Display Numeric Keypad for HTML input box

Tablets and mobile user always expect numeric keypad by default for number text box entry. HTML5 have introduced two text type named “tel” and “number”. All modern browsers supports this new type. Both “tel” and “number” will bring default numeric keypad for tablels like ipad/andoid tab.

<input type=”tel” class=”someclass”/ >
<input type=”number” class=”someclass”/ >

The basic difference between “tel” and “number” is that “tel” type does not allow decimal number, is useful for only telephone number entry.

One problem I have found when I have used this new type in jqery modal. Modal by default setfocus first text and if we use first textbox “tel” or “number” type, ipad does not show numeric keypad.
I do not find any good solution for this. Alternatively we can change default foucs of jqueryui modal to button instead of text box.

open: function(event, ui) {
        $(":button:contains('Submit')").focus(); // 'Submit' is the button text
}
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Javascript string to integer conversion hell

Javascript is great. But some over intelligency cause also great problem to the developer.

Here I give some string to integer conversion result in JavaScript,

1.  parseInt(“01”)=>1

2.  parseInt(“05”)=>5

3.  parseInt(“08”)=>0

4.  parseInt(“09”)=>0

 

Here javascript is giving wrong result for 3 and 4.

Problem:

When javascript get Zero leading string as parseInt parameter, it takes 8 base system for conversion automatically instead of 10 base.

Solution:

Simply set the base explicitly like below,

3. parseInt(“08”,10)=>8

4. parseInt(“09”,10)=>9

It is best practice in javascript to set the conversion “base” during any type number parsing.

 

Open Layer with GeoSever

GeoSever is very good map repository. It supports most of the request including WMS. Open layer work well with Geoserver. Here I try to give a sample to use openlayer with Geoserver especially for beginner.

Add MapSever WMS Layer:
The main goal is that we will add geoserver layer as wms in the open layer. So the layer definition should be,

var dist = new OpenLayers.Layer.WMS(
	"dist_GEO - Tiled", "http://localhost:8088/geoserver/wms",
	{
		srs: 'EPSG:4326',
		width: '395',
		styles: '',
		height: '512',
		layers: 'bdadmin:dist_GEO',
		format: format,
		tiled: 'true',
		tilesOrigin : map.maxExtent.left + ',' + map.maxExtent.bottom,
		isBaseLayer: true,
		visibility: true
	},
	{
		buffer: 0,
		displayOutsideMaxExtent: true
		}
	);

This will include Bangladesh district boundary as base wms layer. Note that we set the srs value wgs84 projection of our data. The example geoserver is running on 8088 port.

Now we add the road layer from wms as openlayer overlay layer.

var bdhw = new OpenLayers.Layer.WMS(
	"Bangladesh Highway",
	"http://localhost:8088/geoserver/wms",
	{
		transparent: 'TRUE',
		srs: 'EPSG:4326',
		layers: 'bdadmin:rds_nr_geo',
		format: format,
		isBaseLayer: false,
		visibility: true
	}
);
 

Now for implantation of identity feature, we need to apply some ticks. We need call a java script ajax request in click/hover event for WMSGetFeatureInfo request to Geserver. In this point, most of the develop have to face problem in cross domain. If hosting apache and geo server(tomcat) listening in sampe pc but different host, there have to take special care for cross domain ajax call. I wrote a post regarding this issue here. Please read this article first to proceed to the next steps.

infoControls = {
            click: new OpenLayers.Control.WMSGetFeatureInfo({
             url: 'http://localhost:8088/geoserver/wms',
             title: 'Identify features by clicking',
             layers: [bdhq,bdhw,dist],
             queryVisible: true,
	infoFormat:'application/vnd.ogc.gml'
           	})
};

Here we set request url to http://localhost:8088/geoserver/wms . but it cannot directly call the request. We have to go via proxy request. So, write a proxy script and bypass the request.
File: geoproxy.php

<?php
$url=$_GET["url"];
$res = file_get_contents($url);
echo $res;
?>

Now we define proxy in openlayer at top,
OpenLayers.ProxyHost = “geoproxy.php?url=”;

Below the full source code is available,


<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>MapServer Layer</title>
    <link rel="stylesheet" href="theme/default/style.css" type="text/css" />
    <style>
		.opmap
		{
			height:500px;
			width:550px;
		}
		/* The map and the location bar */
		#map {
			clear: both;
			position: relative;
			width: 400px;
			height: 450px;
			border: 1px solid black;
		}
		.mypopuphtml{
			 padding-left:5px;
			 padding-top:0px;
			 padding-bottom:0px;
			 padding-right:5px;
			 font-family:Arial;
			 font-size:8pt;
			 background-color:white;
		}

    </style>
    <script src="OpenLayers.js"></script>

    <script defer="defer" type="text/javascript">

        var zoom = 5;
        var map;
		var infoControls;
		var highlightlayer;
		var aktLayer=-1;
		// pink tile avoidance
		OpenLayers.IMAGE_RELOAD_ATTEMPTS = 5;
		// make OL compute scale according to WMS spec
		OpenLayers.DOTS_PER_INCH = 25.4 / 0.28;

		OpenLayers.ProxyHost = "geoproxy.php?url=";

        function init(){

			format = 'image/png';

			var bounds = new OpenLayers.Bounds(
				88.011, 20.59,
				92.683, 26.634
			);

			var options = {
				controls: [],
				maxExtent: bounds,
				maxResolution: 0.023609375,
				projection: "EPSG:4326",
				units: 'degrees'
			};

			map = new OpenLayers.Map('map', options);

			// setup tiled layer
			var dist = new OpenLayers.Layer.WMS(
				"dist_GEO - Tiled", "http://localhost:8088/geoserver/wms",
				{
					srs: 'EPSG:4326',
					width: '395',
					styles: '',
					height: '512',
					layers: 'bdadmin:dist_GEO',
					format: format,
					tiled: 'true',
					tilesOrigin : map.maxExtent.left + ',' + map.maxExtent.bottom,
					isBaseLayer: true,
					visibility: true
				},
				{
					buffer: 0,
					displayOutsideMaxExtent: true
				}
			);

			var bdhw = new OpenLayers.Layer.WMS(
				"Bangladesh Highway",
				"http://localhost:8088/geoserver/wms",
				{
					transparent: 'TRUE',
					srs: 'EPSG:4326',
					layers: 'bdadmin:rds_nr_geo',
					format: format,
					isBaseLayer: false,
					visibility: true
				}
			);

            var bdhq = new OpenLayers.Layer.WMS(
                "Bangladesh Dist HQ",
                "http://localhost:8088/geoserver/wms",
                {
                    transparent: 'TRUE',
                    srs: 'EPSG:4326',
					layers: 'bdadmin:dist_hq_geo',
					format: format,
					isBaseLayer: false,
					visibility: true
                }
            );

			highlightLayer = new OpenLayers.Layer.Vector("Highlighted Features", {
				displayInLayerSwitcher: false,
				isBaseLayer: false
				}
			);

		   //map.addLayers([gphy, gmap, ghyb, gsat]);
           map.addLayers([dist,bdhw,bdhq,highlightLayer]);

			// build up all controls
			map.addControl(new OpenLayers.Control.PanZoomBar({
				position: new OpenLayers.Pixel(2, 15)
			}));

			map.addControl(new OpenLayers.Control.Navigation());
			map.addControl(new OpenLayers.Control.Scale($('scale')));
			map.addControl(new OpenLayers.Control.MousePosition({element: $('location')}));
            map.addControl( new OpenLayers.Control.LayerSwitcher() );
			map.addControl(new OpenLayers.Control.LayerSwitcher({'div':OpenLayers.Util.getElement('layerswitcher')}));
			map.zoomToExtent(bounds);
			map.updateSize();

			infoControls = {
            click: new OpenLayers.Control.WMSGetFeatureInfo({
                url: 'http://localhost:8088/geoserver/wms',
                title: 'Identify features by clicking',
                layers: [bdhq,bdhw,dist],
                queryVisible: true,
				infoFormat:'application/vnd.ogc.gml',
				eventListeners: {
					getfeatureinfo: function(event) {
						map.addPopup(new OpenLayers.Popup.FramedCloud(
							"chicken",
							map.getLonLatFromPixel(event.xy),
							null,
							GenPopText(event),
							null,
							true
						));
                }}
           	}),
            hover: new OpenLayers.Control.WMSGetFeatureInfo({
                url: 'http://localhost:8088/geoserver/wms',
                title: 'Identify features by clicking',
                layers: [bdhq],
                hover: true,
                // defining a custom format options here
                formatOptions: {
                    typeName: 'water_bodies',
                    featureNS: 'http://www.openplans.org/topp'
                },
                queryVisible: true,
				infoFormat:'text/html'
            	})

			};

			for (var i in infoControls) {
				infoControls[i].events.register("getfeatureinfo", this, showInfo);
				map.addControl(infoControls[i]);
			}

			infoControls.click.activate();
			//infoControls.hover.activate();

			// Active layer combo
			populateLayer(0);
        }

		// sets the HTML provided into the nodelist element
		function setHTML(response){
			document.getElementById('nodelist').innerHTML = response.responseText;
		};

		function errorHTML(response)
		{
			alert("req erro:" + response.responseText);
		}

    	function showInfo(evt) {
			if (evt.features && evt.features.length) {

				 highlightLayer.destroyFeatures();
				 highlightLayer.addFeatures(evt.features);
				 highlightLayer.redraw();

				 $('nodelist').innerHTML = GenPopText(evt);

			} else {
				$('nodelist').innerHTML = evt.text;
			}
        }

		function GenPopText(evt){
				 var temstr="<b><i>" + evt.features[0].gml.featureType + "</i></b><br/>";
				 for(var key in evt.features[0].attributes)
				 {
					temstr += "<b>" + key + "</b>:" + evt.features[0].attributes[key] + "<br/>";
				 }
				 return temstr
		}

    </script>
  </head>

  <body onLoad="init()">
    <div id="title">Geosever Layer</div>
    <div id="layerswitcher" class="olControlLayerSwitcher"></div>
    <div id="map"></div>

    <div id="wrapper">
        <div id="location" style="float:left">location</div>
        <div id="scale" style="float:left"></div>
        <div id="scale" style="clear:both"></div>
    </div>
    <div id="nodelist">
        <em>Click on the map to get feature info</em>
    </div>

  </body>
</html>

………………………………………………
Abul Khayer
GIS Programmer
CEGIS

Open Layer with MapSever

Openlayer can add mapserver wms layer. In this writing, I discuss how work with mapserver wms layer using openlayer. I also wrote an article on how to create mapserver wms repository in my another writing here.

So let assume that we have a well configure mapserver repository and now want to view this maps using openlayer.

Add MapSever WMS Layer:

var dist = new OpenLayers.Layer.WMS( "Bangladesh Admin Bourndary",
	 "http://localhost:8080/cgi-bin/mapserv.exe?map=C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/distwms.map",
	{layers: 'dist_geo',
		srs: 'EPSG:4326',
		format: format,
		isBaseLayer: true,
		visibility: true
	}

);
 

This will include Bangladesh district boundary as base wms layer. Note that we set the srs value wgs84 projection of our data.

Now we add the road layer from wms as openlayer overlay layer.

 // add road layer as overlay layer
	var bdhw = new OpenLayers.Layer.WMS(
                "Bangladesh Highway",
                "http://localhost:8080/cgi-bin/mapserv.exe",
                {
                    map: 'C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/distwms.map',
                    transparent: 'TRUE',
                    layers: 'road_geo',
	    srs: 'EPSG:4326',
	   format: format
                },
                {'reproject': true}
            );

Now we implement identity features. When user click on map, we make WMSGetFeatureInfo request to mapserver.


infoControls = {
	click: new OpenLayers.Control.WMSGetFeatureInfo({
	url: 'http://localhost:8080/cgi-bin/mapserv.exe?map=C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/distwms.map',
	title: 'Identify features by clicking',
	layers: [dist],
	infoFormat:'text/html',
	queryVisible: true
	})
};

Below the full source code is available,

<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>MapServer Layer</title>
    <link rel="stylesheet" href="theme/default/style.css" type="text/css" />
    <style>
		.opmap
		{
			height:450px;
			width:550px;
		}
    </style>
    <script src="OpenLayers.js"></script>
    <script src='http://maps.google.com/maps?file=api&amp;v=2&amp;key=ABQIAAAAjpkAC9ePGem0lIq5XcMiuhR_wWLPFku8Ix9i2SXYRVK3e45q1BQUd_beF8dtzKET_EteAjPdGDwqpQ'></script>
    <script type="text/javascript">

		/*######################
		Author: Md Abul Khayer
		Year: 2010
		khayer.wordpress.com
		#######################*/

        var map, layer;
		var infoControls;

        function init(){

			format = 'image/png';

			var bounds = new OpenLayers.Bounds(
				88.011, 20.59,
				92.683, 26.634
			);

			var options = {
				controls: [],
				maxExtent: bounds,
				maxResolution: 0.023609375,
				projection: "EPSG:4326",
			};

			map = new OpenLayers.Map('map', options);

			// Add Google Layer as baselayer
			var gphy = new OpenLayers.Layer.Google(
			"Google Physical",
			{type: G_PHYSICAL_MAP}
            );

			var gmap = new OpenLayers.Layer.Google(
                "Google Streets", // the default
                {numZoomLevels: 20}
            );

			var ghyb = new OpenLayers.Layer.Google(
                "Google Hybrid",
                {type: G_HYBRID_MAP, numZoomLevels: 20}
            );

			var gsat = new OpenLayers.Layer.Google(
                "Google Satellite",
                {type: G_SATELLITE_MAP, numZoomLevels: 22}
            );

            map.addLayers([gphy, gmap, ghyb, gsat]);

			// Add Custom base layer. Bangladesh District boundary.
			var dist = new OpenLayers.Layer.WMS( "Bangladesh Admin Bourndary",
                    "http://localhost:8080/cgi-bin/mapserv.exe?map=C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/distwms.map",
					{layers: 'dist_geo',
						srs: 'EPSG:4326',
						format: format,
						isBaseLayer: true,
						visibility: true
					}

			);

            // add road layer as overlay layer
			var bdhw = new OpenLayers.Layer.WMS(
                "Bangladesh Highway",
                "http://localhost:8080/cgi-bin/mapserv.exe",
                {
                    map: 'C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/distwms.map',
                    transparent: 'TRUE',
                    layers: 'road_geo',
					srs: 'EPSG:4326',
					format: format
                },
                {'reproject': true}
            );

            // Bangladesh distric head queater as overlay layer.
			var bdhq = new OpenLayers.Layer.WMS(
                "Bangladesh Dist HQ",
                "http://localhost:8080/cgi-bin/mapserv.exe",
                {
                    map: 'C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/distwms.map',
                    transparent: 'TRUE',
                    layers: 'dist_hq_geo',
					srs: 'EPSG:4326',
					format: format
                },
                {'reproject': true}
            );

			// Get identities of the map. Can be either click or hover is activated.
			infoControls = {
				click: new OpenLayers.Control.WMSGetFeatureInfo({
					url: 'http://localhost:8080/cgi-bin/mapserv.exe?map=C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/distwms.map',
					title: 'Identify features by clicking',
					layers: [dist],
					infoFormat:'text/html',
					queryVisible: true
				}),
            	hover: new OpenLayers.Control.WMSGetFeatureInfo({
                url: 'http://localhost:8080/cgi-bin/mapserv.exe?map=C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/distwms.map',
                title: 'Identify features by clicking',
                layers: [dist],
                hover: true,
				infoFormat: 'text/html',
                queryVisible: true
            	})
			}

            map.addLayers([dist, bdhw, bdhq]);
			map.zoomToMaxExtent();
            map.addControl( new OpenLayers.Control.LayerSwitcher() );
			map.addControl(new OpenLayers.Control.Navigation());
			map.addControl(new OpenLayers.Control.LayerSwitcher({'div':OpenLayers.Util.getElement('layerswitcher')}));

			map.addControl(new OpenLayers.Control.Scale($('scale')));
			map.addControl(new OpenLayers.Control.MousePosition({element: $('location')}));

			for (var i in infoControls) {
				infoControls[i].events.register("getfeatureinfo", this, showInfo);
				map.addControl(infoControls[i]);
			}

        	infoControls.click.activate();

        }

		function showInfo(evt) {
			if (evt.features && evt.features.length) {
				 //highlightLayer.destroyFeatures();
				 //highlightLayer.addFeatures(evt.features);
				 //highlightLayer.redraw();

				 $('nodelist').innerHTML=evt.text;
			} else {
				$('nodelist').innerHTML=evt.text;
			}
    	}

    </script>
  </head>

  <body onLoad="init()">
    <div id="title">MapServer WMS Layer with Google map.</div>
    <div id="layerswitcher" class="olControlLayerSwitcher"></div>
    <div id="map" class="opmap"></div>

    <div id="wrapper">
        <div id="location" style="float:left">location</div>
        <div id="scale" style="float:left"></div>
        <div id="scale" style="clear:both"></div>
    </div>
    <div id="nodelist">
        <em>Click on the map to get feature info</em>
    </div>

  </body>
</html>

………………………………………………
Abul Khayer
GIS Programmer
CEGIS

Mapserver WMS

While I have been working with Google map api, a lots tutorial over the web can be found. But unfortunately, Map server developer are only working but not willing to anything for new developer. May be they think it is very simple, why you need more than the mapserver documentation? But true is that it is very difficult to new developer to run their first hello world program. So, very first time in my blog I have started to write tutorial on map server related issue.

The main objective of this writing is that a simple wms map repository will be created using Osgeo Mapserver and view the map with openlayer. In this example I have used three layers Bangladesh district boundary, Main Road and District head quarter location. The first two layer map source is ESRI Shape file and third one is postgis. For all the layer I have used wgs84(EPSG:4326) projection system. In my another post I wrote on mapserver projection system, click here to check article.

Map file Creation with WMS support:
I am using osgeo mapserver in windows OS. Below definition have been added  for top level in mapfile,

NAME BdDistMap
STATUS ON
SIZE 500 550

# Extent based on full extent of QGIS view
EXTENT 86.7316 20.5896 93.9623 26.6341
UNITS dd
IMAGECOLOR 225 225 255
IMAGETYPE png
FONTSET "fontlist.txt"

Now the web section is very important for wms. It requires to add meta data information to give WMS support. This example I have added minimum wms definition which are all most mandatory.

WEB
 IMAGEPATH "/OSGeo4W/tmp/tmp_img/"
 IMAGEURL "/tmp/tmp_img/"
 HEADER "query_header.html"
 FOOTER "query_footer.html"
 METADATA
    "wms_title" "WMS Demo Server"
    "wms_onlineresource" "http://localhost:8080/cgi-bin/mapserv.exe?map=C:\OSGeo4W\apache\htdocs\openlayer\sampleapps\distGeo.map"
 "wms_srs" "EPSG:4326"
"wms_feature_info_mime_type" "text/html"
 END
END

In metadata section, wms_title, wms_srs are mendatory. Wms_srs is the projection system definition. wms_feature_info_mime_type is used to GetFeatureInfo request output format.

I have used map lavel projection system for all layers. Below is definition,

PROJECTION
"init=epsg:4326"
END

Now in layer definition, I have added meta info tag again. Below is the definition,

LAYER
  NAME dist_geo
  PROJECTION
  	"init=epsg:4326"
  END
  HEADER "hq_query_header.html"
  TEMPLATE "hq_query_body.html"

  METADATA
    "wms_title" "distwms"
  END
  TYPE POLYGON
  STATUS OFF
  DATA "C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/shp/dist_GEO.shp"
    CLASS
      NAME "State Boundary"
      STYLE
        COLOR  150 123 90
        OUTLINECOLOR 229 210 191
      END
    END
END

Here I add projection parameter again. If you want use map level projection, this section can be removing. This include Bangladesh administrator boundary with wms support. The data source is shape file in wgs84 projection.

Below the complete working mapfile is given which is able response wms request.

MAP
NAME BdDistMap
STATUS ON
SIZE 500 550

# Extent based on full extent of QGIS view
EXTENT 86.7316 20.5896 93.9623 26.6341
UNITS dd
IMAGECOLOR 225 225 255
IMAGETYPE png
FONTSET "fontlist.txt"

WEB
 IMAGEPATH "/OSGeo4W/tmp/tmp_img/"
 IMAGEURL "/tmp/tmp_img/"
 HEADER "query_header.html"
 FOOTER "query_footer.html"
 METADATA
    "wms_title" "WMS Demo Server"
    "wms_onlineresource" "http://localhost:8080/cgi-bin/mapserv.exe?map=C:\OSGeo4W\apache\htdocs\openlayer\sampleapps\distGeo.map"    "wms_srs" "EPSG:4326"
	"wms_feature_info_mime_type" "text/html"
 END
END

QUERYMAP
  STATUS ON
  SIZE 500 550
  STYLE HILITE
  COLOR 255 255 0
END

SYMBOL
   NAME "Circle"
   FILLED true
   TYPE ellipse
   POINTS 5 5 END
END

PROJECTION
  "init=epsg:4326"
END

LAYER
  NAME dist_geo
  PROJECTION
  	"init=epsg:4326"
  END
  HEADER "hq_query_header.html"
  TEMPLATE "hq_query_body.html"

  METADATA
    "wms_title" "distwms"
  END
  TYPE POLYGON
  STATUS OFF
  DATA "C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/shp/dist_GEO.shp"
    CLASS
      NAME "State Boundary"
      STYLE
        COLOR  150 123 90
        OUTLINECOLOR 229 210 191
      END
    END
END

LAYER
  NAME road_geo
  HEADER "hq_query_header.html"
  TEMPLATE "hq_query_body.html"
  PROJECTION
  	"init=epsg:4326"
  END
  METADATA
    "wms_title"	"Cities"
  END
  TYPE LINE
  STATUS OFF
  DATA "C:/OSGeo4W/apache/htdocs/openlayer/sampleapps/shp/rds_nr_geo.shp"
    CLASS
      NAME "State Road"
      STYLE
        COLOR 32 32 32
      END
    END
END

LAYER
  NAME dist_hq_geo
  # for HTML queries
  HEADER "hq_query_header.html"
  TEMPLATE "hq_query_body.html"

  PROJECTION
  	"init=epsg:4326"
  END

  METADATA
    "wms_title" "DistHQ"
  END
  TYPE POINT
  STATUS OFF
  CONNECTION "user=postgres password=cegis dbname=postgis host=localhost port=5432"
  CONNECTIONTYPE postgis
  DATA "the_geom from dist_hq_geo USING UNIQUE gid"
  LABELITEM "distname"
  CLASS
	NAME "dist_hq_geo"
	COLOR 200 255 0
	SYMBOL "Circle"
	  LABEL
		COLOR 132 31 31
		SHADOWCOLOR 218 218 218
		SHADOWSIZE 2 2
		TYPE TRUETYPE
		FONT arial
		SIZE 11
		ANTIALIAS TRUE
		POSITION CL
		PARTIALS FALSE
		MINDISTANCE 300
		BUFFER 4
	  END # end of label
	  STYLE
		OPACITY 100
	  END
  END
END

END # Map File

Call mapserver WMS Layer:
Now the important part, how we can test this repository? Write below address in your web browser,
http://localhost:8080/cgi-bin/mapserv.exe?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetCapabilities&map=C:OSGeo4WapachehtdocsopenlayersampleappsdistGeo.map

This will return respose wms request if everything is okay. And also write below address for testing map image generation of mapserver,

http://localhost:8080/cgi-bin/mapserv.exe?mode=map&layer=dist_geo&layer=road_geo&map=C:OSGeo4WapachehtdocsopenlayersampleappsdistGeo.map

In another article, I wrote how to add mapserver wms layer using openlayer.
Click here

For more information about wms layer, please check below links,
here
here

……………………………..
Abul Khayer
GIS programmer
CEGIS
Bangladesh

Mapserver Projection

I am not a projection expert. So, who know projection very well, this article does not come to any help. Here I give some reference information for new mapserver developer.

We can add projection parameter in map file by two ways,

1. Inline projection
It use detail projection parameter. If you use shape file, using arcgis parameter can be found. And also there .prj file where contains this parameters. Below I give the projection parameter of wgs84,

PROJECTION
“proj=longlat”
“ellps=WGS84”
“datum=WGS84”
“no_defs”
END

2. EPSG Projection reference
For simplicity, some reference number is introducing to identify a set of projection parameter, known as ESPG. We can find epsg from below site,
http://spatialreference.org

In all list reference tab, require reference number can be search. For example, if we search Bangladesh then we get EPSG:3106 code for Bangladesh(BUTM).

EPSG list can be found also in local pc in “OSGeo4W\share\proj\epsg” file.

Now for WGS84 projection, we have add below projection code in map file in EPSG,

PROJECTION
“init=epsg:4326”
END

The projection can be add in layer level in map file. But if the entire layers are in same projection, then no need to add projection in layer level. It is better at in map level.

If we use WMS layer, wms_srs is a mandatory parameter. So the for wgs84 parameter value should be,

METADATA
“wms_srs” “EPSG:4326”
END

Fow more mapserver project documentation, click here.

…………………………
Abul Khayer
GIS programmer
CEGIS

Solution of Cross domain Ajax Call problem

This problem was first identified when I worked with open layer and Geoserver. My Geo server used apache tomcat and have been listening on 8088 port. And my web application uses apache which is listening on 8080 port. Now, when I made Asynchronous call using openlayer for a map layer of geoserver, my browser (firefox 3.5) had been blocking the request due to security issue. Interestingly, internet explorer (6) can do the request successfully. As a result I was stacked for couple hours and was searching for the solution.

This problem can be bypass in several ways,

Solution 1
We can create a proxy files which will bypass the cross domain request. The proxy page will receive a request, and then make a server side requested and response the output. Below I give a PHP solution of the proxy files,
File name: geoproxy.php

<!--?php $url=$_GET["url"]; $res = file_get_contents($url); echo $res;  ?-->

This page receives the request and echoes the response. So, now we do not make ajax call the different port service directly, instead call the proxy page by “geoproxy.php?url=http://somedomain:port/ geoserver/wms?service=WMS&request=GetFeatureInfo”.

This solution has some security risk, because external user can use your bandwith for bypass their route. So, restrict the requester server by checking page referrer. To do that there needs small modification of existing code.

Solution 2
Requests can be bypass using apache mod_proxy.so module. It needs some configuration change in httpd.conf file. Uncomment below module in apache httpd.conf file,
LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so

Now add proxy bypass code below of the file,
ProxyPass /geotest http://localhost:8080/page.html
ProxyPassReverse /geotest http://localhost:8080/ page.html

Restart the apache. Now /geotest requeste are redirected.

Solution 3
Jquery JSONP can be excellent choice to work with cross domain ajax call.

 

………………………….

Khayer
GIS Programmer
CEGIS