[mapserver-users] Setting up a JSONP service

[Lars Fricke]

Hi Steve,

I really appreciate that you took this effort! In the meantime (after I 
wrote my question to you), Andreas has come up with a more direct 
solution and since we will have quite some traffic on the server I 
expect we will need every bit of performance. So I guess we will not use 
templates after all. Anyway, it's great how people on this list respond 
with different good solutions and suggestions! Thank you!

Best

Lars

Am 14.01.2015 um 00:41 schrieb Lime, Steve D (MNIT):
> Hi Lars: Most of what you need was in my last reply. Those are snippets from a working configuration. Here's a simple JSON template for a raster query that creates an array of xyz objects:
>
> // MapServer Template
> {'result':{
>    'points':[
> [resultset layer="elev_dem30ra3"]
>    [feature trimlast=","]{x:[x], y:[y], z:[value_0]},[/feature]
> [/resultset]
>    ]
> }}
>
> You could turn this into JSONP and not use the include strategy (I wanted both JSON and JSONP) simply by wrapping the object in callback (callback is a value passed through MapServer, e.g. &mode=query&callback=foo):
>
> // MapServer Template (jsonp.js)
> [callback]({'result':{
>    'points':[
> [resultset layer="elev_dem30ra3"]
>    [feature trimlast=","]{x:[x], y:[y], z:[value_0]},[/feature]
> [/resultset]
>    ]
> }})
>
> and here's the corresponding OUTPUTFORMAT block:
>
> OUTPUTFORMAT
>    NAME 'JSONP'
>    DRIVER 'TEMPLATE'
>    MIMETYPE 'application/json;'
>    FORMATOPTION 'FILE=templates/jsonp.js'
>    FORMATOPTION 'ATTACHMENT=service.json'
> END
>
> Regarding speed, templates are going to be a bit slower since there are generally two passes through the data, once to identify the candidate records and a second for presentation. Also the template assembly is done in memory so there are limits on how large of datasets you can practically work with. How big a deal this is depends on your situation. It's not perfect but in general I've had great luck with this approach.
>
> Steve
>
> -----Original Message-----
> From: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Lars Fricke
> Sent: Friday, January 09, 2015 4:24 AM
> To: mapserver-users at lists.osgeo.org
> Subject: Re: [mapserver-users] Setting up a JSONP service
>
> Hello,
>
> first of all: Thank you for your support!
> Sorry for the late reply but I unfortunately was ill.
>
> @ Steve:
> I read about templating but also read that it is slower?
> I do not have a lot of experience in writing templates. Would you mind sharing a JSONP template?
>
> @ Even: Thank you for your thoughts. Who would implement that change though? I'm afraid I can't.
>
> @ Jeff: I followed those links but I only found threads referring to GeoServer or that were not related to my question. The GDAL page I did study and that's how I managed to set up the GeoJSON service but thats not the same unfortunately as it conflicts with the same origin policy.
>
> Best
>
> Lars
>
> Am 30.12.2014 um 16:24 schrieb Lime, Steve D (MNIT):
>> You can also use MapServer templates to accomplish this. It's a little more work since you have to write the template but it's quite flexible then. Usually I write the template to produce JSON and then use a simple wrapper template to produce JSONP. For example, jsonp.js looks like (callback is passed in):
>>
>> // MapServer Template
>> [callback](
>>     [include src="templates/json.js"]
>> )
>>
>> Output formats look like:
>>
>>     OUTPUTFORMAT
>>       NAME 'JSON'
>>       DRIVER 'TEMPLATE'
>>       MIMETYPE 'application/json;'
>>       FORMATOPTION 'FILE=templates/json.js'
>>       FORMATOPTION 'ATTACHMENT=service.json'
>>     END
>>
>>     OUTPUTFORMAT
>>       NAME 'JSONP'
>>       DRIVER 'TEMPLATE'
>>       MIMETYPE 'application/json;'
>>       FORMATOPTION 'FILE=templates/jsonp.js'
>>       FORMATOPTION 'ATTACHMENT=service.json'
>>     END
>>
>> Steve
>>
>> -----Original Message-----
>> From:mapserver-users-bounces at lists.osgeo.org
>> [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Lars
>> Fricke
>> Sent: Monday, December 29, 2014 5:34 AM
>> To:mapserver-users at lists.osgeo.org
>> Subject: [mapserver-users] Setting up a JSONP service
>>
>> Dear List,
>>
>> I have a WFS service running under MapServer that I would like to operate as JSONP service. I managed to set GEOJSON as output format but I get "Cross-Origin-Request Blocked" if I try to call it with a Javascript client (using Leaflet L.layerJSON.
>> The question is: Is it possible to set up a JSONP service from Mapserver and if yes, how? My current mapfile looks like this (relevant parts):
>>
>> "
>> # in WEB - METADATA
>> "wfs_getfeature_formatlist" "geojson,csv,ogrgml"
>>
>> OUTPUTFORMAT
>>       NAME "geojson"
>>       DRIVER "OGR/GEOJSON"
>>       MIMETYPE "application/json; subtype=geojson; charset=utf-8"
>>       FORMATOPTION "STORAGE=stream"
>>       FORMATOPTION "FORM=SIMPLE"
>>       FORMATOPTION "LCO:COORDINATE_PRECISION=5"
>>      END
>> "
>> If this would already be a correct JSONP service, I have to look on the Leaflet side for the error...
>> Thanks for your help.
>>
>> Cheers
>>
>> Lars
>> _______________________________________________
>> mapserver-users mailing list
>> mapserver-users at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>> _______________________________________________
>> mapserver-users mailing list
>> mapserver-users at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>>
> _______________________________________________
> mapserver-users mailing list
> mapserver-users at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/mapserver-users
> _______________________________________________
> mapserver-users mailing list
> mapserver-users at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>