Icebergs
of information loiter throughout process manufacturing IT waiting to sink any
information integration project. The impact of semantic technologies is being
felt in medicine, life sciences, intelligence, and elsewhere but can it solve
this problem in process manufacturing? The ability to federate information from
multiple data-sources into a schema-less structure, and then deliver that
federated information in any format and in accordance with any standard schema
uniquely positions semantic technology. Is this a sweet spot for semantic
technologies?
Process Manufacturing Application Focus over the Years
Over the years we have been solving problems within process
manufacturing IT only to uncover more problems. Once the problem was that of
measurement data in silos which was solved by the introduction of real-time data
historians. However that created the problems of data visibility, solved by the
introduction of graphical user interfaces. This introduced data overload which
was partially solved by the introduction of analytical tools to digest the
information and produce diagnostics. Unfortunately these tools were difficult
to deploy across all assets within an organization, so we have been trying to
solve that problem with information models. The current problem is how to
convert the diagnostics into actionable knowledge with the use of work-flow
engines and ensuring the sustainability of applications as solutions increases
in complexity.
Process Manufacturing Application Problems and
Solutions over the Years
|
||||||
1985-
1995
|
1990-
2000
|
1995-
2005
|
2000-
2010
|
2005-
2015
|
2010-
|
|
Problem
|
Measurement
data in silos
|
Data
access and visualization
|
Analysis
and business intelligence
|
Contextualized
information
|
Consistent
actioning
|
Sustainability
|
Industry
Response
|
Real-time databases collecting measurements
(proprietary)
|
Graphical user interfaces, trending and reporting tools
(proprietary)
|
Analytical tools to digest data into information and
diagnostics
|
Plant data models (ProdML, ISA-95, ISO15926, IEC
61970/61968, Proprietary)
|
ISO-9001
|
Outsourcing
Standards
|
Consequence
|
Data but no user access
|
Data overload
|
Deployability of analysis to all assets
|
Interpretation limited to experts
|
Complexity, much more than RTDB, limiting sustainability
|
Improved ongoing application benefits
|
However it is not only the increased technological complexity that is causing
problems. Business decisions now cross many more business boundaries. When
measurement data was trapped in silos we were content with unit-wide or
plant-wide data historians. Now a well performance problem might involve a
maintenance engineer located in Houston accessing a Mimosa[1]-based
maintenance management system, an operations engineer located in Aberdeen
accessing an OPC-UA[2]-based
data historian, a production engineer located in London accessing a custom
system driven by WITSML[3]-based
feeds, and a facilities engineer using an ISO-15926[4]
facilities management model. Not only are the participants in different
locations and business units, but they also rely on different systems using
different models to support their decision making. However they all should be
talking about the same well, measured by the same instruments, producing the
same flows, and processed by the same equipment.
The problem is that these operational support systems are not simply data
silos whose homogeneous data we need to merge into one to answer our questions.
In fact these operational support systems are icebergs of information. Above
the surface they publish a public perspective focused on the core operational function
of the application. However this data needs context, so below the surface is much
of the same information that is contained in other systems. This information
provides the context to the operational data so that the operational system can
perform its required functions. For example the historian needs to know
something about the instruments that are the source of its measurements;
maintenance management systems need to know not only about the equipment to be
maintained but the location of that equipment, physically and organizationally.
Figure 1: Icebergs of Information
Icebergs of information are not limited to the operational data stores
deployed in organizations. An essential practice in these days of
interoperability requirements is the adoption of model standards. However even
these exhibit the same problems as shown by the diagram below. This diagram
maps the available standards to its focus within the hydrocarbon supply chain.
Figure 2: Multiple Overlapping Model Standards
Increasing regulatory and competitive demands on the business are
forcing decision making to be more timely, and to be more integrated across the
traditional business boundaries. However these icebergs are getting in the way
of effective decision making.
One way to make any or all of this information available to consumers is
to create the bigger iceberg. ‘Simply’ create the relational database schema
that covers every past, current, and future business need, and build adapters
to populate this database from the operational data stores. Unfortunately this
mega-store can only get more complex as it has to keep up with an expanding
scope of information required to support the decision making processes.
Figure 3: Integration using the Bigger Iceberg
Alternatively we can keep building data-marts every time someone has a
different business query. However these
do not provide the timeliness required to support operational decision making.
The Need for a Babel-Fish
We cannot meet the needs of the business, and solve their decision
making needs by having one mega-store because it will never keep up with the
changing business requirements. Instead we need a babel-fish (with thanks to
the Hitchhikers Guide to the Galaxy).
This babel-fish can consume all of the different operational data in
different standards, and translate them into any standard that the
end-consumer wants. Thus the babel-fish will need to know that OPC UA's concept
'hasInstrument' has the same meaning as Mimosa's concept of
'Instrumented'. Similarly 10FIC107 from an OPCUA provider is the same as
10-FIC-1-7 from Mimosa.
1. Information providers
(operational data stores) within the business will want to provide information
according to their capabilities, but preferably using the standards appropriate
for their application. For example measurements should be OPC
UA, maintenance should use Mimosa
2. Information consumers will
want to consume information in the form of one or more standards appropriate
for their application.
Figure 4: Integration babel-fish
The Semantic/RDF model comes to the rescue
First of all a definition: a semantic model means organizing all data
and knowledge as RDF triples {subject, property, object}. Thus {:Peter, :hasAge,
21^^:years}, and {:Pump101, :manufacturedBy, :Rotek} are examples of RDF
triples. RDF triples can be persisted in a variety of ways: SQL table, custom
organizations, NoSQL, XML files and many more. If we were designing relational
database to hold these RDF triples we would only have one ‘table’ so it may
appear that we have no schema, in the relational database design-sense when we
have key relationships to enforce integrity, and unique indices to enforce
uniqueness. However we can add other statements about the data such as {:Pump101,
:type, :ReciprocatingPump} and {:ReciprocatingPump, :subClassOf, :Pump}[5].
Used in combination with a reasoner we can infer consequences from these
asserted facts, such as :Pump101 is a type of :Pump, and Peter is not a :Pump,
despite rumors to the contrary. These triples can be visualized as the links in
a graph with the subject and object being the nodes of the graph, and the
property the name of the edge linking these nodes:
Figure 5: RDF Triples as a graph
Over the years, new modeling metaphors have been introduced to solve
perceived or actual problems with their predecessors. For example the
Relational Model had perceived difficulties associated with reporting, model
complexity, flexibility, and data distribution. A semantic model helps solve
these problems.
Figure 6: Evolution of Model Metaphors
·
In response to the perceived reporting issues, OLAP techniques were introduced
along with the data warehouse. This greatly eased the problem of
user-reporting, and data mining. However it did introduce the problem of data
duplication.
o A
semantic model can query against a federated model in which information is
distributed throughout the original data sources.
·
In response to the perceived complexity issues, various forms of
object-orientated modeling were introduced. There is no doubt that it is easier
to think of one’s problem in terms of an object model rather than a complex
relational or ER model, especially when there are a large number of entities
and relations.
o The
semantic model is built around the very simple concept of statements of facts
such as {:Peter, :hasAge, 21^^:years}, and {:Pump101, :manufacturedBy, :Rotek}
combined with statements that describe the model such as {:Pump101, :type, :ReciprocatingPump}
and {:ReciprocatingPump, :subClassOf, :Pump}.
·
The model flexibility problem occurs when, after the model has been designed,
the business needs the model to change. In response to this flexibility issue,
the choice is to make the original model anticipate all potential uses but then
risk complexity, or use an object-relational approach in which it is possible
to add new attributes without changing the underlying storage schema.
o In
semantic models these relationships are expressed in triples, using RDFS, SKOS,
OWL, etc. Thus RDF is also used as the physical model (in RDF stores, at
least).
·
There have been various responses to data distribution.
o In the
relational world there is not much choice other than to replicate the data from
heterogeneous data stores using Extract-Transform-Load (ETL) techniques. In the
case of homogenous but distributed databases distributed queries are possible,
although it does require intimate knowledge of all the schemas in all of the
distributed databases.
o In the
object-orientated world we are in a worse situation: it is very difficult to
manage a distributed object in which different objects are distributed or
attributes are distributed.
The good news is that a semantic approach is the ideal (or even the only)
approach that can solve the information integration problem as follows:
1. Convert to RDF normal form: Convert all source data into RDF. The data
can be left at source and fetched on demand (federated) or moved into temporary
RDF storage
- There are
already standard ways of doing this for any spreadsheet, relational
database, XML schema, and more. For example, TopBraid Suite (http://www.topquadrant.com/products/TB_Suite.html) provides
converters and adaptors for all common data sources. It
is relatively easy to create more mappings such as OPCUA. The
dynamic adapters act as SPARQLEndpoints[6].
2. Federated data model: Create 'rules' that map one vocabulary to another.
- The language of
these rules would be RDFS, SKOS and OWL. For example you
can declare {OPCUA:hasInstrument, owl:sameAs,
Mimosa:Instrumented}. Note that these are simply additional statements expressed
in RDF which are then used by a reasoner to infer the consequences such
as :FI101 is actually the same as :10FIC101.
- More sophisticated
rules can also be created using directly RDF and SPARQL. For some
examples, see SPIN or SPARQL Rules at http://spinrdf.org/ and http://www.w3.org/Submission/2011/SUBM-spin-overview-20110222/
3. Chameleon data services: Create consumer queries that
extract the information from the combined model into the standard required
using SPARQL queries.
- For example even
though all instrument data is in OPCUA, a consumer could use a Mimosa interface
to fetch this data. The results can then be published as
web-services for consumption by external applications using SPARQLMotion
(http://www.topquadrant.com/products/SPARQLMotion.html)
Figure 7: Federation End-to-End
Let’s
look into these steps in detail:
Convert to RDF normal form
Despite the fact that data will be stored in different formats
(relational, XML, object, Excel, etc) according to different schemas they can
always be converted into RDF triples. Always is a strong word, but it really
does work. There are already ways of doing this for any spreadsheet, relational
database, XML schema, and more and it is relatively easy to create
more mappings such as OPC-UA. The data can be left at source and fetched on
demand (federated) or moved into temporary RDF storage. For example, TopBraid
Suite (http://www.topquadrant.com/products/TB_Suite.html) provides converters and adaptors for all common data sources.
Figure 8: Conversion to RDF Normal Form
Federated Data Model
A federated data model allows different graphs (aka databases) to be
aggregated by linking the shared objects. This applies to real-time
measurements (OPC-UA), maintenance (MIMOSA), production data (ProdML), or any
external database. We can visualize this as combining the graphs of the
individual operational data stores into a single graph.
Of
course there will be vocabulary differences between the different data-sources.
For example, in the OPC-UA data-source you might have a property OPCUA:hasInstrument,
and in a MIMOSA data-source the equivalent is called Mimosa:Instrumented. So
the federated data model incorporates 'rules' that map one vocabulary to
another. The language of these rules would be RDFS, SKOS, and OWL.
For example, in OWL, you can declare {OPCUA:hasInstrument owl:sameAs
Mimosa:Instrumented}. Note that these are simply additional statements
expressed as RDF triples which are then used by a reasoner to infer
consequences such as :FI101 is actually the same as :10FIC101.
There
will also be identity differences between the different data-sources. These can
also be handled by additional statements, such as {:TANK#102, owl:sameAs,
:TK102 }. This allows a reasoner to infer that the statement {:TK102,
:has_price, 83^^:$} also applies to :TANK#102, implying {:TANK#102, :has_price,
83^^:$}.
Figure 9: Information Federated from MulTiple
Datasources
Chameleon Data Services
To extract information from the federated information, the best choice
is SPARQL, the semantic equivalent of SQL only simpler. Whilst SQL allows one
to query the contents of multiple tables within a database, SPARQL matches
patterns within the graph. With SQL we need to know in which table each field
belongs. With SPARQL we define the graph pattern that we want to match, and the
query engine will search throughout the federated graphs to find the matches.
In the example illustrated below we do not need to know that the price
attribute comes from one data source, whilst the volume comes from another. In
fact SPARQL allows even further flexibility. The price attribute for Tank#101
could come from a different data source than the price attribute for Tank#102.
This is part of the magic of the semantic technology.
SPARQL can be used to directly query the federated graph for reporting
purposes, however most consumers of the information will expect to interface to
a web-service, with SOAP or REST being the most popular. These services do not
have to be programmed. Instead they can be declared using SPARQLMotion
(http:www.sparqlmotion.org) to produce easily consumed and adaptable
web-services. The designer for SPARQLMotion is shown below:
Figure 11: Example SPARQLMotion
Semantic/RDF advantages for the Process Manufacturing
Despite solving a complex
data integration problem, Semantic/RDF is inherently simpler. Can there be
anything simpler than storing all knowledge as RDF triples? Despite this simplicity, we do not lose any
expressivity.
There is no predefined schema
to limit flexibility. However the schema rules, encoded as tables and keys in
the relational model, can still be expressed using RDFS, OWL, and SKOS
statements.
Deconstructing all
information into statements (triples) allows data from distributed sources to
be easily merged into a single graph.
Any information model can be
reconstructed from the merged graph using SPARQL and presented as web-services
(SOAP or REST).
[1] MIMOSA is a not-for-profit
trade association dedicated to developing and encouraging the adoption of open
information standards for Operations and Maintenance in manufacturing, fleet,
and facility environments. MIMOSA's open standards enable collaborative asset
lifecycle management in both commercial and military applications.
[2] The Unified Architecture
(UA) is THE next generation OPC standard that provides a cohesive,
secure and reliable cross platform framework for access to real time and
historical data and events.
[3] WITSML™ (Wellsite Information Transfer
Standard Markup Language) is an industry initiative to provide open,
non-proprietary, standard interfaces for technology and software that monitor
and manage wells, completions and workovers.
[4] ISO 15926 provides integration of life-cycle data for process plants including oil and gas production facilities
[4] ISO 15926 provides integration of life-cycle data for process plants including oil and gas production facilities
[5] I should really be using
URIs instead of text labels for subject, property, and objects, but the intent
of the semantic model is conveyed more simply if we avoid identifiers like ‘http://www.example.org/equipment#Pump101’
and use :Pump#101
[6] SPARQL is a query language
for RDF. A SPARQL
endpoint is a protocol service that makes it possible to query a data
source using SPARQL. The source itself does not need to be in RDF. It can, for
example, be a traditional relational database. Later in this article we will
describe SPARQL in more detail and show some query examples.
Posts
0 comments:
Post a Comment