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Rob Tweed · Apr 21, 2017

See my recent article on QEWD for the rationale behind its architecture:

https://robtweed.wordpress.com/2017/04/18/having-your-node-js-cake-and-e...

As to benchmarks, the ewd-qoper8 module comes with a benchmarking app - even on a basic Linux VM setup, I can easily get in excess of 10,000 message round-trips per second.  Of course, once you add QEWD's access to Cache via cache.node, that will drop.  cache.node is a bottle-neck currently, for V8-related reasons described here:

https://groups.google.com/forum/#!searchin/v8-dev/bottleneck%7Csort:date...

It would be great if Google could fix this as we'd then get native COS performance via JS

As to moving parts, QEWD is entirely Node.js-based, so no extra moving parts other than Node.

Rob Tweed · Apr 21, 2017

You're probably too far down the line in terms of CSP development, but this kind of multi-lingual capability was something that was available years ago in our (M/Gateway)'s original EWD product which could generate CSP pages as one of its many run-time targets.  In fact, multi-lingual support was there from the beginning as it was developed initially for a customer who needed 6 European language translations of the same CSP application. and needed to minimise the time and effort needed to create the translations (done externally by a third-party service) AND keep them all in sync whilst the application was still in active development and then in ongoing maintenance.

Here's the original documentation for anyone interested:

http://gradvs1.mgateway.com/download/multiLingual.pdf

Although my efforts are now focused on the Node.js/JavaScript based QEWD generation of products, the original EWD is still available - it's actually in production use by Quest Diagnostics as the basis of their Internet-based Care360 application, so it's rock-solid and still fully supported.  For information on EWD, go to www.mgateway.com and click the Legacy link.

Rob

Rob Tweed · Apr 21, 2017

QEWD (and EWD.js before it) has been using WebSockets for years with Cache at the back-end.  Of course, in this case, WebSocket support is provided by the Node.js socket.io module, so it avoids any COS-related issues.  It works extremely well and is very fast, stable and scalable.  Personally I'd always use WebSockets in preference to Ajax for browser to/from back-end communication.

However, one of the tricks QEWD pulls off is to allow you to transparently switch between Ajax and WebSockets as the transport for browser communication - for you, the developer, there's no difference in how you transfer messages, so you can choose the transport that is right for you via a simple configuration switch.  See:

https://www.slideshare.net/robtweed/ewd-3-training-course-part-14-using-...

Rob Tweed · Mar 23, 2017

Chris
 
I've not looked at the V4 Signature rules in detail, but the V1 & V2 rules were implemented in this SimpleDB Client that I created years ago for use with both AWS SimpleDB and my M/DB clone:

https://s3.amazonaws.com/rtweeddata/simpleDBClient.xml

Not sure if that helps, but feel free to adapt as needed if it provides a useful starting point - start around line 426 which is the createHTTPRequest() function that creates a signed HTTP request

Rob

Rob Tweed · Oct 12, 2016

You could go a further step and run a JavaScript-based terminal console in a browser and hooking it up to Cache via Node.js.

See https://robtweed.wordpress.com/2014/03/03/ewd-js-and-vista-adding-a-java... for an example implementation

These days, you could use something like Electron to create what appears to be a Windows application, but in fact is a packaged up Chrome & Node.js environment.  In fact, IMO, this is how Atelier should have been implemented.

Remember that as soon as you have something such as this running in a browser, security (ie who has / hasn't access to the application running in the browser) becomes a major issue - you're giving command-line access to your Cache database!

Rob Tweed · Sep 21, 2016

The very much more elegant forEach construct is precisely what the EWD 3 ewd-document-store JavaScript abstraction of Global storage provides you with.  See:

http://www.slideshare.net/robtweed/ewd-3-training-course-part-22-traversing-documents-using-documentnode-objects

For traversal within ranges, see:

http://www.slideshare.net/robtweed/ewd-3-training-course-part-23-traversing-a-range-using-documentnode-objects

See also:

https://github.com/robtweed/ewd-document-store

Rob

Rob Tweed · Sep 19, 2016

"Perhaps the most difficult concept in Caché/MUMPS is its Global Structure."

A diagram or two might help get the concept of Global structure and the purpose of the $order function, as I've done here in explaining its cache.node implementation:

http://www.slideshare.net/robtweed/ewd-3-training-course-part-19-the-cachenode-apis

from slide 31

Rob Tweed · Sep 12, 2016

IMO that's a depressingly risk-averse approach.  The whole point of the IoT area and the Raspberry Pi is that it's still largely unexplored "solution looking for a problem" territory, where people try novel ideas out because they can and because it's cheap and easy to do so.  Sure, you can wait until the market-place is clearly defined and then provide your own "we can do that too" option (and effectively miss the boat as a result), or you can be truly innovative and put it out there and see what happens, potentially catalysing ideas as a result of it being there.  

That's been my philosophy for the last 20 years - if I'd been waiting for people to give me use cases, I'd not have developed a thing in all that time.

Rob Tweed · Sep 10, 2016

In answer to your question: 

"Can anyone recommend any tutorial or code example with installation instructions?"

I'd recommend reading through the comprehensive training course on EWD 3 at http://www.mgateway.com - click the Training tab there for details

The EWD 3 module called ewd-xpress provides a ready-to-run and easy-to-use Node.js-based platform for your Cache applications.  It uses cache.node to provide the connection to Cache and abstracts its APIs to make Cache behave as persistent JavaScript objects and a fine-grained Document Database. The online course will explain all!