Version 20 (modified by gordonrachar, 13 years ago)

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How Does ISO 15926 Work?


Contents

  1. Abstract
  2. How ISO 15926 Works
  3. ISO 15926 Parts
    1. Part 1 - Overview and Fundamental Principles
    2. Part 2 - Data Model
    3. Part 3 - Reference Data for Geometry and Topology
    4. Part 4 - Reference Data Classes
    5. Part 5 - Registration Procedure
    6. Part 6 - Reference Data Additions
    7. Part 7 - Templates
    8. Part 8 - RDF/OWL Implementation Specification
    9. Part 9 - Façade Specification
    10. Part 10 - Abstract Test Methods
    11. Part 11 - Simplified Industrial Usage including Gellish Implementation …
  4. Putting all the Parts Together
  5. Next
    1. Acknowledgements

Abstract

ISO 15926 works by first providing a publicly-available set of reference data. To use ISO 15926, organizations first map their internal data stores and applications to the reference data. The reference data is also used at the beginning and the end of information exchanges to validate it.


How ISO 15926 Works

The full name of ISO 15926 implies a very ambitious goal, encompassing information about every plant object from conception, engineering, construction, and operations:

Industrial automation systems and integration-Integration of life-cycle data for process plants including oil and gas production facilities

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Figure 1 - How ISO 15926 Works

This diagram shows two organizations, Acme, and Emca who wish to exchange information using ISO 15926. Both organizations use the Reference Data Library (RDL). The RDL is implemented in what we call the "Reference Data System/Work In Progress", or simply the "RDS/WIP".

To use the RDL, the two organizations first map their internal applications to ISO 15926 using the classes and definitions in the RDS/WIP. Data exchanges are made by referring to the Reference Data Library at the beginning and the end of the exchange.

The data exchange has three important parts:

  1. Acme first validates its data against the RDS/WIP to make sure it is compliant
  2. The data exchange takes place
  3. Emca validates the data it receives against the RDS/WIP to verify compliance

After receiving the data, Emca updates its internal systems.

It is important to note two things:

First, neither organization has to change its internal systems at all. ISO 15926 is used on the edges of data exchange outside the organization. (This is the origin of the slogan "ISO 15926 Outside".)

Second, neither organization exposes its internal information to the business partner. Each organization exposes only the information it wants to share. Proprietary information is not mapped to ISO 15926 and is not available for exchange.

ISO 15926 Parts

When ISO 15926 is mature, the example above is all the vast majority of people will need to know in order to use ISO 15926. ISO 15926 is implemented in the software applications people use. If it is required that users know they are using ISO 15926, the name will probably be somewhere in a command. Other information exchanges may not require the user to even know an information exchange is taking place and so may simply happen automatically.

To make all this work, ISO 15926 is divided into a number of parts. Some are completed and have been turned over to ISO, and some are still under development. The parts we are interested in can be compared to different parts of human language and grammar.

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Figure 2 - The Parts of ISO 15926

Part 1 - Overview and Fundamental Principles

You will not need this in your initial investigations of ISO 15926, but it will be worth purchasing if you purchase part 2 during implementation of ISO 15926 at your organization.

This was published by ISO in 2004 and is available from their website:

Abstract:

ISO 15926-1:2003 specifies a representation of information associated with engineering, construction and operation of process plants. This representation supports the information requirements of the process industries in all phases of a plant's life-cycle and the sharing and integration of information amongst all parties involved in the plant's life cycle.

Part 2 - Data Model

Part 2 is the foundation of ISO 15926. It establishes the grammar that is used throughout. In a natural language we have concepts like nouns, verbs, and adjectives. In every language there are rules for how these go together to convey meaning. These rules are different for every language, and are the basis of entire careers for linguists today. It is possible to convey meaning without following the rules of grammar but it is not efficient.

For instance, all of us have probably had, or have overheard, a conversation with someone just learning our native language. For instance, in Canada we have a great many French speakers learning English. It is easy to tell if a Francophone has learned the definitions of English words but not yet picked up the grammar--to native Anglophones the words are all backwards, sometimes humorously so. (Your humble author, being a native English speaker, has heard more than a few snickers while on the phone with French-speaking friends, so it works both ways!)

When we listen to people just learning our native language we can usually interpret what they mean because we use the context of the conversation and our own experience. Sometimes we jump to the wrong conclusion, but in conversation this usually becomes apparent as we reply to each other back and forth. But when machines connect to each other to communicate they do not have context, shared experience, or interactive conversation to rely on.

The data model in Part 2 is the rules and constraints on how we use ISO 15926. It is in the form of entities and relationships. The relationships provide the constraints.

ISO 15926-2 has been in development for many years under different names. It based on what is called the "EPISTLE Core Model". But the EPISTLE Core Model, as it was originally published, would not guarantee interoperability of two conforming data models that had been developed independently. Certain work and methodology was added, morphing into the present form of Part 2.

Using Part 2 is very specialized and requires a fair amount of work to understand. Fortunately, most organizations will only have to deal with Part 7, Templates, which are sort of like preconfigured definitions that point to objects in Part 2.

This was published by ISO in 2003 and is available from their website:

Part 3 - Reference Data for Geometry and Topology

This part is used for representing plant objects in 3D CAD systems in a manner that allows data exchange between systems. It addresses things like how to represent a torus or a slab.

If you are not involved in writing software that displays objects in full 3D, you will not even need to know this exists.

Part 3 is under development and has not been published. When it is available, this is where you will get it:

Part 4 - Reference Data Classes

Part 4 is the classifications of information. It includes definitions and functions much like a dictionary or thesaurus for a natural language. It is a taxonomy of entity types, which is the relationships between entity types into things like parent-child relationships.

By early 2008 there were over 15,000 entity types. The number is expected to grow to over 100,000. A key part of Part 4 is that nobody will ever own the information so it can be used by all without having to license it and pay a royalty. Likewise, when participants extend a definition in Part 4, they are encouraged to put the definition into the public domain by publishing it.

Mapping a database to Part 4 is a good place to start implementing ISO 15926 at an organization.

Part 4 was published by ISO in 2007 and is available from their website:

Abstract:

ISO/TS 15926-4:2007 defines the initial set of reference data for use with the ISO 15926 and ISO 10303-221 industrial data standards.

Part 5 - Registration Procedure

Procedures for registration and maintenance of reference data.

Rumor has it that Part 5 has been replaced by an ISO/IEC (International Electrotechnical Commission) procedure.

Part 6 - Reference Data Additions

The scope and information required when defining additions to ISO 15926.

This is currently under development, and is expected to be submitted to ISO in the fourth quarter of 2009.

Part 7 - Templates

The full name for this part is: "Implementation Methods for the Integration of Distributed Systems Templates Methodology." (OK, why use one word when you can use ten and make just as much sense!)

For full ISO 15926 compliance, information has to follow Part 2. But Part 2 is highly specialized. If everyone were forced to understand Part 2 in order to implement ISO 15926, the standard would be in gestation a long time.

The key to rapid implementation of ISO 15926 is Part 7, Templates. Part 7 leaves the necessary linkage with Part 2 "Under the Hood" so users only have to deal with the part that makes sense.

Metaphor: ISO 15926 Templates are Like the Chemical Elements

When engineers think of templates they tend to think of a blank form for a complete document like an equipment data sheet, or a blank drawing. ISO 15926 templates are sort of like that, but for much smaller pieces of information; for instance, for a single pressure value, or a temperature range. If you want to transfer a full data sheet of information, you will use many templates, and in fact will use many of the templates many times.

Looking at the Periodic Table on Wikipedia, you can see that there are 118 elements listed. Yet with just 118 elements the entire universe is made. Every once in awhile we find a new one (or a new couple dozen by the looks of the Extended Table), but we don't expect to find a great many more.

Currently just under 200 templates have been created. This is enough to get started. If/when more are needed, we have the infrastructure to create new ones.

Part 7 was originally developed a couple years ago. It has since been split into what is now Part 7, 8, & 9. Part 7 was submitted to ISO in mid 2009, and is expected to receive speedy approval in early 2010.

Part 8 - RDF/OWL Implementation Specification

Part 8 is the standardization of the implementation of Part 7 using RDF and OWL. RDF and OWL are standards developed to support the Semantic Web. (RDF, or Resource Description Framework, is a way of making statements about things using what is known as a Triple Store of Subject-Predicate-Object expressions. OWL, or Web Ontology Language, is a method of creating an ontology expressed in RDF syntax.)

Strictly speaking, ISO 15926 is not limited in its implementation to RDF and OWL; it can be implemented with spreadsheets, text files, or word processor documents, just not as easily. The ISO 15926 developers chose RDF and OWL because the things they enable for the Semantic Web also serve ISO 15926 as well.

Part 9 - Façade Specification

A façade is an outward facing view of something. (If you have ever seen "Westerns", movies of the American West, you may have seen how merchants would erect large store fronts for small buildings, making them seem larger than they really were.)

Part 9 is a store front for machines. It is a standardization of the Web service using SPARQL as the method of access. This enables applications to talk to each other over the Internet. The metaphor has deeper similarities too. Using a façade, an organization can control how much information is made public but only copying certain amounts to the façade. Querying software will only have access to the façade, not an organization's entire repository.

When ISO 15926 is mature, all organizations involved in plant design and operation will have a Façade.

Part 10 - Abstract Test Methods

Part 10 was created recently. Not much information is available, other what one can surmise from the name. Obviously, then, it is still under development and is not yet published by ISO. When it is, here is where you will get it:

Part 11 - Simplified Industrial Usage including Gellish Implementation using Reference Data

Part 11 was proposed recently as an easier methodology to implement parts 7 & 8. It is expected some time in 2010.

Putting all the Parts Together

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Figure 3 - ISO 15926 Pyramid

Next

Acknowledgements

Thanks to Onno Paap for the pyramid diagram above.


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