Services Android

Requirements:

• Separate service connection from Activity
• Running in Background Thread Priority
• Communication between Client(Activity or Service) and Service
• Responses from Service to Client (Activity or Service)
• Indications from Service to Client
• Reusable code except for specific service interface.
• Hide details about how parameters are sent from Client and from Service.

Design:

Split Service into three main classes:

• Service – Performs the actual workload.
• A Request interface – Handles communication form Client to Service
• A Confirm interface – Handles communication from Service to Client

Arbitrary Enums / classes

• Respone_e - General Service response codes. Common for all service types.
• Result_e - General Interface response codes. Common for all interface functions.
• Parameters - General Keys for parameters send between service / client. Common for all services.

Dependencies

• Activity needs some type of service from service A.
• Activity needs some type of service from service B.
• Service B needs some type of service from service A.

Base classes

BaseService

Common code for all types of services, handles setting up of background thread and Messenger object for receiving requests. It also provides imple subscriber implementation.

BaseConfirm

Common code for confirm interface, i.e. sendToClient method.

BaseReqeust

Common code for request interface. Connection to service handling and methods for sending requests to service.

Services

ServiceA

Simple service that handles some requests and may send indications if subscribed.

ServiceA_Cnf

Confirm interface utilized by ServiceA class for sending response messages and indications.

ServiceA_Req

Request interface for service A, utilized by a client. Provides callback interface for when responses and indications arrive.

ServiceB

Simple service that handles some request and may send indications if subscribed. Depends on Service A if Request_D is sent to it. Stops depending on ServiceA if Request_E is sent to it.

ServiceB_Cnf

Confirm interface utilized by ServiceA class for sending response messages and indications.

ServiceB_Req

Request interface for service A, utilized by a client. Provides callback interface for when responses and indications arrive.

Activity

Provide simple UI which with edit box, submit and a text view for showing information. In the edit box it is possible to send the following commands:

• h , help, ? - Display help text
• 1 – Starts Service A
• 2 – Sops Service A
• 3 – Send Request A to Service A.
• 4 – Send Request B to Service A.
• 5 – Subscribe for Event C from Service A
• 6 - Unsubsribe for Event C from Service A
• 7 - Start Service B
• 8 – Stop Service B
• 9 – Send Request D to Service B
• 10 – Send Request E to Service B
• 11 – Subscribe to Event F from Service B
• 12 – Unsubscribe to Event F from Service B

Use cases

A> Use case for connecting to ServiceA:

Precondition: None

• User sends command 1 to activity
• Activity calls connect on ServiceA_Req
• ServiceA_Req calls internal method connectToService
• onCreate is called by framework on ServiceA
• onBind is called by framework on ServiceA
• onServiceConnected is called on ServiceA_Req by framework
• ServiceA_Req indicatates to client (Activity) that connection is up by calling onServiceResponse

B> Use case subscribing to indications for Event C from ServiceA:

Precondition: Use case A

• User sends command 5 to activity
• Activity calls subscribe_C on ServiceA_Req
• ServiceA_Req calls internal method sendToClientIfPossible
• handleMessage is called on ServiceA, which processes the request stores the subscriber and set-ups indications with a certain time interval.
• ServiceA calls confirmSubscribe_C on Service_Cnf
• confirmSubscribe_C calls internal method sendToClient
• handleMessage is called on ServiceA_Req, which indicates to client through onServiceReponse that subscribe is in place.

C> Use case indications is sent from ServiceA to Client(Activity)

Precondition: Use case A followed by use case B

• Timer for indications elapses and the Runnable's run method is called.
• BaseService.OnSend send method is called with proper indication parameters for every subscriber
• The send method calls indication_C on ServiceA_Cnf
• The indication_C calls internal method sendToClient
• handleMessage is called on ServiceA_Req, which indicates to client through onServiceIndication

D> Use case unsubscribe to indications for Event C from ServiceA:

Precondition: Use case A

• As use case B but with User sending command 6 to activity
• activity calling unsubscribe_C
• ServiceA calling confirmUnsubscribe_C

E> Use case unbinding from ServiceA:

####Precondition: Use case A

• User sends command 2 to activity
• Activity calls disconnect on ServiceA_Req
• ServiceA_Req calls disconnectFromService
• UnBind is called on ServiceA
• If service is completely terminated onDestroyed is also called on ServiceA
• ServiceA_Req indicates to client that connection is terminated through onServiceResponse