GeoServer production environment on Windows Server with IIS and Apache

In this post Andre explained how to set up a dev environment on win7 so Geoserver can coexist with IIS 7.5.

When it comes to deploying Geoserver to a machine that is exposed to the Internet things may go a bit more difficult. It actually took me a while to figure out how to make all the pieces work together so if you are in a similar situation - trying to run Geoserver on Windows Server - keep on reading.

We have decided to create a subdomain that will take all the traffic targeted at our Geoserver. Apart from looking unusual it certainly makes life easier when setting up rewrite rules for IIS. But let me explain it step by step.

 

1. Installing Apache Tomcat

I had some problems with Tomcat 7.0.6 and Geoserver 2.1RC1 (betas failed too) but luckily Tomcat 6.0.3 was ok. When installing the server it is worth to choose the service startup option so the Tomcat service starts automatically with WIndows. If you are running win x64 make sure you choose x64 JRE as well.

 

2. Making Tomcat pick a proper host name

By default Tomcat binds itself to the port 8080 an I have let it do so in this case as well. The problem though is that geoserver will pick the localhost:8080 for the capabilities documents and also for the example pages generated by the layer preview links. This is not a problem when working with geoserver locally but when accesssing it from another machine, the urls have to be resolved properly.

To make Tomcat know how of the host its pages are requested from I had to edit the tomcat/conf/server.xml file. By default the Connector tag does not have the proxyPort and proxyName properties so I needed to add them. proxyPort is the actual port the resource is requested through (the default is 80 and IIS listens at this port of course) and proxyName specifies the host name that will be used. Adding these two properties to the Connector section makes the geoserver report proxyName:proxyPort as the host name instead of localhost:8080 (in my case geoserver now uses http://geoserver.cartoninjas.net:80).

 

3. Deploying Geoserver

Since I have fixed the server.xml file I can start the Tomcat service and navigate to localhost:8080. After logging in I deployed Geoserver by using the war file available at the download page:

 

4. Setting a rewrite rule in IIS

Having installed Geoserver I was ready to route all the trafic to geoserver.cartoninjas.net to my Tomcat. I had the subdomain already created so there had to be a rewrite rule set appropriately. In my case I needed to have all the incoming traffic routed to localhost:8080:

 

5. Testing the geoserver from a remote computer

The final step was to test if everything worked ok. I have navigated to geoserver.cartoninjas.net/geoserver and tested the tiger ny layer group. It looked like everything was ok now ;-)

 

Why bothering with all the steps above? Initially I had the rewriting set in IIS and I could connect to geoserver through my subdomain. The actual problem though was with the capabilities documents but also with some of the automatically generated preview pages. Of course when knowing the actual resource location it was already possible to connect to the services exposed by geoserver. But clients trying to connect to the geoserver services automatically without knowing there was a problem with the host resolution would obviously fail. A dirty solution was to make the client application replace localhost:8080 with the actual host name and we had it working for quite a while. Luckily there was a bit more elegant way of fixng things and now we have our geoserver instance work as expected. I found that little proxy thing here.

Printing a OpenLayers map in ASP.NET

Printing a map created in OpenLayers or other commercial APIs is still not that easy. There are some problems with transparency of the gif and png images but also with the transparency of the vector canvas used to display vectors. It is possible though to print a road map or layers that do not use transparency without problems. What if we use transparent overlays or vector layers? If our project is utilising geoserver then the problem is solved - there is a mapfish printing module available for geoserver and it does a great job. What if the project does not utilise geoserver but some other custom data sources? Well, we'll need to do some work serverside.

In order to do a serverside tile stitching we will need to collect some data on the clientside so we can then grab all the necessary tiles and assemble them together into one piece:

var tiles = [];
for (var l = 0; l < map.layers.length; l++) {

	//grab the layer
	var layer = map.layers[l];
		
	//skip vector layers	
	if (layer.isVector) continue;

	//now check if it is visible and in range (wms)	
	if (!layer.getVisibility()) continue;
	if (!layer.calculateInRange()) continue;

	// iterate through their grid's tiles, collecting each tile's extent and pixel location at this moment
	for (var r = 0; r < layer.grid.length; r++) { //tile rows (grid is an array of rows)
		for (var c = 0; c < layer.grid[r].length; c++) {//columns

			//grab the tile
			var tile = layer.grid[r][c];

			//when using round there would be some gaps between tiles from time to time so ceil is used instead
			var tilePosX = Math.ceil((tile.bounds.left - mapBounds.left) / resolution);
			var tilePosY = Math.ceil((mapBounds.top - tile.bounds.top) / resolution);                 

			//get the layer opacity
			var opacity = layer.opacity ? parseInt(100 * layer.opacity) : 100;

			//collect data for a tile
			tiles[tiles.length] = {
				url: layer.getURL(tile.bounds),
				x: tilePosX,
				y: tilePosY,
				tileSizeW: layer.tileSize.w,
				tileSizeH: layer.tileSize.h,
				opacity: opacity
			};
		}
	}
}

//data to be sent to the serverside
var printData = {
	mapPixWidth: map.getSize().w,
	mapPixHeight: map.getSize().h,
	tileData: tiles
}

If you searched for some OpenLayers printing examples you may have found examples that use:

tile.position.x,
tile.position.y

instead of:

tilePosX = Math.ceil((tile.bounds.left - mapBounds.left) / resolution);
tilePosY = Math.ceil((mapBounds.top - tile.bounds.top) / resolution);

This is quite weird as I expected both yield the same results but when using OpenLayers within ExtJs layouts I encountered some strange results and found out there were some tile origin positioning shifts. Using the 'manual' tile origin calculation seems to fix the problem so I decided to stay with the adjusted code of course ;)

Since we have the tile data collected already it is the time to move to the serverside. The job to be done here is to download all the necessary tiles (the ones that overlap with the map's viewport), stitch them together and save the final image to jpeg, png, pdf, etc.

I had to do printing to jpeg so the example will use jpeg output.

In order to stitch the images together I had to download them first:

//downloads a remote image from given url
private System.Drawing.Bitmap grabImageFromWeb(string requestUrl, int tileWidth, int tileHeight)
{
    //output image
    System.Drawing.Bitmap outputImage = new System.Drawing.Bitmap(tileWidth, tileHeight);

    //test if the request string was passed and if so request data from the destination server
    if (requestUrl != null)
    {
        //create a new HttpWebRequest
        System.Net.HttpWebRequest webRequest;
        webRequest = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(requestUrl);
        webRequest.Method = "GET";

        System.Net.HttpWebResponse response = (System.Net.HttpWebResponse)webRequest.GetResponse();

        //check if the data was successfully retrieved
        if (response.StatusCode.ToString().ToLower() == "ok")
        {
            System.IO.Stream stream = response.GetResponseStream();
            outputImage = (System.Drawing.Bitmap)System.Drawing.Image.FromStream(stream);
        }
    }

    return outputImage;
}

 Having created a method to grab the images off the web I could now do the actual tile collection and stitching (the output of the code below is an image that maps 1:1 to the map extent visible at the user's display):

//output bitmap
System.Drawing.Bitmap mapBitmap = new System.Drawing.Bitmap(printData.mapPixWidth, printData.mapPixHeight);

//compose the map image
using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(mapBitmap))
{
    //stitch all the tiles together 
    for (int t = 0; t < printData.tileData.Length; t++)
    {
        //test if a tile overlaps with the output image and grab it only if so
        //tile origin + tile size must be > 0
        //and tile origin < bitmap size
        if (printData.tileData[t].x + printData.tileData[t].tileSizeW > 0 && printData.tileData[t].x < mapBitmap.Width && printData.tileData[t].y + printData.tileData[t].tileSizeH > 0 && printData.tileData[t].y < printData.mapPixHeight)
        {
            g.DrawImage(
                grabImageFromWeb(printData.tileData[t].url, printData.tileData[t].tileSizeW, printData.tileData[t].tileSizeH), //source image
                new System.Drawing.Rectangle(printData.tileData[t].x, printData.tileData[t].y, printData.tileData[t].tileSizeW, printData.tileData[t].tileSizeH),//destination rect
                new System.Drawing.Rectangle(0, 0, printData.tileData[t].tileSizeW, printData.tileData[t].tileSizeH),//source rect
                System.Drawing.GraphicsUnit.Pixel //drawing unit
            );
        }
    }
}

//output file name
string fileName = "Printout_" + DateTime.Now.Ticks.ToString() + ".jpg";

//save bitmap
pageBitmap.Save(Server.MapPath (System.Configuration.ConfigurationSettings.AppSettings["printedFiles"] + "\\" + fileName), System.Drawing.Imaging.ImageFormat.Jpeg);

There are a few things worth remembering here:

  • google layers will not print as there is no direct access to the google tiles through OpenLayers. OL 3.0 though should have direct access to the Bing Maps tiles, so it should be possible to create a printout off the Bing tiles
  • when collecting the tile data I was testing for a few conditions specific to my set up, you may require some more tests (for example if you have gmaps layers the js example shown here will fail as gmaps layer does not have a grid property
  • there may be some other issues with the code shown but the generic idea should be easy to follow
  • with a bit more work one could collect vector data as well and draw the features on the top of the stitched tiles (I actually did it for my app but it wouldn't make sense to show it here as the code was simply too customised)

ASP.NET xDomainProxy for OpenLayers getInfo requests

After a long time of just talking about using geoserver we have eventually installed it on our server. Making it work behind IIS is a subject for another article and I am hoping to post it soon.

Anyway, we decided to make our geoserver available at geoserver.cartoninjas.net, while the applications we write are likely to be hosted under different subdomains or even under different domains. Since x-domain requests are not allowed in JavaScript due to some security restrictions I needed to create a simple server side proxy that would be exposed to application as a local resource and would take care of pulling the info when a getInfo requests are issued by OpenLayers.

I started with setting up a proxyHost in OpenLayers:

//proxy host
OpenLayers.ProxyHost = 'xDomainProxy.ashx?url=';

Then a server side script for a generic handler:

<%@ WebHandler Language="C#" Class="xDomainProxy" %>

using System;
using System.Web;

public class xDomainProxy : IHttpHandler {
    
    public void ProcessRequest (HttpContext context) {

        //OpenLayers.ProxyHost = 'xdomainProxy.aspx?url=' so the requested url is passed in a url param
        string requestUrl = HttpUtility.UrlDecode(context.Request.QueryString["url"]);

        //test if the request string was passed and of so request data from the destination server
        if (requestUrl != null)
        {
            //create a new HttpWebRequest
            System.Net.HttpWebRequest webRequest;
            webRequest = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(requestUrl);
            webRequest.Method = "GET";

            System.Net.HttpWebResponse response = (System.Net.HttpWebResponse)webRequest.GetResponse();

            //check if the data was successfully retrieved
            if (response.StatusCode.ToString().ToLower() == "ok")
            {
                //set the appropriate response content type
                context.Response.ContentType = response.ContentType;

                //Read the stream associated with the response.
                System.IO.StreamReader reader = new System.IO.StreamReader(response.GetResponseStream());

                //and write it to response
                context.Response.Write(reader.ReadToEnd());
            }
        }
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }
}

And voila, it's ready to be used ;)

A side note: although in many cases this proxy will work properly this is a mini version of the code and should not be implemented in the production environment - it does not catch any errors and will fail if the connection is not available. Also it was written to work with OpenLayers specifically (OpenLayers.ProxyHost) and needs some extra work before it can act as a bit more flexible proxy allowing one to pull data without having to escape the passed url.

A generic error occurred in GDI+

Recently I have been working on a tile serving utility that would generate tiles on the fly but also cache them at the same time for future usage. After releasing our map tiling tool for manifold this was the next step.

The tile rendering functions were working nicely and the process was fairly quick so enabling data caching functionality could only speed things up ;-) So far so good... It was supposed to be just a matter of saving the output bitmap to a file... So I did it the way I usually do and tried to save my tile this way:

mapImageBitmap.Save(path, _outputTileFormat);

 Apparently this was throwing an error. A very descriptive one: A generic error occurred in GDI+... Not very helpful, is it?

After googling for a while it looked like this was supposed to be a permissions problem but allowing my IUSR to write to the specified folder did not help at all. What's worse I have found some info on the msdn that one should avoid using the System.Drawing namespace in ASP.NET: Classes within the System.Drawing namespace are not supported for use within a Windows or ASP.NET service. Attempting to use these classes from within one of these application types may produce unexpected problems, such as diminished service performance and run-time exceptions.

Nice huh?

Another solution I found on the web was to clone the bitmap in question and then save it, though that gave the same error. No avail in my case.

Luckily after messing with the problem a bit more I have discovered that writing a bitmap to a memory stream and then saving the data using Sytem.IO.File.WriteAllBytes did the trick:

System.IO.MemoryStream outStream = new System.IO.MemoryStream();
mapImageBitmap.Save(outStream, _outputTileFormat);
System.IO.File.WriteAllBytes(_requestedTilePath, outStream.ToArray());

Defitions of Polish projections for manifold

With version 8.0.19 manifold team added some of the Polish projections to manifold projection presets. Basically they added five zones of the National Coordinate System 1965 (PUWG 1965, zones I, II, III, IV and V). There seems to be a mistake though with the way they named the projections: National Coordinate System 1965 was named 1942 while the only one that has 5 zones for Poland is 1965.

For those interested in using Polish coordinate systems with manifold attached is a custom projection xml (it will display in a folder Poland_Custom in the assign / change projection dialog). This is the best we came up with so far so please bear in mind that it may not be 100% perfect. For some more details please see a discussion at georeference.org.