Cart
|
[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: A question about REST and transaction isolation
 Please pardon me for entering this thread a few weeks later, but stepping out side of REST, this reminds me of some of the emerging Web Services specs. More comments at end. "K. Ari Krupnikov" wrote: > > David Megginson <dmeggin@a...> writes: > > > K. Ari Krupnikov wrote: > > > > > Suppose I want to build a RESTful interface to an ACID system. I want > > > to allow the user to incrementally change the state of the system, but > > > only "commit" the changes when he is satisfied with their sum. I > > > imagine a user GETting a resource, POSTing some changes to it which > > > may have side effects on other resources, GETting other resources to > > > observe the side effects, and eventually committing to the changes or > > > rejecting them. > > > > If the scope of the potential side effects is small and well-defined, > > you might be able to reduce everything to a single exchange: get all > > of the potentially-affected state to the client in a single XML > > document (or collection of XML documents), allow the client to make > > changes locally until satisfied, then post the modified state back to > > the server. Since modifications live on the client side until > > committed, there is no need to come up with any separate URL scheme. > > You are talking about a very thick client here. It's not how much > state there is this application (not much), it's how much logic there > is (a lot). The server already knows how to do this logic. I don't > want to duplicate the logic on the client. I want to use a browser, > and I don't want a ton of JavaScript to handle the state > client-side. A full-blown Java client is a future possibility, but > again, I'd like to keep the business logic in it to a minimum. I > definitively don't want three separate codebases for business logic, > one on the server one in JavaScript (possibly in multiple versions for > different browsers) and one in a Java client. > > Client does presentation, server does business logic. Is that not in > line with REST? > > > This approach would work for, say, a movie database, where the user > > might check out a full movie description to change the director's > > name, then check the entire description in again. It might not work > > so well for, say, a geographical database, where a modification to a > > shoreline may also require corrections to landuse data, roads and > > railroads, and so on, in no easily-predictable way. > > > > It is entirely possibly that your project is one in the second > > category, but I wouldn't give up on the simpler approach until it were > > proven inadequate. Stupid-and-easy usually wins: moving 50K of XML > > each way once can be much more efficient than many 100 byte > > transactions. > > It's not about reducing redundant traffic, it's about reducing > redundant logic. One node should know how to do a process, be the > final authority and bear the ultimate responsibility for that process. > > Ari. Stepping away from REST for a second (but acknowledging that REST was your main intent), this is the essence of service-oriented architectures (SOAs) - shared (non-redundant) business logic encapsulated as shared services that can be published, discovered, and bound/invoked (at design time and/or run time). The coordination aspects you discuss above are covered by emerging specifications such as IBM/Microsoft/BEA's WS-Coordination/WS-Transaction (WS-Transaction is now segmented into 2 specs, WS-AtomicTransaction and WS-BusinessActivity) [1][2], WS-Resource Framework (WSRF) [3] from the Globus Alliance/IBM/HP, and OASIS Composite Application Framework [4]. References [1][2][4] involve the specification of a "coordinator" that coordinates the actions of multiple Web services for requirements such as 2-phase commits, error notification, etc. Reference [3] addresses interations of Web services with stateful resources. It is important to note that none of these specifications are "open standards" (in OASIS and W3C-"like" terms) - the one closest to becoming an open standards at this point is WS-CAF. Kind Regards, Joe Chiusano Booz | Allen | Hamilton Strategy and Technology Consultants to the World [1] http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnglobspec/html/wscoor.asp [2] http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnwebsrv/html/wsacoord.asp [3] http://www-fp.globus.org/wsrf/ModelingState.pdf [4] http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=ws-caf > -- > Elections only count as free and trials as fair if you can lose money > betting on the outcome. > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org <http://www.xml.org>, an > initiative of OASIS <http://www.oasis-open.org> > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > To subscribe or unsubscribe from this list use the subscription > manager: <http://lists.xml.org/ob/adm.pl> 
|
PURCHASE STYLUS STUDIO ONLINE TODAY!Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced! 
Download The World's Best XML IDE!Accelerate XML development with our award-winning XML IDE - Download a free trial today! Subscribe in XML format
|
|||||||||
