Service identification and description

2 Copyright e-Government Program (Yesser) Service identification - Summary Slide  Definition - Service  Definition - Interface  Service interface – operation - parameters  Example of a service  What needs documenting?  From specification to design  Service identification + description - the process  Identify Service operations  Naming: Service operations  Add service operations to the use case steps  Create descriptions  Audit Use cases and term model

3 Copyright e-Government Program (Yesser) Definition - Service A service is executable software which offers a well-defined interface, accessible to other, independently developed and functioning, pieces of software A service displays functionality for others in form of operations P3 P4 P2 P5 P1 Programstruktur Datamodel Service Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Operation 6 Operation 1 Operation 2 Operation 3 Operation 4 Operation 5 Interface P3 P4 P2 P5 P1 Program structure Data model Service Interface

4 Copyright e-Government Program (Yesser) A service has the following properties  Use:  A (business) service only exists if the business understands it  The service user does not need to know anything but the ”service agreement” for using the service  The service is autonomous – loosely coupled – without a state  The service works independently, i.e. that one use of the service is independent of other uses and of user context  Services are a standardised way of modelling functionality across suppliers and platforms  Technical:  Services can be access from all platforms through a well-defined interface  There are several ways of implementing a service – e.g. web service  Service data can only be accessed through its operations  Thus it is not allowed to access service data by going around the operations (join across service tables is forbidden)

5 Copyright e-Government Program (Yesser) Definition - Interface  The interface of the receiving system, to which the using systems must relate and refer  Used in several different places in IT architecture:  Between human and computer (e.g. GUI)  Between programs  Between other elements in IT architecture Service Output parameter Input parameter Output parameter Input parameter Output parameter Input parameter Output parameter Input parameter Output parameter Input parameter Output parameter Input parameter Operation 6 Operation 1 Operation 2 Operation 3 Operation 4 Operation 5 Interface

6 Copyright e-Government Program (Yesser) Service interface – operation - parameters The service interface has the following properties  Service contact with the outside world  Consists of operations and input / output parameters  The interface must be well-documented  The interface must be on display and easily accessible Operations:  Operations are the service functionality  Without operations, no functionality Input parameters:  The data elements (attributes), which the operation needs to be able to perform the specified functionality Output parameters:  The data elements (attributes), which the operation returns after performing the specified functionality

7 Copyright e-Government Program (Yesser) Example of a service Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter List Interface Customer Send Delete Update Read Create

8 Copyright e-Government Program (Yesser) What needs documenting? Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter List Interface Customer Service description Service operation description Service operation description Service operation description Service operation description Service operation description Service operation description Send Delete Update Read Create

9 Copyright e-Government Program (Yesser) From specification -> design Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Outputparametre Inputparametre Opret Søg Ret Hent Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Outputparametre Inputparametre Output parameter Input parameter Create Read Update Delete Interface Customer Logical layer <definitions xmlns=" …… …… …… …… ……….. OpRegister customer in customer file index ………. Short service description ……. Operational layer WSDL = ”Service contract” Send List

10 Copyright e-Government Program (Yesser) Service identification + description - the process Agency Complete descriptions Initial state: - use cases identified and specified Final state: - All services identified and documented All Services Finished ? yesno Audit Use cases and term model Identify Service operations Link to: -Use Case modelingUse Case modeling -Term modelingTerm modeling

11 Copyright e-Government Program (Yesser) Identify Service operations  Identify Service operations  For each use case, add service operations  Generalise Services – think big picture, consider reuse  Create services and operations in the service catalogue  Categorise services

12 Copyright e-Government Program (Yesser) Naming: Service operations Service operations are composed as follows:  Term.Sub term_Operation Term:  The term describes an overall operational object, present in the term model. The term is also the name of the service.  The term is never in plural form. Sub term:  The sub terms belongs to the overall operations object; e.g. customer- optional, where Optional is a sub term to Vehicle. The sub term is only used when it does not represent the overall term that relates to the operation – it is equipment that needs listing/getting/registering, not the vehicle itself. The sub terms is never in plural form, and is separated from the overall term by a ”.” (period). Operation:  The operation is the description fo the task the service performs, e.g. Get, Create, List, Correct. The list of operations is not final, but will at first be kept at a minimum – though it is vital that the operation that the operation covers the actual task the service provides. If there is no operation to cover the task, one must ”invent” a new one The operation is referred to as an imperative verb, and separated from the sub term by a ”_” (underscore). If there is no sub term, use a ”.” to separate operation from overall term.

13 Copyright e-Government Program (Yesser) Naming: Service operations Read:  Read is used to acquire (read) data, an instance, from a data source List:  Lists the instances in the database. Create:  Creates a new instance, and saves it to a database. Only instances that have been created can subsequently be retrieved (Get). Update:  Update makes content changes to an already created instance. Send:  Sends data to a given recipient, when it is necessary to push data. Delete:  This operation deletes an instance.

14 Copyright e-Government Program (Yesser) Example of service description template

15 Copyright e-Government Program (Yesser) Example of template for service operation description

16 Copyright e-Government Program (Yesser) Add service operations to the use case steps

17 Copyright e-Government Program (Yesser) Create descriptions  Create descriptions  Describe the service  Describe the operations  Add input and output parameters for each operation – typically harvested from term model

18 Copyright e-Government Program (Yesser) Audit Use cases and term model Revise Use cases  If there is a need for use case changes, these are re- vised on the go  Make use of professional specialists Revise the term model  If there is a need for term model changes, these are re- vised on the go  Make use of professional specialists