best way to build a server for clients via the internet

[LAUJJL]

Hi

I want to allow people to use models via the internet, eventually with fees.

What is the best way to do that.

thank you in advance.

JJ

[Administrator]

Most users would use Forio to host the models. You can also publish models in Vensim that run in a browser (all you need is webspace for that).

Beyond that, it's difficult to offer any real advice.

[LAUJJL]

Hi

Thank you for your answer!

Webspace from General electric?

JJ

[Administrator]

You can get webspace from many different companies, I cannot really recommend one.

[LAUJJL]

Hi

Thank you very much.

JJ

[tomfid]

The fee part is a good argument for Forio. They have the architecture for paid use of models; creating that yourself is probably a substantial bit of work.

[LAUJJL]

Hi Tom

I do not need to create the architecture myself. I can find someone and pay him for that.

I have already seen the Forio web site.

I have two main drawbacks with using Forio.

Forio has many proprietary features especially for the interface.

Is it possible to work with Forio not using them and working only with the Venapp for instance?

If I work with forio and am successful I have much more chances to be copied, the success being visible either by building a similar model or even by having access to the source code of the model.


With a proprietary server I am totally anonymous and nobody will know if I am successful or not and be tempted to copy me.

Best regards.

JJ

[Travis]

There is SDEverywhere, which is basically designed to publish SD models to the web. It does more, like compiling to C and WASM, and also unit testing and other features that make it possible to have a continuous integration workflow when building a model.

SDEverywhere is free, open source, and able to be hosted for pennies since the resulting web app isn't run on the server. It is also very fast – the code sometimes runs faster than Vensim, depending on the features that are used and if your model is big enough to have 'dead structure' in the MDL file.

You can find more info about SDE here:
https://sdeverywhere.org

Climate Interactive is the main organization behind the effort, and they use it to publish there models to the web, like En-ROADS, which you can see here:
https://en-roads.climateinteractive.org/

SDE is available for anyone to use. There is a way to get a basic web UI by default using the tool, and then you can hire a programmer (basic HTML and JS) to make a more complicated (and likely nicer) UI.

[LAUJJL]

Hi Travis

Thank you for your suggestions.

In fact, i should use different methods, something that takes time, especially for me, having always worked for myself, and not having to manage the undestanding of other people, which seems to be the main difficulty of system dynamics and simulation in general.

I will probably start with Forio, that seems the easier way to start with.

Best regards.

JJ

[Travis]

Forio probably has a gentler learning curve (been a while since I used it) but you might learn more about SDE's default web app UI. SDE should allow someone to define the variables they want to graph and define the variables they want to be sliders (in a table, like XLS), and then do all the rest of the work. There is setup/installation too, but hopefully the basic web functionality is easy for you and a person like a PhD/masters student with a research model.

But is good there are different avenues for publishing models – something that is important for SD to have greater impact.

[LAUJJL]

Hi Travis

Thank you for your answer.

I have no web site, and I wonder if there is a necessity to have one when using sdeverywhere.

I need for the moment to allow users to use my models by guiding them starting with very simple models.

I have no experience working with users, even if I have built complex models where I was the only user.

I will start with a very general model simulating the growth of a business starting at the beginning and will develop the model following the needs of the users;

I have to learn simultaneously to manage the needs of the users and how to do it technically.

When using forio I want to be able to quit them and chose another environment.

I am for the moment trying to learn the Venapp and I have not found any simple Venapp example to run in the vensim documentation and compare the code to what it does!

I have too visited the forio site. I would like to be able to host a simple model (one view), in forio and be able to run it as a forio user.

All these things are too simple and then not documented.

Best regards.

JJ

[Travis]

Yeah currently all the tools have some learning curve. The easiest tool might be Stella Architect right now, since their web tools are integrated into Stella (visual web page design, kinda like Forio) and they also have a way to upload your model so it is hosted on the web. Basically a whole package.

SDEverywhere does require a web server somewhere, but the server requirement are the most basic possible so there are lots of ways to do it, and free options too.

Good luck with this new process!

[LAUJJL]

Hi Travis!

Do you mean that just by translating my simple model to Stella, without anything else, no server, no hosting, anybody with a web browser can use my model and be at the same time guided the same way that Venapp can guide an end user or course with a minimum of coding?

Is it worth moving to Stella? Has Stella the same powerful subscript mapping system, the dll equivalent that I can use through Excel for example?

I have more than 20 years of Vensim experience and I can model any complexity.

Do you use currently Vensim or Stella?

Regards.

JJ

[Travis]

My main goal in this Vensim-focused forum was to help with your original question about publishing SD models to the web and helping you think through different tools. I would have negligent not to mention Stella Architect as an option.

Vensim also have some built-in web app tools but I haven't used them recently. The functionality was basic when I tried it several years ago and didn't include a pathway to hosting.

I currently use both Vensim and Stella – both have their strengths.

Your original question was about publishing to the web so clients could see the app. Now it seems you're exploring "local" user interfaces, like VenApp. Just noting that is a different question.

[LAUJJL]

Hi Travis

Thank you for your help.

I wil have to experiment and adapt the solution to my needs which are not know for the moment.

For the moment i am just trying to run the world model as a Venapp in the venapp directory kof the sample directory with .vcd extension.

Do you know how to do that?

Best regards.

JJ