Thanks again for your answer Peter! ok, I think I'll do it by myself over websockets. Andy
Am Donnerstag, 11. Dezember 2014 20:51:08 UTC+1 schrieb Peter Donald: > > > Hi, > > ... > >> Names I read when searching for gwt and server push or synchronization >> between server and client are for example: >> >> - gwteventservice >> - RequestFactory >> - gwt-comet >> - Atmosphere >> - Jboss Errai >> >> From that list I would suggest Errai as being the best candidate but I > have not actually used it while the others I have investigated and found > that they didn't work for one reason or another.. > > > In short: >> A framework where I can register a list of Pojos on server side and have >> the corresponding list on client side to work with including the >> possibility to listen for changes on client side. Is there something coming >> close? Of course it would be great if the framework is doing something >> fancy to minimize the necessary traffic too. But the transparent event and >> data exchange is more important than that. >> > > However to be honest I think if I was in your scenario I would simply > create simple json messages on the server and explicitly send them to the > clients. I would typically do this over websockets if supported by the > browser, otherwise use long polling. > > I have attached a response I made to a similar question that may help you. > > > On Fri, Nov 7, 2014 at 7:08 AM, Peter Donald <pe...@realityforge.org > <javascript:>> wrote: > >> Hi, >> >> On Thu, Nov 6, 2014 at 12:07 AM, Marcel K <marcel...@gmail.com >> <javascript:>> wrote: >> >>> Which framework for Server Push do you recommend, since Atmosphere >>> doesn't seem to work with GWT 2.7.0? >>> >> >> It sort of depends on your environment and what your underlying platform >> supports. Below is a response I made to another similar question on the >> mailing list. >> >> In short if you can use latest JEE or jersey then I would recommend that >> you use >> * built-in web sockets ( >> https://github.com/realityforge/gwt-websockets-example/blob/master/src/main/java/org/realityforge/gwt/websockets/example/server/ChatServer.java >> ) >> * addon support for EventSource/ServerSent events ( >> https://github.com/realityforge/gwt-eventsource-example/blob/master/src/main/java/org/realityforge/gwt/eventsource/example/server/ >> ) >> * Servlet 3 async services for long polling ( >> https://github.com/realityforge/gwt-webpoller-example/tree/master/src/main/java/org/realityforge/gwt/webpoller/example/server >> ) >> >> We use all three in our server push apps with GWT clients. >> >> HTH >> >> >> On Fri, Oct 31, 2014 at 5:22 AM, Peter Donald <pe...@realityforge.org >> <javascript:>> wrote: >> >>> Hi, >>> >>> We have built several systems like this where we want to push data to >>> clients from the server. The client is responsible for subscribing to a >>> channel possibly with filters in place. Rather than use GWT-RPC we have >>> tended to move to using raw messages that are typically json blobs. We have >>> used 4 basic strategies depending on the clients supported and the >>> application requirements. The strategies are; >>> >>> 1. WebSockets >>> 2. Server-Sent Events >>> 3. Long polling >>> 4. Periodic Polling >>> >>> I had a poke around and found a good stack overflow answer to this (See >>> [1]) >>> >>> When we faced the same issues, we ended up putting together a couple of >>> libraries >>> to help with in GWT. >>> >>> * websockets: https://github.com/realityforge/gwt-websockets >>> * Server-sent Events: https://github.com/realityforge/gwt-eventsource >>> * Polling: https://github.com/realityforge/gwt-webpoller (Warning this >>> API is not yet at 1.0 status) >>> >>> The tricky part is actually managing the channels and messages >>> sequencing in each channel but we never got arounf to releasing our code >>> for that part of the problem. >>> >>> HTH >>> >>> [1] >>> http://stackoverflow.com/questions/11077857/what-are-long-polling-websockets-server-sent-events-sse-and-comet >>> >> >> -- >> Cheers, >> >> Peter Donald >> > > > On Fri, Dec 12, 2014 at 2:12 AM, andymel <sound...@gmail.com <javascript:> > > wrote: > >> HI Peter, >> >> thank you very much for taking the time to write this very interesting >> post! Especially the 'delta-hierarchy'-graphs and the TransactionRegistry >> will inspire me if I have to implement it by myself. But my main hope was >> that someone could point me to something that handles the synchronization >> between server and client for me. >> >> More about my context: >> My server doesn't use any persistence framework. Different clients >> connect and stream byte data to my server directly to disk. During the >> stream I extract meta data. When the client ends the stream the metadata is >> saved as file to the streamed data on disk. >> The browser gui is used to browse and work with this data in different >> ways and should be updated automatically when new streams arrive. >> >> During my research I found a list of libraries that seem to be meant to >> solve the synchronization between server and gwt-client side objects. >> >> Names I read when searching for gwt and server push or synchronization >> between server and client are for example: >> >> - gwteventservice >> - RequestFactory >> - gwt-comet >> - Atmosphere >> - Jboss Errai >> >> As there is no time to try everything and find all pro and cons before I >> decide my best case scenario would be if someone could point me in the >> right direction after I write down what is needed. >> >> In short: >> A framework where I can register a list of Pojos on server side and have >> the corresponding list on client side to work with including the >> possibility to listen for changes on client side. Is there something coming >> close? Of course it would be great if the framework is doing something >> fancy to minimize the necessary traffic too. But the transparent event and >> data exchange is more important than that. >> >> Only if nothing fits I will implement it by myself. Thanks Peter once >> again for adding a great answer for that exit scenario. >> >> Andy >> >> >> Am Donnerstag, 11. Dezember 2014 01:49:00 UTC+1 schrieb Peter Donald: >>> >>> Hi, >>> >>> So we have several applications where we follow a similar pattern. We >>> use java EE but any framework that allows you to intercept your business >>> services and supports JPA EntityListener's should be capable of directly >>> implementing this. >>> >>> Our EntityListener implementation has a @PostPersist, @PostUpdate and >>> @PreRemove that captures the delta of the jpa entity. These deltas are >>> stored in TransactionSynchronizationRegistry. We need to use the >>> registry rather than thread locals to deal with EJBs that are run in >>> separate threads. >>> >>> Then we add an interceptor on our business services and the >>> boundary/very first service that is invoked by the client is responsible >>> for collecting all the changes out of the >>> TransactionSynchronizationRegistry >>> and routing them to "interested" clients. The clients then receive the >>> deltas and apply them to their local model. The changes are packaged up >>> into one message per transaction, which ensures the client-side state is >>> always consistent. >>> >>> The content based routing is the hard part. Clients subscribe to >>> "graphs". Typically we define graphs that have a single root entity. When >>> an entity delta is routed we allocate it to 0 or more graphs. Then the >>> graphs determine which clients the delta is routed to. Then the deltas are >>> aggregated into a single message for each client. >>> >>> Imagine a domain model as simple as the following. >>> >>> class Company { int id: String name; } >>> class Person { int id: String name; Company company; Person reportsTo; } >>> >>> And there is two possible subscriptions. You can either subscribe to a >>> Company and receive all changes for a company or you can subscribe to a >>> person and all the direct reports. >>> >>> So if we imagine data like >>> >>> Company {1, "Bobs Bobcats"} >>> Company {2, "Marys Mowers"} >>> >>> Person {1, "Bob", 1, null} >>> Person {2, "Bill", 2, 1} >>> Person {3, "Mary", 2, null} >>> >>> So imagine a change happens to Person 2. The change would be associated >>> with the "Supervisor Graph" rooted at Person 1 and it would be associated >>> with the "Company Graph" rooted at Company 1. If a change happens to Person >>> 3. The change would be associated with the "Company Graph" rooted at >>> Company 2. >>> >>> The changes are pushed out to the clients based on a combination of long >>> polling, server-sent events and websockets. >>> >>> Of course this is quite complicated so we have a DSL that generates the >>> majority of this with a couple of extensions points where developers can >>> write routing code etc. >>> >>> Mostly this means have fairly complex apps with up to 80 entities that >>> are replicated to the client with most developers being completely unaware >>> of how it works and being able to write simple code paths. The UI >>> developers only care about receiving changes and reflect them on the UI, >>> the server side developers just write simple state transform code, the >>> network layer is extremely efficient and it is trivial to build >>> multi-client interactive applications. >>> >>> HTH >>> >>> On Wed, Dec 10, 2014 at 4:27 AM, andymel <sound...@gmail.com> wrote: >>> >>>> Hi, >>>> >>>> I think about how to implement a *browser GUI that primarily will show >>>> a list of a lot of data objects*. When something is added to the list >>>> on server side or one of those objects is changed, the client side *GUI >>>> should be updated*. So I need a *server push*. I already have a >>>> websocket connection and used the AutoBean functionality for something >>>> else. In theory I could immediately implement the whole thing by either >>>> pushing the whole list each time something is changed or even do any >>>> suitable caching. But I'm relatively new to GWT and I'm sure there are a >>>> lot of things that I don't know yet. I'm curious* how people with more >>>> experience would implement it*. >>>> >>>> During my research today I discovered the RequestFactory where caching >>>> seems to be included. At least I found the sentence *"Furthermore, the >>>> EntityProxy interface enables RequestFactory to compute and send only >>>> changes ("deltas") to the server.*" Can this be used to have a >>>> List/Result entity on the server and client that is updated automatically >>>> with just a little bit of traffic in between without thinking about what >>>> was changed by myself? >>>> >>>> Do you recommend anything else for this use case? >>>> Thanks in advance! >>>> Andy >>>> >>> >>> -- >>> Cheers, >>> >>> Peter Donald >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "Google Web Toolkit" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to google-web-toolkit+unsubscr...@googlegroups.com <javascript:>. >> To post to this group, send email to google-we...@googlegroups.com >> <javascript:>. >> Visit this group at http://groups.google.com/group/google-web-toolkit. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Cheers, > > Peter Donald > -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. 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