What do you mean by interfaces and services?

Generally a network service is an application which runs at application layer and above and is used in computer networking.

Network service provides data Storage, manipulation, presentation, communication. This is implemented using client-server architecture or peer-to-peer architecture.

Service Interface is used to implement a Service-Oriented Architecture (SOA). This is implemented to achieve interoperability among the applications among various technologies.

The basis of functions of each and every layered structure is to provide a service to the layer above it.

Types of interface’s services

The types of interface’s services are as follows −

Entities and peer entities

An entity is an active element in each and every layer, It can be either a software entity or hardware entity.

Example of software entity − Process.

Example of hardware entity − I/O chip's.

Services provider and services user

The entities and layer n implement services for the (n+1) which is above the nth layer to layer n which provides services is called services provider and layer (n+1) which takes these services is called as services user.

Services Access Points

They are available at the interfaces of n and n+1 layer. Services are available at SAP’s that means the layer n SAPs are those placed at the interfaces where layer n+1 access the service being offered.

Interface Data Unit (IDU)

For the successful exchange of information between two layers, a set of rules about the interfaces should be presented, the layer (n+1) entity passes an IDU to the layer and entity through the SAP. IDU contains mainly two parts: ICI and SDU.

SDU − Services Data Unit is a part of IDU, The SDU is the information which is passed across two networks from peer network to peer entity and then goes to the help layer (n+1).
ICI − ICI contains the control information which is necessary to help the lower layer n to do the necessary job.

Protocol data unit

In order to transfer the SDU the layer n entity has to divide into many smaller pieces. Each pieces in given header is buying the entities to their peer protocol as shown in below figure