Re: [Pharo-dev] Chrome DevTools Protocol and Pharo

(Moving to pharo-users as Serge suggested)

Sending the email also made me realise that it would be possible to
check for the presence of a particular node while waiting for Chrome to
load the page, which would avoid the long timeout.  I'll look at adding
this later.

Cheers,
Alistair


On Sun, May 28, 2017 at 10:49:14AM +0700, [hidden email]
wrote:
> Thank you guys for your contributions, but I think that this kind of
> discussions should be done on pharo-users mailing-list, not here.
>
> pharo-dev should be use only if you contribute to core-pharo.
>
> Thank you
>
> Envoy? de mon iPhone

>
>     On May 27, 2017, at 3:23 PM, Alistair Grant [via Smalltalk]
>     <[hidden email]
>     > wrote:
>
>
>         Hi Torsten and All,
>
>         Quick Introduction for those not familiar with Pharo-Chrome:
>
>         Pharo-Chrome enables Pharo to control and query Chrome /
>         Chromium, in particular to retrieve the DOM of a page.  This
>         is useful as many modern pages are just a template which then
>         loads some javascript to asynchronously build the DOM, meaning
>         that the ZnEasy / Soap combination doesn't get the bulk of the
>         information on a page.
>
>
>
>         Pharo-Chrome is now mostly working, i.e. it is possible to
>         open a connection to Chrome, navigate to a requested URL, wait
>         for it to load, retrieve the DOM and then navigate the DOM
>         using a subset of the Soap API, e.g. #findAllStrings:,
>         #findAllTags:, attributeAt:, etc..
>
>         GoogleChrome class>>exampleNavigation has been updated to
>         retrieve the DOM from http://pharo.org.
>
>         GoogleChrome class>>get: is analogous to ZnEasy class>>get:,
>         although it returns a ChromeNode, not an html string.
>
>         I wasn't able to get rid of the delay while waiting for the
>         page to finish loading.   This actually makes sense, since, as
>         mentioned above, many modern pages build the DOM
>         asynchronously, so there's no clear indication of when it is
>         complete.  The default delay is currently 2000 milliseconds,
>         which is about twice the maximum I saw needed (983ms), but
>         this can be changed (ChromeTabPage>>pageLoadDelay:).
>
>         I had three use cases for this library: one which works with
>         ZnEasy+Soap, one that used to work with ZnEasy+Soap, but
>         doesn't due to a page redesign, and one which I hadn't got
>         working before.  All three are working now.
>
>         Unlike Soap, I've currently modelled the nodes as a single
>         class, and have only implemented a subset of Soap's methods,
>         but is enough for what I need.
>
>         I've introduced a dependency on the Beacon logging framework.
>         I find it useful, but can remove it if you don't want the
>         additional dependency.  (I'm planning to add some GoogleChrome
>         specific logging classes and use those to better understand
>         what pageLoadDelay should be).
>
>         I was focussed on trying to understand the events that Chrome
>         generates, so documentation is still lacking (read "missing"
>         :-)).
>
>         I'll generate a pull request after some more testing, tweaking
>         and documenting, but if you would like to take a look, the
>         code is available at:
>
>         https://github.com/akgrant43/Pharo-Chrome/tree/development
>
>         I haven't yet updated BaselineOfChrome with the Beacon
>         dependency.  I did merge in your two commits from May 23.
>
>         If you, or anyone else, finds this useful, I welcome any
>         feedback.
>
>         P.S.  I've just realised that I need to tidy up #sendMessage:,
>         #sendMessageDictionary and #sendMessageDictionary:wait:.  I'll
>         do that as part of the genral tidy up.
>
>         Cheers, Alistair
>
>

>         On Sun, May 21, 2017 at 09:37:56PM +0000,
>         Alistair Grant wrote:
>
>         > Hi Torsten,
>         >
>         > On Fri, May 19, 2017 at 09:20:48PM +0000, Alistair Grant
>         > wrote:
>         > >
>         > > On Fri, May 19, 2017 at 10:50:41PM +0200, Torsten Bergmann
>         > > wrote:
>         > > > Hi Alistair,
>         > > >
>         > > > cant look right now but two things:
>         > > >
>         > > >   - there are also events in the protocol - if we could
>         > > >   hook Pharo into them
>         > > >   this would solve the problem without abusing delay
>         > > >   (because then you will
>         > > >     get informed when the page loading is finished)
>         > >
>         > > That would be great.  It will be a while before I get a
>         > > chance to look
>         > > at this (I want to finish some proposed changes to the
>         > > FileSystem packages first), but I'll try and include it
>         > > then.
>         >
>         > I've got basic event listening working.  It requires that
>         > all messages
>         > are read asynchronously, so I'll need to change the
>         > interface to handle that.
>         >
>         > Knowing when a page has finished loading isn't quite as
>         > simple as looking for an event - a page can consist of
>         > multiple frames, and notifications are delivered for each
>         > frame.  The page I'm interested in
>         > has around 25 frames.
>         >
>         > If anyone has a good design pattern for writing an
>         > asynchronous WebSocket client please let me know, I don't
>         > have anything concrete in mind.
>         >
>         > Thanks, Alistair