Client Repositories

Similar to the server repositories, client repositories are there to handle the lower-level connection code to the server. As seen earlier in the AI Repositories chapter, client repositories doesn’t necessarily have to be on end-user machines but can also be used on servers. A basic client repository implementation may look as follows or should at least implement the following set of functions to work properly.

from direct.distributed.ClientRepository import ClientRepository
from panda3d.core import URLSpec, ConfigVariableInt, ConfigVariableString
from DGameObject import DGameObject

class GameClientRepository(ClientRepository):

    def __init__(self):
        dcFileNames = ['direct.dc', 'yourOwnDCFile.dc']

        # a distributed object of our game.
        self.distributedObject = None
        self.aiDGameObect = None

        ClientRepository.__init__(
            self,
            dcFileNames = dcFileNames,
            threadedNet = True)

        # Set the same port as configured on the server to be able to connect
        # to it
        tcpPort = ConfigVariableInt('server-port', 4400).getValue()

        # Set the IP or hostname of the server we want to connect to
        hostname = ConfigVariableString('server-host', '127.0.0.1').getValue()

        # Build the URL from the server hostname and port. If your server
        # uses another protocol then http you should change it accordingly.
        # Make sure to pass the connectMethod to the ClientRepository.__init__
        # call too.  Available connection methods are:
        # self.CM_HTTP, self.CM_NET and self.CM_NATIVE
        self.url = URLSpec('http://{}:{}'.format(hostname, tcpPort))

        # Attempt a connection to the server
        self.connect([self.url],
                     successCallback = self.connectSuccess,
                     failureCallback = self.connectFailure)

    def lostConnection(self):
        """ This should be overridden by a derived class to handle an
        unexpectedly lost connection to the gameserver. """
        # Handle the disconnection from the server.  This can be a reconnect,
        # simply exiting the application or anything else.
        exit()

    def connectFailure(self, statusCode, statusString):
        """ Something went wrong """
        exit()

    def connectSuccess(self):
        """ Successfully connected.  But we still can't really do
        anything until we've got the doID range. """

        # Make sure we have interest in the by the AIRepository defined
        # TimeManager zone, so we always see it even if we switch to
        # another zone.
        self.setInterestZones([1])

        # We must wait for the TimeManager to be fully created and
        # synced before we can enter another zone and wait for the
        # game object.  The uniqueName is important that we get the
        # correct, our sync message from the TimeManager and not
        # accidentaly a message from another client
        self.acceptOnce(self.uniqueName('gotTimeSync'), self.syncReady)

    def syncReady(self):
        """ Now we've got the TimeManager manifested, and we're in
        sync with the server time.  Now we can enter the world.  Check
        to see if we've received our doIdBase yet. """

        # This method checks whether we actually have a valid doID range
        # to create distributed objects yet
        if self.haveCreateAuthority():
            # we already have one
            self.gotCreateReady()
        else:
            # Not yet, keep waiting a bit longer.
            self.accept(self.uniqueName('createReady'), self.gotCreateReady)

    def gotCreateReady(self):
        """ Ready to enter the world.  Expand our interest to include
        any other zones """

        # This method checks whether we actually have a valid doID range
        # to create distributed objects yet
        if not self.haveCreateAuthority():
            # Not ready yet.
            return

        # we are ready now, so ignore further createReady events
        self.ignore(self.uniqueName('createReady'))

        # Now the client is ready to create DOs and send and receive data
        # to and from the server

First of all, we need to initialize the ClientRepository. This will handle the connection code to the server. We pass it our dc files as well as the threadedNet parameter which will have the same effect as described in the server repositories.

ClientRepository.__init__(
    self,
    dcFileNames = dcFileNames,
    threadedNet = True)

Having the client repository ready, we can try to connect to the desired server with the ConnectionRepository.connect() call available from the CR. Dependent on the outcome, one of the functions given to the call will be used.

self.connect([self.url],
             successCallback = self.connectSuccess,
             failureCallback = self.connectFailure)

In the connectSuccess method we have to make sure that the client is interested in the correct zones in which a time manager has been instantiated. How the time manager is set up and what it is used for will be shown in a later section. For now we just expect it to exist in zone 1 on the AI Server.

As soon as the client is synced, the TimeManager will send a gotTimeSync event. It is recommended to show some kind of waiting screen to the user at this point until the client is fully connected to the server.

In the syncReady and gotCreateReady methods you’ll see the ClientRepository.haveCreateAuthority() function called. This is a check to see if we are already able to create DOs and give them a correct doId. You can create DOs earlier already, but they may have invalid doIds then.

At the end of the gotCreateReady method you can fully use the client and create whatever DOs you may need and add other client related logic.

At this stage, you may also want to set interest in different zones for the client to see objects created by the server and other clients which are placed in those specific zones. You can do this by calling the ClientRepository.setInterestZones() method which you simply pass a number of zoneIds that this client should see.

ShowBase Client Repository

After setting up your main client repository, you should add it to your ShowBase instance in a variable called cr, as in the following example:

base.cr = MyMainClientRepository()