Number of Web Services found by Seekda.com in the last 52 Months... but Verizon has about 1,500Services Internally ...
Web APIs are the Widely used and reused Publicly availablenew WEB services With a real business model behind them Although harder automation!
Reality Check• Survey based on 220 Web APIs from ProgrammableWeb from 21 categories• Types of Web APIs – 45.5% REST, RPC 33.8%, Hybrid 20.7%• 40% of Web APIs do not state the used HTTP method!• Input and Output information – 72% do not state the data type of the input parameters – 61% use optional parameters, 45% use default values – 90% have as output XML, 42% JSON – 84% provide example request and 75% example response
Linked ServicesExploiting the complementarity of Services and Linked Data
“Linking Open Data cloud diagram, by Richard Cyganiak and Anja Jentzsch. http://lod-cloud.net/”
256 Datasets30+ Billion TriplesCovering many diverse domains:- Media- Government- Geography- Life Sciences... “Linking Open Data cloud diagram, by Richard Cyganiak and Anja Jentzsch. http://lod-cloud.net/”
Linked Data Principles• Create a Web of Data by these 4 principles: • Use URIs as names for things • Use HTTP URIs so that people can look up those names. • When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL) • Include links to other URIs
Developing Applications The development of Linked Data Applications is more an art than an engineering discipline
Linked Services• Linked Services are services described as Linked Data (inputs, outputs, functionality...) • In other words, it is Linked Data describing reusable functionality• With supporting machinery Linked Services are Linked Data consumers and/or producers• Core building blocks for Linked Data Applications
Issues with Services on the Web• Their semantics are unclear• The data they consume and produce is modelled in heterogeneous formats• They are not Web-ready • Their results are not globally identiﬁed • Their results are not de-referenceable
A typical Web API Pain HTML Not machine processabledescription Missing semantics
From Legacy Services to Linked Services• Services can be annotated using the Web of Data as background knowledge• This description makes the services • More accessible (semantics) • More applicable as they are expressed in terms of existing vocabularies used on the Web of Data
Reﬂections• Services need to be (in principle) commercially proﬁtable for a public deployment• Trust and fault tolerance will be essential for their adoption• Current climate favours openness for creative collaborative innovation
Outlook• Service-orientation can provide the necessary engineering principles for advanced Linked Data Applications• Existing Linked Data and its principles may provide the necessary support for a Web-scale adoption of services• Service-orientation is subject to the network effect so ...