Hi DND.. I did mention earlier that I wasn't thinking any 1 particular platform.. I've got more thick client experience than thin, but was thinking that in ASP.Net an async call to the web service/wcf with a callback action may do the trick..
Again.. just thinking out loud. On Wed, Mar 30, 2011 at 9:12 AM, DotNet Dude <adotnetd...@gmail.com> wrote: > On Wed, Mar 30, 2011 at 9:46 AM, Grant Molloy <graken...@gmail.com> wrote: > > Thanks for your input Paul.. > > I'm currently building a DAL which I want to be able to transport between > > projects with no recoding required of the DAL, just configuration.. I've > got > > it all working wonderfully, and is very fast too.. I've coupled this with > a > > code generator which I point at a database (SQL or ORACLE) and can create > > stored procs (SQL or Oracle), model or entity classes (marked up with > class > > and property decorations to work with the DAL) in the click of a few > > buttons. I'm also working on outputting forms, views, view model stubs, > and > > listing and search pages for ASP.Net, WPF and MVC to start with.. > > The DAL can work with any app type really as it's just a DLL and the host > > app just needs some config settings to hook it all up. > > The idea of having updates through the DAL for the host app was something > I > > was just thinking about.. I thought it would be a nice addition to the > DAL > > you just hook up and database data changes are propagated back to the app > > for you.. It's looking like it may be too much trouble, or as you > suggest, > > in the wrong layer of the app.. > > Maybe the following is a better solution.... > > > > SQL Trigger on tables call a .Net assembly from Sql Server (see here) > when > > data is modified. > > The .Net assembly talks to a web service to notify of the db change. > > Apps subscribe to the web service which is setup in the Observer pattern. > > The web service notifies the app of the change > > The app responds to the change as it needs to.. > > Haven't read all the responses on this thread but I don't see how for > a web app a web page can be updated on this notification when the > client's (browser's) connection to the server is already closed. > Unless the client side script polls the server. > > > > > again.. just thinking out aloud... > > > > On Tue, Mar 29, 2011 at 11:54 PM, Paul Stovell <paul.stov...@readify.net > > > > wrote: > >> > >> And note that System.Data.SqlClient.SqlDependency (which uses service > >> broker) is different to System.Web.Caching.SqlCacheDependency (which > uses > >> triggers and polling, making it kind of useless): > >> > >> > >> > >> > >> > http://msdn.microsoft.com/en-us/library/system.web.caching.sqlcachedependency > >> > >> > >> > >> Paul > >> > >> > >> > >> From: ozdotnet-boun...@ozdotnet.com [mailto: > ozdotnet-boun...@ozdotnet.com] > >> On Behalf Of Paul Stovell > >> Sent: Tuesday, 29 March 2011 11:50 PM > >> > >> To: ozDotNet > >> Subject: RE: Propagate Database changes to application > >> > >> > >> > >> This is what I was talking about (I think): > >> > >> > >> > >> http://msdn.microsoft.com/en-us/library/ms172133.aspx > >> > >> > >> > >> Personally I'd probably just poll unless my demand load suggested > >> notifications would work better. > >> > >> > >> > >> Paul > >> > >> > >> > >> From: ozdotnet-boun...@ozdotnet.com [mailto: > ozdotnet-boun...@ozdotnet.com] > >> On Behalf Of Paul Stovell > >> Sent: Tuesday, 29 March 2011 11:45 PM > >> To: ozDotNet > >> Subject: RE: Propagate Database changes to application > >> > >> > >> > >> Correct, though once upon a time I did have an experiment that worked > with > >> query notifications. From memory you attach some kind of SqlDependency > >> object to your SqlCommand (not the type that works with triggers - it > used > >> the same code as clustered views from memory). > >> > >> > >> > >> There is a trade off either way you go. With a notification system you > can > >> end up "drinking from a fire hose" if the events happen too frequently > under > >> load (e.g., an Orders table probably isn't good for notifications). > Systems > >> that rely on polling tend to scale better (for example: this little > thing > >> called the internet) but that's a generalization. > >> > >> > >> > >> Out of curiosity, is this something that needs to happen at the database > >> level? Should more than one process really be writing to the database at > >> once? Could it be done using a messaging system above the database? > >> > >> > >> > >> Paul > >> > >> > >> > >> From: ozdotnet-boun...@ozdotnet.com [mailto: > ozdotnet-boun...@ozdotnet.com] > >> On Behalf Of Grant Molloy > >> Sent: Tuesday, 29 March 2011 9:32 PM > >> To: ozDotNet > >> Subject: Re: Propagate Database changes to application > >> > >> > >> > >> Ok.. > >> > >> well it looks like bindable linq only propagates changes from what it's > >> got in memory already, not from changes in the database.. > >> > >> > >> > >> On Tue, Mar 29, 2011 at 9:26 PM, Grant Molloy <graken...@gmail.com> > wrote: > >> > >> Hi Joseph, > >> > >> > >> > >> I wasn't really looking at any particular single client solution.. > >> > >> > >> > >> If Paul Stovell is listening, what did you use in Bindable Linq.. I am > >> downloading now to have a look, but thought you may be able to put into > >> words for larger audience.. > >> > >> > >> > >> thanks > >> > >> > >> > >> > >> > >> On Tue, Mar 29, 2011 at 9:59 AM, Joseph Cooney <joseph.coo...@gmail.com > > > >> wrote: > >> > >> Re: client type - I was more wondering is it a web app? Windows app? > >> Silverlight? Windows intranet app could do udp broadcast of changes from > the > >> server or something like that. > >> > >> Sent from my iPhone > >> > >> On 29/03/2011, at 8:18 AM, Grant Molloy <graken...@gmail.com> wrote: > >> > >> Thanks everyone for feedback.. > >> > >> > >> > >> Joseph, > >> > >> SQL Server, yes, version either 2008 or 2008 R2.. More than likely R2, > but > >> not nailed down yet. > >> > >> Client type is a DAL DLL.. I want the DAL to know when the data changes, > >> and the client will subscribe to DAL events, and then DAL can fire off > event > >> when data is changed, and App can decide what to do about it. Kind of > like > >> a publisher / subscriber model implementation. > >> > >> > >> > >> I'm not 100% sure I'm going about it the right way or have the events in > >> the right place (ie in the DAL).. > >> > >> > >> > >> On Tue, Mar 29, 2011 at 1:55 AM, Joseph Cooney <joseph.coo...@gmail.com > > > >> wrote: > >> > >> What type of client is it? Do you control the means by which data is > >> written to the table? Are clients deployed to the internet or intranet? > What > >> kind of database are we talking about here (I assume you mean SQL > Server, > >> since you mention SqlDependency) but which version? > >> > >> > >> > >> Joseph > >> > >> > >> > >> On Mon, Mar 28, 2011 at 8:33 AM, Grant Molloy <graken...@gmail.com> > wrote: > >> > >> Hi list, > >> > >> > >> > >> I'm looking to have an application automagically update it's view of the > >> data when the data in the connected database table changes. > >> > >> I've seen two main ways to do this so far. > >> > >> 1. Poll the database every n seconds > >> > >> 2. Use the System.Web.Caching.SqlDependancy object. > >> > >> > >> > >> Does anyone else know of any other better or smarter way of doing this ? > >> > >> > >> > >> thanks > >> > >> Grant > >> > >> -- > >> > >> > >> > >> w: http://jcooney.net > >> > >> t: @josephcooney > >> > >> > >> > >> > >> > >> > >> > >> > > >
