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POMono / Lighttpd - Garbage text added to SVG file returned via Response.Write()
 

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  1. POMono / Lighttpd - Garbage text added to SVG file returned via Response.Write()
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    <p>I am developing a web application that manages a population of plants. One feature of the application is the ability to view relationships between plants as a graph. This visualisation is generated as a dot file, then turned into SVG using GraphViz. The resulting SVG markup is then rendered to the browser via an .aspx file, using the Response.Write() technique.</p> <p>Aspx markup:</p> <pre><code>&lt;%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Visualisation.aspx.cs" Inherits="Webapp.PopulationManager.Visualisation" %&gt; </code></pre> <p>Codebehind:</p> <pre><code>protected void Page_Load(object sender, EventArgs e) { if(!Page.IsPostBack) { // ...snip... string svgString = PopulationModule.VisualiseTable(connectionTable, title, url.ToString()); Response.Clear(); Response.ClearContent(); Response.ClearHeaders(); Response.ContentType = "image/svg-xml"; Response.AddHeader("Content-Disposition", string.Format("inline;filename={0}", filename)); Response.Write(svgString); Response.Flush(); } } </code></pre> <p>This techniques works perfectly on my Windows development machine (a dialog pops up asking me to save/open the SVG file).</p> <p>However it fails when deployed to the Linux server that is hosting this app - the page returns the SVG markup, but a garbage string of about 5-6 characters is added as the first line, causing the browser to fail parsing the SVG file.</p> <p>The Linux host runs RHEL5, Mono 1.9, and Lighttpd (with fast-cgi to talk to Mono).</p> <p>I have verified that the SVG markup is generated cleanly on the Linux server; and if I run the web app with XSP2 instead of Lighttpd, the page works as expected. The garbage line is added somewhere after the SVG markup is generated (so I can't simply remove the first line before writing out the response).</p> <p>Does anyone know what might be causing this? Options, ideas, and thoughts greatly recieved!</p> <p>Thanks.</p> <p>EDIT:</p> <p>The characters vary depending on the entity I create a visualisation for - but remain the same for a given entity. So if I create an SVG visualtion for object A, I'll always get the string 1f35 as garbage in the first line.</p>
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    1. CODo you get different garbage characters every time? Or the same ones? Unicode BOMs?
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      1. POMono / Lighttpd - Garbage text added to SVG file returned via Response.Write()
      1. USErik Dahlström
 

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