[aerogear-dev] Client Paging Strawman

Kris Borchers kris at redhat.com
Tue Jan 15 08:52:53 EST 2013 

Though this discussion has been great, I feel like it has headed "down a path I (JS) cannot follow". Luke, that Star Wars quote was for you. ;)

When doing a read() (or next() or prev()…), I would expect the exact same type of response, which is a list of objects. This is easily accomplished in JS, we overload the read method to accept a parameter that tells it to use paging and which page to grab and then return only the results that were requested. This can then be made easier with helper functions like next(), prev(), etc. that use the overloaded read() method so the dev doesn't even need to know it exists of they don't want. This would be accomplished by maintaining the current paging state on the pipe so a call to next() just knows what to do. Also, via a couple of setter methods on the pipe instance, we can adjust the offset and limit at any time.

I honestly feel like this is going to be the best developer experience on JS, I just don't know how or if it even makes sense for iOS and Java to try to get there but for JS I just can't get myself onboard with this idea of returning an object that contains next(), prev(), etc. methods instead of just the data that the user wants.

On Jan 15, 2013, at 7:45 AM, Sebastien Blanc <scm.blanc at gmail.com> wrote:

> Just to summarize what have until now :
> 
> 1. Kris's proposition: https://gist.github.com/4531575
> 
> 2. Summers's proposition: https://gist.github.com/4532661
> 
> 3. qmx's propositon: https://gist.github.com/4538709
> 
> 4. Sebi's propositionhttps://gist.github.com/4538725
> 
> 
> 
> 
> On Tue, Jan 15, 2013 at 2:32 PM, Matthias Wessendorf <matzew at apache.org> wrote:
> On Tue, Jan 15, 2013 at 2:25 PM, Matthias Wessendorf <matzew at apache.org> wrote:
> > I was wondering, if the result should be received on every rquest,
> 
> 
> ideally on the callback..., to not block (at least in iOS land, I
> would pass that "result set" on to the "success" block)
> 
> -M
> 
> >
> > thx
> >
> > On Tue, Jan 15, 2013 at 2:01 PM, Sebastien Blanc <scm.blanc at gmail.com> wrote:
> >> In the same spirit (inspired from
> >> http://stackoverflow.com/questions/5412059/how-to-implement-general-pagination)
> >> :
> >>
> >>
> >> public interface PagedResult<T> {
> >>
> >>     PagedResult<T> next();
> >>
> >>     PagedResult<T> prev();
> >>
> >>     PagedResult<T> withOffset(int offset);
> >>
> >>     PagedResult<T> withLimit(int limit);
> >>
> >>     List<T> result();
> >>
> >> }
> >>
> >>
> >> On Tue, Jan 15, 2013 at 1:38 PM, Douglas Campos <qmx at qmx.me> wrote:
> >>>
> >>> I'm not a fan of those PageContext objects (remembers me of some wild-ass
> >>> ThreadLocals leaking all over)
> >>>
> >>> My proposal for the paging aware APIs would be something like this:
> >>>
> >>> public interface PagedResult<T> {
> >>>
> >>>     List<T> next();
> >>>
> >>>     List<T> prev();
> >>>
> >>>     List<T> page(int offset, int limit);
> >>>
> >>> }
> >>>
> >>> and the Async counterpart
> >>>
> >>> public interface AsyncPagedResult<T> {
> >>>
> >>>     void next(Callback<List<T>> callback);
> >>>
> >>>     void prev(Callback<List<T>> callback);
> >>>
> >>>     void page(int offset, int limit, Callback<List<T>> callback);
> >>>
> >>>     public static interface Callback<U> {
> >>>         public void onResult(U result);
> >>>     }
> >>> }
> >>>
> >>> I don't like the idea of having a companion object for holding the
> >>> pagination state.
> >>>
> >>> Thoughts?
> >>>
> >>> -- qmx
> >>>
> >>> On 15/01/2013, at 08:37, Matthias Wessendorf <matzew at apache.org> wrote:
> >>>
> >>> > Hi Summers,
> >>> >
> >>> >
> >>> > https://gist.github.com/4532661
> >>> >
> >>> > That is a way to do paging which keeps Pipes immutable, uses
> >>> > readWithFilter, and doesn't impose any (for convenient definitions of any)
> >>> > bookkeeping on the developer.
> >>> >
> >>> >
> >>> > from your Andorid gist:
> >>> >
> >>> > A) Once the response has been received, the Pipe implementation will
> >>> > return a List of objects. If this List instance is passed to
> >>> > Pipe.getPageContext the appropriate PageContext will be returned
> >>> >
> >>> > Note: There is no 'return' - the readWithFilter is void, instead a
> >>> > Callback is invoked (onSuccess(list)), see Pipe.java
> >>> >
> >>> > B) The developer will receive from readWithFilter() a List of object. If
> >>> > she passes this list into Pipe.getPageContext(List result) she will receive
> >>> > the PageContext associated with this result.
> >>> >
> >>> > Do you mean like:
> >>> >
> >>> > ...
> >>> > myPipe.readWithFilter(filter, new Callback<List<Data>>() {
> >>> >
> >>> >
> >>> > @Override
> >>> >
> >>> >
> >>> > public void onSuccess(List<Data> data) {
> >>> >
> >>> >
> >>> >
> >>> > // get the PageContext:
> >>> >
> >>> >
> >>> > PageContext ctx = myPipe.getPageContext(data);
> >>> >
> >>> >
> >>> > ...
> >>> >
> >>> >
> >>> > }
> >>> >
> >>> >
> >>> >
> >>> > @Override
> >>> >
> >>> >
> >>> > public void onFailure(Exception e) {
> >>> >
> >>> >
> >>> > }
> >>> > });
> >>> > Not sure about that.....
> >>> >
> >>> > But for iOS I am thinking about passing in the PageContext into the
> >>> > closure/block of the readWithFilter, like:
> >>> >
> >>> > -(void) readWithFilter:(void (^)(id<AGFilterConfig> config)) config
> >>> >
> >>> >
> >>> > success:(void (^)(id listOfObjects, id pageContext))success
> >>> >
> >>> >
> >>> > failure:(void (^)(NSError *error))failure;
> >>> > A usage would look like:
> >>> >
> >>> >     [pipe readWithFilter:^(id<AGFilterConfig> config) {
> >>> >
> >>> >
> >>> > // set the filter args and override the given defaults
> >>> >
> >>> >
> >>> > } success:^(id listOfObjects, id pageContext) {
> >>> >
> >>> >
> >>> > // work with the listOfObjects reponse.
> >>> >
> >>> >
> >>> > // for paging/query info, access the given pagecontext,
> >>> >
> >>> >
> >>> > // of the CURRENT request
> >>> >
> >>> >
> >>> > ...
> >>> >
> >>> >
> >>> > } failure:^(NSError *error) {
> >>> >
> >>> >
> >>> > // handle errorz
> >>> >
> >>> >
> >>> > }];
> >>> > Any thoughts ?
> >>> >
> >>> > Not sure I like (or understand) the Pipe.getPageContext(List result)
> >>> > call. Current mindset is that thePageContext just (and only) belongs to the
> >>> > previous (executed) request... Not sure I want to support something like
> >>> >
> >>> > // first call:
> >>> > List<SomeType> first;
> >>> > myPipe.readWithFilter(.....) // set first inside of callback
> >>> > ...
> >>> > // second call:
> >>> > List<SomeType> second;
> >>> > myPipe.readWithFilter(.....) // set second inside of callback
> >>> > ...
> >>> > // third call:
> >>> > List<SomeType> third;
> >>> > myPipe.readWithFilter(.....) // set third inside of callback
> >>> > ...
> >>> >
> >>> >
> >>> >
> >>> >
> >>> > /// A BIT LATER ....:
> >>> > myPipe.getPageContext(first);
> >>> >
> >>> >
> >>> > I am not sure if that (myPipe.getPageContext(first);) is really desired
> >>> > (or would even easily work, as it would need to store the "metadata").....
> >>> >
> >>> >
> >>> > Perhaps I am just wrong.
> >>> >
> >>> >
> >>> > --
> >>> > Matthias Wessendorf
> >>> >
> >>> > blog: http://matthiaswessendorf.wordpress.com/
> >>> > sessions: http://www.slideshare.net/mwessendorf
> >>> > twitter: http://twitter.com/mwessendorf
> >>> > _______________________________________________
> >>> > aerogear-dev mailing list
> >>> > aerogear-dev at lists.jboss.org
> >>> > https://lists.jboss.org/mailman/listinfo/aerogear-dev
> >>>
> >>>
> >>> _______________________________________________
> >>> aerogear-dev mailing list
> >>> aerogear-dev at lists.jboss.org
> >>> https://lists.jboss.org/mailman/listinfo/aerogear-dev
> >>
> >>
> >>
> >> _______________________________________________
> >> aerogear-dev mailing list
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> >> https://lists.jboss.org/mailman/listinfo/aerogear-dev
> >>
> >
> >
> >
> > --
> > Matthias Wessendorf
> >
> > blog: http://matthiaswessendorf.wordpress.com/
> > sessions: http://www.slideshare.net/mwessendorf
> > twitter: http://twitter.com/mwessendorf
> 
> 
> 
> --
> Matthias Wessendorf
> 
> blog: http://matthiaswessendorf.wordpress.com/
> sessions: http://www.slideshare.net/mwessendorf
> twitter: http://twitter.com/mwessendorf
> _______________________________________________
> aerogear-dev mailing list
> aerogear-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/aerogear-dev
> 
> _______________________________________________
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