topic Re: esri js api post for exportMap in ArcGIS JavaScript Maps SDK Questions

esri js api post for exportMap

NicolasGIS — Sat, 11 Dec 2021 16:47:16 GMT

Hello,

I have an arcgis ArcGISDynamicMapServiceLayer with quite a big number of "layerDefinitions" applied with the "setLayerDefinitions" method.

The problem is that the GET export REST function of ArcGIS Server 10.4.1 (with webadaptor on IIS) does not work as the request is too big so a POST would be necessary.

It is stated in the documentation that "If the layer definition expression is longer than approximately 2000 characters you will need to set up a proxy page.".

I configured the ESRI proxy GitHub project on my server and configured JS api (3.20) to always use the proxy:

esriConfig.defaults.io.proxyUrl = "<url_to_proxy>"
esriConfig.defaults.io.alwaysUseProxy = true;

The problem is that requests are still sent as GET operation so it does not work as well.

How am I supposed to tell JS API to POST for export map operation either directly to the REST api or to the proxy ?

Thanks for your help,

Nicolas

Re: esri js api post for exportMap

NicolasGIS — Thu, 20 Apr 2017 09:30:28 GMT

Really nobody for this ? Thought it was a relevant question as the problem can quickly occurs if using parameters such as "Dynamic Layers" with big services.

Have I missed anything ?

Any hint on the way to go would be great.

Cheers,

Nicolas

Re: esri js api post for exportMap

RobertScheitlin__GISP — Thu, 20 Apr 2017 14:01:25 GMT

Nicolas,

You will want to look at this link for adding proxy rules:

https://developers.arcgis.com/javascript/3/jsapi/esri.urlutils-amd.html#addproxyrule

Re: esri js api post for exportMap

NicolasGIS — Sun, 23 Apr 2017 16:56:48 GMT

Hello Robert,

Thanks for your reply.

I did have a look at your link before posting here and it did not solve my problem. Indeed, I added a rule as you suggested :

esri.addProxyRule({
urlPrefix: "https://hostname/arcgis/rest/services/MyServiceWithLonglayerDefinitions/MapServer/export",
proxyUrl: '/proxy.ashx'
});

And indeed, it works, my request is sent to the proxy but still with GET method, so it still get a 404 error.

I am reading everywhere that proxy should help to POST instead of GET but isn't suppose to POST by itself according to the size of the request ?

Thanks,

Nicolas

Re: esri js api post for exportMap

RobertScheitlin__GISP — Sun, 23 Apr 2017 18:47:02 GMT

So you are saying that you see the request going through the proxy for the exportmap request but it is just not switching to POST?

Re: esri js api post for exportMap

NicolasGIS — Sun, 23 Apr 2017 19:00:40 GMT

Exactly ! And I tried with several versions of ESRI javascript API (3.16,3.17,3.18,3.19,3.20) with the same results.

Re: esri js api post for exportMap

RobertScheitlin__GISP — Sun, 23 Apr 2017 19:51:48 GMT

Nicholas,

So you app is using the https protocol right? And you are using the latest version of the proxy 1.1.0 or 1.1.1-beta?

I tend to make my proxy rules a little less explicit:

esri.addProxyRule({
urlPrefix: "https://hostname/arcgis/rest/services",
proxyUrl: '/proxy.ashx'
});

Re: esri js api post for exportMap

NicolasGIS — Sun, 23 Apr 2017 20:41:52 GMT

Thanks for your time Robert !

Yes, https is used.

I restricted the url but it did not change anything (at the beginning, in order to be sure, I configured all requests to be proxied:

esriConfig.defaults.io.alwaysUseProxy = true;

)

I am using latest esri Github .NET proxy 1.1.1 beta but isn't it more about javascript here ? The request does not reach the proxy unfortunately because of the use of GET method.

Thanks,

Nicolas

Re: esri js api post for exportMap

RobertScheitlin__GISP — Mon, 24 Apr 2017 13:44:26 GMT

Nicolas,

I guess at this point you should open an esri tech support ticket then.

Re: esri js api post for exportMap

NicolasGIS — Mon, 24 Apr 2017 14:28:42 GMT

Thanks Robert. I was hoping to get a reply from ESRI directly here but I guess I will open a ticket then...

Honestly I am surprised to be the first one asking : I was sure I missed something !

Re: esri js api post for exportMap

ForrestCain1 — Tue, 15 Aug 2017 00:15:11 GMT

Hi Nicolas,

Did you ever find a solution to this issue? I'm experiencing the same problem and also just being directed to use the proxy.

Re: esri js api post for exportMap

NicolasGIS — Tue, 15 Aug 2017 06:19:08 GMT

Hi Forrest,

Unfortunately not.

I would love an ESRI opinion on this issue but I finally ended up splitting my service so as to make it work ... It does not follow ESRI best practice to have one big service instead of several...

Nicolas

Re: esri js api post for exportMap

ForrestCain1 — Wed, 16 Aug 2017 13:59:08 GMT

esriConfig.defaults.io.postLength = 1;‍

Nicolas, I found that setting the postLength to 1 (or any number smaller than your url) will force a post for all layers and tasks without using the proxy. I don't see this documented anywhere but I do see in the api source code its checking this to determine to make a post. When this happens, your request to the server comes back as some json with a url to an image. The api automatically does another request to get this image and add it to the map (sorta like print task). If you are using https, another problem occurs because the url you get back from the first request is in http (so you'll get mixed content warnings or errors). I had to create a custom ArcGISDynamicMapServiceLayer using the createSubclass method and alter the getImageUrl function to swap it out to https. I don't love it but its better than not working...

I have a ticket open with ESRI but so far they are just telling me to use the proxy... I'm also really surprised more folks aren't having the same problem. Maybe large layer defs and using https aren't an issue for most folks?

Re: esri js api post for exportMap

NicolasGIS — Wed, 16 Aug 2017 14:25:18 GMT

Many thanks Forrest for the follow up. It is very interesting.

I am just like you very surprised that there is no others use cases (now we are 2 !).

Please let me know the outcome of your ticket ! I can't wait to read it

Re: esri js api post for exportMap

NicolasGIS — Mon, 25 Sep 2017 09:35:22 GMT

Hi Forrest,

Juste wondering if you had had any news from ESRI ?

Thanks