Service layer
Encyclopedia
In intelligent network
s (IN) and cellular networks, service layer is a conceptual layer within a network service provider architecture. It aims at providing middleware
that serves third-party value-added service
s and applications at a higher application layer
. The service layer provides capability servers owned by a telecommunication network service provider, accessed through open and secure Application Programming Interface
s (APIs) by application layer servers owned by third-party content providers. The service layer also provides an interface to core networks at a lower resource layer. The lower layers may also be named control layer and transport layer
(the transport layer is also referred to as the access layer in some architectures).
The concept of service layer is used in contexts such as Intelligent network
s (IN), WAP
, 3G
and IP Multimedia Subsystem
(IMS). It is defined in the 3GPP
Open Services Architecture
(OSA) model, which reused the idea of the Parlay
API for third-party servers.
In software design, for example Service-oriented architecture
, the concept of service layer has a different meaning.
architecture provides multimedia services to the overall IMS network. This layer contains network elements which connect to the Serving-CSCF (Call Session Control Function) using the IP multimedia Subsystem Service Control Interface (ISC). The ISC interface uses the SIP
signalling protocol.
in a pre-IMS network, however it is specifically tailored to support the SIP signalling protocol for use in an IMS network.
(this is typically a SIP
to Parlay
gateway)
and CAMEL
.
Intelligent network
The Intelligent Network , is the standard network architecture specified in the . It is intended for fixed as well as mobile telecom networks...
s (IN) and cellular networks, service layer is a conceptual layer within a network service provider architecture. It aims at providing middleware
Middleware
Middleware is computer software that connects software components or people and their applications. The software consists of a set of services that allows multiple processes running on one or more machines to interact...
that serves third-party value-added service
Value-added service
A value-added service is popular as a telecommunications industry term for non-core services, or in short, all services beyond standard voice calls and fax transmissions. However, it can be used in any service industry, for services available at little or no cost, to promote their primary business...
s and applications at a higher application layer
Application layer
The Internet protocol suite and the Open Systems Interconnection model of computer networking each specify a group of protocols and methods identified by the name application layer....
. The service layer provides capability servers owned by a telecommunication network service provider, accessed through open and secure Application Programming Interface
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
s (APIs) by application layer servers owned by third-party content providers. The service layer also provides an interface to core networks at a lower resource layer. The lower layers may also be named control layer and transport layer
Transport layer
In computer networking, the transport layer or layer 4 provides end-to-end communication services for applications within a layered architecture of network components and protocols...
(the transport layer is also referred to as the access layer in some architectures).
The concept of service layer is used in contexts such as Intelligent network
Intelligent network
The Intelligent Network , is the standard network architecture specified in the . It is intended for fixed as well as mobile telecom networks...
s (IN), WAP
Wireless Application Protocol
Wireless Application Protocol is a technical standard for accessing information over a mobile wireless network.A WAP browser is a web browser for mobile devices such as mobile phones that uses the protocol.Before the introduction of WAP, mobile service providers had limited opportunities to offer...
, 3G
3G
3G or 3rd generation mobile telecommunications is a generation of standards for mobile phones and mobile telecommunication services fulfilling the International Mobile Telecommunications-2000 specifications by the International Telecommunication Union...
and IP Multimedia Subsystem
IP Multimedia Subsystem
The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem is an architectural framework for delivering Internet Protocol multimedia services. It was originally designed by the wireless standards body 3rd Generation Partnership Project , as a part of the vision for evolving mobile...
(IMS). It is defined in the 3GPP
3GPP
The 3rd Generation Partnership Project is a collaboration between groups of telecommunications associations, known as the Organizational Partners...
Open Services Architecture
Open Services Architecture
The Open Service Access or OSA is part of the third generation mobile telecommunications network or UMTS. OSA describes how services are designed in a UMTS network....
(OSA) model, which reused the idea of the Parlay
Parlay
'Parlay/OSA' was an open API for the telephone network. It was developed by The Parlay Group, which worked closely with ETSI and 3GPP, which all co-publish it. Within 3GPP, Parlay is part of Open Services Architecture.- Overview :...
API for third-party servers.
In software design, for example Service-oriented architecture
Service-oriented architecture
In software engineering, a Service-Oriented Architecture is a set of principles and methodologies for designing and developing software in the form of interoperable services. These services are well-defined business functionalities that are built as software components that can be reused for...
, the concept of service layer has a different meaning.
Service layer in IMS
The service layer of an IMSIP Multimedia Subsystem
The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem is an architectural framework for delivering Internet Protocol multimedia services. It was originally designed by the wireless standards body 3rd Generation Partnership Project , as a part of the vision for evolving mobile...
architecture provides multimedia services to the overall IMS network. This layer contains network elements which connect to the Serving-CSCF (Call Session Control Function) using the IP multimedia Subsystem Service Control Interface (ISC). The ISC interface uses the SIP
Session Initiation Protocol
The Session Initiation Protocol is an IETF-defined signaling protocol widely used for controlling communication sessions such as voice and video calls over Internet Protocol . The protocol can be used for creating, modifying and terminating two-party or multiparty sessions...
signalling protocol.
Elements of the IMS service layer
The network elements contained with in the service layer are generically referred to as 'service platforms' however the 3GPP specification (3GPP TS 23.228 V8.7.0) defines several types of service platforms:- SIP Application Server
- OSA Service Capability Server
- IM-SSF
SIP Application Server
The SIP Application Server (AS) performs the same function as a Telephony Application ServerTelephony Application Server
The term telephony application server refers to an entity in a telephone network that carries out functions that are not directly related to the routing of messages through the network....
in a pre-IMS network, however it is specifically tailored to support the SIP signalling protocol for use in an IMS network.
OSA Service Capability Server
An OSA Service Capability Server acts as a secure gateway between the IMS network and an application which runs upon the Open Services ArchitectureOpen Services Architecture
The Open Service Access or OSA is part of the third generation mobile telecommunications network or UMTS. OSA describes how services are designed in a UMTS network....
(this is typically a SIP
Session Initiation Protocol
The Session Initiation Protocol is an IETF-defined signaling protocol widely used for controlling communication sessions such as voice and video calls over Internet Protocol . The protocol can be used for creating, modifying and terminating two-party or multiparty sessions...
to Parlay
Parlay
'Parlay/OSA' was an open API for the telephone network. It was developed by The Parlay Group, which worked closely with ETSI and 3GPP, which all co-publish it. Within 3GPP, Parlay is part of Open Services Architecture.- Overview :...
gateway)
IM-SSF
The IM-SSF (IP Multimedia Service Switching Function) acts as a gateway between the IMS network and application servers using other telecommunication signalling standards such as INAPINAP
The Intelligent Network Application Part is a signalling protocol used in the intelligent network architecture. It is part of the SS7 protocol suite, typically layered on top of TCAP.It can also be termed as logic for controlling telecommunication services migrated from traditional switching...
and CAMEL
Customised Applications for Mobile networks Enhanced Logic
Customised Applications for Mobile networks Enhanced Logic, or CAMEL for short, is a set of standards designed to work on either a GSM core network or UMTS network. They allow an operator to define services over and above standard GSM services/UMTS services...
.
Service layer in SOA
In Service oriented architecture (SOA), the service layer is the third layer in a five abstraction layer model. The model consists of Object layer, Component layer, Service layer, process layer and Enterprise layer.. The service layer can be considered as a bridge between the higher and lower layers, and is characterized by a number of services that are carrying out individual business functions.See also
- IP Multimedia SubsystemIP Multimedia SubsystemThe IP Multimedia Subsystem or IP Multimedia Core Network Subsystem is an architectural framework for delivering Internet Protocol multimedia services. It was originally designed by the wireless standards body 3rd Generation Partnership Project , as a part of the vision for evolving mobile...
(IMS) - Open Services ArchitectureOpen Services ArchitectureThe Open Service Access or OSA is part of the third generation mobile telecommunications network or UMTS. OSA describes how services are designed in a UMTS network....
(OSA) - Hierarchical internetworking modelHierarchical internetworking modelThe Hierarchical internetworking model, or three-layer model, is a network design model first proposed by Cisco. Thethree-layer model divides enterprise networks into three layers: core, distribution, and access layer. Each layer provides different...
- Multi-tier architecture