Information about Yawl
YAWL (Yet Another Workflow Language) is a workflow language based on the Workflow patterns. The language is supported by a software system that includes an execution engine and a graphical editor. The language and its supporting system were originally developed by researchers at Eindhoven University of Technology and the Queensland University of Technology. Subsequently, several organizations such as InterContinental Hotels Group, first:telecom and ATOS Worldline have joined this initiative and the YAWL system is now available as an Open source software under the LGPL license.
The original drivers behind YAWL were to define a workflow language that would support all (or most) of the Workflow Patterns and that would have a formal semantics. Observing that Petri nets came close to supporting most of the Workflow Patterns, the designers of YAWL decided to take Petri nets as a starting point and to extend this formalism with three main constructs, namely or-join, cancellation sets, and multi-instance activities. These three concepts are aimed at supporting five of the Workflow Patterns that were not directly supported in Petri nets, namely synchronizing merge, discriminator, N-out-of-M join, multiple instance with no a priori runtime knowledge and cancel case. In addition, YAWL adds some syntactical elements to Petri nets in order to intuitively capture other workflow patterns such as simple choice (xor-split), simple merge (xor-join), and multiple choice (or-split). During the design of the language, it turned out that some of the extensions that were added to Petri nets were difficult or even impossible to re-encode back into plain Petri nets. As a result, the original formal semantics of YAWL is defined as a Labelled transition system and not in terms of Petri nets. The fact that YAWL is based on a formal semantics has enabled the implementation of several techniques for analyzing YAWL processes. In particular, the YAWL system includes a static analysis tool called WofYAWL.
A yawl (from Dutch Jol) is a two-masted sailing craft similar to a sloop or cutter but with an additional mizzen mast well aft of the main mast, often right on the transom. A small mizzen sail is hoisted on the mizzen mast.
The yawl is often confused with the ketch, which also has two masts with the main mast foremost. The common view is that a ketch has the mizzen mast forward of the rudder post whereas the mizzen on a yawl is aft of the rudder post. This definition is a relatively recent definition and the historical definition is likely to be quite different.
In practice, on a ketch the principal purpose of the mizzen mast is to help propel the vessel, while on a yawl it is mainly used for the purposes of trim and balance. In consequence the mizzen sail of a yawl tends to be smaller, and the mainsail larger, when compared to a ketch of similar size. The mainsail of a yawl will be similar in size to that of a similarly sized and proportioned sloop.
The yawl was originally developed as a rig for commercial fishing boats, one good example of this being the Salcombe Yawl (a traditional small fishing boat built in Devon). In its heyday, the rig was particularly popular with single-handed sailors, such as circumnavigators Joshua Slocum and Francis Chichester. This was largely due to the remarkable ability of a yawl to be trimmed to follow a compass course accurately despite minor wind shifts. Modern self-steering and navigation aids have made this less important, and the yawl has generally fallen out of favor.
In the 1950s and 60s yawls were developed for ocean racing to take advantage the handicapping rule that did not penalize them for flying a mizzen staysail, which on long ocean races, often down wind, were a great advantage, the best example of this being Olin Stephens' Finisterre.
The seminal American Yacht Designer of the first half of last century, Francis Herreshoff, reflected this traditional definition of a Yawl was as "a ship's boat resembling the pinnace" set up to be primarily rowed.
To add a sailing rig to a rowboat the masts must not interfere with the rowers. The Mainmast is placed well forward and the mizzen as far back as possible. The mizzen has to be small in size to keep the sail area balanced around the hull's centre of lateral resistance to ensure the boat will sail in a straight line without excessive correction.
According to Herreshoff "yawl" had nothing to do with rudder placement relative to the mizzen - a yawl rig is the sail and mast configuration that suits a yawlboat.
The mizzen is bigger to hold the bow (front)of a boat toward the wind and oncoming waves. The mainsail at the front of the boat would have been dropped and the mizzen trimmed tight on the centreline. Set up this way most boats will point directly into the wind in a reliable way. It is also possible to ease the mizzen slightly to allow the boat to move slowly forward.
In a fishing boat this attitude allows the nets to be handled without the boat becoming "broadsides" to the waves allowing them to break over the sides of the boat. Fishnets can then be handled without putting the boat at risk.
For enough sail area to propel a fishing boat the mizzen mast has to move forward toward the middle of the boat which allows its sail to be bigger without upsetting the sail balance or distribution.
A "Ketch Rig" is simply the rig that matches the function of a "Ketch" or "Catch" or fishing boat.
The CCA (Cruising Club of America) rating rule was developed following World War II to allow different styles of boats to race against each other with a handicap calculated from measurements of each boat. It was later combined with the RORC (Royal Ocean Racing Club) rule to become the IOR (International Offshore Rule) rule in the late 50s which was used to handicap international racing until the late 1980s.
The CCA and the following rules used the rudder post definitions of ketch and yawl so they had a cut and dried definition for measuring sail so boats could be handicapped with boats fulfilling their new and arbitrary definition of Yawl and Ketch receiving slightly different handicaps.
The rudderpost definition can be argued to be a relatively recent sailing handicap development rather than something that refers to traditional use.
The purpose of the boats and the group was for recreational cruises along the coast of England over several days, camping on beaches and riverbanks. Some of the boats were small enough to be taken to Europe by commercial steamer and then used for travelling the canal, lake and river systems of Europe.
"Canoe Yawls" had a pointed stern similar to a canoe. Rudders were usually placed on the back of the boat which allows the rudder to be raised to allow the boat to be landed on a beach.
Despite the mizzen sail being ahead of the rudder the boats were termed Yawls because of their size and their good rowing capability.
The original drivers behind YAWL were to define a workflow language that would support all (or most) of the Workflow Patterns and that would have a formal semantics. Observing that Petri nets came close to supporting most of the Workflow Patterns, the designers of YAWL decided to take Petri nets as a starting point and to extend this formalism with three main constructs, namely or-join, cancellation sets, and multi-instance activities. These three concepts are aimed at supporting five of the Workflow Patterns that were not directly supported in Petri nets, namely synchronizing merge, discriminator, N-out-of-M join, multiple instance with no a priori runtime knowledge and cancel case. In addition, YAWL adds some syntactical elements to Petri nets in order to intuitively capture other workflow patterns such as simple choice (xor-split), simple merge (xor-join), and multiple choice (or-split). During the design of the language, it turned out that some of the extensions that were added to Petri nets were difficult or even impossible to re-encode back into plain Petri nets. As a result, the original formal semantics of YAWL is defined as a Labelled transition system and not in terms of Petri nets. The fact that YAWL is based on a formal semantics has enabled the implementation of several techniques for analyzing YAWL processes. In particular, the YAWL system includes a static analysis tool called WofYAWL.
YAWL x BPEL
YAWL is sometimes seen as an alternative to BPEL. A major advantage of BPEL is that it is driven by a standardization committee supported by several IT industry players. As a result, BPEL is supported by a significant number of tools (both proprietary and open-source) while YAWL has a single implementation at present. Also, several researchers have captured the formal semantics of subsets of BPEL in terms of various formalisms, including Petri nets, Process algebra and Finite state machine. This has paved the way for the development of static analysis tools for BPEL that can compete with the static analysis capabilities provided by the YAWL system. On the other hand, it has been noted that standard BPEL fails to support human tasks, that is, tasks that are allocated to human actors and that require these actors to complete actions, possibly involving a physical performance. A number of BPEL engines already provide extensions to BPEL for human tasks, but these extensions are yet to be standardized. In contrast, YAWL provides a unified interface for worklist services based on Web services standards. This interface allows developers to build their own worklist service to support human tasks according to their needs. In addition, the YAWL system comes with a default worklist service that supports several types of human task allocation and handling. Another advantage of YAWL is its support for the Workflow Patterns, although the gap between YAWL and BPEL in this respect may be reduced by new constructs that are included in BPEL version 2.0.Features
- Comprehensive support for the workflow patterns.
- Extends Petri nets, a powerful theory for concurrency.
- The YAWL (control-flow) language is formally defined, both syntax and semantics.
- Sophisticated support for workflow analysis at build time.
- Supports persistence, automated form generation, workflow administration.
- Approach based on worklets and Ripple Down Rules (RDR) provides unique solution to dynamic workflow.
- Service-oriented architecture facilitating the development of sophisticated extensions.
- Support for temporal aspects.
- Support for data perspective based on XML technologies (XML Schema, XPath, XQuery).
- Support for resource perspective through a worklist service interface.
See also
External links
- Official website
- Workflow Patterns
- SF.net homepage
- BPM Center
- BPM group at Queensland University of Technology
This article is about the sailing craft. For the workflow system, see YAWL.
)
Yawl sailing vessel.
A yawl (from Dutch Jol) is a two-masted sailing craft similar to a sloop or cutter but with an additional mizzen mast well aft of the main mast, often right on the transom. A small mizzen sail is hoisted on the mizzen mast.
The yawl is often confused with the ketch, which also has two masts with the main mast foremost. The common view is that a ketch has the mizzen mast forward of the rudder post whereas the mizzen on a yawl is aft of the rudder post. This definition is a relatively recent definition and the historical definition is likely to be quite different.
In practice, on a ketch the principal purpose of the mizzen mast is to help propel the vessel, while on a yawl it is mainly used for the purposes of trim and balance. In consequence the mizzen sail of a yawl tends to be smaller, and the mainsail larger, when compared to a ketch of similar size. The mainsail of a yawl will be similar in size to that of a similarly sized and proportioned sloop.
The yawl was originally developed as a rig for commercial fishing boats, one good example of this being the Salcombe Yawl (a traditional small fishing boat built in Devon). In its heyday, the rig was particularly popular with single-handed sailors, such as circumnavigators Joshua Slocum and Francis Chichester. This was largely due to the remarkable ability of a yawl to be trimmed to follow a compass course accurately despite minor wind shifts. Modern self-steering and navigation aids have made this less important, and the yawl has generally fallen out of favor.
In the 1950s and 60s yawls were developed for ocean racing to take advantage the handicapping rule that did not penalize them for flying a mizzen staysail, which on long ocean races, often down wind, were a great advantage, the best example of this being Olin Stephens' Finisterre.
An alternative view from historical usages
The derivation of "yawl"
The above is an accepted definition, but it may not be correct within a historical context.- YAWL, n. A small ships boat, usually rowed by four or six oars. (Webster's dictionary 1828)
The seminal American Yacht Designer of the first half of last century, Francis Herreshoff, reflected this traditional definition of a Yawl was as "a ship's boat resembling the pinnace" set up to be primarily rowed.
To add a sailing rig to a rowboat the masts must not interfere with the rowers. The Mainmast is placed well forward and the mizzen as far back as possible. The mizzen has to be small in size to keep the sail area balanced around the hull's centre of lateral resistance to ensure the boat will sail in a straight line without excessive correction.
According to Herreshoff "yawl" had nothing to do with rudder placement relative to the mizzen - a yawl rig is the sail and mast configuration that suits a yawlboat.
The derivation of "ketch"
Ketch was a "catch" or fishing boat.The mizzen is bigger to hold the bow (front)of a boat toward the wind and oncoming waves. The mainsail at the front of the boat would have been dropped and the mizzen trimmed tight on the centreline. Set up this way most boats will point directly into the wind in a reliable way. It is also possible to ease the mizzen slightly to allow the boat to move slowly forward.
In a fishing boat this attitude allows the nets to be handled without the boat becoming "broadsides" to the waves allowing them to break over the sides of the boat. Fishnets can then be handled without putting the boat at risk.
For enough sail area to propel a fishing boat the mizzen mast has to move forward toward the middle of the boat which allows its sail to be bigger without upsetting the sail balance or distribution.
A "Ketch Rig" is simply the rig that matches the function of a "Ketch" or "Catch" or fishing boat.
The development of the rudder oriented definitions of yawl and ketch
The common definition of Yawl and Ketch using the rudderpost does not reflect the nautical tradition and was created by much more recent developments of a handicap system for racing yachts.The CCA (Cruising Club of America) rating rule was developed following World War II to allow different styles of boats to race against each other with a handicap calculated from measurements of each boat. It was later combined with the RORC (Royal Ocean Racing Club) rule to become the IOR (International Offshore Rule) rule in the late 50s which was used to handicap international racing until the late 1980s.
The CCA and the following rules used the rudder post definitions of ketch and yawl so they had a cut and dried definition for measuring sail so boats could be handicapped with boats fulfilling their new and arbitrary definition of Yawl and Ketch receiving slightly different handicaps.
The rudderpost definition can be argued to be a relatively recent sailing handicap development rather than something that refers to traditional use.
The Humber Yawl Club
The Humber Yawl Club was created in England on the river Humber in the late 1800s. Its fleet of "Canoe Yawls" were primarily sailing boats that could be rowed effectively.The purpose of the boats and the group was for recreational cruises along the coast of England over several days, camping on beaches and riverbanks. Some of the boats were small enough to be taken to Europe by commercial steamer and then used for travelling the canal, lake and river systems of Europe.
"Canoe Yawls" had a pointed stern similar to a canoe. Rudders were usually placed on the back of the boat which allows the rudder to be raised to allow the boat to be landed on a beach.
Despite the mizzen sail being ahead of the rudder the boats were termed Yawls because of their size and their good rowing capability.
Famous yawls
- Gipsy Moth IV
- Islander
- Spray
- Finisterre, designed by S&S
- Concordia yawls
- Zeearend, designed by S&S
- Drascombe Lugger and derivatives
See also
External links
- Dorade
- Brief History of the Humber Yawl Club
- A page on historical Canoe Yawls - many with ketch and some with sloop rigs
- Restoration of a Humber Yawl
Types of sailing vessels and rigs |
|---|
| Barca-longa |
A workflow is a reliably repeatable pattern of activity enabled by a systematic organization of resources, defined roles and mass, energy and information flows, into a work process that can be documented and learned.
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A workflow pattern is a specialized form of a design pattern as defined in the area of software engineering. Workflow patterns refer specifically to recurrent problems and proven solutions related to the development of workflow applications in particular, and more broadly,
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Eindhoven University of Technology (in Dutch: Technische Universiteit Eindhoven or TU/e, and formerly Technische Hogeschool Eindhoven or THE) is a university of technology located in Eindhoven, the Netherlands.
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Queensland University of Technology (QUT) is located in Brisbane, Queensland, and is one of Australia's largest universities.
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QUT is marketed as "A university for real world".
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InterContinental Hotels Group
Public (LSE: IHG NYSE: IHG )
Founded 15 April 2003
Origins trace back to 1777
Headquarters Windsor, England, UK
Key people David Webster, Chairman
Andrew Cosslett, Chief Executive RIchard Hartman, EMEA
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Public (LSE: IHG NYSE: IHG )
Founded 15 April 2003
Origins trace back to 1777
Headquarters Windsor, England, UK
Key people David Webster, Chairman
Andrew Cosslett, Chief Executive RIchard Hartman, EMEA
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Open source is a set of principles and practices that promote access to the design and production of goods and knowledge. The term is most commonly applied to the source code of software that is available to the general public with relaxed or non-existent intellectual property
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A Petri net (also known as a place/transition net or P/T net) is one of several mathematical representations of discrete distributed systems. As a modeling language, it graphically depicts the structure of a distributed system as a directed bipartite graph with
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In theoretical computer science, a state transition system is an abstract machine used in the study of computation. The machine consists of a set of states and transitions between states.
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A Petri net (also known as a place/transition net or P/T net) is one of several mathematical representations of discrete distributed systems. As a modeling language, it graphically depicts the structure of a distributed system as a directed bipartite graph with
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In computer science, the process calculi (or process algebras) are a diverse family of related approaches to formally modelling concurrent systems. Process calculi provide a tool for the high-level description of interactions, communications, and synchronizations between a
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finite state machine (FSM) or finite state automaton (plural: automata) or simply a state machine is a model of behavior composed of a finite number of states, transitions between those states, and actions.
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Writing system: Latin alphabet (Dutch variant)
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Writing system: Latin alphabet (Dutch variant)
Official status
Official language of: Aruba
Belgium
European Union
European Union
Netherlands Antilles
Suriname
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Sailing ship is now used to refer to any large, wind-powered, vessel. In technical terms, a ship was a sailing vessel with a specific rig of at least three masts, square rigged on all of them, making the sailing adjective redundant.
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sloop (From Dutch sloep) in sailing, is a vessel with a fore-and-aft rig. A sloop carries a single mast stepped farther forward than that of a cutter. The sloop's fore-triangle is smaller than a cutter's.
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cutter is:
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- a small single-masted vessel, fore-and-aft rigged, with two or more headsails, a bowsprit, and a mast set further back than in a sloop
- a ship's boat, powered by oars, sails or motor, used to carry passengers or light stores
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mast of a sailing ship is a tall vertical pole which supports the sails. Larger ships have several masts, with the size and configuration depending on the style of ship.
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The term transom has several different meanings.
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Ship terminology
In naval architecture, a transom is the surface that forms the stern of a vessel. Transoms may be flat or curved and they may be vertical (probably the least usual), raked forward (known as retroussé), or..... Click the link for more information.
sail is any type of surface intended to generate thrust by being placed in a wind — in essence a vertically-oriented wing. Sails are used in sailing.
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Use of sails
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ketch is a sailing craft with two masts: a main mast, and a shorter mizzen mast abaft (rearward of) the main mast. Both masts are rigged mainly fore-and-aft. From one to three jibs may be carried forward of the main mast when going to windward.
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rudder is a device used to steer ships, boats, submarines, aircraft, hovercraft or other conveyances that move through air or water. Rudders operate by re-directing the flow of air or water past the hull or fuselage, thus imparting a turning or yawing motion to the craft.
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Devon
Motto: Auxilio divino (Latin: By divine aid)
Geography
Status Ceremonial & (smaller) Non-metropolitan county
Region South West England
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Motto: Auxilio divino (Latin: By divine aid)
Geography
Status Ceremonial & (smaller) Non-metropolitan county
Region South West England
Area
- Total
- Admin. council
- Admin.
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circumnavigate a place, such as an island, a continent, or the Earth, is to travel all the way around it by boat or ship. More recently, the term has also been used to cover aerial round-the-world flights.
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Joshua Slocum (February 20, 1844 – on or shortly after 14 November, 1909) was a Canadian-American seaman and adventurer, a noted writer, and the first man to sail single-handedly around the world. In 1900 he told the story of this in Sailing Alone Around the World.
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Sir Francis Chichester (September 17 1901 – August 26 1972), aviator and sailor, was knighted by Queen Elizabeth II for becoming the first person to sail single-handed around the world by the clipper route, and the fastest circumnavigator, in nine months and one day overall.
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Olin James Stephens II (born 1908) has been described as the best-known and most successful yacht designer of the 20th century. His name is well known in connection with the America's Cup, as he assisted W.
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The Royal Ocean Racing Club also called RORC is a principal organiser of offshore yacht races in the UK, including the Fastnet race
Founded in 1925 with a fine clubhouse at 20 St. James's Place.
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Founded in 1925 with a fine clubhouse at 20 St. James's Place.
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The International Offshore Rule (IOR) is a measurement rule for racing sailboats. The IOR evolved from the Cruising Club of America (CCA) rule for racer/cruisers and the Royal Ocean Racing Club (RORC) rule.
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