Pei Zheng's Mobile Computing Blog

Moving to zhengpei.wordpress.com

Dr. Pei Zheng — Thu, 26 May 2011 22:03:00 GMT

As requested by Microsoft, I will stop using this blog as I am no longer with Microsoft.

I will start to use my new blog at zhengpei.wordpress.com. Please feel free to check it out.

"Save To My Skydrive" Come True

Dr. Pei Zheng — Tue, 23 Nov 2010 03:05:00 GMT

More than two years ago, I wrote a blog post of my view on Cloud Computing, titled "Save To My Skydrive". Back then both OfficeLive and Google Docs provided online Office applications and collaboration tools. But one thing missing in both offerings was the feature that allows one to easily save local docs to the cloud, by simply clicking "File"-->"Save To Skydrive" in MS Office software.

Today, Google announced Google Cloud Connect for Microsoft Office, a tool that enables local MS office files to sync to Google Docs.

Update: Microsoft Office 2010 comes with Office Web Apps that allows file sharing and editing with Sharepoint or Skydrive. Windows Phone 7 has "Upload to Skydrive" for pictures and videos, and the Office OneNote app supports real-time sync with Skydrive.

This gives Google Docs a leverage over the office tools on your local computer. The idea could open the door for a plethora of cloud based scenarios that are more closely integrated with common applications on a local OS. Here are a couple of examples that we will see in the next couple of years:

"Sync To Cloud" on Mobile: On Android, if you open a file, you should be able to sync it to Google Docs or Skydrive; no need to save it to your crowed and unreliable SD card; Similar feature on Windows Phone;
"Backup My Phone To Cloud": No need to use phone backup software. Phone OS should allow you to backup your phone state to the cloud, and restore whenever you want;
"Send File Using Cloud": On PC or a phone, when you want to share a big file (video clips, many photos, an iso file, etc) with someone or some other device, you should be able to just do it without worrying about what transport will be used. Behind the scene the cloud system should be able to break the file into chunks, and leverage a mobile grid (peer to peer on transport layer) to distribute these pieces to the cloud and then assemble at the target.

Essentially all the hassles with version control, data security, and limited storage on a local device or PC can be addressed by leveraging the cloud, as long as it is secure, reliable, and user-friendly. I expect to see more and more interesting cloud based user cases in the next couple of years.

Chromium Device Performance Evaluation

Dr. Pei Zheng — Thu, 04 Nov 2010 06:40:00 GMT

It is widely known that Google is busy workign on a Chrome OS device, which is a netbook with everything in the Chrome browser. It remains to be seen how cool it is, as this is essentially the biggest thing from Google after the evidently successful Android effort (so far).

Many people in the mobile device community is trying Chromium OS, the open source version of the Google Chrome OS. So how do we evaluate the performance of such a device? This article aims at giving you some preliminary information on Chromium device performance benchmarking: what are being tested, and what tools are used for now. If you are interested, go put Chromium OS on a USB drive and try it out.

Here is Chromium OS architecture, from top to bottom (source here).

Performance benchmarking on Chromium OS devices are mostly falling into two categories:

· General Linux system benchmarking, using tools such as Phoronix Test Suite or lmbench.

· Browser performance benchmarking in the following areas:

o Javascript engine performance, using Sun Spider;

o DOM parsing performance, using Dromaeo;

o Hardware-accelerated graphics rendering performance, using GUIMark2, Microsoft Psychedelic test, Potato Gun or Fish Tank

o HTML5 video performance; as of now there is no reliable way to do this as HTML5 video doesn’t provide an api to catch frame dropping events, or a way to determine the playback fps, according to author of GUIMark2;

For browser HTML5 support validation, vendors use this site: http://html5test.com/.

Latest Chrome browser canary build is 8.0.559.0 (http://tools.google.com/dlpage/chromesxs).

Some results on earlier Chromium OS using Phoronix Test Suite is here: . Other than this, there is no publicly available performance comparison of Chromium OS devices at this time.

A side note: major browsers (Chrome, IE9 , firefox 4) are all leveraging GPU for 2D/3D rendering.

N Things Google Needs to Fix in Android

Dr. Pei Zheng — Mon, 09 Aug 2010 19:27:00 GMT

Wired runs a story about "5 Things Google Needs to Fix in Android". Here are the 5 things identified with my comment:

Push for More Consistency

"What makes it worse, he says, is that the Android experience is even inconsistent across manufacturers, as each phone maker layers their own interface on top (think HTC Sense and Motorola’s Motoblur) as a way of making their Android phones stand out. And these extra layers, of course, make it especially hard to update a phone to the latest version of Android, creating an even larger disparity between what Android phones can and can’t do."

This is indeed a dilemma. On one hand, OEMs need to have a software platform that supports the creation of hardware and software differentiations to build brand affinity, which naturally leads to some unique user experience of the home screen, the out-of-the-box application portfolio, OEM value-add contents and services on the device or in the cloud, and sometimes an application SDK for devices made by the same OEM. On the other hand, the software platform vendors (Google, Microsoft, and Symbian/Nokia) don't want to see their own ecosystem get too fragmented and thus would like to build more consistency into the platform. My take is that OEMs must be able to innovate on top of the software platform--this is Rule #1. Therefore Google must figure out a way to maintain UI design and platform customization consistency with their frequently updated releases, making it possible for OEMs to catch up with the new releases quickly.

Reorganize Android Market

"The lack of spell-check when searching for apps is just a minor reason why navigating the Android Market can be so frustrating. It’s also difficult to sift through apps. While users can whittle apps down to broad categories, such as games, they can’t sort by rating or recently added."

Can Android Market offer some sort of 'shopping wizard' that leverages some Q&As with the user as well as social networking data to create app recommendations? Or can it provide something similar to Apple Genius in the apple app store?

Update: Android Market now has the "Just In" list of apps.

Make it Easy to Kill Apps

"Steve Jobs himself said, “If you see a task manager, they blew it.” By “they” he means Google’s Android team. The problem is that there’s no visual indicator of which apps are running, nor is there an easy way to exit them or force them to close. (Slacker’s player lets you tap a soft key to quit, but this isn’t a consistent experience — it varies from app to app.)"

Task Manager as a platform component is definitely needed. No matter how smart the OS is (in terms of being able to track and kill long-run resource intensive applications that bring down device performance), user will still need a tool to do it themselves.

Don’t Let Apps Run Wild

"While we’re on the subject of multitasking, both Castonguay and Horman agree that the freedom that draws developers to Android in the first place has a downside: It also lets apps go overboard, slowing down phones and draining their battery life. Google should step in, they say, and enforce guidelines for how often an app pings the cloud or notifies the user when it’s running in the background."

This is about the Android SDK design and Android Market certification process. The Android SDK is very powerful and flexible, not to mention the NDK. And this is one of the greatest advantages of the Android platform. So keep it as-is. Instead, what Google should do is to create a technical acceptance process for Android applications, and only allow those applications that pass a certain App Health check to publish. Microsoft is doing something similar at this point.

Cater to the Attention-Deficit Crowd

"...the platform needs to be more nimble at switching between open apps. Right now, Android users have to hit the home button to exit an app and return to the home screen (they can also hold down the home button to see key apps, but it’s the same idea)."

This is no a problem, I suppose. Right now one just needs to press and hold the home button to see and launch the applications used recently. Given a form factor of around 4" screen, I am not sure if there are better ways of doing application switching.

I also want to share my thought on the improvement that Google should make for Android platform development, from OEM's perspective.

A platform development IDE

Currently native code is debugged using gdb. A better integrated development environment similar to Microsoft Platform Builder will make platform development a lot easier. Ideally, the tool should provide easy kernel and platform level debugging capabilities (ddd-like), dmesg and logcat windows, flashing capability, and other small tasks that are currently enabled by miscellaneous command line tools scattered around the Android building environment.

A better UI layout tool

Historically, Java application framework adopts a layout engine that was designed to allow easy adaption of various screen sizes. It works OK, but not very natural. Developers have to think about several layers of layouts, one embedded into another, for a hardly complicated UI. The SDK should have included a tool to make it easier.

A set of performance troubleshooting tools

While traceview can help profile the performance of the device, there is no real-time thread and events monitoring tool (such as Kernel Tracker on Windows CE) on Android now. In addition, it would be of great help if there is a tool that breakdown UI delay at the application layer, within the Dalvik runtime, within system libraries, and even in kernel drivers. Of course, this requires the framework and system libraries source code to have built-in performance counters. As of now, performance troubleshooting on Android can be accomplished by instrumenting at different layers and investigate the logs, which usually turns out to be very tedious and time consuming. Google should do something to make it easier.

Overall Google is doing an excellent job creating the ever-growing Android ecosystem in such a short period of time. I am sure the Googlers in Mountain View are smart enough to find out what are missing in their current offerings. Just bear in mind that Android innovations comes not only from Google, but also from device OEMs.

I Want An APP That ...

Dr. Pei Zheng — Thu, 15 Jul 2010 22:15:00 GMT

Let's face it: the App Store is great idea. Fact is, mobile device is very personal, and should be heavily customized or tailored for individuals specific computing need, for day-to-day life. The device must have the capability to allow a user to choose whatever tools that can make her work/life easier and happier. There are already over 225,000 apps in Apple App Store, and 60,000+ in Android Market. Many people are becoming app-hungry as you can always run into some apps that you think useful or just funny. It is an app world, indeed.

One may argue that a web browser based computing model would suffice--user just goes to various web sites from their device and do the stuff there. This argument fails to acknowledge a fundamental software design rationale for mobile devices: mobile devices usually have a small form-factor (which means the software UI must be well optimized to be simple and less typing), and are equipped with peripherals that mobile software can leverage to create unique mobile experience. In sheer contrast to desktop computing where more applications are migrating to become browser based, mobile software are increasingly standalone apps that offer very finger friendly interactions.

So what apps do you want to put onto your iPhone/iPod, Android, Windows Phone 7? Some of my most frequently used apps on my iPod Touch are:

Email, outlook, gmail, etc;
Stanza ebook reader, free download of many books, magazines from difference sources;
Weather;
eBuddy messager;
Engadget app;
cnBeta app, Chinese digg;
Yelp, location aware local search and review;
Sina microblogging (Sina weibo), Chinese twitter;
Seattle Times app;
NY Times app;
CCTV mobile tv app;
Skype;
LinkedIn app;
Free RSS app;
mitbss.com app, wasting time on meaningless forum gossips;

If you are an app developer, and want to find a good app idea, I suggest you read "App We Wish We Had" by New York Times. There are some amazingly cool idea in this story, such as:

One popular idea: a To Do-list program that, thanks to the phone’s GPS, would remind you of things to do when you’re in the right place to do them — to “pick up a saw when you’re near the hardware store...But the Twitterites were quick to identify programs that already do that: Reqall, Omnifocus, Remember the Milk, Geostrings, Pocket Informant, Astrid, Task Aware and so on.
Shazam for movies and TV, art work, plants, Chinese/Italian restaurant menu, person, and pretty much everything, : Shazam is the app that identifies a pop song on the radio just by listening to it. Now think about the device is a genius standing by: for whatever you are interested in getting more information, the genius can just whisper by your ear or show you in the air. This is so called "augmented reality", such as the wikitube world browser.
Location aware parking app that can tell the parking rules for the spot;
Six-degree of separation app that can tell you how you may be tied to someone you just met;
Rejuvenator: Aim iPhone camera at your face, snap a pic — it digitally subtracts 5, 10, 15, 20 years from your image.” You don't want to have such an app on your PC; but, this is mobile, and you want to play with it for fun!
An app that takes a picture of the shopping/restaurant receipts and record it.

Having read the story, I was thinking what apps I need. Here are some ideas:

Hot Tweets: the app should give a daily summary of hot tweets (of specific categories such as mobile phones, celebrities, etc) on Twitter and Google Buzz so one will never miss anything big;
Price Drop Notifier: the app should gather information from various bargain deal sites, grocery store sites, online shopping sites, and let user set some triggers when the price of certain stuff dropped into your expected range. And when you are close to a store, the app reminds you to check out the price-dropped items that you have been watching for;
Want More Apps app: An app that tells me some new apps that I may be interested in, by using recommendations from people of similar interest; This is very useful for non-English users-it is difficult to find popular Chinese apps in Apple App Store;
Eat What app: based on your diet so far this week, the app suggests you eat more veggie and fruits, or just "no worries; go enjoy the fries";

You get the idea. More to come...

Windows Phone 7: A New Generation of User Experience?

Dr. Pei Zheng — Sun, 20 Jun 2010 04:38:00 GMT

By far we all know the first wave of Windows Phone 7 devices (to be available Oct 2010) will provide a complete new user experience. Here are some 'leaked' videos of WP7 devices (disclaimer: unverified sources):

Samsung:

LG:

Unknown OEM:

So the UI looks pretty cool-instead of placing a matrix of application icons on the screen, Microsoft chooses to let user build "tiles" on the home screen, with each tile linking to an application. Actually I believe this design is a bit ahead of iPhone. Look at Windows 3.1 and iPhone. Do you see some similarity?

Windows 3.1	iPhone

Naturally, one may ask: other than the "icon matrix", is there a better way to present a list of applications on a screen? Maybe this one?

It seems to me that the WP7 UI is kind of a big leap from the "icon matrix" style--this is like Win95 versus Windows 3.1.

Microsoft has finally figured out how to leverage the company's other assets to grow the Windows Phone ecosystem: XBox, Zune, Office Mobile, and Sharepoint.Granted, a significant part of the new system borrowed ideas from iPhone: "touching is believing", the capacitive multi-touch screen, MarketPlace (app store), few buttons (3 instead of 1 on iPhone), etc. Still, WP7 has some edge over other platforms:

XBox Live: neither Apple and Google has such a gaming network; Nintendo and Sony do; but are they planning to make phones?
Office Mobile: view and edit your Office documents on the device;
Zune: very similar to iTunes, and what you already see on a Zune HD device. Sleek UI, simple PC client;

Hopefully these new things, plus a stable, touch-friendly, and "simple" UI will win back many deeply unsatisfied Windows Mobile users.

Multitasking is good, but the OS has to be smart

Dr. Pei Zheng — Fri, 09 Apr 2010 16:09:00 GMT

One of the biggest complaints for iPhone OS is the lack of multitasking-you have to close the foreground app before you run another one. By "close" I mean literally stop it, not just minimize its window. This is bad - imagine you are uploading pictures to picasa while receiving a Skype call. Your picture upload task will be paused.

The new iPhone OS 4.0 now supports multitasking - for applications such as VoIP, background audio, location service, photo uploading etc. As Steve Jobs said,

"It's easy to do this in a way that drains battery life, and a way that reduces performance of the foreground app. If you don't do it right, your phone will feel sluggish."

We know other mobile operating systems usually have a Task Manager where you can kill an app (a process, in Computer Science terms). Why do you need this? Well, this is because usually on mobile devices an application will not be terminated when you taps the "Close" button-the process is still there, the window is minimized, and its threads are either suspended or keep running. When you run many apps, and each will consume system resources, and the device will become sluggish. Thus clearly there is a need to terminate some apps completely to free up some resources such that other apps can run smoothly. The operating system may have a smart algorithm to select and skill some "bad" apps for you, in which case you don't need to run your OS task manager or an OEM utility to do that.

So really it is about creating the best user experience on a mobile device. To average consumers, it is kind of difficult to guide her to Task Manager where she can make a choice and terminate an app when the device becomes sluggish. The OS should either

build an app framework that prevent this from happening, by offering limited multitasking capabilities to apps; or
offer full multitasking but figure out a smart and non-intrusive way to manage system resources and free up whenever needed

Looks like iPhone and Windows Phone 7 is taking Approach #1. And Android and Windows Mobile 6.x are using approach #2. It is hard to say which approach will work best on today's smart devices. But one thing is for sure, it is definitely stupid and dumb to clone a desktop experience (thus the way to managing multitasking) to mobile devices: when your PC becomes slow, you "Exit" from WORD or Outlook, "Close" your 10+ IE windows, and "Stop" your P2P file download, and sometimes you just reboot the PC, wait 2 minutes until all the craps are settled down.

On mobile devices, however, you need Instant Access to phone functions, to web browsing, to turn-by-turn navigation, and so on. To average users, the device has two states: it is ON that you can do things; or it is OFF that nothing is running. It just requires a quick button press to switch between ON and OFF. No worries about 'power it off', or 'suspend and resume', and things like that.

Managing APN Settings on Google Android

Dr. Pei Zheng — Tue, 13 Oct 2009 16:53:00 GMT

An APN (Access Point Name) is the information needed to establish a GPRS/EDGE/UMTS cellular packet data connection on a mobile device. Usually the device can be configured by the operator, the OEM, and users with an APN address such as wap.cingular or epc.tmobile.com that will be eventually resolved to the IP address of the GGSN in the operator's network.

Users can go to Settings-->Wireless control-->Mobile networks-->Access point names to view and edit existing APNs.

Google Android uses a SQLite data table to store all APNs configured on the device, as shown below:

Database: /data/data/com.android.providers.telephony/databases/telephony.db
Table: carriers
URI: content://telephony/carriers

_id	name	numeric	mcc	mnc	apn	user	server	password
1	T-Mobile US	310260	310	260	epc.tmobile.com	none	*	none

proxy	port	mmsproxy	mmsport	mmsc	type	current
				http://mms.msg.eng.t-mobile.com/mms/wapenc	default	1

This is a data record in the carriers table. the "_id" is the primary key auto-generated when you add new APN records using APIs or the UI manually. The "name" filed will appear on the setting UI. The 'numeric' field identifies the network that the APN associates with, which is a combination of mcc (mobile country code) and mnc (mobile network code). An operator may have a number of 'numeric' values to cover all this network. The "mmsproxy", "mmsport", and "mmsc" fields are for MMS configurations. The "type" field for an APN can be either 'default' for general data traffic, or 'mms' for MMS.

Note: Android does not support multiple actively APNs (simultaneous PDP contexts), as of 1.6 SDK. In other words, if MMS APN is activated, then the default web APN will be disconnected.

The Android SDK (1.5 and 1.6) does not provide APIs to manage APN (Access Point Name)s directly. So you have to use the Telephony content provider to do that. Take a look at the TelephonyProvider.java source code will definitely help.I wrote some quick test code to enumerate and add APNs to the system, as well as set an APN to be the default one such that the device will use it for subsequent connections (this is indicated by the radio button in the APN list UI).

Enumerate all APNs in the system:

    /*
    * Information of all APNs
    * Details can be found in com.android.providers.telephony.TelephonyProvider
    */
    public static final Uri APN_TABLE_URI =
        Uri.parse("content://telephony/carriers");
    /*
    * Information of the preferred APN
    *
    */
    public static final Uri PREFERRED_APN_URI =
        Uri.parse("content://telephony/carriers/preferapn");

    /*
     * Enumerate all APN data
     */
    private void EnumerateAPNs()
    {
       Cursor   c = context.getContentResolver().query(
               APN_TABLE_URI, null, null, null, null);
        if (c != null)
        {
           /*
           * Fields you can retrieve can be found in
               com.android.providers.telephony.TelephonyProvider :

               db.execSQL("CREATE TABLE " + CARRIERS_TABLE +
               "(_id INTEGER PRIMARY KEY," +
               "name TEXT," +
               "numeric TEXT," +
               "mcc TEXT," +
               "mnc TEXT," +
               "apn TEXT," +
               "user TEXT," +
               "server TEXT," +
               "password TEXT," +
               "proxy TEXT," +
               "port TEXT," +
               "mmsproxy TEXT," +
               "mmsport TEXT," +
               "mmsc TEXT," +
               "type TEXT," +
               "current INTEGER);");
           */

            String s = "All APNs:\n";
            Log.d(TAG, s);
            try
            {
               s += printAllData(c); //Print the entire result set
           }
            catch(SQLException e)
            {
               Log.d(TAG, e.getMessage());
            }

            //Log.d(TAG, s + "\n\n");
           c.close();
        }

    }

Add a new APN record:

   /*
     * Insert a new APN entry into the system APN table
     * Require an apn name, and the apn address. More can be added.
     * Return an id (_id) that is automatically generated for the new apn entry.
     */
    public int InsertAPN(String name, String apn_addr)
    {
        int id = -1;
        ContentResolver resolver = context.getContentResolver();
        ContentValues values = new ContentValues();
        values.put("name", name);
        values.put("apn", apn_addr);

        /*
         * The following three field values are for testing in Android emulator only
         * The APN setting page UI will ONLY display APNs whose 'numeric' filed is
         * TelephonyProperties.PROPERTY_SIM_OPERATOR_NUMERIC.
         * On Android emulator, this value is 310260, where 310 is mcc, and 260 mnc.
         * With these field values, the newly added apn will appear in system UI.
         */
        values.put("mcc", "310");
        values.put("mnc", "260");
        values.put("numeric", "310260");

        Cursor c = null;
        try
        {
            Uri newRow = resolver.insert(APN_TABLE_URI, values);
            if(newRow != null)
            {
                c = resolver.query(newRow, null, null, null, null);
                Log.d(TAG, "Newly added APN:");
                printAllData(c); //Print the entire result set

                // Obtain the apn id
                int idindex = c.getColumnIndex("_id");
                c.moveToFirst();
                id = c.getShort(idindex);
                Log.d(TAG, "New ID: " + id + ": Inserting new APN succeeded!");
            }
        }
        catch(SQLException e)
        {
            Log.d(TAG, e.getMessage());
        }

        if(c !=null )
            c.close();
        return id;
    }

Set an APN to be the default

   /*
     * Set an apn to be the default apn for web traffic
     * Require an input of the apn id to be set
     */
    public boolean SetDefaultAPN(int id)
    {
        boolean res = false;
        ContentResolver resolver = context.getContentResolver();
        ContentValues values = new ContentValues();

        //See /etc/apns-conf.xml. The TelephonyProvider uses this file to provide
        //content://telephony/carriers/preferapn URI mapping
        values.put("apn_id", id);
        try
        {
            resolver.update(PREFERRED_APN_URI, values, null, null);
            Cursor c = resolver.query(
                    PREFERRED_APN_URI,
                    new String[]{"name","apn"},
                    "_id="+id,
                    null,
                    null);
            if(c != null)
            {
                res = true;
                c.close();
            }
        }
        catch (SQLException e)
        {
            Log.d(TAG, e.getMessage());
        }
         return res;
    }

Two helper functions are created to print data using a cursor:

    /*
     * Return all column names stored in the string array
     */
    private String getAllColumnNames(String[] columnNames)
    {
        String s = "Column Names:\n";
        for(String t:columnNames)
        {
            s += t + ":\t";
        }
        return s+"\n";
    }

    /*
     * Print all data records associated with Cursor c.
     * Return a string that contains all record data.
     * For some weird reason, Android SDK Log class cannot print very long string message.
     * Thus we have to log record-by-record.
     */
    private String printAllData(Cursor c)
    {
        if(c == null) return null;
        String s = "";
        int record_cnt = c.getColumnCount();
        Log.d(TAG, "Total # of records: " + record_cnt);

        if(c.moveToFirst())
        {
            String[] columnNames = c.getColumnNames();
            Log.d(TAG,getAllColumnNames(columnNames));
            s += getAllColumnNames(columnNames);
            do{
                String row = "";
                for(String columnIndex:columnNames)
                {
                    int i = c.getColumnIndex(columnIndex);
                    row += c.getString(i)+":\t";
                }
                row += "\n";
                Log.d(TAG, row);
                s += row;
            }while(c.moveToNext());
            Log.d(TAG,"End Of Records");
        }
        return s;
    }

The Android emulator's default APN is a T-Mobile APN as shown in the picture below:

Then, let's add a new APN and set it to default:

       //Let's try insert a new APN, whose name is 'google2' and apn address is google.com, just for fun.
        int id = InsertAPN("google2","google.com");

        //Set the newly added APN to be the default one for web traffic.
        //The new one will show up in settings->Wireless controls->Mobile networks->Access Point Names),
        //and has been set as default (indicated by the green check button)
        SetDefaultAPN(id);

Then the newly added APN will appear in the UI and shown as 'default'.

Mobile Service Innovations In Developing Countries

Dr. Pei Zheng — Mon, 05 Oct 2009 00:24:00 GMT

Check out the latest special report on mobile marvels by Economist. For many of the people in Kenya who don't have a bank card and a named address, mobile phones are increasingly becoming an indispensable part of day-to-day life. Farmers in Uganda are using SMS based query services o know the weather forecast for the coming season so they can decide when to plant. The trends of mobile services in developing countries are summarized as follows:

The third trend is the development of new phone-based services, beyond voice calls and basic text messages, which are now becoming feasible because mobile phones are relatively widely available. In rich countries most such services have revolved around trivial things like music downloads and mobile gaming. In poor countries data services such as mobile-phone-based agricultural advice, health care and money transfer could provide enormous economic and developmental benefits. Beyond that, mobile networks and low-cost computing devices are poised to offer the benefits of full internet access to people in the developing world in the coming years.

And where are the new mobile subscribers?

What does this mean to mobile OEMs and software vendors? I think there are at least two aspects to look into:

From business development perspective: Do we have acknowledged this trend in the global mobile ecosystem and have developed strategy to build products optimized for those booming emerging markets?
Form R&D perspective: What technologies can be applied to these new services to provide better user experience, productivity, security, interoperability, and reliability? Beyond mobile money, text query service, social finance, and village computing, what else can be developed to address big problems that people in developing countries are facing everyday?

Sounds like unlimted potential if you look at the wide range of devices/services that can be developed for emerging markets, and keep in mind that their buying power will increase significantly as these become an essential part of their lives.

ConnectivityManager in Android SDK: Compared with Connection Manager in Windows Mobile

Dr. Pei Zheng — Wed, 23 Sep 2009 08:03:00 GMT

Anyone who has ever used Windows Mobile (actually WinCE) Connection Manager will probably share mix feelings: on one side, the ConnMgr APIs provide a nice abstraction for applications to request and use a connection without knowing and controlling the physical connectivity; on the other side, it has been a pain in the neck to override or bypass Connection Manager's connection selection logic if the application should use a specific physical connection (for example, GPRS rather than WiFi). And the concept of metanetworks, Internet, Work, WAP network, Secured WAP, is indeed very confusing and difficult to manipulate.

So how does Android manage connections?

In Android SDK 1.5 (code named cupcake), the android.net.ConnectivityManager class (this is Java, not C++) provides connection state management and notification functionality. Specifically, it can be used to:

Obtain broadcast intents when network connectivity changes by checking ConnectivityManager.CONNECTIVITY_ACTION and ConnectivityManager.EXTRA_NETWORK_INFO in a class extended from BroadcastReceiver. (For a brief introduction to Android application fundamentals, read this document. An example of network connectivity listener can be found here.
Query the coarse-grained or fine-grained state of the available networks using ConnectivityManager.GetActiveNetworkInfo() or ConnectivityManager.GetNetworkInfo(int networkType).

This is same-old same-old as in Windows Mobile, which provides similar APIs like ConnMgrRegisterStatusNotification(), ConnMgrConnectionStatus, and ConnMgrQueryDetailedStatus() (examples of these APIs can be found in WM SDK cmhelper).

However, the ConnectivityManager class does offer an interesting method called requestRouteToHost():

public boolean requestRouteToHost (int networkType, int hostAddress)

Since: API Level 1

Ensure that a network route exists to deliver traffic to the specified host via the specified network interface. An attempt to add a route that already exists is ignored, but treated as successful.

Parameters

networkType the type of the network over which traffic to the specified host is to be routed

hostAddress the IP address of the host to which the route is desired

Returns

true on success, false on failure

networkType	the type of the network over which traffic to the specified host is to be routed
hostAddress	the IP address of the host to which the route is desired

This method is very useful--it allows your application to ensure that a desired physical connectivity (represented by the networkType) is available to reach a specific destination. If a route to the destination IP address from the desired network type is in place (in the routing table), then it simply returns success. Otherwise, it will try to make that happen--this is not mentioned in the above description but can be traced to ConnectivityService class:

In ConnectivityManager class where mService is a ConnectivityService object:

/**
     * Ensure that a network route exists to deliver traffic to the specified
     * host via the specified network interface.
     * @param networkType the type of the network over which traffic to the specified
     * host is to be routed
     * @param hostAddress the IP address of the host to which the route is desired
     * @return {@code true} on success, {@code false} on failure
     */
    public boolean requestRouteToHost(int networkType, int hostAddress) {
        enforceChangePermission();
        if (!ConnectivityManager.isNetworkTypeValid(networkType)) {
            return false;
        }
        NetworkStateTracker tracker = mNetTrackers[networkType];
        /*
         * If there's only one connected network, and it's the one requested,
         * then we don't have to do anything - the requested route already
         * exists. If it's not the requested network, then it's not possible
         * to establish the requested route. Finally, if there is more than
         * one connected network, then we must insert an entry in the routing
         * table.
         */
        if (getNumConnectedNetworks() > 1) {
            return tracker.requestRouteToHost(hostAddress);
        } else {
            return tracker.getNetworkInfo().getType() == networkType;
        }
    }

The mNetTrackers array contains NetworkStateTracker objects for different network types (mobile data and WiFi).

In MobileDataStateTracker class, which extends from NetworkStateTracker:

/**
     * Ensure that a network route exists to deliver traffic to the specified
     * host via the mobile data network.
     * @param hostAddress the IP address of the host to which the route is desired,
     * in network byte order.
     * @return {@code true} on success, {@code false} on failure
     */
    @Override
    public boolean requestRouteToHost(int hostAddress) {
        if (mInterfaceName != null && hostAddress != -1) {
            if (DBG) {
                Log.d(TAG, "Requested host route to " + Integer.toHexString(hostAddress));
            }
            return NetworkUtils.addHostRoute(mInterfaceName, hostAddress) == 0;
        } else {
            return false;
        }
    }

Notice the NetworkUtils.addHostRoute() call. This will add a host route into the system's routing table for the specified destination address via the mobile WWAN interface. This enables the scenario where you want your MMS go through a specific APN for MMS while other traffic on another APN. As of Android SDK 1.5, only MobileDataStateTracker class will actually does this--the WiFiStateTracker class does not do anything yet at this point.

"Wireless Networking Complete" Book Published!

Dr. Pei Zheng — Mon, 14 Sep 2009 03:12:00 GMT

I was told by my dear friends at Elsevier (formerly Morgan Kaufmann publishers) that the book "Wireless Networking Complete" has been published!

This book is a desktop reference covering everything about wireless networking, mainly from R&D perspective. Below is the TOC. Chapter 1: Supporting Wireless Technologies was excerpted from my book "Smart Phone and Next Generation Mobile Computing" published by Elsevier in 2005.

Contents

Chapter 1 Supporting Wireless Technologies

Chapter 2 Wireless Networks

Chapter 3 An Overview of Wireless Systems

Chapter 4 Wireless Application Protocol

Chapter 5 Wireless Local Area Networks

Chapter 6 Fourth Generation Systems and New Wireless Technologies

Chapter 7 Mesh Networks: Optimal Routing and Scheduling

Chapter 8 Ad Hoc Wireless Sensor Networks (WSNs)

Chapter 9 Sensor Network Platforms and Tools

Chapter 10 Mobile IP

Chapter 11 Mobile IPv6

Chapter 12 Security and Survivability of Wireless Systems

Microsoft OneApp: A Could-Enabled App Framework for J2ME

Dr. Pei Zheng — Tue, 01 Sep 2009 10:03:00 GMT

The latest announcement of Microsoft OneApp does create some buzz in the mobile device community. Just to be clear, based on limited information Microsoft made available to the public, OneApp is a Java application for feature phones that provides a framework for developers to write apps using XML or JavaScript to leverage underlying device capability and, more importantly, cloud service (server side computing power and storage). Some sample apps running within OneApp are Windows Live Messager, Facebook, and Twitter. According to the OneApp site, OneApp has a very small footprint (less than 150KB), and has been highly optimized to reduce data traffic cost.

OneApp is reportedly to be able to run on any feature phones with Java (most likely J2ME CLDC+MIDP). So here come the questions:

1. Why bother with OneApp? Just go ahead downloading those Java apps from the Internet...

Today, even complex software like Opera Mini provides Java client for many feature phones, as long as the phone has J2ME. However, keep in mind that OneApp introduces a middle-man between your device and the software service provider (Twitter, Facebook) that, very likely, acts as a proxy or an agent to process transmitted and received data. This is the same idea as UCWeb Java version. It seems optimization enabled by the cloud is the key benefit of OneApp.

2. How difficult is it to develop an app (or widget?) for OneApp such that it runs on most cell phones in the world?

We know that Palm WebOS, Google Android, and Windows Mobile 6.5 both allow developers to write widgets using just JavaScript and some flash. Opera Mobile browser also provides such a framework. And then here is another framework. We've yet to see a tutorial with some sort of OneApp emulator such that we can try develop a Digg for OneApp widget.

3. Is it only available from the operators? No free download?

It seems to me that OneApp folks are seeking collaboration with phone OEMs and operators to ship the product. No indication of free download yet at this moment. Well, to make this massively popular, it has to be made available for download from a Java midlet manager or some sort. To feature phone end-users, this should be like an one-stop shopping for several cool Java apps in a single JAR/JAD. If this is true, naturally the next question is, without charging license fee from OEMs and operator, how can Microsoft make money from this product? The underlying platform is NOT Windows Mobile, so boosting WM market share is not the goal here.

Building a WAP Push Test Environment

Dr. Pei Zheng — Thu, 27 Aug 2009 21:01:00 GMT

For smart phone OEMs, it is generally difficult to test WAP Push and OMA OTA provisioning without having access to operator's testing facility. When operators or customers report issues related to SI (Service Indication) or SL (Service Loading) message handling, a local test environment to reproduce those issues will be a great help. For example, if an operator requires a specific handling of SL messages that the operating system does not support by default, we have to develop a customized SMS provider to enable it, and an environment for SL testing is needed for this task.

To build a small WAP Push test environment, we need to have SMS gateway software on the PC side that can send WAP Push as well as other SMS/MMS messages. For example, NowSMS is a pretty good SMS gateway tool that can allow you to send SMS text message, binary message, WAP Push, MMS, and OMA OTA settings to a phone, as long as you have either a GSM modem or a phone that can act as a GSM modem supporting SMS. Microsoft SMS Sender is another PC-side tool but it does not provide MMS and flash SMS capability. Hush SMS can be used to send SMS, Flash SMS, and SI/SL messages directly from the device.

My recommendation for building a WAP Push test environment is:

1. Purchase NowSMS and install on a desktop computer

2. Purchase a GSM Modem, either a Sierra Wireless PC card or an external GSM model (Wavecom Fasttrack modem, for example).

3. Setup NowSMS with the GSM modem, and then use the web interface NowSMS provides to send WAP Push messages.

Note: before setting up NowSMS with the GSM modem, make sure you first use HyperTerminal to verify the modem (with your SIM card) can actually send SMS messages. The following AT sequence is usually used to send a text SMS from the modem:

ATE1V1
OK

AT+CSMS=0
+CSMS: 1,1,1
OK

AT+CSMS? (check if modem supports SMS)
+CSMS: 0,1,1,1
OK

AT+CSMS=?
+CSMS: (0-1)

OK
AT+CMGF=1 (to send text SMS)
OK

AT+CMGS="##########"
> hello (when modem returns ">", type your message and press Ctrl+Z)
+CMGS: 48
OK

3rd Party Software Integration: What Quality Gates are Needed?

Dr. Pei Zheng — Tue, 18 Aug 2009 20:25:00 GMT

One of the key phases for a mobile device project is 3rd party software integration, which is usually done after initial software baseline has been established (BSP migration complete, driver stabilized, hopper & battery life pass). According to device software product definition, a number of 3rd party applications and modules (for example, some DShow filters) have been identified and made available for integration at this phase. Some of these software may not be the final release as the vendors may also need to conduct technical evaluation and testing with a sample device on their side before releasing a final release. Vendors will provide in-ROM integration instructions, and the ROM build team just needs to follow the instructions to generate test images.

Nonetheless, a well-defined strategy and process for 3rd party software quality gating turn out to be highly critical for device software stability. At minimum, for each 3rd party application, the following quality gates must be used:

Detecting leaks using Application Verifier: Make sure the application does no have significant memory leaks, handle leaks, GDI leaks. For modules/drivers, develop test tools to run within Application Verifier. This can be done within 3 days for a single application or module.

MTTF using hopper: Any application should not take down hopper number by more than 10%. Some applications were not designed with hopper testing in mind (for example, an application runs full-screen but does not enable "Start" button). These will bring down hopper numbers so they must be fixed. Having a focused hopper tool handy such that you can stress a specific application. Also useful is to enable debug messages in those 3rd party applications such that you can always check CElogs for a failed hopper run. This will usually take 3-6 days depending on the degradation of hopper numbers caused by the application.

Battery life/DoU: Windows Mobile application design guideline suggests that an application should follow device power management (by registering for power notification events) and react to system power state changes accordingly. No polling or animations when the application is in background. Use power monitor to check power consumption when the application is running and the device is in various power states. DoU test can be performed to ensure an application does not bring down more than 10% of the DoU number. This will take one or two weeks if the application needs to be modified and re-tested.

No device crashes/hang: this is quite obvious. A 3rd party application often comes with an acceptance test plan, which identifies test cases in different priorities. Perform all the tests and make sure there is no crash (we're sorry messages) or device hang. If there are crashes, the root cause must be found and fixed (if it is in the application) by looking into the dump files (kdmp) with symbols. A consistent repro of a crash is ship-blocking and must be fixed. Depending on the complexity of the test plan, this step may take 2-3 weeks and even longer if the 3rd party software does not come with good quality.

In summary, for a single 3rd party application, it may take several weeks to perform the integration and quality gating, during which effective communication with the vendors is important and both sides understand the device will not ship unless these quality gates are passed (according to the license agreement with the vendors). Issues uncovered should be properly prioritized such that key blocking/critical issues are resolved in the new builds from the vendor, whereas low-user-impact issues can be punted to maintenance releases later.

To ensure high quality of the 3rd party software and overall device stability, and importantly device software will be delivered as planned, an earlier planning of integration and quality gating for each 3rd party software is a must-do for overall device software engineering management, along with required QA/Dev resources pre-allocated.

Windows CE Storage Manager Breakdown

Dr. Pei Zheng — Sat, 15 Aug 2009 00:45:00 GMT

The best architectural pictures for Windows CE / Windows Mobile Storage Manager are the followings (from msdn site):

Now, if you look at the following call stack on a WM6.5 device emulator (CE5), the above picture is much easier to understand:

Call Stack: filesys.exe: 0x1FFE9356

0x0406eb18 AMDNORD!CNorFmd::ReadSector(unsigned long) fmd.cpp line 256
0x0406eb18 AMDNORD!FMD_ReadSector() fmd.cpp line 1168
0x0406eb24 AMDNORD!Fal::ReadFromMedia() fal.cpp line 160 + 36 bytes
0x0406eb50 AMDNORD!ReadFromMedia() falmain.cpp line 1064 + 20 bytes
0x0406eb7c AMDNORD!DSK_IOControl(unsigned char *, unsigned long, unsigned long *) falmain.cpp line 695 + 8 bytes
0x0406ebb4 FSDMGR!CBlockDevice::Control(void *, unsigned long, unsigned long *, _OVERLAPPED *) blockdev.h line 90 + 40 bytes
0x0406ebe0 FSDMGR!FS_DevDeviceIoControl(void *, unsigned long, unsigned long *, _OVERLAPPED *) blockdev.cpp line 24
0x0406ec00 NK!SC_DeviceIoControl(void *, unsigned long, unsigned long *, _OVERLAPPED *) kmisc.c line 2871 + 52 bytes
0x0406ec74 COREDLL!xxx_DeviceIoControl(void *, unsigned long, unsigned long *, _OVERLAPPED *) twinbase.cpp line 49 + 52 bytes
0x0406ecac FSDMGR!CStore::InternalStoreIoControl(void *, unsigned long, unsigned long *, _OVERLAPPED *) store.cpp line 887
0x0406eccc FSDMGR!FSDMGR_DiskIoControl(void *, unsigned long, unsigned long *, _OVERLAPPED *) fsdserv.cpp line 567 + 60 bytes
0x0406ed10 MSPART!ReadPartition(unsigned long, unsigned long *) part.cpp line 600 + 60 bytes
0x0406ed40 MSPART!PD_DeviceIoControl(unsigned char *, unsigned long, unsigned long *) part.cpp line 754 + 36 bytes
0x0406ed74 FSDMGR!CPartDriver::DeviceIoControl(unsigned long, void *, unsigned long, unsigned long *) partition.h line 273 + 52 bytes
0x0406edac FSDMGR!PartitionIoControl(void *, unsigned long, unsigned long *, _OVERLAPPED *) partition.cpp line 57 + 40 bytes
0x0406edd8 FSDMGR!FSDMGR_DiskIoControl(void *, unsigned long, unsigned long *, _OVERLAPPED *) fsdserv.cpp line 567 + 60 bytes
0x0406ee1c FSDMGR!ReadWriteDiskEx() fsdserv.cpp line 215 + 48 bytes
0x0406ee4c FSDMGR!FSDMGR_ReadDiskEx() fsdserv.cpp line 317
0x0406ee50 IMGFS!CVolume::ReadDisk() imgfsvol.cpp line 1715 + 32 bytes
0x0406eeac IMGFS!CStream::LoadBlockAllocationTable() imgfsfile.cpp line 326 + 16 bytes
0x0406eedc IMGFS!CStream::CStream(unsigned long) imgfsfile.cpp line 215
0x0406eee4 IMGFS!CFile::GetStream() imgfsfile.cpp line 172 + 36 bytes
0x0406ef00 IMGFS!CVolume::FS_CreateFileW_read(unsigned long, unsigned long, unsigned long) imgfsvol.cpp line 944 + 12 bytes
0x0406f138 IMGFS!FSD_CreateFileW(unsigned long, _SECURITY_ATTRIBUTES *, unsigned long, unsigned long, void *) imgfsapi.cpp line 95
0x0406f150 FSDMGR!FSDMGR_CreateFileW(unsigned long, _SECURITY_ATTRIBUTES *, unsigned long, unsigned long, void *) fsdapis.cpp line 1020 + 76 bytes
0x0406f1b0 COREDLL!xxx_AFS_CreateFileW(unsigned long, _SECURITY_ATTRIBUTES *, unsigned long, unsigned long, void *) textfile.c line 95
0x0406f1dc FILESYS!FS_CreateFileW(unsigned long, unsigned long, void *) fsmain.c line 2246 + 60 bytes
0x0406f6fc NK!SC_CreateFileW(unsigned long, unsigned long, void *) kmisc.c line 2600 + 56 bytes

From the top to the bottom of the stack:

AMDNORD.DLL: flash driver, which is a block driver FMD (Flash Media Driver) linked with FAL (Flash Abstraction Layer) lib. Source code for this FMD used in the device emulator is in \PLATFORM\DeviceEmulator\SRC\COMMON\AMD\FMD\. Real world examples of MSFLASHFMD are avaliable here PUBLIC\COMMON\OAK\DRIVERS\BLOCK\MSFLASHFMD.

FMD exposes standard stream interface to device manager. The associated storage file is specified in the Drivers registry key.

[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\AmdNorFMD]
   "Dll"="amdnord.dll"
   "Order"=dword:2
   "Prefix"="DSK"
   "Ioctl"=dword:4
   "Profile"="MSFlash"
   "IClass"="{A4E7EDDA-E575-4252-9D6B-4195D48BB865}"
   "MemBase"=dword:A8020000
   "MemLen"=dword:05FE0000
   "Flags"=dword:00010000

FSDMGR.DLL: file system driver manager, which looks into the storage profile in the registry to find partition driver (if any) and file system drivers (FSDs) for those partitions (and possiblely file system filter drivers as well). If no partition driver is specified, then entire device is exposed as a single partition. In this example, the file systems to be loaded are Imgfs and FATFS (FMD for RAM file system (root) plus hive storage is ramfmd.dll in PUBLIC\COMMON\OAK\DRIVERS\BLOCK\MSFLASHFMD\RAM). Note that the MSFLASH flash block driver has been specified as auto-load block driver, meaning that it will be loaded by storage manager instead of device manager, and it cannot be unloaded.

[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\MSFlash]
    "PartitionDriver"="mspart.dll"
    "MountAsROM"=dword:1
    "MountHidden"=dword:1
    "Folder"="Flash Disk"
    "Name"="FLASH Disk Block Device"

; Keep FATFS from trying to shadow \Windows
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\MSFlash\FATFS]
    "MountAsROM"=dword:0
    "MountHidden"=dword:0

; Support XIP in IMGFS
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\MSFlash\IMGFS]
    "XIP"=dword:1

; Default settings for ImgFS. These can be overriden per profile.
[HKEY_LOCAL_MACHINE\System\StorageManager\IMGFS]
    "FriendlyName"="Image-Update Filesystem"
    "Dll"="imgfs.dll"
    "Paging"=dword:1
; @CESYSGEN IF IMGFS_IMGFS_NOWRITE
    ; By default, a read-only imgfs partition will shadow ROM.
    "ShadowROM"=dword:1
; @CESYSGEN ENDIF

; Override names in default profile
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\MSFlash]
    "Name"="MSFLASH for AMD Nor"
    "Folder"="NOR Flash"

[HKEY_LOCAL_MACHINE\System\StorageManager\AutoLoad\MSFlash]
    "DriverPath"="Drivers\\BuiltIn\\AmdNorFMD"
    ; LoadFlags 0x01 == load synchronously
    "LoadFlags"=dword:1
    "Order"=dword:0
    "BootPhase"=dword:0

MSPART.DLL: partition driver to be used for the MSFLASH profile bound with the flash block driver.

IMGFS.DLL: file system driver for Imgfs which is mounted at \Windows.

So from the bottom to the top, when the file system (filesys.exe) is about to create a file, file system manager (fsdmgr.dll) finds the file system driver (imgfs.dll) which in turn asks for ReadDisk from file system manager. Then the file system driver issues FSDMGR_DiskIoControl to partition driver (mspart.dll), which eventually goes to the flash block driver (amdnord.dll). If there is a file system filter driver in place, then it will reside as an extra lightweight file system driver on top of the standard one. I hope this helps clarify the architecture of CE/Mobile storage management.

Using Power Monitor to Tackle Battery Life Problems: Examples

Dr. Pei Zheng — Tue, 11 Aug 2009 20:37:00 GMT

Power monitor (made by Monsoon solutions) is a very useful to improve device battery life. I think every OEM/ODM engineering team should have on handy to watch and troubleshoot battery life issues. Even better, bring the power monitor with your devices into the field, and perform filed tests or comparison tests. For example, how's power consumption of the GPS chip on your device? Just take a drive with your device and connected power monitor with GPS on and capture the logs. Then power monitor will parse the logs and give you a power consumption graph for the test.

The following are some examples of using power monitor to uncover mysterious battery life issues.

1. Standby Current - 30mA !

This graph shows power consumption data of several scenarios on a device: 2G MT call, 2G MO call, Switching to 3G (by changing phone settings), 3G MT call, 3G MO call, and then device gets back to standby with screen off. Device backlight, which burns about 50mA of current, will be turned off after 30 seconds of idle time. When that happens the standby current is around 2-8mA, as can seen after the 2G MT, 2G MO, and 3G MT calls.

The problem is that after the 3G MO call, and device backlight off and suspends, the standby current stays at around 30mA forever. Back-of-the-envelop calculation shows for a whole day 30mA * 24h = 720mAH, about half of the battery capacity on the device.

As this can be reproduced pretty easily, modem log and CE log can be collected and investigated. Eventually this turned out to be the audio path not being properly closed when the 3G MO out ended. After fixing it in RIL driver, the problem was solved.

2. Mysterious thread

This is a classic example of power-unaware programming. At some point the device starts to run a mysterious thread exactly every minute (see the 120mA spikes, even if in suspend mode. Essentially this leads to an average current of about 20-30mA, which is definitely unacceptable. More specifically, when the thread runs, it drains an average of 50mA for 16 seconds, and that will be 13.3mAh for an hour, or 320mAh a day!

How to find the culprit thread? Use Kernel Tracker. Try to look for WaitForSingleObject() calls that has a timeout of 1 minute. If the kernel tracker GUI does not work for you, get the CE log and look for mysterious threads that run every 60 seconds:

0:10:35.890.640 , Switch Thread , hThread=0x07A9FFAE
0:10:35.890.645 , Migrate Thread , hProcess=0x07AB230E
0:10:35.890.741 , Wait for Multiple Objects , Timeout=60000ms , WaitAll=0 , NumObjects=8 , Object 0: 0x07AA8C2A , Object 1: 0x07A9A2C6 , Object 2: 0xC7A9A5D2 , Object 3: 0x07A9A392 , Object 4: 0xC7A9A506 , Object 5: 0x07A9FAAA , Object 6: 0x47A9A986 , Object 7: 0x07AC15E2

0:11:15.961.408 , Switch Thread , hThread=0x07A9FFAE
0:11:15.961.412 , Migrate Thread , hProcess=0x07AB230E
0:11:15.961.508 , Wait for Multiple Objects , Timeout=60000ms , WaitAll=0 , NumObjects=8 , Object 0: 0x07AA8C2A , Object 1: 0x07A9A2C6 , Object 2: 0xC7A9A5D2 , Object 3: 0x07A9A392 , Object 4: 0xC7A9A506 , Object 5: 0x07A9FAAA , Object 6: 0x47A9A986 , Object 7: 0x07AC15E2

This can be further mapped to a thread name as long as you have flat release directory. For the issue, it turned out a battery monitor thread in devices.exe that has a bug which will keep the thread running forever even if the device has been suspended.

Summary:

Power monitor is a great weapon to attach battery life problems for mobile devices. Use it along with other tools such as kernel tracker, CE Log, and KITL to pinpoint what has been wrong in your system. Always has a reference device handy so you know what are normal and what are not. When you perform a scenario test, have CE Log running will be a good idea, but you have to be aware that CE Log flush will drain some battery and create some spikes in your power graph.

Windows Mobile Device DRM Integration

Dr. Pei Zheng — Mon, 10 Aug 2009 01:26:00 GMT

Many devices today provide an OMA DRM 1.x/2.0 solution from a 3rd party (for example, from irdeto). So how to verify if the integration has been properly done? Well, aside from the tests that your vendor performed, you can also use the following site to verify:

http://www.drmtest.com

Common use of this site is to test those Forward Lock and Combined Delivery content such as images (JPG, GIF) and media formats (WAV, mp3, etc).

To make a Windows Mobile phone DRM-ready, i.e., be able to recognize DRM content received via MMS, email, or from the web, a specific file system filter driver has to be loaded into the system. This is often done by adding the the filter into the MODULES section of the memory bib file such that it will be loaded into Slot 1 (unless Slot 1 is so crowded that the module overflows into Slot 0), and put required registry values (for registering the filter driver with file system) to BOOT HIVE.

; HIVE BOOT SECTION
[HKEY_LOCAL_MACHINE\System\StorageManager\Filters]
[HKEY_LOCAL_MACHINE\System\StorageManager\Filters\DrmFSFilter]
"Order"=dword:00000001
"Dll"="DrmFSFilter.dll"
; END HIVE BOOT SECTION

MA DRM specifications can be downloaded from http://www.openmobilealliance.org/technical/release_program/drm_archive.aspx

DirectShow Tool GraphEdt on Windows Mobile

Dr. Pei Zheng — Sat, 08 Aug 2009 02:49:00 GMT

On Windows and Windows CE, the GraphEdt tool can be used to investigate (visually) what DShow filters are used for a given media file, and it is also very useful to verify if your filters work as expected. For desktop Windows, this tool is included in the platform SDK or so called Windows SDK. On Windows CE, the following steps have been suggested to do this:

To use graphedt on CE 5.0, you need to do the following:

1. set WINCEREL=1

2. graphedt uses MFC, so set SYSGEN_MFC=1. Then do "sysgen -p dcom mfc"

3. sysgen -p directx graphedt

Then you should see graphedt.exe in your _flatreleasedir.

On a Windows Mobile AKU build environment, if you follow the steps above, you will hit errors like there at Step 3:

\public\common\sdk\lib\ARMV4I\retail\corelibc.lib
graphedt.lib(filtervw.obj) : error LNK2001: unresolved external symbol IID_IDirectDrawSurfaceKernel
graphedt.lib(filtervw.obj) : error LNK2001: unresolved external symbol IID_IDirectDrawKernel
graphedt.lib(filtervw.obj) : error LNK2001: unresolved external symbol IID_IDDVideoPortContainer

Meantime I am looking into this and see if this can be fixed. Or it can't be fixed because it is by-design because officially Microsoft does not support GraphEdt on Windows Mobile?

Mobile 2.0 - Critical Issues and Why Japan and Korea are the Mobile Time Machines

Dr. Pei Zheng — Mon, 29 Jun 2009 23:39:00 GMT

I came across a great presentation deck on "Mobile 2.0" written by Gerhard Fasol, CEO of Eurotechnology Japan K. K. In the presentation, Gerhard shared his insight into next generation mobile services and four critical issues, Platforms, Business Models, Globalization, and Standardization vs Risk Taking & Early Adoption. Definitely worth a read.

The presentation also has some interesting data showing Japan and Korea being the "Mobile Time Machines" - they are way ahead of EU (and US) in adopting new technologies and business models. Speaking of my personal experience, in Tokyo I saw people use cell phone at the gate to enter train stations. I don't know if people can do the same anywhere in the US.

Source: Eurotechnology.com

Update: Watch for the latest development of China's recent 3G launch. All the players are trying to ride this wave with app stores, oPhone/hiPhone, reduced data fee, and the upcoming iPhone launch.

Best Client Apps of Twitter, Facebook, LinkedIn, Youtube, Picassa for Windows Mobile

Dr. Pei Zheng — Sat, 27 Jun 2009 20:34:00 GMT

Here is the outcome of my little research...

Best Twitter Client for Windows Mobile

PocketTwit

---------------------------------------------------------------------------------------------------------------------------------------

Best Facebook Client for Windows Mobile

Offical Facebook Client by Microsoft

---------------------------------------------------------------------------------------------------------------------------------------

Best LinkedIn Client for Windows Mobile

There is no LinkedIn client for Windows Mobile yet at this moment.

---------------------------------------------------------------------------------------------------------------------------------------

Best Youtube Client for Windows Mobile

The official Youtube client

---------------------------------------------------------------------------------------------------------------------------------------

Best Picasa Client for Windows Mobile

No standalone app available yet. From a web browser you can visit m.google.com/photos to acccess the mobile picasa site.

Twitter-Fanfou, Omegle-LuGuoDe, and ppstream ...

Dr. Pei Zheng — Fri, 05 Jun 2009 08:11:00 GMT

Twitter: Fanfou (饭否)

Omegle: Luguode (路过的)

LinkedIn: Wealink

Facebook: KaiXin (开心)

For every popular social networking site in the US, several Chinese copycats have been created--the idea was adopted, but the business model and user experience are often totally different.

Keep in mind that Chinese people are quite open and willing to chat/comment in online forums or using SMS. According to data published by China Mobile and China Unicom, every Chinese cell phone user sent more than 850 text messages on average in 2008. The need for communication with close friends, with people in the same industry, and with whoever wants to chat is evident. Those copycats (山寨) above were created by those entrepreneurs who see the huge opportunity of capitalizing on the localized Chinese social networking service market. Will they succeed? Hard to say, depending on how good the localization is done, how to build a hype(?) for the site, and perhaps how to convince a Internet giant to acquire it......

On the other hand, there are very cool home-grown Chinese online services and also financially successful. Some examples are ppstream, xunlei, and of course, QQ. Their US competitors (if any) are nowhere close to them by all means.

With 3G services launched in China, and upcoming iPhone and oPhone launches, a new battlefield is emerging.

Remote-Desktop into MacOS from Windows Mobile

Dr. Pei Zheng — Sat, 07 Mar 2009 01:23:00 GMT

Windows Mobile 6 has the built-in remote desktop client. So you can use it to remote desktop into any Windows machine running terminal services (i.e., running the RDP service that listens at Port 3389). For example, once you enable remote desktop on your XP box, you can remote into it using the client on Windows Mobile. For any other platforms, as long as you have the open source xrdp package installed (which is a RDP server), you can remote into it.

RDP is only one flavor of the remote-desktop world. VNC (Virtual Networking Computing) has been there way before RDP becomes pupular on Windows.

For MacOS, there is an easier way to remote-desktop into it:

Enable Apple Remote Desktop (an implementation of VNC service): Preferences > Sharing > select Apple Remote Desktop
Install a VNC client on your Windows Mobile device. I tried several, but only ZoomVNC works on my WM6.1 device.

Done. Isn't that simple?

Verifying If a File has Been Signed By a Specific Certificate in Device Cert Store

Dr. Pei Zheng — Tue, 10 Feb 2009 03:53:00 GMT

Is there a quick way to decide if a file has been signed by a specific certificate? This is definitely part of Windows Mobile code, but it seems there is no easy-to-use APIs for this task. I spent some time investigating this using Windows Mobile AKU and the SDK. Here is my way of doing this:

1. Use CertFindCertificateInStore(seen in wincrypt.h in SDK) to find the certificate you want to use to verify a file; This function returns a PCCERT_CONTEXT.

2. Use MinCryptVerifySignedFileEx(seen in mincrypt.h in AKU) to verify a file is indeed signed by that certificate; The way this API verifies the file is trying to root chain the certficiate used to sign the file, following the certificate path to look for a root certficiate in the specified store.

Let's say we want to check if file my.dll is signed by a self-issued certificate called mycert, which is in the device's privileged certificate store. Now, we open the cert store, find our that certificate using the cert’s SHA-1 hash (or subject, etc), and use it to call MinCryptVerifySignedFileEx() to verify. If my.dll is signed by mycert, or is signed by a code signing certificate issued by the issuer of mycert, then the API return TRUE, meaning that my.dll is indeed signed and should be 'trusted'.

The core part of this who thing is this:

    DWORD CheckBinary(LPWSTR lpwsFileName, PCCERT_CONTEXT pDesiredCert)
    {
        DWORD dwRet;
        MINCRYPT_TRUST_INFO _trust = {0};   // Used by MinCryptVerifySignedFileEx, details see mincrypt.h
        MINCRYPT_ROOT_CERT _rootcert;       // Used by MinCryptVerifySignedFileEx
        MINCRYPT_TRUST_STATUS _trust_status = {0};

        _trust.version = MINCRYPT_TRUST_INFO_VER;
        _trust.flags   = 0;
        _trust.cRootCerts = 1;              // number of root certs in pRootCerts array
        _trust.cRevocationList = 0;         // number of entries in revocation list
        _trust.pRootCerts = &_rootcert;

        BYTE* pPubKey = pDesiredCert->pbCertEncoded;
        PCRYPT_DER_BLOB prgCertBlob = _rootcert.rgCertBlob;
        dwRet = MinAsn1ParseCertificate(pPubKey, pDesiredCert->cbCertEncoded, prgCertBlob);
        if(dwRet < 0)
        {
            wprintf(L"Error parsing the certificate!\n");
            return -1;
        }
        dwRet = MinCryptVerifySignedFileEx(
            MINCRYPT_FILE_NAME,
            lpwsFileName,
            &_trust,
            &_trust_status,
            0,
            0,
            0,
            0
            );
        if(dwRet != ERROR_SUCCESS)
        {
            //Error code can be found here: http://blogs.msdn.com/eldar/archive/2007/04/03/a-lot-of-hresult-codes.aspx
            //Or use VS error lookup tool
            //Note, if error is 6, then file not found.
            wprintf(L"The file %s was not certified by our cert!: Error: %x\n", lpwsFileName, dwRet);
        }
        else
        {
            wprintf(L"The file %s was certified by our cert!\n", lpwsFileName);
        }
        return dwRet;
    }

Note: In visual studio, you need to add paths to those headers and libs (crypto32.lib, mincrypt.lib, and rsaenh.lib are all in AKU common OAK lib directory).

Chinese Input Method on English Windows Mobile Devices

Dr. Pei Zheng — Wed, 28 Jan 2009 15:04:00 GMT

My Windows Mobile devices usually run WWE (World Wide English). To view Chinese on the device I download and install http://cid-8a0406089aad8752.skydrive.live.com/self.aspx/Shared/Yahei.cab

Then the question is how to input Chinese as I bring to my devices to China quite often and I need to send SMS in Chinese. Well, as you know there is CE-Star but it is not free. Good news is there is a pretty good FREE Chinese input method for Windows Mobile: Dayhand Input Method (点迅).

Update: font link updated.

Pei Zheng's Mobile Computing Blog

Moving to zhengpei.wordpress.com

"Save To My Skydrive" Come True

Chromium Device Performance Evaluation

N Things Google Needs to Fix in Android

I Want An APP That ...

Windows Phone 7: A New Generation of User Experience?

Multitasking is good, but the OS has to be smart

Managing APN Settings on Google Android

Mobile Service Innovations In Developing Countries

ConnectivityManager in Android SDK: Compared with Connection Manager in Windows Mobile

public boolean requestRouteToHost (int networkType, int hostAddress)

Parameters

Returns

"Wireless Networking Complete" Book Published!

Microsoft OneApp: A Could-Enabled App Framework for J2ME

Building a WAP Push Test Environment

3rd Party Software Integration: What Quality Gates are Needed?

Windows CE Storage Manager Breakdown

Using Power Monitor to Tackle Battery Life Problems: Examples

Windows Mobile Device DRM Integration

DirectShow Tool GraphEdt on Windows Mobile

Recommended China IT Web Links

Mobile 2.0 - Critical Issues and Why Japan and Korea are the Mobile Time Machines

Best Client Apps of Twitter, Facebook, LinkedIn, Youtube, Picassa for Windows Mobile

Twitter-Fanfou, Omegle-LuGuoDe, and ppstream ...

Remote-Desktop into MacOS from Windows Mobile

Verifying If a File has Been Signed By a Specific Certificate in Device Cert Store

Chinese Input Method on English Windows Mobile Devices