Summary
Interfaces, contracts, methods, operations, entities, objects, and tables, oh my! The OSID Specification defines its own language solely in reference to itself. Developers The vocabulary is defined and built upon without importing words from outside the OSIDs.
However, developers will look at it from the OSID Language Binding perspective. Others Many will import concepts from what they have worked with in databases, web services, or MVC-based platforms. The result is can be a mash of terms that matters once in a whilegets in the way of understanding the OSIDs and how they can be applied.
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Perspectives
The OSID Perspective
You can look at the The OSID Specification schema for its specification terminology. It (S-OSID) defines:
- osid: a bunch of interfaces an enumerations
- enumeration: a list of values
- interface: a bunch of method definitions
- method: something that is invoked with parameters, returns a value or an error
- parameter: defines what may be supplied to a method as an argument, can be an interface, enumeration, or a language primitive
- return: defines what may be returned from a method, if anything, can be an interface, enumeration, or a language primitive
- language primitive: boolean, byte, cardinal. decimal integer, object. string, timestamp
- error: an error from a method such as OPERATION_FAILED or ILLEGAL_STATE
- compliance: a compliance statement for a method - mandatory or optional
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The Java Perspective
- package: a bunch of interfaces, classes, enums, annotations, and other sub-packages
- enums: constants and methods
- interface: a bunch of method definitions
- class: a pile of attributes that include methods and may implement one or more interfaces
- object: an instance of a single class
- method: something that is invoked with parameters, returns a value or throws an exception
- parameter: defines the type supplied to a method as an argument, can be a class, interface, enum, or a primitive
- return: defines the type of return value, can be a class, interface, enum, primitive, or void
- primitive: boolean, byte, char, double, float, int, long, short
- exception: an event that occurs during the execution of a program that disrupts the normal flow of instructions such as SecurityException or NullPointerException
The OSID Java Binding Perspective
The OSID Specification is transformed into the OSID Java Binding. The resulting merge creates the following OSID terminology in Java:
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Concepts like classes and objects disappear. Others like parameter and primitive have a narrower connotation than what a Java developer would be accustomed. . An OSID Language Binding can hide certain aspects of the OSID Specification that are conceptually relevant because it is an interpretation. The Java is pretty close, but can cause some head scratching about why something was done one way or the other. The specifications on osid.org display the OSIDs, not the OSID Java Binding.
Terminology Issues
These are a list of terms that often get tossed around. Mixing terminology across frameworks will always cause confusionresult in complacent agreements over different things and heated debates over the same thing. When a term is in direct conflict with the OSID Specification or its few basic concepts, it's a good idea to lose it and adapt. This . Other terms are kinda similar, but not equal. Level setting can be difficult when trying to learn something by comparing it to something else you already know.
Others terms are more conceptual in nature and we tend to use them informally.
terminology compatible with OSIDs shaky terminologywith caveats
terminology incompatible with the OSIDs
API
OSIDs are consumed by OSID Consumers in software. OSIDs are Application Programming Interfaces.
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An OSID Provider may likely employ data objects to satisfy the contract of an OsidObject. An OSID Consumer sees this through the window of the interface. The OSID Consumer may do whatever it likes with this information, including referring to them as simple data elements. However it can be an impediment when trying to understand the nature and applications of these interfaces whose implementation may require an underlying OSID Provider rather than a pull from a database table, for example.
Boundary (Service Boundary)
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Many listeners will assume it means the scope of a service, i.e. "There's a service boundary between authentication and authorization." However, jumping laterally between two OSIDs also implies a movement between OSID Providers. This interpretation would not be wrong but it may fail to clarify exactly what is meant.
Contract (Service Contract)
The term contract is often used in service designs to distinguish an interface from a message structure or DTO. The message structure and DTO are considered data while the contract defines the operations on that data. OSIDs define the agreement between service consumers and service providers. In the OSID world, most everything in the specification can be considered a contract, i.e. "The AgentList is a contract."
DTO (DAO, Bean, Domain Object)
A Data Transfer Object is used to transfer bags of data values. However, OSIDs are interfaces into OSID Providers. OSID Providers may be dynamic and DTOs are static.
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Because OSIDs abstract away issues of serialization and protocol, we are just left with interface definitions that are utilized directly in software. The SOA concepts of endpoint and contract still apply but without the web services part. SOA - WS = OSIDs
Entity (Service Entity)
In the modeling world, entity is simply a fancy way of saying thing. They are the boxes in an entity model and often correspond to OsidObjects in the OSIDs.
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OSIDs have a special kind of OsidObject called OsidRelationship. An OsidRelationship is an entity relation between two OsidObjects that exists for a period of time. Not every entity relation between two entities is an OsidRelationship.
Service (OSID, Package)
The term "service" doesn't have any formal definition in the OSID Specification. It's tossed around because this is a Service Design Methodology and OSIDs are specifications for how OSID Providers provide services to OSID Consumers.
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Standard (Specification)
OSIDs have historically been referred to as specifications. The difference between a standard and a specification is confusing at best. Typically, one incorporates standards into specifications while others refer to specifications as a type of standard. Some believe a standard has accreditation associated with it, as in meets the standard while others perform quality assurance based on a specification. Some believe that a standard is based on a consensus process but a specification is not. However, most use these terms interchangeably today and more often they get strung together. Who knows.
See Also
About OSIDsAnchor About OSIDs About OSIDs
Structure & Definitions of OSIDs (S-OSID)Anchor OSID Specification Framework OSID Specification Framework
OSID SpecificationsAnchor OSID Specifications OSID Specifications - OSID Language Binding
OSID Java BindingAnchor OSID Java Binding OSID Java Binding - osid.OsidObjects