Hi Greg... i would like to know how are we supposed to open the
Channels in the current state of the server and SDK that are served
from a backend, i'm currently opening the channel from within the
backend and passing the token to my frontend but to no avail, here's a
little sample code:
*** On the frontend:
cmd = Command.login(id, password)
campaign= "campanamsl"
# Enqueue on the backend command list
task_name = "backend_%s_counter" % (campaign)
dct = cmd.to_dictionary()
idx = int(memcache.incr(task_name,
initial_value=0))
key_name = "%s_cmd_%i" % (task_name, idx)
memcache.set(key_name, dct, time=1000)
# Wait the token from the backend
channel = None
num = 0
while (channel is None) and (num < 10): # This (1)
loop will unlock when the backend replies with the usr info
channel = memcache.get(key_name+"_resp")
num += 1
if channel is None:
time.sleep(0.01)
if channel is not None:
ent = User(id)
memcache.set(id, ent)
sess['usr'] = ent
sess.save()
self.response.out.write(simplejson.dumps({"sta": ":-)", "chtok":
channel}))
*** On the backend:
cnt = int(memcache.get(self.counter_name)) # counter_name is
the same as task_name in the frontend
if cnt is not None:
while (cnt > self.cmds_count):
self.cmds_count += 1
cmd = memcache.get("%s_cmd_%i" % (self.counter_name,
self.cmds_count))
if (cmd is not None):
command= Command()
command.from_dictionary(cmd)
ent = None
if command.mapa is None:
map = self.campaign.pos['map']
else:
map = int(command.map)
ents = self.ents_per_map[map]
try:
ent = ents[command.origin]
except KeyError:
# Probably a SPAWN or LOGIN
if command.tipo == Command.SPAWN:
ent = memcache.get(command.origin)
elif command.tipo == Command.LOGIN:
# Not verifying user password yet
chan =
channel.create_channel(command.origin)
memcache.set("%s_cmd_%i_resp" %
(self.counter_name, self.cmds_count), chan, time=1000) # This unblock
the (1) loop in the frontend
***
The client side channel gets the token correctly, however nothing is
received on the onmessage event of my channel handler. After a while
the backend instance begins throwing "ProtocolBufferDecodeError:
corrupted" on line 481 on google\net\proto\ProtocolBuffer.py :-(
Please, tell me what i'm doing wrong here (if you can figure it out,
of course)
On 13 mayo, 14:16, "Greg Darke (Google)" <[email protected]>
wrote:
> This sounds like a excellent use of backends.
>
> I believe that there is currently a limitation that a channel created
> in a frontend (ie, your default version) is not able to be used to
> send messages from a backend.
>
> As noted in the Google IO talk, we are currently working on removing
> this restriction. For the moment, you could work around this
> limitation by creating the channel in the backend that you want to
> send messages from, then pass it back to the frontend/user.
>
> On 13 May 2011 02:37, Richard Arrano <[email protected]> wrote:
>
>
>
>
>
>
>
> > Ah that's great news then, I didn't realize that.
>
> > Greg: Thanks for the link, I was a bit misunderstood and didn't see it
> > in the App Engine Samples.
>
> > One thing that's intrigued me about the reserved backend, and it
> > mentions in the documentation, is to keep track of game states. I was
> > hoping someone could tell me if this setup would make sense: if I need
> > to update possibly hundreds of game states, and by update I mean
> > sending out actual updates via the Channel API, I thought I could do
> > this by two separate instances. One of which holds the data(there
> > isn't much data to keep track of, 128MB may be sufficient), the other
> > operates on a while loop that only exits when all games have completed
> > and runs every second or every other second using time.sleep(1000) or
> > 2000. It sends out updates to each client in each game that requires
> > updates, and gets the data from the other backend instance. Then it
> > would sleep until the next iteration. Is this a sensible use of
> > backends or is this actually more suited to tasks? I was originally
> > using tasks that enqueue a new task each following second to
> > accomplish this. Which one would be better and why?
>
> > Thanks,
> > Richard
>
> > On May 12, 11:10 am, "Gregory D'alesandre" <[email protected]> wrote:
> >> On Thu, May 12, 2011 at 3:32 AM, Richard Arrano
> >> <[email protected]>wrote:
>
> >> > Hello,
> >> > I have a few questions about the new Backends feature:
> >> > It seems like a reserved backend allows us to have access to a sort of
> >> > unevictable memcache, is this correct? If I were doing something like
> >> > a game, would it be reasonable to have a single instance keep track of
> >> > a few pieces of vital information about each game? The sum of which
> >> > might be around 1MB of information at any given time.
>
> >> > How would I go about this anyway? Address the reserved instance and
> >> > how would I set a value in its memory?
>
> >> > And just to be clear, there's no free version of Backends, correct?
>
> >> Actually, there is! You get $0.72 worth of backends free per day (this can
> >> be used in any configuration you'd like 9 hours of a B1 or 1 hour of a B8 +
> >> 1 hour of a B1, etc).
>
> >> Greg
>
> >> > Thanks,
> >> > Richard
>
> >> > --
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>
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