Request A Service

Owned by Thomas Watteyne
Last updated: Oct 21, 2014

This section refers to the following sample application(s):

  • 01-join
  • 01-service

 

The 01-join application uses the "base bandwith" to send data to the 

SmartMesh manager

.

For a discussion on base bandwidth, refer to the SmartMesh IP User's Guide.

In a real scenario, your application should request a service with the bandwidth corresponding to the amount of traffic if will actually send. This will cause the 

SmartMesh manager

 to install resources appropriate for the network's data requirements.

It is important that your application requests the amount of bandwidth which corresponds to the amount of data it will produce:

  • If you request too much bandwidth, the network will have a higher power consumption than needed.
  • If you request too little bandwidth, a portion of your application's data packets will be denied by the

    SmartMesh IP

    stack when trying to send.

Requesting bandwidth consists in sending a request message to the 

SmartMesh manager

, and waiting for a DN_API_LOC_EV_SVC_CHG event from the stack. This is implemented in the loc_task helper module.

The 01-service Sample Application

This application requests a 1000ms service after having joined the network. When it is granted, it queries the 

SmartMesh IP

 stack and prints the bandwidth which has actually been allocated by the 

SmartMesh manager

.

As explained in the SmartMesh IP User's Guide, the

SmartMesh manager

rounds off the bandwidth your request. This is because of the periodic nature of the network's communication schedule. The bandwidth you are assigned may therefore be slightly larger than the bandwidth you requested. In the example below, your request 1000ms, and received 993ms (which is a more bandwidth).

 

The following is a capture of the CLI output of the 01-service sample application:

service app, ver 1.0.0.1
SmartMeshIP stack, ver 1.2.1.3
 23978 : Joining
 24970 : Connected
 31258 : Active
Done joining!
Service granted!
Service:
- dest:   0xfffe
- type:   0
- status: 0
- value:  993 ms
>

Implementation Details

The 01-service sample application uses the Helper Modules to initialize the CLI Module and interaction with the local interface. In particular, it configures the loc_task helper module to join the network and open a socket bound to UDP port 60000.

It uses a single task (serviceTask) which:

  • waits for the loc_task helper module to have joined the network (by pending on the joinedSem semaphore);
  • waits for the loc_task helper module to be granted the requested service service (by pending on the serviceSem semaphore);
  • every 10s, request the current service to the manager (by calling dnm_loc_getAssignedServiceCmd()), and print that over CLI.

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