This document defines key terms used in developing a service-oriented grid architecture, including resource, network protocol, network-enabled service, API, SDK, and syntax. It describes an API as a specification for routines to facilitate application development, providing portability but not interoperability. A SDK is defined as an instantiation of an API that may include libraries and tools. Syntax is defined as rules for encoding information.

1. Prof. Neeraj Bhargava
Pooja Dixit
Department of Computer Science
School of Engineering & System Sciences
MDS, University Ajmer, Rajasthan, India
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2. Definitions
 A service-oriented grid architecture is
descriptive: it provides a common vocabulary
for use when describing grid systems.
 A grid architecture is normative: it provides
guidance and identifies key areas in which
services are required.
 A grid architecture is also prescriptive: it
defines standard “Intergrid” protocols and
application programmer interfaces (APIs) to
facilitate creation of interoperable grid systems
and portable applications.
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3.  Some important definitions used in the development of the
architecture definition are:
◦ Resource: An entity that is to be shared; e.g., computers, storage,
data, software
◦ Network protocol: A formal description of message formats and a set
of rules for message exchange across a variety of subsystems such as
SANs, LANs, MANs, WANs, and Global Area Networks (GANs)
◦ Network-enabled service: Implementation of protocols that define a
set of capabilities
Figure: Network
based Grid Services
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4.  API: A specification for a set of routines to facilitate application development.
 Examples include GSS API (Generic Security Service API) and MPI
 (Message Passing Interface). A protocol can have multiple APIs (e.g., TCP/IP
 APIs include BSD sockets, Winsock, and System V streams). The protocol
 provides interoperability: programs using different APIs can exchange information
 and one does not need to know the remote APIs. An API can have
 multiple protocols. For example, MPI provides portability: any correct program
 compiles and runs on a platform. MPI does not provide interoperability:
 all processes must link to same SDK (e.g., MPICH and LAM versions of
 MPI).
 Software Development Kit (SDK): A particular instantiation of an API (it
 may consists of libraries and tools). Examples of SDKs include MPICH and
 Motif Widgets.
 Syntax: Rules for encoding information. Examples include XML, Condor
 ClassAds, Globus RSL, X.509 certificate format [Request For Comments
 (RFC) 2459], Cryptographic Message Syntax (RFC 2630), and ASN.1. Syntaxes
 are distinct from protocols in the sense that a syntax may be used by
 many protocols (e.g., XML), and be useful for other purposes. Syntaxes may
 be layered (e.g., Condor ClassAds uses XML, which uses ASCII.)
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5.  API: A specification for a set of routines to facilitate application
development. Examples include GSS API (Generic Security Service
API) and MPI (Message Passing Interface). A protocol can have
multiple APIs (e.g., TCP/IP APIs include BSD sockets, Winsock, and
System V streams). The protocol provides interoperability:
programs using different APIs can exchange information and one
does not need to know the remote APIs. An API can have multiple
protocols. For example, MPI provides portability: any correct
program compiles and runs on a platform. MPI does not provide
interoperability: all processes must link to same SDK (e.g., MPICH
and LAM versions of MPI).
 Software Development Kit (SDK): A particular instantiation of an API
(it may consists of libraries and tools). Examples of SDKs include
MPICH and Motif Widgets.
 Syntax: Rules for encoding information. Examples include XML,
Condor ClassAds, Globus RSL, X.509 certificate format [Request For
Comments (RFC) 2459], Cryptographic Message Syntax (RFC 2630),
and ASN.1. Syntaxes are distinct from protocols in the sense that a
syntax may be used by many protocols (e.g., XML), and be useful
for other purposes. Syntaxes may be layered (e.g., Condor ClassAds
uses XML, which uses ASCII.)
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