Ups - correct left that out. So we agree - we are talking about structure not interpretation of the structure to event or context Guy Sharon Manager Event-based Middleware & Solutions Group Event-based Middleware & Solutions phone : +972 4 8296587 mobile : +972 54 6976417 address : IBM R&D Labs in Israel, Haifa University Campus, Mount Carmel, Haifa, 31905, Israel email : guysh at il.ibm.com From: Moltchanov Boris <boris.moltchanov at telecomitalia.it> To: Guy Sharon/Haifa/IBM at IBMIL, "fiware-data at lists.fi-ware.eu" <fiware-data at lists.fi-ware.eu> Date: 15/06/2011 14:20 Subject: RE: [Fiware-data] Tentative definition of basic concepts: data, context and events ?make is that not every data with time-stamp is necessarily an event? ? exactly, but the structure if of that of an event. The question whether it is event or not will depend not on the structure but on the context of that structure (data_types and names). And no, it is still not a context ? we have to add to it EntityID (actor, subject, owner, object, whatever we call it) and we will get a context. Best Regards, Boris From: fiware-data-bounces at lists.fi-ware.eu [ mailto:fiware-data-bounces at lists.fi-ware.eu] On Behalf Of Guy Sharon Sent: Wednesday, June 15, 2011 1:17 PM To: fiware-data at lists.fi-ware.eu Subject: Re: [Fiware-data] Tentative definition of basic concepts: data, context and events I think we are aligned - I agree with you - my point that I was trying to make is that not every data with time-stamp is necessarily an event e.g - you get the same piece of data multiple times during different time-stamps - this could be a repeated broadcast of a location of some device which has not changed over this time - there is no event here. But still you have context. Guy Sharon Manager Event-based Middleware & Solutions Group Event-based Middleware & Solutions phone : +972 4 8296587 mobile : +972 54 6976417 address : IBM R&D Labs in Israel, Haifa University Campus, Mount Carmel, Haifa, 31905, Israel email : guysh at il.ibm.com From: Moltchanov Boris <boris.moltchanov at telecomitalia.it> To: Guy Sharon/Haifa/IBM at IBMIL, "fiware-data at lists.fi-ware.eu" <fiware-data at lists.fi-ware.eu> Date: 15/06/2011 13:28 Subject: RE: [Fiware-data] Tentative definition of basic concepts: data, context and events Hi, It depends what type of the data and data itself you put in the context. For example: The data = 5 (value) The event is The data + The meta-data -> event_type = ?rain conditions? (so there 5 is the rain (or raining) with the rate 5 (mm/hours); The context is The event+EntityID or The data+context_type+EntityID and Entity ID=?Turin (city or location) (so there is rain of 5 force in the city Turin). I?m not discussing here about the types and values, I?m speaking about the data structure. Generally speaking, everything is a data (values) + metadata (types), however we may go deeper and define that adding the time-stamp and saying that the meta-data is an event-type we obtain an event, adding to that the EntityID we obtain a context. This vision is also in line with the OMA data structure definition, which goes even deeper, so it is not only saying that the data could have the meta-data but saying that also the data meta-data (context) could also have a nestled meta-data as context-type and so on. Please think about this, about the structure and have a look at the OMA specification. I will try to answer to Juanjo mails. Best Regards, Boris From: fiware-data-bounces at lists.fi-ware.eu [ mailto:fiware-data-bounces at lists.fi-ware.eu] On Behalf Of Guy Sharon Sent: Wednesday, June 15, 2011 12:13 PM To: fiware-data at lists.fi-ware.eu Subject: Re: [Fiware-data] Tentative definition of basic concepts: data, context and events Hi, OK but timestamp and scope name still dont make it an event - although the concepts have similar structural needs (context has a bit more) - it doesnt make sense to 'inherit' the structure. Although context can be interpreted from data or from events Guy Sharon Manager Event-based Middleware & Solutions Group Event-based Middleware & Solutions phone : +972 4 8296587 mobile : +972 54 6976417 address : IBM R&D Labs in Israel, Haifa University Campus, Mount Carmel, Haifa, 31905, Israel email : guysh at il.ibm.com From: Moltchanov Boris <boris.moltchanov at telecomitalia.it> To: Guy Sharon/Haifa/IBM at IBMIL Cc: "fiware-data at lists.fi-ware.eu" <fiware-data at lists.fi-ware.eu> Date: 15/06/2011 12:59 Subject: RE: Tentative definition of basic concepts: data, context and events Hi Guy, No, entity only is not sufficient, the context must have the time-stamp (in order to check its real-timeness) and could have a type as well (context scope name). Best Regards, Boris From: Guy Sharon [mailto:GUYSH at il.ibm.com] Sent: Tuesday, June 14, 2011 6:38 PM To: Moltchanov Boris Cc: fiware-data at lists.fi-ware.eu Subject: Tentative definition of basic concepts: data, context and events Boris - wouldn't it be also true to be able to obtain context by associating data with entity? i.e. No need to go through an event to get to context? So something like this Guy Sharon Manager Event-based Middleware & Solutions Group Event-based Middleware & Solutions phone : +972 4 8296587 mobile : +972 54 6976417 address : IBM R&D Labs in Israel, Haifa University Campus, Mount Carmel, Haifa, 31905, Israel email : guysh at il.ibm.com From: Moltchanov Boris <boris.moltchanov at telecomitalia.it> To: Juanjo Hierro <jhierro at tid.es>, "fiware-data at lists.fi-ware.eu" <fiware-data at lists.fi-ware.eu> Date: 14/06/2011 18:51 Subject: Re: [Fiware-data] Tentative definition of basic concepts: data, context and events Sent by: fiware-data-bounces at lists.fi-ware.eu Dear Juajo, I would put the event definition before the Context. As I?ve said during the last conf-call, the data (including everything related to numbers and values) is a most generic case where only number (value) is the must. Everything else (meta-data, types, etc.) is optional. Then we would have an event as data + time when happened (the object referred by the data is implicit therefore could be omitted). Then adding the subject or object (referenced entity) we obtain the context, which inherit legacy properties of both the data (value) and event (when happened) as must and adding another must ? explicit object or subject (entity) making it the context. I hope I?ve succeeded to explain my point of view. Thank you. Best Regards, Boris From: fiware-data-bounces at lists.fi-ware.eu [ mailto:fiware-data-bounces at lists.fi-ware.eu] On Behalf Of Juanjo Hierro Sent: Tuesday, June 14, 2011 12:58 PM To: fiware-data at lists.fi-ware.eu Subject: [Fiware-data] Tentative definition of basic concepts: data, context and events Dear all, As you know, one of the action points from our last confcall had to do with providing a tentative definition of basic concepts in our chapter like data, context and event. Please find the document I have produced on the matter at: https://forge.fi-ware.eu/docman/view.php/9/141/Notes+and+Thoughts+on+definition+of+data-context-event.doc Just in case you believe it would be more easy to run a discussion via email following this email, I have attached the text of this document below. Hope you find it useful. Your feedback is welcome. Best regards, -- Juanjo 1. Motivation This document intends to provide a precise description of some basic concepts like data, context and events in FI-WARE. These concepts are fundamental in the description of the Data/Context Management platform in FI-WARE and the way applications are developed based on that platform. Contents of this document will be considered as baseline for a post to publish in our Data/Context Management blog in www.fi-ware.eu ( http://data.fi-ware.eu) 2. Definition of Data Data refers to information that is produced, generated, collected or observed that may be of relevance for processing, further analysis or information and knowledge generation. Essentially refers to information relevant to applications. Data in FI-WARE has associated a data type and a value. FI-WARE will support a set of built-in basic data types like in most programming languages. Values linked to these basic data types supported in FI-WARE are referred as basic data values. So we have the notion of the integer basic data type and basic values like ?2?, ?7? or ?365? that belong to the integer basic data type. A data element refers to data whose value is defined as a sequence of one or more <name, type, value> triplets referred as data element attributes, where the type and value of each attribute is either linked to a basic data type and a basic value or is linked to the data type and value of another data element. Note that each data element has an associated data type as any data in the system. This data type determines what concrete sequence of attributes characterizes that data element. There may be meta-data (also referred as semantic data) linked to attributes in a data element. However, existence of meta-data linked to a data element attribute is optional. Any data element has an entity in any FI-WARE Instance and, as such, it has an associated EntityId which universally and unequivocally indentifies the data element among the whole set of existing data elements. The basic concepts introduced so far are represented in Figure 1. Figure 1. Basic Model for Data A cornerstone concept in FI-WARE is that data elements are not tied to a specific format. They can be transferred as an XML document or in some sort of efficient binary representation and then be stored in a Relational Database or as entries in a noSQL data base like MongoDB. 3. Definition of Context Context in FI-WARE is represented through context elements. A context element is just a particular case of data element. However, there may be some attributes as well as meta-data associated to attributes that we may define as mandatory for any type of context element in FI-WARE. 4. Definition of Event An event is an occurrence within a particular system or domain; it is something that has happened, or is contemplated as having happened in that domain. The word event object is used to mean a programming entity that represents such an occurrence (event) in a computing system [EPIA]. Events are represented as event objects within computing systems to distinguish them from other types of objects and to perform operations on them, also known as event processing. It is common to refer to event objects simply as events. In FI-WARE, event objects are defined as a data element to which a number of standard event object properties (similar to a header) are associated. The concrete set of standard event object properties in FI-WARE is still to be defined but we may anticipate that one of these properties would be the time at which the event object was created. The data element and the standard properties linked to an event are used to describe, as mentioned above, something that has happened or is contemplated as having happened in a given domain. A context event The relationship (or difference) of the terms data and event is continuously debated. One summary of the philosophical and technical aspects of such debates is included in the background section of [Grove 06] with several references to the different opinions and definitions. For the purpose of FI-WARE and in specifically of the Context and Data Management Generic Enablers, we need to distinguish between the semantic level and the technical level of such a relationship that FI-WARE wishes to adopt, communicate, through its interfaces, and implement. Semantically speaking, the term data subsumes the term event meaning that some data can be semantically interpreted as events. From a technical perspective data is the way information is communicated in FI-WARE and it needs to be explicitly or implicitly identified as an event object and vice versa for processing the data as event. Este mensaje se dirige exclusivamente a su destinatario. Puede consultar nuestra política de envío y recepción de correo electrónico en el enlace situado más abajo. This message is intended exclusively for its addressee. We only send and receive email on the basis of the terms set out at. http://www.tid.es/ES/PAGINAS/disclaimer.aspx Questo messaggio e i suoi allegati sono indirizzati esclusivamente alle persone indicate. La diffusione, copia o qualsiasi altra azione derivante dalla conoscenza di queste informazioni sono rigorosamente vietate. 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