PHP MapScript WMS failing on GetMap requests

[jwgda]

PHP Mapscript WMS GetMap requests are not returning any result.

WMS requests going through CGI requests with a static mapfile are successful, e.g.

http://localhost:8080/cgi-bin/mapserv.exe?map=mymap.map&SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&FORMAT=image%2Fpng&TRANSPARENT=TRUE&LAYERS=L_01&SRS=EPSG%3A3857&CRS=EPSG%3A3857&STYLES=&WIDTH=1920&HEIGHT=1068&BBOX=-19200000%2C-10680000%2C19200000%2C10680000

However, loading that same mapfile in PHP Mapscript with exact same parameters returns no result.

No errors are written in the MS_ERRORFILE, and owsDispatch command returns 0 (MS_SUCCESS).

Example of code that returns no result.

$oMap = new mapObj("mymap.map");
$request = new OWSRequest();
$request->setParameter('service','WMS');
$request->setParameter('SLD_VERSION','1.1.0');
msIO_installStdoutToBuffer();
$oMap->owsDispatch($request);
$contenttype = msIO_stripStdoutBufferContentType();
header('Content-type: image/png');
msIO_getStdoutBufferBytes();
msIO_resetHandlers();

[sdlime]

Hi @jwgda... This should be reported via the mailing lists where many more eyes can take a look at it. Lot's of PHP/MapScript users out there but I'm not one of them. --Steve

[jwgda]

Seems like I'm not the only one

#5130

[sdlime]

@jwgda, what version of everything are you running? I'll reopen this and close the old ticket... I would still take the question to the user list to see if others are experiencing the same issue. I thought this was a pretty common use case. --Steve

[jwgda]

Thanks Steve. I'm using the MS4W 4.0 package build which contains: MapServer 7.4.0-dev, GDAL 2.4.0, Apache 2.4.38, PHP 7.2.16, MapCache 1.7dev.

I also posted to the MS4W User mailing list a couple weeks ago, but no response yet (https://lists.ms4w.com/pipermail/ms4w-users/2019-April/thread.html). If there's another list I can post to, let me know.

[sdlime]

So this is with the Swig-based version of PHP MapScript. I'll try the same script in Perl and see what happens. You might want to try mapserver-users as well.

[jwgda]

Correct. Thank you.

[geographika]

Here is a working SWIG Python MapScript GetMap request:

extent = map.extent
print(extent)

bbox = "BBOX={},{},{},{}".format(extent.minx, extent.miny, extent.maxx, extent.maxy)
querystring = "SERVICE=WMS&REQUEST=GetMap&VERSION=1.3.0&LAYERS=lakespy2&CRS=EPSG:26915&FORMAT=image/png&WIDTH=400&HEIGHT=400&{}".format(bbox)

ows_req = mapscript.OWSRequest()
ows_req.loadParamsFromURL(querystring)
success = map.OWSDispatch(ows_req)
assert success == mapscript.MS_SUCCESS

# clear the HTTP headers or we will have an invalid image
headers = mapscript.msIO_getAndStripStdoutBufferMimeHeaders()
result = mapscript.msIO_getStdoutBufferBytes()

output_file = "wms.png"
with open(output_file, "wb") as f:
    f.write(result)

[jwgda]

This is the piece I'm missing -- could it be the reason?
headers = mapscript.msIO_getAndStripStdoutBufferMimeHeaders()

However, there is no such function (msIO_getAndStripStdoutBufferMimeHeaders) defined in the PHP SWIG Mapscript library (/ms4w/apps/phpmapscriptng-swig/include/mapscript.php) -- code attached.
mapscript.zip

[geographika]

This function was made available in the 7-4 beta release as part of the Perl updates:

https://github.com/mapserver/mapserver/pull/5778/files

There is a new 7.4 release candidate out very soon, so maybe try with this?

[bragef]

I ran into the same issue porting some old PHP Mapscript code to PHP7 and SWIG Mapscript.

The problem here is apparently with msIO_getStdoutBufferBytes(), as there is no obvious way to get the content of this buffer in SWIGH PHP Mapscript.

According to the SWIG Mapscript documentation:

msIO_getStdoutBufferBytes()binary data
Fetch the current stdout buffer contents as a binary buffer. The exact form of this buffer will vary by mapscript language (eg. string in Python, byte[] array in Java and C#, unhandled in perl)

Calling $res=msIO_getStdoutBufferBytes() in PHP outputs nothing, and returns a resource handle to the buffer. (See also http://osgeo-org.1560.x6.nabble.com/PHP-Mapscript-Swig-td5404624.html).

Contrast this with the old, non-SWIG PHP Mapscript, where calling ms_iogetStdoutBufferBytes() would write content of the current buffer to stdout:

ms_iogetStdoutBufferBytes()
Writes the current buffer to stdout. The PHP header() function should be used to set the documents’s content-type prior to calling the function. Returns the number of bytes written if output is sent to stdout. See MapScript Wrappers for WxS Services for more info.

[jmckenna]

This has been just fixed by @bragef (#5943) and merged into master. Please re-try your tests with today's git-master; I confirmed the fix on Windows with PHP 7.2.

[jmckenna]

MS4W will now be updated with this fix, for Windows users.