D Web Services Application Potential?

[Rikki Cattermole via Digitalmars-d]

On 29/07/2015 12:12 p.m., Brandon Ragland wrote:
> On Monday, 27 July 2015 at 06:10:29 UTC, Sebastiaan Koppe wrote:
>> On Monday, 27 July 2015 at 04:11:50 UTC, Rikki Cattermole wrote:
>>> What I currently have is code templates as follows:
>>>
>>> <?lua
>>>     echo("<p>" .. consumeNextText() .. "</p>")
>>> ?>
>>>
>>> Hi there, this is some text!
>>> Woopity doo.
>>>
>>> <?lua
>>>     include_text("<?lua echo(\"boo\") ?>")
>>> ?>
>>>
>>> So it would output something like:
>>> <p>
>>> Hi there, this is some text!
>>> Woopity doo.
>>> </p>boo
>>>
>>> The languages supported would have to be known and configured at
>>> compile time. But theoretically other languages such as Squirrel and
>>> PHP should work.
>>> D on the other hand, would be ugh hard.
>>>
>>> I will be supporting the ability to pass in e.g. data models and even
>>> query them. Thanks to reflection that I've added since Cmsed.
>>
>> I don't think it makes sense doing any page rendering in D, there are
>> plenty of good tools that you don't want to compete with.
>>
>> For instance, for rendering pages I would rather front the D backend
>> with some (stateless) node app that fetches the data from the D
>> backend and uses something like React to render server/client side. If
>> the D backend could implement the upcoming GraphQL that would be awesome.
>>
>> It has the benefit that a) the frontend-end devs still get their
>> familiar language, tools and libraries; and b) that all the real stuff
>> happens in D.
>>
>> But I thought this was about Web Services Applications? Which I assume
>> to be the outer container/process manager that allows services to be
>> registered, re-loaded, routed, etc.
>
> The reality is D would be adapted for Web Apps in the tradition sense
> much more readily if indeed we implemented just the Web Services in D
> and left the familiar languages such as Java, PHP, etc. alone.
>
> However, those languages (erhmm, especially PHP) are terribly slow and
> do not scale well. Java on the other hand may use vast amounts of Ram,
> but does actually perform fairly well, considering the extremely high
> level of abstraction, and then the complexity of that very same
> extraction with the JMS and EJBs.
>
> A web services container in D would be the most _readily_ useful method
> of injecting performant D into the web services and web apps fields.
>
> The idea that D is difficult to use as rendering language is certainly
> true, as is PHP in many respects.
>
> A JSP style implementation without the stupid scriptlets that people try
> to inject is much better for this kind of a task.
>
> Say we have a templated, standard, HTML / CSS / JS page. We could then
> take a tagging language such as the ones like Java's JSTL and Expression
> Language to insert information from the D based servlets.
>
> Rendering a complete page inside D would be unnecessary, and a major
> source of headaches. However a D based servlet that consists of maybe
> ~50 lines total that could make callbacks to a database, or the web
> services containers to retrieve basic information, wouldn't be a bad idea.
>
> Joking aside, a web services container would be best for D. And vibe.d
> seems to have a fairly good standing ground for this.
>
> For actual web applications, and front-end development currently done in
> your more traditional languages, D could be used, in a style similar to
> Java's JSP, JSTL, and EL. Just without the notion of scripts in the
> pages themselves, as this would mean writing an on-the-fly interpreter,
> or compiling whole pages, which surely isn't an option for a compiled
> performant language; if we want it to be readily adapted.
>
> Apologizes if I jumped around a lot, and misspelled. More difficult than
> I thought typing from my phone.

One of the benefits for D is that we can build up e.g. RESTFUL/SOAP web 
services rather easily. We don't need to serve up generated html/css/js 
but we can serve up assets which are html/css/js that could go through a 
preprocessor and then cache the result.

Either way, I have long since felt that using D in templates is a waste 
of resources. It's doable, very. Just not really worth it.