Hi Adligo, On Thu, Sep 10, 2009 at 6:15 PM, Adligo <sc...@adligo.com> wrote:
> > Hi All, > > Ok this is all very interesting, and in a nut shell GAE isn't true > J2EE impl. So now I am wondering; Is there a way to tell if my servlet is running on GAE? > As far as I'm aware, the J2EE specification doesn't provide any guidelines for supporting 'hanging gets' or minimum/maximum request durations. > > This may seem like a really stupid question, however if you think > about it a little from my point of view IT's NOT. The reason I am > asking it is because I am trying to write Components (Server and Client > [browser] side), which are for sale. So I may not be the one > installing some of these Components, and it would be nice if the > Component could simply figure out if it was running on GAE. Otherwise > I will need to put some configuration settings in place; > Something like > web.xml > .... isGae=true > isGae=false > I can tell you how to do this in Python (check the 'SERVER_SOFTWARE' environment variable), but I'm not familiar with how to check it in Java. You're probably better off asking this on the google-appengine-java group. -Nick Johnson > > Cheers, > Scott > > On Sep 9, 5:24 am, "Nick Johnson (Google)" <nick.john...@google.com> > wrote: > > Hi Adligo, > > > > > > > > On Tue, Sep 8, 2009 at 6:39 PM, Adligo <sc...@adligo.com> wrote: > > > > > Hi Nick, > > > > > Please see below; > > > > > On Sep 4, 10:04 am, "Nick Johnson (Google)" <nick.john...@google.com> > > > wrote: > > > > Hi Adligo, > > > > App Engine is not really designed for 'long polling' setups like you > > > > describe. Since the number of simultaneous runtimes your app has at a > > > given > > > > traffic level is limited, waiting like this will consume them all > very > > > > quickly. > > > I understand this, which is why I was asking if you could pay for > > > more. > > > So can you? > > > > No. As stated, this is not something App Engine is designed to support, > and > > thus your number of concurrent requests is limited proportional to the > > traffic your app gets. > > > > > > > > > > > > > > Also, because your app may be distributed over many computers, a > > > > synchronization primitive like the one you're using will not work - > the > > > > process doing the notifying may not be on the same machine as the > > > > process(es) that need notifying! > > > Well this depends a little on Session management, the > > > ArrayBlockingQueue > > > I mentioned is stored as a Session Attribute. I assume that the app > > > engine must be > > > keeping the Session in a location that can be accessed by all > > > threads. Otherwise how > > > could anyone maintain any sort or security on the server side (most > > > Jaas HttpFilters I have seen store the Subject[User] as a Session > > > Attribute, including 2 that I wrote by hand for custom requirements > > > and Spring security) ? > > > > The issue is not multiple threads on one runtime, but the fact that a > single > > App Engine app may be running on multiple runtimes, on multiple separate > > machines. You cannot expect a standard locking primitive to function > across > > multiple machines. > > > > Or in other words how does the app engine treat HttpSessions and their > > > > > attributes, in the normal J2EE way, or some other way? > > > > Sessions are stored in the datastore. > > > > -Nick Johnson > > > > > > > > > > > > > Cheers, > > > Scott > > > > > > -Nick Johnson > > > > > > On Thu, Sep 3, 2009 at 9:06 PM, Adligo <sc...@adligo.com> wrote: > > > > > > > Hi Nick, > > > > > > > I am not calling sleep but I am using a server side > > > > > ArrayBlockingQueue, with methods like > > > > > queue.poll(waitTime, TimeUnit.SECONDS); > > > > > So I am not buffering but simply responding with current messages > > > > > and if there arn't any waiting until some show up and then > > > > > responding. If no messages show up in 20 seconds or so I respond > with > > > > > a empty message list and then the client sends a new request. > > > > > > > I am using GWT's rpc, here is my service api, which is open souce. > > > > > > > > http://cvs.adligo.org/viewvc/gwt_util/src/org/adligo/gwt/util/client/. > > > .. > > > > > > > So I am anticipateing that I will have a lot of threads that are > > > > > simply waiting on the ArrayBlockingQueue's poll method. This > allows > > > > > me to do things like; > > > > > 1) send log messages between two browser windows > > > > > 2) send system messages from a admin console to anyone viewing the > app > > > > > like; > > > > > (System is going off line in 10 minutes) > > > > > (There is pizza in the lobby for anyone who wants it) > > > > > exc > > > > > 3) Implement a IM client in the browser > > > > > 4) Send 'event' data between browser windows so a user can click a > > > > > button in one window > > > > > and have it do something to another window. Currently the > only > > > > > application of this is to > > > > > reload the adligo_log.properties file, so you can change your > log > > > > > levels at runtime. However > > > > > there are a lot of other applications for this, windows can now > > > > > communicate. > > > > > > > Also there shouldn't be much of a drain on the processor, since > most > > > > > of the threads are simply waiting (not doing a lot of processing). > It > > > > > just requires a large number of threads (one per browser window). > > > > > > > Cheers, > > > > > Scott > > > > > > > PS I would really like to host on Google Apps, the server > > > > > > http://zeuhl.adligo.com/gwt_util_demo_v3_1/GwtDemo.html?show_log=true > > > > > was down all morning, since I had my phone turned off to respect > for a > > > > > concert last night I didn't get a 'your server is down' text from > > > > > hosttracker.com. > > > > > > > On Sep 3, 3:51 am, "Nick Johnson (Google)" < > nick.john...@google.com> > > > > > wrote: > > > > > > Hi Adligo, > > > > > > The limit on concurrent instances of your app is not a hard one - > it > > > will > > > > > > increase as your app gets more traffic. The only situation you're > > > likely > > > > > to > > > > > > run into it is if you have a lot of requests that take a long > time to > > > > > > complete - eg, if you're calling time.sleep() in your request > > > handler. As > > > > > > long as you're serving your requests reasonably efficiently, you > can > > > > > expect > > > > > > the number of concurrent requests your app is allowed to scale up > > > with > > > > > load. > > > > > > > > -Nick Johnson > > > > > > > > On Wed, Sep 2, 2009 at 1:33 AM, Adligo <sc...@adligo.com> wrote: > > > > > > > > > Hi, > > > > > > > > > I am developing a app (or more than one) that I would like to > > > host > > > > > > > on Google App Engine, however the architecture of the app > involves > > > > > > > cranking up the maxThreads (I am using my home grown hosting > which > > > now > > > > > > > has Tomcat set to 2,000 maxThreads :) ). > > > > > > > > > For example (1 six+ year old machine in my basement) > > > > >http://zeuhl.adligo.com/gwt_util_demo_v3_1/GwtDemo.html?show_log=true > > > > > > > > > I was reading somewhere that my app will be limited to 30 Max > > > > > > > simultaneous requests (maxThreads), and I didn't see anything > about > > > > > > > being able to change this (EVEN IF YOU PAY FOR IT). > > > > > > > > > So is it possible to change this? > > > > > > > If not why, it should be billable like everything else... > > > > > > > How much would it cost? > > > > > > > > > Also I think that it seems like a silly limit (although > probably a > > > > > > > good starting point for most apps). Some apps need a lot of > > > threads, > > > > > > > some have a lot of page requests. > > > > > > > For instance my app needs a lot of threads (the above > version > > > uses > > > > > > > at least 1 per user ALL THE TIME) and will go to 2 per user in > the > > > > > > > next release :) Or rather to be more specific One thread per > open > > > > > > > browser window, so I can 'send' data to the browser window in > near > > > > > > > real time with out having the browser window send a request > every > > > > > > > millisecond (which causes other problems). > > > > > > > So it will be limited to 15 users on Googles App Engine yikes! > > > > > > > > > Cheers, > > > > > > > Scott > > > > > > > > -- > > > > > > Nick Johnson, Developer Programs Engineer, App Engine- Hide > quoted > > > text - > > > > > > > > - Show quoted text - > > > > > > -- > > > > Nick Johnson, Developer Programs Engineer, App Engine- Hide quoted > text - > > > > > > - Show quoted text - > > > > -- > > Nick Johnson, Developer Programs Engineer, App Engine > > > -- Nick Johnson, Developer Programs Engineer, App Engine --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. 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