[mapguide-internals] Re: Please review RFC 66

[Trevor Wekel]

Hi Zac,

I think ResourceExists is implemented in 2.1.  I wonder if MgResourceService.ResourceExists would work on the root of the session repository "Session:xxyyzz-abc//"?  Alternatively you could check for the existence of the MgMap object "Session:xxyyzz-abc//MyMapName.Map".

ResourceExists does return a boolean.

Thanks,
Trevor

________________________________________
From: mapguide-internals-bounces at lists.osgeo.org [mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Zac Spitzer [zac.spitzer at gmail.com]
Sent: Monday, June 22, 2009 2:10 AM
To: MapGuide Internals Mail List
Subject: Re: [mapguide-internals] Re: Please review RFC 66

Frustratingly, there isn't currently a nice simple way to check if a
session is valid without getting into exception and error log territory

Adding something like MgSite.isValidSession(sessionId) which returns
a boolean result would be really useful and elimate the need for klunky
workarounds.

z


On Mon, Jun 22, 2009 at 4:55 PM, Kenneth Skovhede, GEOGRAF
A/S<ks at geograf.dk> wrote:
> 1)
> On my setup "GETFEATUREPROVIDERS" returns 13Kb worth of xml.
> It may not consume CPU resources, but it does consume bandwidth,
> especially since it is not required, and it happens a fixed intervals,
> even if the user is inactive.
>
> If its too much work to put in a real function, I think Zac's proposal is
> way better,
> but I'm not sure it will work if admin functions are disabled in the
> WebTier.
>
> 2)
> There is a clear 1-1 relation between the server timeout setting and the
> client ping setting.
> If you can read the timeout value on viewer startup, that is fine, but I
> don't think you can.
>
> If you require the admin-user to change the time in two places, you can be
> certain
> that there will be a pile of support requests.
> Also, for a non-specialist, it is not immediately obvious that the two
> should not be the
> same, eg. setting both to 15 minutes will make the sessions expire at
> random, due to races
> and clock drift.
>
> 3) I have seen scenarios where a single reqest fails.
> If you know the duration of the session, it is easy to ignore "connection
> broken" responses,
> and only stop pinging when there has been no positive response within a
> session duration.
>
> I think you need to adress issue 1 and 2.
> Issue 3 is easy and will improve failure resilience, but not required.
>
> Regards, Kenneth Skovhede, GEOGRAF A/S
>
>
>
> Zac Spitzer skrev:
>>
>> how about GETSITEVERSION ? that's what I have used for keepalives in
>> my own stuff
>> and it returns a much smaller response?
>>
>> z
>>
>> On Mon, Jun 22, 2009 at 4:05 PM, Christine
>> Bao<Christine.Bao at autodesk.com> wrote:
>>
>>>
>>> Hi Kenneth,
>>>
>>>    Thank you for your suggestion. Here are my comments:
>>>
>>>
>>> 1.       A real function to support "keep alive" pings
>>>
>>> We plan to call "GETFEATUREPROVIDERS" through MapAgent to keep alive.
>>> This function is light-weighted and won't cause much overhead. Using this
>>> method is the easiest way to approach it. Your suggestion makes sense, but
>>> we'll need to add another API which is only for this purpose, so we decide
>>> not to do this.
>>>
>>>
>>>
>>> 2.       The client read out timeout value to adjust ping interval
>>>
>>> I'm afraid it's too much complicated. The plan is to ping server at a
>>> fixed time interval (of course you can set it in configuration), and the
>>> interval won't change during runtime. It works as Fusion does.
>>>
>>>
>>>
>>> 3.       Connection broken
>>>
>>> Once the connection broken or timeout because server down, the client
>>> will stop ping server. But it will not recovery from a broken/timeout
>>> session.
>>>
>>> Thanks & regards,
>>> Christine
>>>
>>>
>>> ------------------------------
>>>
>>>
>>>
>>> Message: 3
>>>
>>> Date: Fri, 19 Jun 2009 12:41:14 +0200
>>>
>>> From: "Kenneth Skovhede, GEOGRAF A/S" <ks at geograf.dk>
>>>
>>> Subject: Re: [mapguide-internals] RE: Please review RFC 66
>>>
>>> To: MapGuide Internals Mail List <mapguide-internals at lists.osgeo.org>
>>>
>>> Message-ID: <4A3B6B4A.7050206 at geograf.dk>
>>>
>>> Content-Type: text/plain; charset=ISO-8859-3; format=flowed
>>>
>>>
>>>
>>> I commented on the issue as well.
>>>
>>>
>>>
>>> You are free to ignore it, but in case you somehow missed it, here it is:
>>>
>>> http://n2.nabble.com/Please-review-RFC-66-tc3090381.html#a3092233
>>>
>>>
>>>
>>> Regards, Kenneth Skovhede, GEOGRAF A/S
>>>
>>>
>>>
>>> _______________________________________________
>>> mapguide-internals mailing list
>>> mapguide-internals at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/mapguide-internals
>>>
>>>
>>
>>
>>
>>
>
> _______________________________________________
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> mapguide-internals at lists.osgeo.org
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>



--
Zac Spitzer -
http://zacster.blogspot.com
+61 405 847 168
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