Markus Lanthaler

A semantic description language for RESTful Data Services to combat Semaphobia

RESTful Web services are an increasingly popular way for companies to expose their data on the Web. On the other hand, the Linked Open Data initiative is gaining traction recently. Since RESTs principles align well with those of Linked Data, there is an increasing interest in the relationship of the two. Nevertheless, in practice they still largely remain separated, creating islands of data instead of a global graph of data forming the envisioned Semantic Web. There are different reasons for this. One is the reluctance of most Web developers to use Semantic Web technologies, a phenomenon we denote as Semaphobia. Another reason is that the Semantic Web is considered to be a disruptive technology which does not consider existing infrastructure. This makes it difficult for enterprises to update their legacy systems. To solve these and other issues, we propose a novel approach to semantically describe RESTful Data Services which in consequence leads to a mechanism to transform the data provided by such services to semantic resources. This aims to contribute to the availability of more semantic datasets. By keeping the approach as familiar and simple as possible for Web developers, we hope to lower the entry barrier and to foster the adoption of our approach.

Creating 3rd generation web APIs with hydra

In this paper we describe a novel approach to build hypermedia-driven Web APIs based on Linked Data technologies such as JSON-LD. We also present the result of implementing a first prototype featuring both a RESTful Web API and a generic API client. To the best of our knowledge, no comparable integrated system to develop Linked Data-based APIs exists.

Towards a RESTful service ecosystem

Average information workers spend most of their time for searching, analyzing, reformatting and consolidating information. The recent advent of service-oriented architectures (SOA) built on Web services is a first attempt to streamline respectively automate those tasks in order to increase productivity. SOAP-based services work well within a company and are thus mainly used to for the integration of legacy systems which have not been built to be Web-friendly or to make new systems more flexible for changing requirements in business ecosystems. Nevertheless, the utopian promise of uniform service interface standards, metadata and universal service registries, in the form of the SOAP, WSDL and UDDI standards have proven elusive. Instead, for Internet-scale applications, lightweight REST-based architectures which gained a lot of momentum recently provide a number of important advantages such as better scalability, reliability and visibility and are thus the preferred choice for Internet-scale applications. Despite the foreseeable potential, the increasing interest on and growing acceptance of lightweight services, there are still problems on formal describing, finding and orchestrating services as well as a lack of a holistic framework covering the entire service lifecycle. This paper focuses on an extensive survey comparing the traditional SOAP-based architecture to the emergent lightweight REST-based architectural style as a first step towards a framework proposal.

Model your application domain, not your JSON structures

Creating truly RESTful Web APIs is still more an art than a science. Developers have to struggle with a number of complex design decisions because concrete guidelines and processes are missing. Consequently, often it is decided to implement the simplest solution which is, most of the time, to rely on out-of-band contracts between the client and the server. Instead of properly modeling the application domain, all the effort is put in the design of proprietary JSON structures and URLs. This then forms the base for the contract which is communicated in natural-language (with all its ambiguity) to client developers. Since it is the server who owns the contract it may be changed at any point, which, more often than not, results in broken clients. In this position paper, we discuss some of the challenges and choices that need to be made when designing RESTful Web APIs. In particular, we compare how contracts are supposed to be established and how they are defined in practice. We illustrate the problems that are the cause of these divergences. As a first step to address these issues we describe and motivate an alternative, domain-driven approach to design Web APIs.

Seamless integration of RESTful services into the web of data

We live in an era of ever-increasing abundance of data. To cope with the information overload we suffer from every single day, more sophisticated methods are required to access, manipulate, and analyze these humongous amounts of data. By embracing the heterogeneity, which is unavoidable at such a scale, and accepting the fact that the data quality and meaning are fuzzy, more adaptable, flexible, and extensible systems can be built. RESTful services combined with Semantic Web technologies could prove to be a viable path to achieve that. Their combination allows data integration on an unprecedented scale and solves some of the problems Web developers are continuously struggling with. This paper introduces a novel approach to create machine-readable descriptions for RESTful services as a first step towards this ambitious goal. It also shows how these descriptions along with an algorithm to translate SPARQL queries to HTTP requests can be used to integrate RESTful services into a global read-write Web of Data.

Aligning Web Services with the Semantic Web to Create a Global Read-Write Graph of Data

Despite significant research and development efforts, the vision of the Semantic Web yielding to a Web of Data has not yet become reality. Even though initiatives such as Linking Open Data gained traction recently, the Web of Data is still clearly outpaced by the growth of the traditional, document-based Web. Instead of releasing data in the form of RDF, many publishers choose to publish their data in the form of Web services. The reasons for this are manifold. Given that RESTful Web services closely resemble the document-based Web, they are not only perceived as less complex and disruptive, but also provide read-write interfaces to the underlying data. In contrast, the current Semantic Web is essentially read-only which clearly inhibits networking effects and engagement of the crowd. On the other hand, the prevalent use of proprietary schemas to represent the data published by Web services inhibits generic browsers or crawlers to access and understand this data, the consequence are islands of data instead of a global graph of data forming the envisioned Semantic Web. We thus propose a novel approach to integrate Web services into the Web of Data by introducing an algorithm to translate SPARQL queries to HTTP requests. The aim is to create a global read-write graph of data and to standardize the mashup development process. We try to keep the approach as familiar and simple as possible to lower the entry barrier and foster the adoption of our approach. Thus, we based our proposal on SEREDASj, a semantic description language for RESTful data services, for making proprietary JSON service schemas accessible.

Leveraging Linked Data to Build Hypermedia-Driven Web APIs

In this chapter we will illustrate how Linked Data can be used to create loosely coupled, hypermedia-driven Web APIs. Apart from introducing JSON-LD and showing how it can be used as a generic data format for Web APIs, we will demonstrate how a short list of concrete design guidelines and a small vocabulary can be used to create APIs that expose enough information to be usable by a completely generic API browser. Based on a simple prototype, we will show how easily such a, at first sight, disruptive approach can be integrated in current Web frameworks and how it can be used to build interoperable and evolvable APIs in considerably less time. Last but not least, we will give an outlook of how such an approach opens the door to other Semantic Web technologies.

A Web of Things to reduce energy wastage

Western Australias economy is largely driven by the extraction and processing industry. Caused by inhospitable climate and living conditions in the remote regions, where the vast majority of the natural resources are found, housing needs for personnel are both difficult and costly to meet. The provision of energy accounts for a big part of this since it often requires the transportation of large quantities of fuel over long distances. This would suggest a responsible and effective use of energy, but often the opposite is the case. Excessive wastage is more the rule than the exception. This results not only in high costs but also considerable greenhouse gas emissions. To address these issues, we present a distributed system which drastically reduces the amount of energy wastage without affecting the quality of living of the residents. By building the system to form a Web of Things we try to simplify its management, assure its scalability, and hope to foster its use in unanticipated ways.

SAPS: Semantic AtomPub-Based Services

The utopian promise of a uniform service landscape in the form of SOAP, WSDL, and UDDI made by service-oriented architectures (SOA) built on Web services has proven elusive. Instead more and more prominent Web service providers opted to expose their services based on the REST architectural style. Nevertheless there are still problems on formal describing, finding, and orchestrating Restful services. While there are already a number of different approaches, none so far has managed to break out of its academic confines. Thus, we propose a novel approach to build Semantic Restful Services based on proven technologies. The combination of those proven technologies leads to scalable and loosely coupled systems and has the additional advantage, that developers are already familiar with its functioning.

Towards a RESTful Service Ecosystem Perspec tives and Challenges

Average information workers spend most of their time for searching, analyzing, reformatting and consolidating information. The recent advent of service-oriented architectures (SOA) built on Web services is a first attempt to streamline respectively automate those tasks in order to increase productivity. SOAP-based services work well within a company and are thus mainly used to for the integration of legacy systems which have not been built to be Web-friendly or to make new systems more flexible for changing requirements in business ecosystems. Nevertheless, the utopian promise of uniform service interface standards, metadata and universal service registries, in the form of the SOAP, WSDL and UDDI standards have proven elusive. Instead, for Internet-scale applications, lightweight REST-based architectures which gained a lot of momentum recently provide a number of important advantages such as better scalability, reliability and visibility and are thus the preferred choice for Internet-scale applications. Despite the foreseeable potential, the increasing interest on and growing acceptance of lightweight services, there are still problems on formal describing, finding and orchestrating services as well as a lack of a holistic framework covering the entire service lifecycle. This paper focuses on an extensive survey comparing the traditional SOAP-based architecture to the emergent lightweight REST-based architectural style as a first step towards a framework proposal.