multiple microservices which requires an additional layer for coordination and orchestration, service discovery, error handling etc. Locating a malfunctioning component from such a system is not a trivial task. In addition, each service can be developed independently, but testing of a business feature requires that all the related services or their mock versions are available.

At this point you might be wondering what all this has to do with X-Road? Keep on reading, you will find it out soon.

What about X-Road?

X-Road is an open source data exchange layer solution that enables organizations to exchange information over the Internet. X-Road is a centrally managed distributed data exchange layer between information systems that provides a standardized and secure way to produce and consume services. X-Road ensures confidentiality, integrity and interoperability between data exchange parties. The data is always exchanged directly between a service consumer and a service provider, and no third parties have access to it.

X-Road is not based on microservice architecture, but the X-Road ecosystem shares many of the same characteristics – on a higher level, though. Instead of a single information system consisting of multiple small atomic services, X-Road is a data exchange layer between service consumers and business services provided by various information systems owned by different organisations. The services available via X-Road are independently deployable and loosely coupled, and they communicate with each other using language-agnostic APIs. Each service can be developed, deployed and scaled independently without affecting other services as long as the API remains unchanged. Sounds familiar?

However, X-Road is just a data exchange layer – an enabler for secure and standardized data exchange that is transparent to end-users. Just like microservice architecture is enabler for building scalable, fault-tolerant and highly-available systems. The real value comes from services that are built on top of the technical infrastructure and the content that they provide to users.

It’s all about content

X-Road enables citizens, entrepreneurs and officials to operate via different portals and applications (document management systems, institutional information systems) in a more efficient and flexible manner. For example, it helps to check for relevant information in various base registries or securely exchange documents between organisations.

X-Road is used nationwide in the Estonian data exchange layer X-tee and in the Suomi.fi Data Exchange Layer service in Finland. Both Estonia and Finland have their own state portals that provide users access to different public registers and services. In general, a state portal is a single point-of-entry to public services for citizens, entrepreneurs and officials. X-Road is used in the background to connect the portal to different information systems and registers maintained by various organizations. Instead of going through websites and portals of different authorities one by one, there’s one centralized place to search and access services.

Image 2. A state portal connected to various information systems and base registers via X-Road.

A state portal is a Netflix of public services. It is a centralized place that gives 24/7 access to public services provided by different authorities. It is a platform that citizens can use to communicate with different authorities, and search, access and update information. New services are added to the platform and old ones are removed. Also the platform itself is constantly developed based on the feedback received from users. X-Road is a transparent data exchange layer in the background that enables secure and standardized data exchange between the portal and various information systems and base registers. X-Road plays a key role in the architecture, but the most important thing is the actual content – what would be the value of Netflix without all films, documentaries, TV series etc.? The same goes with a state portal, it’s all about the available content and services.

Two Steps from X-Road REST Support

Over the last year I’ve written multiple blog posts about X-Road and REST. In those blog posts I have shared insights on our implementations plans, details about the technical design and status updates on the progress. In the last months we’ve concentrated on the technical implementation of the X-Road Message Protocol for REST and now we’ve arrived at a point when only the finishing touches are missing from completing the first stage of the REST support implementation. Therefore, in this blog post, I’m not going to write about plans, but the actual implementation instead. 

And for the readers interested in the technical details on source code level, the code implementing the REST support is now available in the develop branch of the X-Road master repository on GitHub. 

For clarity, adding support for REST does not mean dropping support for SOAP. No changes are required to information systems consuming and producing SOAP services via X-Road. Instead, the two architectural styles can co-exist side by side which means that all the current SOAP services are supported in the future too.

REST support implementation

For a recap, let’s start with defining what REST means in the context of X-Road. Unlike SOAP that is a protocol with a detailed specification, REST is an architectural style consisting of the best practices and guidelines. In X-Road’s case supporting REST means consuming and producing REST-style API’s via X-Road. A loose definition would be supporting any content type over HTTP.

One of the guiding principles in designing the X-Road Message Protocol for REST has been the ease of use for both service providers and service consumers. Therefore, consuming and producing REST-style services via X-Road is made possible without an additional adapter service component. X-Road-specific information required by Security Server (e.g. service client identifier, service provider identifier, message id etc.) is transferred and processed so that existing REST-style services and service consumers can be connected to X-Road with minimal changes or no changes at all. This has been achieved by transferring X-Road specific information required by Security Server in HTTP headers and URL parameters, outside of the message payload.

X-Road’s REST support is not limited to just JSON and XML messages as Security Server does not set any restrictions to the content type of the payload that is transferred between a service consumer and a service provider. The content type of the payload is defined using “Content-Type” HTTP header that is transferred between a service consumer and a service provider just like the payload itself. The payload is transferred as-is, Security Server does not modify, convert or validate the processed payload. The same goes with almost all the consumer and service provider defined HTTP headers and URL parameters – they are passed as-is between a service consumer and a service provider. The list of filtered HTTP headers is included in the X-Road Message Protocol for REST specification – all the other headers are passed as-is.

When it comes to non-repudiation of REST messages, message payload, URL parameters and HTTP headers are all included in the digital signature and logs generated and verified by Security Server. Hence, X-Road guarantees non-repudiation of REST request and response messages just like it does for SOAP messages. Currently it is possible to disable logging of SOAP message body and the same feature is available for REST services too. In that case REST message payload, URL parameters and consumer/provider defined HTTP headers are excluded from the message log.

Consuming REST services 

Consuming REST services via X-Road is simple – the service to be called is defined in the request URL and the X-Road client subsystem sending the request is defined in an HTTP header. Other X-Road specific information (e.g. user ID, issue, id) is optional and it is passed using HTTP headers. Other HTTP headers, path parameters and URL parameters are passed end-to-end as-is which means that from a service client’s perspective the only difference compared to a direct service call is the mandatory HTTP header defining the X-Road client subsystem.  

Providing REST services 

Producing REST services via X-Road is as simple (if not even simpler) as consuming services. Existing REST services can be published in X-Road as-is – it is enough to add the base URL of the REST API to be published and define access rights on the Security Server UI. Unlike with SOAP services, Security Server does not require X-Road specific information to be present in the responses returned by REST services. Certain X-Road-specific information is still included in the response message returned to a client information system, but Security Server takes care of adding the required information to response message’s HTTP headers. 

Service descriptions for REST 

Currently SOAP services must be described using WSDL descriptions. It is not possible to publish a SOAP service in X-Road without providing a WSDL description for the service.  

In the first X-Road version including REST support (v6.21.0) service descriptions for REST services are not required. When a new REST service is added, it is enough to provide the base URL of the REST API to be published. In later versions support for describing REST services using OpenAPI 3 specification will be added.  

How about automatic SOAP-REST conversions?

Services must be consumed using their native implementations – SOAP or REST. If a service provider wants to provide both SOAP and REST versions of the same service, the provider must implement both versions. In other words, Security Server will not provide automatic SOAP-REST conversion. In case automatic SOAP-REST conversion is needed, REST Adapter Service X-Road extension could be used. REST Adapter Service is an off-the-shelf component that provides an X-Road compatible REST-SOAP converter. The service supports a limited set of use cases. 

Machine-to-machine authentication 

The REST implementation supports mutual TLS authentication between a Security Server and a REST service consumer/provider. Support for JWT (JSON Web Token) based authentication between a Security Server and an information system may be provided in later versions. 

However, it is already possible to use JWT based authentication between a service client and a service provider. As described before, Security Server passes all HTTP headers between a service consumer and a service provider as-is, so there aren’t restrictions for implementing JWT based authentication on application level.

It’s time for beta! 

Soon it’s time to release the beta version of 6.21.0 that includes the long-awaited REST support. The official release version of 6.21.0 will be released at the end of April 2019. However, the beta version already provides all the REST-related features included in the final release. The last weeks are reserved for fine tuning and testing.

The version 6.21.0 will provide a basic support for consuming and producing REST services which includes:

• Basic REST functionality

  • Message exchange with signing and time-stamping

  • Message logging with archiving

  • Downloading and verification of log records

• Adding a REST service using an URL

  • No support for OpenAPI definitions

• Operational monitoring of REST services

• Service-level authorization

• Certificate based authentication (clients + services)

• X-Road Message Protocol for REST 1.0

That’s not all folks!

The REST support implementation will be done in phases which means that REST related features will be added along several X-Road versions – every new version adding something new. The next versions 6.22.0 and 6.23.0 will add more REST-related features later.

X-Road 6.22 (full support)

• Minor fixes and enhancements based on user feedback

• Metaservices for REST (listClients + listMethods)

• Support for OpenAPI

  • Add APIs using OpenAPI specification

  • Meta-service for querying services' OpenAPI definitions (getOpenAPIDefinition)

• Potential improvements

  • Path and method level authorization

  • JWT-based authentication (clients + services)

X-Road 6.23 or later (advanced support)

• Support for URI rewriting by Security Server

• Other API-Gatewayish features based on user feedback

X-Road Core Development in 2019

The new year 2019 has kicked off a few weeks ago, and X-Road core development keeps on rolling. Even if there haven’t been many updates regarding the X-Road core development lately, it doesn’t mean that NIIS has been resting on its laurels. Instead, we have been working on the version 6.20.0 and features for the other upcoming versions. We have also published the high-level X-Road development roadmap for 2019 so that everyone can see what kind of new features are coming out and when. The roadmap is available on the X-Road website.

The version 6.20.0 will be released on 25th January and it is the first of the three releases to be published in 2019. The official v6.20.0 release notes will be published in the X-Road Knowledge Base on the date of the release. The biggest change in the version 6.20.0 is support for Ubuntu 18.04 LTS operating system. The improvement is important, because the currently supported Ubuntu 14.04 LTS will quit receiving maintenance updates in Q2/2019 which is why migration is required. In addition, there’s a number of other improvements and fixes included in v6.20.0.

REST support

One of the most important features in 2019 is the long-awaited, native REST support. NIIS has been working on the X-Road REST support since spring 2018. Since then we have organized workshops and surveys for collecting input and feedback from X-Road users on the required features. We’re currently working on the implementation using all the comments and feedback as an input.

The implementation will be done in phases which means that REST related features will be added along several X-Road versions – every new version adding something new. The first version to support REST is v6.21.0, and it will be released in April 2019. Versions 6.22.0 and 6.23.0 will add more REST related features later.

X-Road 6.21 (basic support)

• Basic REST functionality

  • Message exchange with signing

  • Message logging

• Adding a REST service using an URL

  • OpenAPI definition not required

• Service-level authorization

• Certificate based authentication (clients + services)

• Metaservices for REST (listClients + listMethods)

• X-Road Message Protocol for REST 1.0

X-Road 6.22 (full support)

• Minor fixes and enhancements based on user feedback

• Path and method level authorization

• Support for OpenAPI

  • Possible to add a service using OpenAPI specification

  • Meta-service for querying services' OpenAPI definitions (getOpenAPIDefinition)

  • OpenAPI definition required

• JWT based authentication (clients + services)

X-Road 6.23 or later (advanced support)

• Support for URI rewriting by Security Server

• Other API-Gatewayish features based on user feedback

Right now, the version 0.3.0 of the Message Protocol for REST is out for comments – it is possible to leave comments until 28th January. All the feedback will be reviewed, and the protocol will be further developed based on the received input. NIIS welcomes everyone to comment the protocol draft!

API Based UI

Another major change taking place in 2019 is a new UI for both Security Server and Central Server. The new UI is not just a facelift – the UI will be redesigned and implemented from scratch. The aim of the change is to improve the usability and user experience of X-Road. Therefore, X-Road users will be closely involved in the design and implementation process so that their voice will be heard.

Together with the new UI, an administrative REST API will be implemented. The new UI will be using the API, but the API can be used for automating maintenance and configuration tasks too. The API will provide Security Server and Central Server administrators with the opportunity to automate maintenance and configuration tasks that currently require manual work.

According to the current schedule the new UI and the administrative API will be included in the version 6.22.0 that will be released in autumn 2019.

Streamlined onboarding process

Onboarding process of new X-Road members is one of the focus areas in X-Road core development this year. The aim is to streamline the onboarding process and reduce the number of steps that require manual work in the process. In practice this means enabling automatic approval of registration requests which speeds up the registration process and reduces the daily management tasks of the X-Road operator.

X-Road 7

The development of the core components of X-Road version 6 continues actively throughout the year 2019. At the same time NIIS is already looking ahead and the preparations for X-Road version 7 are already kicked off. Research and planning phase will be completed in 2019 so that the implementation can begin in 2020. Research and design are based on user-centered approach, and users are involved through the whole design and research process. Input, feedback and ideas are collected through interviews, workshops, events and surveys. In addition, one part of the research and planning phase is academic research in selected areas through collaboration with Estonian and Finnish universities.

And there is more!

This writing covers only the most important changes to be implemented in 2019. In addition, many smaller changes will be included in every release. It seems that we have a busy year ahead of us. If you’re interested in more detailed information about the upcoming changes, please visit the X-Road backlog. Anyone can access the backlog, and submit enhancement requests through the X-Road Service Desk portal. Accessing the service desk requires creating an account which can be done in few seconds using the signup form.

Functional changes and new features implemented this year change the X-Road technology stack too. X-Road Tech Radar provides up-to-date information on different technologies used in X-Road.

Stay tuned!

Standalone Security Server

X-Road is a centrally managed distributed data exchange layer between Information Systems that provides a standardized and secure way to produce and consume services. The identity of each organization and Security Server is verified using certificates that are issued by a trusted Certification Authority (CA) when an organization joins an X-Road ecosystem. The identity of service producers and consumers is maintained centrally, but all the data is exchanged directly between a consumer and a provider.

X-Road’s distributed architecture makes it highly scalable and very resilient against different kinds of cyber attacks. X-Road creates a trusted network where message exchange takes always place between two trusted parties as the identities of all message exchange parties are verified using certificates. In general, these are major strengths of X-Road, but in some cases they’re also weaknesses, because they make the onboarding process of new members slower compared to a standalone solution that does not require any registration or verification to be completed. In production like environments certain controls are required as they enforce trust between member organizations. However, there are situations in which more agile approach is needed, e.g. testing and development purposes.

Currently the only way to be able to test Security Server is to join an existing X-Road ecosystem or set up an own environment. The time that is required for completing any of the two alternatives depends on the policies of an existing X-Road ecosystem and the experience level of the expert who is responsible for the task. Nevertheless, the time required for completing the task varies from hours to days. A developer who just wants to test a new service together with Security Server would like to have a solution that is available in minutes and requires minimal configuration. Sounds too good to be true - is something like that possible?

Is this a dream or is it now? 

Standalone Security Server is a special version of Security Server that is ready-to-use in minutes without the normal Security Server installation, configuration and registration process. It is meant for testing purposes in X-Road service development and it cannot communicate with other Security Servers. Therefore, it is targeted especially to developers and organizations that are developing services to be published via X-Road.

It is possible to add new services on the standalone Security Server and invoke the services using the same Security Server. It comes with two pre-configured subsystems – one for providing and another for consuming services. In addition, it does not require connection to Central Server, OCSP service or time-stamping service. Therefore, standalone Security Server can be set up in minutes and once it has been downloaded it does not even require an internet connection. It is ideal for testing purposes in service development or for someone who’s interested in giving a quick try.

Image 1. Standalone Security Server.

Standalone Security Server has not been published yet, but a proof of concept (PoC) level implementation has been completed by NIIS. Before publishing the standalone Security Server we would like to hear X-Road community’s opinion regarding the format in which it should be published. Do you want to have it as a Docker image, VirtualBox image, AWS AMI, Azure virtual machine image or something else? NIIS is going to publish a standalone version of Security Server using the format that receives the most votes.

NIIS welcomes everyone to give their vote by 1st November 2018!

X-Road REST Support – Where Are We Today?

As you already know, NIIS has been working on the X-Road REST support since spring 2018 when a survey regarding the topic was done. The results did not leave any room for doubts – 93 % of the participants wanted X-Road to support REST. After the survey NIIS organized an X-Road REST support ideation and planning workshop in Tallinn in May. The aim of the workshop was to get more insight on implementing REST support from real X-Road users. The feedback received from the workshop has been used as an input for the following phases of the planning process. Now the planning has reached a state where the designed implementation approach can be shared with the X-Road community. Let’s take a look where we are today.

From SOAP…

To be able to better understand the selected approach for implementing REST support, let’s have a look at the current SOAP based implementation first.

Image 1. Current SOAP based implementation.

Currently X-Road has two message protocols: X-Road Message Protocol and X-Road Message Transport Protocol. X-Road Message Protocol defines how service consumers and service producers communicate with Security Server. The protocol is based on SOAP profile 1.1 and it comes with some X-Road specific limitations and additional requirements, e.g. support for synchronous request-response operations only, some mandatory SOAP headers are required, document/literal style SOAP body is required.

Instead, X-Road Message Transport Protocol is a proprietary protocol that defines how Security Servers communicate with each other. The protocol uses HTTP 1.1 over TLS and MIME multipart framing. The protocol wraps the X-Road Message Protocol payload and adds some additional authentication data and message signature. The key limitation of the current implementation is that only SOAP payload is supported.

…to REST 

First, let’s define what REST means in X-Road’s context. Unlike SOAP that is a protocol with a detailed specification, REST is an architectural style consisting of best practices and guidelines. In X-Road’s case supporting REST means consuming and producing REST-style APIs via X-Road. A loose definition would be supporting JSON and/or XML over HTTP.

Image 2. Supporting SOAP and REST.

To be able to support REST-style services some changes to the current implementation are required. In addition to the current X-Road Message Protocol for SOAP, a new X-Road Message Protocol for REST will be created. The protocol will define how REST-style service consumers and service producers communicate with Security Server. The current X-Road Message Protocol for SOAP will remain unchanged – no changes are required to SOAP service consumers and service providers when REST support will be added. For clarity, adding support for REST-style services does not mean dropping support for SOAP services.

Adding support for REST-style services means that also X-Road Message Transport Protocol must be updated – a new extended version of the protocol will be created. The protocol will be changed so that the transport message will contain in place of SOAP request part a more generic payload part that can contain SOAP, JSON, XML etc. In fact, Security Server will not set any restrictions to the content type of the payload that is transferred between a service consumer and a service provider. The content type of the payload is defined using “Content-Type” HTTP header that is transferred between a service consumer and a service provider just like the payload itself.

Image 3. X-Road transport message before and after REST support is added.

In practice, the payload is transferred as-is – by default, Security Server does not modify, convert or validate the processed payload. However, validating that XML and JSON payloads are well-formed might be implemented. In general, services must be consumed using their native implementations – SOAP or REST. If a service provider wants to provide both SOAP and REST versions of the same service, the provider must implement both versions. In other words, Security Server will not provide automatic SOAP-REST conversion. In case automatic SOAP-REST conversion is needed, REST Adapter Service X-Road extension could be used. REST Adapter Service is an off-the-shelf component that provides an X-Road compatible REST-SOAP converter. The service supports a limited set of use cases.

The built-in REST support will have some limitations too. The implementation is restricted to request-response messaging model and it does not support HTTP streaming. Supporting these features would require some bigger changes to the X-Road architecture and therefore, they’re of out scope of REST support implementation.

Design goals 

Backwards compatibility is one of the most important design goals when implementing support for REST-style services. The behavior of SOAP payload will stay compatible with the current implementation. This means that no changes are required to information systems consuming and producing SOAP services via X-Road. 

When designing X-Road Message Protocol for REST, the aim is to design the interface for REST clients and services as future-proof. This means that the protocol will remain the same in the future versions of X-Roads which makes migrating to new X-Road versions significantly easier. Instead, the X-Road Message Transport Protocol, the protocol used between Security Servers, may change in the future versions of X-Road, but that does not have an effect on the service consumers and producers as long as X-Road Message Protocol for SOAP and REST remain unchanged.

One of the guiding principles in designing the X-Road Message Protocol for REST is the ease of use for both service producers and service consumers. In practice, this means that consuming and producing REST-style services via X-Road should be possible without an additional adapter service component. X-Road specific information required by Security Server (e.g. service client identifier, service provider identifier, message id etc.) should be transferred and processed so that existing REST-style services and clients can be connected to X-Road without making changes to services and clients to be connected. Therefore, X-Road specific information required by Security Server must be transferred outside of the message payload, in HTTP headers or URL parameters, for example.

Your input is needed!

The next phase in the REST support implementation process is a technical proof of concept (PoC) for validating the feasibility of the described approach before starting the actual implementation. The PoC has already started and the aim is to complete it in October.

Another task to be completed before starting the implementation is the definition of X-Road Message Protocol for REST. The protocol defines how REST-style service consumers and service producers communicate with Security Server. I have not covered the protocol in more detail in this blog post intentionally, because the first draft version of the protocol has just been completed and it is now available for comments. All the feedback will be reviewed, and the protocol will be further developed based on the received input.

NIIS welcomes everyone to comment the protocol draft! It is possible to leave comments until 18th October 2018.