As I’ve stated in my other post, I’m slowly (but surely!) getting my BRAT to work with Robotics Studio. I have walking and all OUTPUT figured out, but my next step is dealing with input from sensors.
I’ve looked through the SSC32 MSRS code and I’m still hunting for a hint about what commands get input into code. Something like:
int signal = SSC32.getInput("A");would be great, but I’ve learned that things are never that simple. Can anybody point me in the right direction?[/code]
For ease of reference I’m going to talk about 2 services here, A and B. I’m assuming A wants the data and B has the data.
The MSRS model really provides 2 methods for A to get data from B. The most-used version is a publish-subscribe model where A subscribes to changes in B. When a change occurs a message is sent to A with the state of B.
The second model is for service A to send a GET message to service B. The reply to this message will be the entire state of service B.
I’ll give an example for publish/subscribe. Big disclaimer: I’ve done this many times but the code fragments here are just for examples. They might compile directly.
The first thing you need to do near the top of the class is establish ports to the partner service. This can be done statically like this or via communication with the directory service to look them up. There are 2 ports; one is used to communicate to the service and the other is to receive the subscription responses.
[Partner("ServiceB", Contract = serviceB.Contract.Identifier, CreationPolicy = PartnerCreationPolicy.UseExistingOrCreate)]
serviceB.ServiceBOperations _serviceBPort = new serviceB.ServiceBOperations();
serviceB.ServiceBOperations _serviceBNotify = new serviceB.ServiceBOperations();
Further down in the code (this can be done in Start() or somewhere else after the constructor is run) we send a subscribe message to service B. This tells it to send us any changes in the service’s state.
Arbiter.Choice(
_serviceBPort.Subscribe(_gameControllerNotify),
delegate(SubscribeResponseType response) { },
delegate(Fault fault) { LogError(fault); }
);
Once the subscription is performed you need to enable a handler to receive notifications when a change has occurred. This example shows it in the concurrent receive group so other messages could be handled at the same time. If this is a problem you can move it up to the exclusive section where only one message at a time will be handled.
Activate(Arbiter.Interleave(
new TeardownReceiverGroup
( // we have no interleaved handlers
),
new ExclusiveReceiverGroup
(
// we have no exclusive handlers
),
new ConcurrentReceiverGroup
(
Arbiter.ReceiveWithIterator<serviceB.Replace>(true, _serviceBNotify, ServiceBReplaceHandler)
)
));
Now we need the actual handler for the message:
public IEnumerator<ITask> ServiceBReplaceHandler(serviceB.Replace replace)
{
// do whatever you wish with the contents of replace.Body
yield break;
}
That’s all it takes for subscription.
Now, performing the GET is a bit different. In this case you format up a GET message:
serviceB.get getRequest = new serviceB.get(new GetRequestType());
Then send it to the service:
_serviceBPort.Post(getRequest);
Then you need to wait for the response. The wait will occur in a separate thread so you can continue operating.
Activate(
Arbiter.Choice(getRequest.ResponsePort,
delegate(serviceB.ServiceBState response)
{
// handle the data back from service B
},
delegate(Fault fault)
{
LogError("Request for service B state failed.");
})
);
When the delegate is invoked it will have as the variable “response” the entire state of the service.
Hope that helps!
That’s a great summary of how MSRS works in general, but I’m looking for the specific service to subscribe to in Lynxmotion code to get the sensor updates. This is what i have so far:
using Ssc32 = CoroWare.Robotics.Services.Lynxmotion.Ssc32.Proxy;
[Partner("SSC32", Contract = Ssc32.Contract.Identifier, CreationPolicy = PartnerCreationPolicy.UseExistingOrCreate)]
Ssc32.SSC32Operations ssc32Operations = new Ssc32.SSC32Operations();
Ssc32.SSC32Operations ssc32Subscribed = new Ssc32.SSC32Operations();The problem is, there is no valid command such as:
ssc32Subscribed.subscribe(_sensorUpdates);That’s a fake line, because Ssc32.SSC32Operations has no .subscribe() function. Am I looking in the wrong place, or is there a different way to get sensor updates?
While the board has the ability to have some digital inputs connected to it there is no code to read them and produce output as far as I know. You’re going to need to write that part first.
Thanks for the info. That will be my project next semester. A few things in the Lynxmotion MSRS support files should be updated, so I think I’ll work on them while adding the sensor functionality as well.
Has anyone added code to ssc32 to provide a subscribe() function?