dhis2-devs team mailing list archive

[Mark Polak <mark@xxxxxxxxx>]

Hey Dehan,

Sorry for the slow response from my side.

It is true that SPA applications have better responsiveness while using the
app. The goal of the project is then also not to totally replace the SPA
stuff with rendering on the server.

The goal of the project is more to see if/how we can utilise the
capabilities that Nashorn gives us to pre-render the initial SPA payload on
the server. Due to the nature of React its "diffing" of the DOM the SPA
could "continue" on the client side. This could potentially save some
requests which (in some of our working areas, high latency places) could be
a good thing. Also a reduced "perceived loading time" gives a more pleasant
user experience in general.

As the product (DHIS2) is primarily a web application, that is behind a
login wall, we generally don't have much to index for search engines.
Therefore this benefit is not really of importance. As an additional
benefit (not initially part of the task description, but could be added if
enough time, the Nashorn integration could enhance our architecture of
custom apps (which are currently client side Javascript only) with the
ability to run server side code and possibly even interact with the service
layer. (I'm just thinking out loud here ;))

Regarding your concern of the increased payload. I don't believe the
payload increase would decrease performance that much, but during the
development of the test cases we could see if this concern is legitimate
and see if there is perhaps a hybrid/different solution. I think the
project in general is more of a prototyping experience and a change to work
with cool fairly cutting edge stuff ;)

Regards,

Mark

On Wed, Mar 9, 2016 at 6:56 PM, Dehan De Croos <dehandecroos@xxxxxxxxx>
wrote:

> Hi Mark Polak,
>
> I am Dehan currently finishing off my final year at University of
> Moratuwa, Sri Lanka. I am really interested in web technologies and
> therefore also this project.
>
> Considering the project idea, it has the idea of partial rendering
> introduced to increase performance or
> as per the article sighted in the project idea page improve web crawler
> indexing[1]
>
> It's true that a SPA takes time to load initially, but after the initial
> loading point the SPA performance is greatly increased because now only a
> simply JSON/XML data structure is called for each REST call. But there is
> the obvious drawback when indexing because when using mechanisms like
> angular routing I assume they will not be crawled again as per the article
> provided earlier.
>
> But if indeed the startup time is what you are looking at to reduce,
> wouldn't it come at a cost of each page taking more time to lead due to the
> increased markup which now should be brought in for each request?. Isn't it
> better to sacrifice more start up time to have more responsiveness when
> actually using the web app? which is the principal behind SPAs?
>
> Furthermore which version of Spring is used ? Is it Spring 4 and beyond or
> a version before that?
>
>
> If we are to work with Nashorn we will have to work with Clojure I
> guess?[2]
>
>
>
> [1] - http://augustl.com/blog/2014/jdk8_react_rendering_on_server/
> [2] -
> https://carouselapps.com/2015/09/11/isomorphic-clojurescriptjavascript-for-pre-rendering-single-page-applications-part-1/
>
> best regards,
> *Dehan de Croos*
>
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