software page 2 - Dave's Blog

Command line for finding missing URLACTIONs

I wanted to ensure that my switch statement in my implementation of IInternetSecurityManager::ProcessURLAction had a case for every possible documented URLACTION. I wrote the following short command line sequence to see the list of all URLACTIONs in the SDK header file not found in my source file:

grep URLACTION urlmon.idl | sed 's/.*\(URLACTION[a-zA-Z0-9_]*\).*/\1/g;' | sort | uniq > allURLACTIONs.txt
grep URLACTION MySecurityManager.cpp | sed 's/.*\(URLACTION[a-zA-Z0-9_]*\).*/\1/g;' | sort | uniq > myURLACTIONs.txt
comm -23 allURLACTIONs.txt myURLACTIONs.txt

I'm not a sed expert so I had to read the sed documentation, and I heard about comm from Kris Kowal's blog which happilly was in the Win32 GNU tools pack I already run.

But in my effort to learn and use PowerShell I found the following similar command line:

diff 
(more urlmon.idl | %{ if ($_ -cmatch "URLACTION[a-zA-Z0-9_]*") { $matches[0] } } | sort -uniq) 
(more MySecurityManager.cpp | %{ if ($_ -cmatch "URLACTION[a-zA-Z0-9_]*") { $matches[0] } } | sort -uniq)

In the PowerShell version I can skip the temporary files which is nice. 'diff' is mapped to 'compare-object' which seems similar to comm but with no parameters to filter out the different streams (although this could be done more verbosely with the ?{ } filter syntax). In PowerShell uniq functionality is built into sort. The builtin -cmatch operator (c is for case sensitive) to do regexp is nice plus the side effect of generating the $matches variable with the regexp results.

IE9 Document Mode in WebOC

Working on GeolocMock it took me a bit to realize why my HTML could use the W3C Geolocation API in IE9 but not in my WebBrowser control in my .NET application. Eventually I realized that I was getting the wrong IE doc mode. Reading this old More IE8 Extensibility Improvements IE blog post from the IE blog I found the issue is that for app compat the WebOC picks older doc modes but an app hosting the WebOC can set a regkey to get different doc modes. The IE9 mode isn't listed in that article but I took a guess based on the values there and the decimal value 9999 gets my app IE9 mode. The following is the code I run in my application to set its regkey so that my app can get the IE9 doc mode and use the geolocation API.

        static private void UseIE9DocMode()
        {
            RegistryKey key = null;
            try
            {
                key = Registry.CurrentUser.OpenSubKey("Software\\Microsoft\\Internet Explorer\\Main\\FeatureControl\\FEATURE_BROWSER_EMULATION", true);
            }
            catch (Exception)
            {
                key = Registry.CurrentUser.CreateSubKey("Software\\Microsoft\\Internet Explorer\\Main\\FeatureControl\\FEATURE_BROWSER_EMULATION");
            }
            key.SetValue(System.Diagnostics.Process.GetCurrentProcess().MainModule.ModuleName, 9999, RegistryValueKind.DWord);
            key.Close();
        }

Thought Experiments and Design Principles

Raymond Chen has some thought experiments useful for discovering various kinds of stupidity in software design:

• What if two programs did this?
• Who says there's only one?
• Imagine if this were possible. / Imagine if things actually worked that way.

Tim Berners-Lee's principles of Web design includes my favorite: Test of Independent Invention. This has a thought experiment containing the construction of the MMM (Multi-Media Mesh) with MRIs (Media Resource Identifiers) and MMTP (Muli-Media Transport Protocol).

The Internet design principles (RFC 1958) includes the Robustness Principle: be strict when sending and tolerant when receiving. A good one, but applied too liberally can lead to interop issues. For instance, consider web browsers. Imagine one browser becomes so popular that web devs create web pages and just test out their pages in this popular browser. They don't ensure their pages conform to standards and accidentally end up depending on the manner in which this popular browser tolerantly accepts non-standard input. This non-standard behavior ends up as de facto standard and future updates to the standard essentially has had decisions made for it.

View PDFs on Android

Irritatingly, my G1 won't show me PDFs so I've made the Google Docs PDF viewer which will load PDFs on the web up in Google Docs. Google Docs has the useful ability to display PDFs in web browsers without any Adobe software and works (mostly) on Android.

This was very easy to put together as an Android activity. First its necessary to register the application as handling PDFs from the web. This is done via the intent-filter declaration in the manifest:

   intent-filter
      action android:name="android.intent.action.VIEW"/
      data android:scheme="http" android:mimeType="application/pdf"/
      category android:name="android.intent.category.DEFAULT"/
      category android:name="android.intent.category.BROWSABLE"/
   /intent-filter

Second, the activity opens up the browser to Google Docs pointing to the PDF.

   Intent intent = new Intent();
   intent.setAction(getIntent().getAction());
   intent.setData(Uri.parse(
    "http://docs.google.com/gview?embedded=true&url=" + 
    percentEncodeForQuery(getIntent().getData().toString())));

   startActivity(intent);

Grocery Shopper Data Use

QFC, the grocery store closest to me, has those irritating shoppers cards. They try to motivate me to use it with discounts, but that just makes me want to use a card, I don't care whose card and I don't care if the data is accurate. They should let me have my data or make it useful to me so that I actually care.

I can imagine several useful tools based on this: automatic grocery lists, recipes using the food you purchased, cheaper alternatives to your purchases, other things you might like based on what you purchased, or integration with dieting websites or software. At any rate, right now all I care about is getting the discount from using a card, but if they made the data available to me then the grocery store could align our interests and I'd want to ensure the data's accuracy.