Knowledge as a service

Knowledge as a service (KaaS) is a computing service that delivers "knowledge" to users. In relation to KaaS, "knowledge" is data + context, that is, data with the addition of information that enables users' understanding of the data - definitions and semantics - its relation to the users' situation or the situation in which the data was produced or that which it aims to provide information about. 
Knowledge as a service is one of the series of "... as a Service" computing services.
Overview.
KaaS is a new type of "...as a Service" offerings that has been discussed with only nascent examples demonstrated in recent computer (2019) science conferences, in particular ISWC '19, the 18th International Semantic Web Conference. At that conference, it was described how knowledge can be made live and evolve on the web allowing users to learn directly from elaborated knowledge, now appearing in the form of knowledge graphs (KGs). KaaS appear when KGs are accessed via services This is opposed to DaaS which might "compute large volumes of data; integrate and analyzes that data; and publish it in real-time, using Web service APIs" (from Data as a Service) where the KaaS is able to exploit "context" - both the context of the user in relation to their information requests of the KaaS (where and when they make the request) and also the context of the information in relation to some objective or purpose of the users either understood by the KaaS automatically or indicated to it by the user.
KaaS is described as being more related to Data as a Service, Content as a Service and other services which supply information to users, more than other *aaS, such as Software as a Service which provide functionality however, the idea that a KaaS may analyse "context" at query time indicates that there is overlap between KaaS and *aaS such as Search as a Service and that perhaps not all KaaS responses are idempotent since their results depend on a context that might be time-dependent.
Differentiating knowledge from data.
As per the description in the overview above, KaaS is differentiated from DaaS or other information *aaSes by its delivery of "knowledge" as opposed to "data" where "knowledge" is defined by relations of data/information to context that is relevant to the user. This then indicates that the sensible description of KaaS as a service type is dependent on the differentiation of "knowledge" from "data" and/or "information".
Conceptual models that make such a differentiation such as the so-called DIKW pyramid have existed for perhaps more than 40 years (see a 1974 journal article about this) however definitions are not stable and universally accepted (see the discussion about the conceptualizations of DIKW within the DIKW Wikipedia article that question value of "wisdom"). The knowledge component of DIKW is generally agreed to be an elusive concept which is difficult to define, however Rowley 2007, in a well known student textbook differentiated knowledge from data by stating that knowledge is "defined with reference to information" and that it contains more than just facts but also "beliefs and expectations". 
In relation to knowledge graphs, knowledge may be additional content they provide over and above pure data which is the definition of the categories, properties and relations between the concepts, data and entities that substantiate one, many or all domains of discourse (see the definition of Ontology).
The ability to represent "beliefs and expectations" or other forms of not so straightforwardly explicit knowledge is an on-going area of improvement in information sciences (see Tacit knowledge) and, with relation to KaaS, the establishment of recent informatics mechanics to do so it critical to the legitimacy of KaaS as it is differentiated from just value-added DaaS.
Knowledge graphs' ability to represent "context" via the definition of the categories, properties and relations between the concepts, data and entities that substantiate one, many or all domains of discourse that they provide (see the definition of Ontology) has led to the idea that supplying access to KNs might be a required competency of a KaaS.
Delivery of knowledge.
Much service-delivered content is dependent on a session to provide much of the context that the user (client) needs to understand answers to questions. For example, using current HTTP internet protocols, a codice_1 request to retrieve information identified by a URI, such as a web page, a client (a human or a machine) may have access information supplied automatically to enable that client to bypass paywalls or other content access controls. Such context, in this case about the client's information access allowances, can alter the information provided.
In a logical extension to this internet protocols example, a server would receive from the client, either manually or automatically, a full "context" which would be information about the situation the client is in and this would allow the server to best interpret the client's request. Current internet protocols allow for formats, languages and related preferences to be expressed by clients but make no mention of what a client already knows and what they may understand. The recent "Content Negotiation by Profile" proposes additions to both the HTTP internet protocols and related services that allow clients to also request information - a response from the server - that accords with an identified information model. This then allows clients to indicate not just formats and languages that they understand (technically that they prefer) but also domains of discourse that that do, which is a step towards comprehensive client context provision.
Service mechanics.
With the differentiation of KaaS from DaaS - the data/knowledge difference - the crucial test points used to identify KaaS are not the service "mechanics", e.g, whether the service is stateful or uses an API style such as REST but instead that its content is differentiated from that of a DaaS. If this proposition is accepted, it would be possible to find a DaaS and a KaaS that use the same data source and even implement the same "mechanics" perhaps such as GraphQL, but deliver different results.
This notwithstanding, if a service to be a KaaS must deliver knowledge then the mechanics implemented must not exclude that possibility. This may prevent mechanics that rule out annotations or definitions for packets of data delivered or perhaps data delivered that is not able to be deterministically associated with the question asked since that would destroy result context.
Proposed KaaS "Modes".
This section proposes generic "modes" that KaaSes do or might use to differentiate themselves from DaaS or other services.
Current expressions of KaaS characteristics.
A survey of current (January, 2020) websites and vendors using the phrase "KaaS" indicate that no single model of KaaS is shared by all those using the phrase. Some aspects of the service suggested as typifying it and differentiating it from DaaS are:
Some of the definitional overlaps that can be seen in the quotes above are:
Systematic listing of potential KaaS "modes".
The following image describes Data as a service and processing services, such as the Web Processing Service's components. 
The following diagram indicates that a KaaS is a DaaS or WPS "+", that is, a DaaS or WPS plus some additional element that realises the "knowledge" offering of the service.
The following diagrams provide several potential "modes" of KaaS operation in which different sources of the information/calculation that separates a KaaS from a DaaS or a WPS are utilised. A real-world KaaS might indeed utilise multiple.