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The (Java) MIDlet Bible

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Thanks Meter: 139
By Menneisyys, Retired Moderator on 25th October 2007, 01:13 PM
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(Note that this Bible does NOT discuss Java applets or applications. For more info on running applets under Windows Mobile, see the Web Browsing Bible; for application-related info, see my generic Java articles.)

You may have already heard at least of Java games (more precisely, MIDlets) running on almost all current “dumb” phones. These games are all the rage today, especially with teenagers, which also means there are thousands of sometimes really high-quality games for ordinary phones, all written using the portable Java language, ready to be played on (almost) any kind of mobile phone. Just an example: in THIS HowardForums thread, the topic starter post lists some (but not all!) games available for the Samsung QVGA 240x320 phones (d600, d900, e900 etc – not only Windows Mobile ones!). Quite an impressive list, isn’t it? And it’s just the tip of the iceberg – there are a lot more games, all waiting for you to purchase, download and run!

No, don’t think MIDlets are only for gamers and are absolutely useless otherwise. You can make a good use of them in the enterprise too. There are several solutions already for, for example, mobile payment, reservations etc. done using a MIDlet as opposed to the Web, which is, in a lot of cases, is much harder to access / operate on a small-screen device. Controlling for example your bank transfers via SMS can also be less intuitive and/or require a lot more work / data entry than using a GUI to do this. Other, known enterprise-related MIDlets are Jupiter, which is basically a financial data streaming program (also see THIS) and Betfair (also see THIS). Should you be interested in these “MIDlets in the Enterprise” questions, I really recommend Michael Juntao Yuan’s excellent book “Enterprise J2ME: Developing Mobile Java Applications – I’ve learnt a LOT from it. Highly recommended!

1.1 Microsoft and third party MIDlet manager developers

Unfortunately, Microsoft doesn’t support Java (and its, in this Bible discussed subset, MIDlets) at all. The sole reason for this is the fact that Java is a direct competitor to the .NET (Compact) Framework, and is (also) supported by almost all major competitors of Microsoft; in the telco area, most importantly, Nokia and Sony-Ericsson (S-E), the two major players in producing “consumer”, “entertainment”, “not-strictly-enterprise” handsets.

This, unfortunately, means that, under Windows Mobile, MIDlets are not as widely supported as on competing mobile platforms; most importantly, Symbian. Nokia, S-E and the rest have spent a lot of $$$ on implementing really usable and top-notch MIDlet runner environments (MIDlet managers or KVM’s) in the last few years. Microsoft didn’t do the same, only third-party developers, who, because they considered Windows Mobile not to be a gaming platform, didn’t pay much attention to implementing a very good MIDlet manager on the platform (back then, there were far fewer enterprise / productivity MIDlets than today). Just an example: while the mid-2003 Nokia N-Gage certainly lacked at the MIDlet department (very few current games run on it and if they run – for example, the River Storm chopper simulator -, they are almost unplayably slow, as opposed to current Nokia handsets like the N95), the year 2005 Nokia 6680 already had almost flawless MIDlet support. For example, it even supports Bluetooth, which still (as of late 2007) hasn’t made it to the Windows Mobile MIDlet managers, “thanks” for the third-party, uninterested, unmotivated software developers’ neglecting the platform.

1.2 Is it worth it for gaming?

The lack of Microsoft’s commitment to the decent support of MIDlets, unfortunately, means Windows Mobile users are, generally, in a far direr situation than owners of phones from manufacturers involved in developing Java further and spending a lot of $$$ on making their Java support as good as possible. A perfect example of this is, as has already been stated, Nokia. Nokia’s latest, gaming-enabled, top-of-the-line smartphones (most importantly, the PowerVR 3D-accelerated N95 (-3 / 8GB ), the N93(i) (the jBenchmark page is HERE) and E90; the complete list of current phones, based on their 3D benchmark results, can be found HERE) run truly three-dimensional (and, therefore, hardware accelerated) MIDlets considerably faster and FAR better than anything on Windows Mobile. S-E, with its 3D accelerated, touchscreen Symbian UIQ 3 models like the W950, the P990 and the M600, shouldn’t be forgotten either.
25th October 2007, 01:13 PM |#2  
OP Retired Moderator
Thanks Meter: 139
1.2.1 3D support

Currently, I don’t know of any Windows Mobile devices with 3D hardware accelerated Java (MIDlet) graphics. The Aplix folks (developers of Jblend) told me their KVM does support the underlying 3D hardware accelerator. Unfortunately, the (very few) models available outside Japan that it comes with preinstalled do not have 3D acceleration and the (comparatively old) Jblend version available for installing on any device don’t show any kind of 3D acceleration support (I’ve tested this on my 3D accelerated, 2700G-based Dell Axim x51v). Therefore, I’m not really sure it will indeed work with, say, future GoForce 5500 (currently, the O2 XDA Flame and the Toshi G900 has the CPU (neither of them come with Jblend)) and/or the new Qualcomm 7200 chipset, which is to be found in several last-generation HTC and just-announced I-Mate handsets. I don’t think they’ll come with Jblend (why would HTC change their MIDlet manager OEM again, only about a year after switching to Esmertec from the dying TAO?) either. Let’s hope for the best (for example, Esmertec’s (re-)introducing M3G support with support for hardware acceleration into Jbed), though.

The situation, now that – unlike with the 2700G and the GoForce 5500 – the Qualcomm MSM7200 chipset will be a de facto standard in many current- and most next-generation WM phones, will surely change in the future. I’m, however, pretty much sure you won’t see a 3D accelerated MIDlet manager any time soon under Windows Mobile. Again, software developers still consider Windows Mobile a non-gaming platform not really deserving 3D MIDlet acceleration.

What does this all mean? If you’ve got used to the quality of game MIDlets on your favorite Nokia N93(i)/N95/E90 or Sony-Ericsson handsets, you’ll be pretty much disappointed; particularly if you want to run 3D and/or Bluetooth (multiplayer)-based games.

1.2.2 Bluetooth support

Yes, the lack of Bluetooth is another major problem with all current Windows Mobile MIDlet managers. Don’t think of only multiplayer games – there are other uses of Bluetooth used from MIDlets; an example of them is Blooover (a great Bluetooth Sniffer), data exchange over Bluetooth and so on. You can find more information on the latter for example HERE.

Note that, as opposed to what the folks stated, few games refuse to deploy / run because of the lack of the Bluetooth support. (See the main games compatibility chart for more info on these titles.)

1.2.3 Sound issues

There will be other problems too if you plan to play the HUGE library of MIDlet games available today. The most important of them is the bad sound emulation, which is quite big a problem with some MIDlet managers severely affecting the gaming experience. Actually, currently, it’s only Esmertec’s Jbed that didn’t have any problems playing back ALL the midi music I’ve thrown it at (and, of course, that of Nokia on Symbian); all the other (Windows Mobile) MIDlet managers had a much worse sound. In many cases, the music they produced was very hard to even recognize – in a way, they sounded like for example an SNES emulator running on a not-fast-enough Windows Mobile or Symbian phone.

1.2.4 Control issues

Furthermore, you’ll surely be faced control problems. Depending on the MIDlet manager you use AND the game you’re trying to run, you will face sometimes severe control problems. Either the two softkeys won’t work (not even on Pocket PC’s, where you can also try to use the stylus to “press” them) or the D-pad / Action button, or both. Note that there are some solutions to this problem (particularly if you have a Smartphone (or an, in this regard, similar Pocket PC phone like the Asus A525) with a hardware phonepad). I’ve elaborated on these questions in a separate article HERE (cross-posted to PPCT, AximSite, XDA-Developers - 1, XDA-Developers - 2, XDA-Developers - 3, FirstLoox, BrightHand, HowardForums, SPT, MoDaCo,,
25th October 2007, 01:14 PM |#3  
OP Retired Moderator
Thanks Meter: 139
1.2.5 Screen size issues

The question of the screen size and MIDlets displayed in full screen mode should also be mentioned. As MIDlets are, generally, written for a multitude of different devices (to maximize revenue and minimize developing costs), they, generally, support three screen resolutions: 176*208 (the traditional Nokia screen size), 176*220 (the traditional Sony-Ericsson screen size which is, incidentally, the same as that of the traditional Windows Mobile Smartphone) and, finally, QVGA (240*320) – the screen size of the latest Nokia / Ericsson handsets and, of course, higher-end MS Smartphones. And, naturally, Pocket PC’s as well, which, in addition, may also have VGA (640*480) or even WVGA (800*480) screens.

MIDlet games come in two flawors: either dynamically stretching themselves to fill in the entire screen estate of the device they run on in-game (while, in most cases, using the least common denominator, that is, 176*208, to display menus), or fixed to a given resolution. Of course, using the former is preferable (when possible) because you will have a great chance of being able to run it on your even WVGA Pocket PC full-screen. Interestingly, the game speed will, in many cases, remain acceptable even at such high resolutions. This was one of the best surprises I’ve encountered during my thorough tests.

As opposed to the, technically, much more superior and mature Nokia MIDlet Manager, Windows Mobile KVM’s aren’t, generally, full-screen, which, unfortunately, mean some 20-25 or even 40-50 pixels at the bottom of MIDlets hard-coded to the QVGA resolution will be not shown on QVGA screens, depending on whether the actual MIDlet manager shows both (top and bottom) screen bars (TAO, IBM J9 or Jeodek M3G on the Smartphone platform) or “only” the top bar (Jeodek M3G on the PPC platform; non- M3G-capable Jeodek on both WM platforms, Jblend). Nevertheless, there will be missing information; in most cases, the softkey labels, but, with many games, also status messages, speedometers and the like. You can find a lot of comparative screenshots in both the previous 3D MIDlet article and the main game compatibility chart. In all these cases (when the missing information does get into your nerves), you will want to try very hard to, first, find a KVM that does full screen (Jbed or, if you can live with the bad or non-existing audio support, the full screen version of Jblend) and if they turn out to be unable to run your title, switch to a MIDlet version written for a device with a smaller screen (for example, the 176*220 version instead of the QVGA one). In the latter case, however, a large part of your screen estate will remain unused.

As far as application programs (Opera Mini, Gmail, Google Maps etc.) are concerned, they all dynamically stretch themselves to make use of the available screen estate; therefore, you won’t have problems with them on any device, with any MIDlet manager.

1.2.6 (Free) alternatives to MIDlet gaming

As several MIDlets are just rewrites of old classics like Bonk, you may find it useful to look around any online console ROM or abandonware game repository for versions of the game you plan to play. In a top-notch emulator like SmartGear, they might run FAR better than ANY MIDlet manager on your particular handset. Make sure you read ALL my previous, emulation-related articles (the Emulator category of my blog is HERE) to see what gaming console platforms there are and how they are emulated by Windows Mobile.

Just an example. The recently released Bonk’s Return runs MUCH slower (and/or using MUCH more battery) on all my test Windows Mobile devices than the same title under a PC Engine emulator like SmartGear.

All in all, if you find a MIDlet that you find a bit on the slow side, make sure you look around on, say, WikiPedia to see whether the game (originally) had handheld / desktop console versions (or, for that matter, a home computer one – even many home computers of the eighties and the early nineties are better emulated than MIDlets, particularly if you can’t use Jbed because of the compatibility issues). If it did, make sure you check out the console version first, under an emulator. Again, it can’t be stressed enough how important it is for you to thoroughly read through my console/computer emulation-related articles so that you know what emulators there are, how the original titles are emulated under Windows Mobile, what platforms to prefer when there are ports to multiple platforms of a given title etc. Yeah, I know you’ll end up having to spend hours to read all those articles, but, if you’re a hardcore gamer, you’ll certainly find it useful.

1.3 Is it worth it for non-gaming?

It definitely is; most importantly, for Web browsing with the brand new Opera Mini 4 (current, recommended version: beta 2) reviewed HERE. Opera Mini 4 is a freaking good and, what is more, FREE Web browser – in many cases, it’s preferable over all the other Web browsing solutions available for Windows Mobile.

There are other productivity MIDlets meant for non-vertical markets too; the most important example of this is the Gmail MIDlet, which offers a very nice alternative to browsing, searching, answering etc. your Gmail mailbox from your handheld, including Windows Mobile ones. It’s WAY better than any Web-based solutions (see the Web Browsing Bible for the why’s) and, given that it allows for using some really advanced functionality (for example, searching) on the server side (this wasn’t available before; now, Gmail has just implemented IMAP access (another, related PPCT thread), which might let do this from a capable IMAP client as well – see my IMAP Bible for more info), it might still be preferable on a device that, otherwise, is properly configured to access Gmail via POP3. You may also want to take a look at THIS, THIS, THIS, THIS and THIS thread / article too.

Note that now that Google has released an excellent, native Windows Mobile version of the client, (as of the current, version) the need for the MIDlet version of Google Maps is decreased. The native version works just great on both WM platforms and is accessible HERE for download as a directly installable CAB file. Note that there may still be cases you will want to prefer the MIDlet (that is, non-native) version of this program; see for example the comments HERE, where user “fixup” complains of the native version’s keeping the backlight and the connection on (as opposed to running the Java version under a MIDlet manager), which both may lead to (vastly) increased battery consumption.

Finally, as you most probably WILL want to run at least Opera Mini (or its modded version) on your device, the answer is YES.
25th October 2007, 01:14 PM |#4  
OP Retired Moderator
Thanks Meter: 139
2. Available MIDlet managers

In this chapter, I give you a thorough overview of what current (!) MIDlet environments there are, how they compare to each other and which one you should prefer. As you’ll see, particularly if you’re a power user and/or player, you will want to keep different KVM’s on your Windows Mobile handheld simultaneously so that you can make use of the functionality of each of them (there’s no “best” KVM – unfortunately, the otherwise best Jbed lacks some functionality only provided by other KVM’s).

Note that I don’t provide you download /purchase links here. You can find all of the download sources and / or accessibility remarks in the main chart, in the second, “Price / availability” row.

Also note that this is just a sketchy list of what KVM’s there are and what (dis)advantages they have. For a full list of tips, tricks, capability and problem lists, you MUST consult the above-mentioned main chart. Note that, in Chapter 4, I will also elaborate on the meaning of the rows in the chart.

2.1 Esmertec Jbed

This is by far the best and most recommended KVM for Windows Mobile, (QVGA; NOT 176*220 – on the latter, it refuses running deployed MIDlets) Smartphones and Pocket PC’s alike. Its only problems are the lack of M3G (3D gaming) support and the inability to run more than one MIDlet concurrently. As with the other products of Esmertec, it isn’t compatible with pre-WM5 operating systems and needs to be “hacked” in order to be able to run it on non-Phone Edition Pocket PC devices. (See the “Platform compatibility: non-phone PPC” row in the main chart to see how this hacking must be done.)

Note that the latest, currently available Jbed version has problems with the cookie handling of Opera Mini 4 beta 2. This means you can’t log in to many (but not all; for example, Yahoo Mail works) Web sites with OM4b2 running under Jbed. As this isn’t an issue with Opera Mini Mod 2.04/2.05, this seems to be a problem exclusively with the given Opera Mini version and not that of Jbed. If this is a problem, consider switching to another MIDlet manager (for example, Jeodek), where the cookies of Opera Mini 4 beta 2 do work.

2.2 Esmertec Jeodek

There are, basically, two versions of this KVM. The non-M3G-enabled, newer version isn’t really recommended (Jbed is definitely better in almost every respect, except for the Opera Mini 4 beta 2 cookie issues). There is, however, an older, M3G-enabled version out there, which allows for playing a wide variety of games. I’ve explained how the latter should be used HERE, in the 10/11/2007 update. That is, if you’re into gaming, you might want to go for the M3G version; otherwise, I recommend upgrading / switching to Jbed.

2.3 IBM J9

This is a well-known but, now that both Jblend and the two product lines of Esmertec are considerably better in most respects (except for some deliberate questions like the ability to run multiple MIDlets at the same time, in which it’s, together with TAO Intent, is clearly better than Esmertec’s products), not any more recommended KVM. You should prefer Jbed to it and only consider using it if you do need J9’s special capabilities or its compatibility with pre-WM5 operating systems.

Note that, lately, IBM has made much harder to download a trial version of J9 if you’re situated outside the States.

2.4 TAO Intent

This is the MIDlet manager having come with almost all HTC-manufactured WM5 Pocket PC’s and Smartphones. Now that the developer no longer exists, the HTC folks have switched to Esmertec Jeodek / Jbed instead (and independent MS Smartphone / PPC PE manufacturers like Sharp or Samsung prefer Aplix JBlend instead). However, this still means there’s a HUGE number of installed userbase of this MIDlet manager.

Currently, two major releases of these titles are widely used: the 10.1 series (also compatible with WM2003(SE) and the MS Smartphone platform) and the latest 11.1 series (the latter being only WM5+ & Pocket PC-compliant).

In general, you will want to prefer Jbed to this title. It has only few areas where it’s clearly better. Just like with IBM J9, in addition to WM2003(SE) support, it also supports running MIDlets concurrently.

If you have a (non-rebranded!) HTC WM6 Pocket PC device, go for the latest, .1036 version; otherwise (you have a rebranded and/or WM5 device), go for .1034. Should you have a plain (non-phone) Pocket PC, make sure you apply the SMS.dll / Phone.dll hacks already mentioned with Jbed.

Note that, at, there is a separate “turbo” version. While I haven’t really measured remarkable speed increase with the jBenchmark tests, many users have reported generic speedup with at least starting / loading MIDlets. This is because many library files have been decompressed by the creator, meaning no decompression needed in runtime. This may indeed result in some speed increase. (Note that this trick doesn’t work the 10.1-series TAO Intent MIDlet managers (MM’s); this is why only the new series has a separate “turbo” version.) Note that this also means this version occupies about two times more storage than the non-turbo one; therefore, if you have little built-in storage, consider installing it on a storage card. Also, it’s a bit older (version 1023) than the – currently – latest, 1036 version.

2.5 Aplix JBlend

This OEM MIDlet manager comes with, compared to Esmertec’s KVM’s, very few Windows Mobile models. Compared to Jbed, it has both advantages and disadvantages; for example, it supports M3G (and, therefore, far more games) BUT it doesn’t support midi / MP3 playback (that is, you won’t really hear music anywhere) and has a messed-up security model making it pretty useless for Net access like Opera Mini or Gmail. This means you will only want to use it for gaming – if the other two, decent alternatives (the M3G-enabled Jeodek or Jbed) don’t work or work slower.

In THIS HowardForums thread, you’ll find many titles compatible with this MIDlet manager; and, of course, my main games compatibility chart will provide you with a lot of additional compatibility information with current MIDlets.

2.6. Not recommended KVM’s

Note that the charts (and this tutorial) don't elaborate on the following MIDlet managers:

2.6.1 NSICom CrE-ME

This manager is still (as of version 4.12) pretty weak (MIDP 1-only, really low resolution, problems with connecting to the Net, pretty complicated to install a MIDlet etc.). This means it, in most cases, should not be used. Strange the developers still call it "the world's most reliable J2ME/CDC Java Virtual Machine technology for Embedded platforms". While CrE-ME is without doubt the BEST JVM out there right now for running individual applications / applets (which are vastly different from MIDlets), its MIDlet support is really bad.

2.6.2 Coretek Delta Java Manager

This MIDlet manager is only slightly better than NSICom's above-mentioned CrE-ME. While it's compatible with quite a few games, it has severe problems; most importantly, its utilized screen estate is tied to 176*220 (fortunately, it’s pixel doubled on VGA devices). This means you won't be able to run your MIDlets using the real, full screen estate of your QVGA / VGA / WVGA Pocket PC's or QVGA Smartphones. Therefore, I only recommend it if you want to run MIDlets tied to 176*220 (or smaller) screen sizes and/or you have a 176*220 MS Smartphone.

A related (Russian) thread is HERE (BabelFish HERE)

2.6.3 Mitac JVM

This is an old (2003), pretty bad and not recommended MIDlet manager.

Related thread: MoDaCo Working midlets and non-working midlets.
25th October 2007, 01:15 PM |#5  
OP Retired Moderator
Thanks Meter: 139
3. Introduction to using MIDlets

Now, let’s see how you can install (deploy) MIDlets on your Windows Mobile device and how you can use them. Fortunately, doing this is very simple.

First, make sure you do have a KVM on your handheld. If you don’t, install one. If you have a non-phone Pocket PC and want to use any MIDlet manager (except for IBM J9), make sure you install the SMS.dll and Phone.dll hacks and / or if you have a pre-WM5 device, you’ll need to choose from either IBM J9 or old versions of TAO Intent.

After this, your life will be pretty easy.

3.1 Two ways of deployment (installation): online vs. offline

In general, there are a lot of MIDlets available online. In general, if you click them on the Web from your Windows Mobile device (preferably, using a built-in Web browser), they get downloaded to your handheld and automatically deployed in your device. The same happens with JAR files you copy to your handheld and, then, deploy them locally by either making your KVM explicitly search for it or clicking it / pressing the Action button from a local file manager. In the following two subsections, I elaborate on these questions.

Note that, generally, there are two kinds of files you’ll run into: JAD files and JAR files. When you download a MIDlet to your desktop PC so that you can, later, deploy it into your handheld’s KVM, only download JAR files, not the JAD ones.

If there’s no way of directly accessing JAR files, only JAD ones (as is, for example, the case with the Opera Mini 4 beta download page HERE - note that you should visit it from a Wap-capable desktop browser (Opera), that is, NOT from IE!), the “Download high memory version” download link will download you a JAD file, not a JAR one. You can directly copy this file to your handheld but, then, it’ll need to have Internet connection to be able to download the JAR file referenced by the small JAD file. If you can’t guarantee this or prefer collecting the JAR files offline, do the following: open the JAD file you downloaded with a text / file viewer (editor) and look for the attribute named “MIDlet-Jar-URL”. Copy the URL after the colon (for example, to your desktop Web browser. Now, you’ll have direct access to the JAR file – you can already safely save it.

Note that some KVM’s support separating MIDlets into different folders. Some allow for selecting the folder at deployment time (an additional step in the deployment process; this is what, initially, the “root” screen stands for when deploying into Esmertec products), the others after deployment. (And, on the Nokia, as it has no MIDlet manager interface at all but all deployed MIDlets are listed as regular applications, you can use the system file explorer tools to move them elsewhere, in another folder. This is slightly different from the way MIDlets were handled or early MIDlet-capable Nokia phones like the N-Gage, where there was a separate folder for them.) Also see the “Possible to use folders for better MIDlet separation?” row in the main chart for more info & screenshots.

Also note that, during the deployment process, you will also need to let the installation continue, particularly when the given MIDlet isn’t signed with a trusted certificate. (The vast majority of MIDlets are like this.) This, in general, only means you will need to press the left softkey some times on both Windows Mobile and Symbian.

3.1.1 Offline: originating the deployment from inside the manager vs. doing the same from the outside

There are two ways of deploying a local MIDlet JAR file to your MIDlet browser. The easiest is the default way of just clicking / pressing the Action key while viewing it from a local file explorer tool. This, as long as the file associations are correctly set (which may NOT be the case if you install more than one KVM’s on your handheld – more on this later), will automatically invoke the JVM and deploy the MIDlet.

Another way to select the related menu item inside the given KVM is to search for JAR files in the local file system (for example, Menu / Install / Local with TAO and Menu / Install / Local Files with Esmertec’s KVM’s). Unfortunately, it’s pretty flawed with most of the KVM’s; for example, the lack of alphabetical sorting, some of them can’t display all the files at once if there are more than 200-250 of them, some are only looking in a given directory or have no search capabilities at all, which is the case with IBM J9. The latter, as it doesn’t allow for browsing the file system for a given JAR file, forces you to enter the full (local, that is, Error! Hyperlink reference not valid. ) URL of the JAR file, which is really a pain in the back. Finally, Jblend doesn’t offer any local file browsing / deployment at all – with it, you must initiate the deployment from any file explorer tool. The latter is “only” highly recommended with other KVM’s because of the other annoyances and bugs they have.

3.1.2 Online

This is much easier: you just navigate to the given page with the MIDlets online and just click the JAD (or JAR) files. Note that some KVM’s may not allow for installing Web-based JAR’s directly; with them, you will need to click the JAD file instead. This is in stark contrast with the local install: all the tested (non-disqualified) browsers allow for the direct installation of JAR files and no local JAD’s are needed.

3.2 Running the already-deployed MIDlets

After your MIDlet is deployed, you will need to click it from inside the KVM if it’s not started automatically: most current, recommended KVM’s ask the user whether the MIDlet should be started right after the deployment.

Otherwise, you just start the KVM environment (it’s, in general, in the main Start Menu / Programs folder (except for the HTC Kaiser / Tilt, where it’s in the Tools subdirectory there) and is called “Jbed”, “Java”, “Jeodek” or “Esmertec Jbed/Jeodek” with the Esmertec products, “MIDlet Manager” with TAO Intent, “Midlet HQ” with IBM J9 (linking emulator.exe) and “Jblend” with Jblend) and simply double-click the given, already-deployed MIDlet. With IBM J9, you must select the uppermost “Launch” menu item in Actions instead, after highlighting your MIDlet.

Now that I’ve made it clear it’s only Nokia’s (Symbian) MIDlet manager that puts the deployed MIDlet icons in the traditional Applications folder, you may also want to know whether you can also hack the Windows Mobile KVM’s to do the same. This, as you may have already guessed, also greatly speeds up starting a given MIDlet: you don’t need to start an additional layer of managers. The answer is: yes, with most KVM’s (except for Jblend), you can. Then, you won’t need to separately start the KVM interface to gain access to the deployed MIDlets. See the “Direct, system-level links (shortcuts) to MIDlets” row in the main chart for more info on this. Note that, as opposed to Nokia’s system-level links (or, for that matter, the way the excellent Palm OS emulator, StyleTap, works on Windows Mobile), all these links will have the same icon, unlike under Symbian – not that of the icon of the MIDlet itself. This is a definite disadvantage if you prefer looking for a MIDlet based on its icon and not its name / position.

3.3 Security issues

Unlike with native Windows Mobile (or Symbian) applications, you’ll always run into security prompts. Therefore, it’s worth knowing a bit about what they are all about.

Java programs, in general, put a lot of weight on security measurements. This is why they continuously prompt the user when they try to access “sensitive” resources like the Net or the local file system.

Fortunately, you can, in general (except for Jblend), easily get rid of this problem:

- if you have any of the Esmertec KVM’s, use the MIDlets signed by the MXit LifeStyle-signed JAR’s available in THIS thread. Note that I’ve separately linked in the most common non-game (games, in general, aren’t affected by these issues, unless they want to use Bluetooth) MIDlets you may want signed. Then, you’ll be able to set their security model for “Blanket”, which means you’ll never be prompted for permission. It’ll certainly be easier for you than with the default “Session” (you’re asked once per session – that is, after starting the MIDlet) and the even more restrictive “One Shot” security model. Incidentally, Jblend employs exclusively the latter model with accessing the Net; this means it’s pretty much useless for applications like Opera Mini or the Gmail MIDlet. This is particularly true with the Gmail client, where it prompts the user to allow going on upon downloading every single mail (header). That is, never use Gmail under Jblend.

- if you have a KVM where you can “hack” the security descriptor files (all Esmertec KVM’s and IBM J9 belong to here; TAO Intent is also said to be but the opinions do differ on the latter and I haven’t tested this hack), do the hacking to get rid of the annoying security prompts. See the “Security: Allow permanent Net access without prompting ("Blanket" security model, as opposed to "Session" / "Oneshot")?” row in the main chart for more info / links.
25th October 2007, 01:16 PM |#6  
OP Retired Moderator
Thanks Meter: 139
3.4 Runtime issues: concurrent (parallel) and background execution

The KVM’s slightly differ in how they handle concurrent execution of MIDlets – or, simply running something in the background. Some (TAO and J9) allow for the concurrent execution of MIDlets, while the rest don’t. This means the, otherwise, excellent Esmertec KVM’s will only run one MIDlet at a time, while the certainly, in most respects, inferior J9 and TAO Intent will run any number of them. TAO, in addition, also supports the in-environment switch between running MIDlets, unlike J9.

Support for parallel MIDlet execution can be very useful; for example, the Gmail MIDlet could continuously check Gmail for incoming messages, while, in another MIDlet, you could browse the Web. You can find some other uses for example HERE, in the comment section (the comments HERE are also pretty instructive and shed light on related issues).

The ability to execute a MIDlet in the background is also very important. Just an example: you start downloading a Web page in Opera Mini but quickly realize the download will take ages. In order to save time and do something useful in the meantime, you decide to minimize the Opera Mini task, do something else in another program and only return later, expecting Opera Mini has already finished downloading and rendering. All the tested WM and Symbian KVM’s support this kind of operation; the only exception is Jblend, which immediately pauses when it loses the focus. Incidentally, Jblend’s behavior also has some other consequences; for example, in no way can you use external character injectors to it (unless they’re continuously running and, therefore, don’t result in executing a new process; PQzII is one of these) and you will even have problems uploading Jbenchmark results to the server (because it constantly thinks the MIDlet has been paused and prompts you for resuming).

I also recommend Solnyshok’s excellent article for more information on the advantages of parallel execution of some MIDlets. Also note that the article contains an excellent hacking tutorial on how multiple instances of the same MIDlet can be executed at the same time.

4. The main chart

Again, this is where you’ll find most information. It contains an order of magnitude more information than the article you’re just reading in a well-condensed, tabular, easy-to-compare form, packed with tons of screenshots helping in finding out how a given feature should be enabled / used.

I’ve already elaborated on several (for example, security-related) of the rows this chart has; now, let me elaborate on the rest.

In the “Price / availability” row, as has already been stated, you’ll find where to get / download the given KVM from.

In the “Platform compatibility” group, I’ve listed three rows: compatibility with non-phone Pocket PC’s, Pocket PC Phone Edition devices and, finally, touchscreen-less Smartphones (abbreviated as SP’s).

As has already been pointed out, you MUST apply the SMS/Phone DLL hack explained in the Jeodek column if you have a phone-less, “classic” Pocket PC. Also, if you have a MS Smartphone (as opposed to Pocket PC’s), pay special attention to the compatibility remarks here as, unfortunately, not all titles are Smartphone-compliant or, if they are, you may encounter some problems when trying to run them.

The “Generic compliance with standards” group is more for techies: people that would like to know everything about the standards support of the given KVM. As can clearly be seen, the Nokia N95 KVM blows all the other KVM’s out of the water (in this respect too); this is particularly true of, under Windows Mobile, never (except for some very old and long-discontinued IBM J9-specific add-on projects I’ve elaborated on HERE) implemented, for, for example, multiplayer gaming (give a try to the MIDlet version of 3D Constructo Combat in multiplayer mode on even slower / older Nokias like the 6680 – you’ll LOVE it! The same stands for for example the infamous Naval Battle: Mission Commander) Bluetooth support. The same stands for other goodies like support for camera: all WM KVM’s lack the support for it, as can clearly be seen in the “MMAPI Video-capture” cell of the “JVM Multimedia (JSR 135)” row. It could be VERY useful; see for example the posts HERE, seeking for support for barcode reader applications. Audio capture (which isn’t really supported by many apps either) is also pretty useful; see for example the TellMe MIDlet for a real-world usage example. Yeah, you can clearly see MIDlets are in no way for gaming only – there have a LOT of enterprise uses and are particularly useful when you have a lot of different platforms you need to quickly develop a business solution for!

In the “JVM Memory” row, I’ve listed the appropriate heap (free memory) size available for each KVM. The more, the better for running memory-hungry MIDlets – unless the given KVM uses dynamic (de)allocation of memory when the need arises. Then, it’ll be able to run even the most memory-hungry MIDlets (for example, a full JBenchmark category, in High Quality, packed into one JAR). Unfortunately, only Nokia’s KVM and Jbed support the latter. Also note that you can set the memory allocated for Jblend in the Registry.

Support for “JVM M3G”, that is, the Mobile 3D Graphics API is the dream of most Java MIDlet gamers. As can be seen, several KVM’s support it. (Speed, without hardware acceleration, is another question.)

The “JVM File Connection” group is also very important, particularly with applications like Opera Mini Mod, the unofficial (and, unfortunately, illegal; therefore, I cannot provide a link to it either) “hack” of Opera Mini, adding a lot of goodies like (pretty rude, but still working) page saving and IEM favorite import / export. These all require access to the file system, which, unlike with real Java, isn’t built-in or required by the basic standard. This is why so few WM KVM’s support it: IBM J9 with an additional hack (I’ve elaborated on the installation in the chart) and Jbed. Interestingly, some real-world tests were failed by Jbed, while IBM J9 passed all of them. The support for accessing the local file system is certainly a big plus with IBM J9 – one of the very few advantages of the environment, along with, for example, the ability to run several MIDlets at the same time.

The “Storage usage” group is very important because internal storage memory is doomed to fill up very quickly (especially with low-end WM devices only having 64M of Flash ROM – an example is the HTC s310/Oxygen WM5 Smartphone), particularly if you install sizable games (current games are 300-600 kbytes in size). In this group, I’ve explained the following:
  1. Where can a given MIDlet manager KVM be installed to – that is, can it be installed to a storage card? All of them can (note that we’re, mostly, dealing with XDA-Dev-created installers and hacks in here!), except for Jbed, which MAY require some additional manual file copying (also explained in the chart).
  2. Where the deployed MIDlets are kept: This is also highly important. Fortunately, it’s only IBM J9 that is doomed to store the deployed MIDlets in the internal storage (I’ve tried to hack it to a card very hard – see my related article – but in vain); other MIDlet managers, when installed to a storage card, don’t. Note that, should Jblend and TAO be an OEM-installed KVM on your handset, you can still easily “hack” them to store their MIDlets on a storage card with a simple Registry edit.
25th October 2007, 01:16 PM |#7  
OP Retired Moderator
Thanks Meter: 139
In the “Text input” group, first, I’ve listed the copy / cut / paste capabilities of the KVM’s. One of the biggest problems with TAO is the complete lack of copy / paste functionality in any of its textboxes. This is a real pain in the back. Note that some 4pda users have implemented an external, not very reliable way of pasting text to the TAO textboxes (via MortScript), it’s still far from perfect.

Known text input-related bugs? Maximal editable pre-populated text area size?” elaborates on the text input-related bugs of the tested KVM’s. The most important of them (without any exception – not even Nokia’s implementation did fare well in this respect) is the text input areas’ limited size. This means the following: when you, for example, post an answer in a forum using the “QUOTE” button, you may end up not being able to enter anything and/or your answer getting completely deleted. In general, the threshold is between 1 and 8 kilobytes, depending on the actual KVM and the Web browser you use (Opera Mini fares far better in this respect than its modded version; I think because the latter uses 16-bit Unicode for input, which take up double the memory as the 8-bit input of Opera Mini.) Therefore, make sure you either quote VERY short answers and try to remain under the threshold or try not to quote anything.

In addition, TAO has a very bad, additional bug: if the quoted (and/or, original) text contains line breaks, you won’t be able to edit it at all.

I really recommend giving the test HTML page I’ve created for this test a thorough try to see what restrictions there are, whether your input is retained (after you exit the edit mode) etc so that you can be absolutely sure you don’t mess up anything when you do start filling in Web forms or post to forums with Opera Mini (Mod).

The “Display” category contains information on the usage of font smoothing technologies like ClearType (also see THIS request). As can clearly be seen, it’s only when using the smallest character size and only with some KVM’s that there is font smoothing (with OM4b2)

I’ve devoted two separate rows (and a lot of screenshots) to demonstrate the font sizes of Opera Mini 4 beta 2 in both VGA and QVGA because a great deal of misinformation is all around the Net on the different font sizes of each. For this test, I’ve also created a test page. As can be seen, the font sizes are roughly equal with all KVM’s, as opposed to what some people state. Also note that I’ve also published how you can increase the font size in TAO with a simple Registry edit (I’ve also attached the import file) – the ability to do this is clearly is a definite advantage of TAO.

As far as the “Keyboard, SIP, softkeys” group is concerned, please read THIS for a very thorough explanation.

I’ve already elaborated on most rows of the “MIDlet installation, separation, direct invocation, uninstall” group; therefore, I won’t go into this once more. It’s probably only “Registry import files to quickly reassociate JAR / JAD files” that still hasn’t been explained. Please see the “2.4 Co-existing on the same Windows Mobile devices” section in the Definitive Guide to Running 3D-enabled Java MIDlets on Windows Mobile to see why you might need these Registry import files if you plan to use more than one KVM’s on your Windows Mobile device and want to retain (or, quickly restore) the ability of a given KVM to deploy a MIDlet you click on in an external (Windows Mobile) Web browser or in the file system.

The “Security” group has already been explained above.

The “Misc (sound, compatibility with some popular apps, proxy, etc)” group contains some miscellaneous tests and rows like
  1. support for full screen: as can clearly be seen, in this regard, Jbed is the best (it indeed offers full screen) and Jeodek is the second (it only displays the upper task bar but not the lower menu bar; Jeodek M3G being the only exception when run on the MS Smartphone platform). So does Jblend. TAO and IBM J9, unfortunately, both display the two bars at the top and bottom. Needless to say, Nokia’s KVM also makes use of the full screen estate.
  2. Sound support: as has turned out during the tests, Jbed (along with Nokia’s KVM) is by far the best KVM when it comes to playing in-game music. Note that I’ve tested it being stereo by running Doom RPG, a very famous MIDlet (even’s infamous Sponge likes it). Strangely, while Jbed does support stereo, Nokia has failed the stereo test: it only plays music in mono. At last something that Nokia’s KVM gets beaten at
  3. Proxy support is also very important and in high demand among Opera Mini users (as Opera Mini, by default, doesn’t support proxies, unlike Opera Mini Mod, where you can enter the proxy address right in the browser settings). In these tests, I’ve used my custom-written Web client MIDlet and Web server to easily find out which of the several possible ways Opera Mini (or, any other Web browser not supporting custom, local proxy settings) can be made use a proxy. As can clearly be seen, only Jbed and IBM J9 support this. (I haven’t tested Nokia’s KVM in this respect; I assume it works OK.)
  4. the compliance test of three highly popular productivity (non-game) MIDlets: Gmail, Opera Mini and Opera Mini Mod.

5. jBenchmark Benchmark Results

I’ve also made some serious benchmarks with the well-known jBenchmark suite.

First, it’s worth pointing out that, while Esmertec Jbed does promise speedup by compiled code, in reality, it doesn’t mean THAT big a speed increase. That is, you won’t even see a twofold speed increase in everyday apps / games – if there will be any speed difference at all. In the charts, I’ve emphasized the tests where Jbed produced FAR better results than other MIDlet managers running on the same device. I’ve used plain bold to emphasize differences up to two; to emphasize even bigger differences (for example, the Chess test), I’ve additionally used Italic and <u>Underline</u>.

It’s also worth pointing out that while high-resolution (VGA) devices (in the test, the Dell Axim x51v and the HTC Universal) tend to run standard 2D graphics tests (at times a LOT) slower than standard-resolution (QVGA) models like the HTC Wizard or the HTC Vox / s710, with 3D (with the only currently available, 3D-capable MIDlet manager, the TAO Intent 11.x series), the differences aren’t that big.

As far as the 3D benchmarks are concerned, which show a clear, sometimes 20-fold speed difference in favor of the 3D hardware accelerated Nokia N95, don’t think Windows Mobile devices are THAT bad at playing the currently available 3D games. While M3G games indeed run pretty much flawlessly on the Nokia N93(i), N95 and E90 (the current Nokias with 3D hardware acceleration), the currently available, non-accelerated Windows Mobile KVM’s don’t produce MUCH worse results either – most 3D games still remain playable under WM too. In practice, the 20-fold difference in these synthetic tests reduce to two to three-fold difference with currently available, tested 3D MIDlets. Never ever believe anyone that states the opposite – he or she, then, hasn’t compared (unaccelerated) Windows Mobile and (accelerated) N95. I did and know the difference, which is certainly not even tenfold, no matter what the JBenchmark results suggest. Note that the reason the Nokia N95 scores so good in 3D is not because the built-in PowerVR 3D chip would be so much faster than, currently, the 2700G. It’s just because the former is supported by the built-in MIDlet manager and the latter isn’t supported by any Windows Mobile MIDlet managers.

Otherwise, speed-wise, there’s no clear winner. In general, all MIDlet managers have their strengths and weaknesses; there isn’t a single one with the best speed / efficiency (not even that of Nokia). Also note that, in general, the Nokia benchmarks don’t differ much from those of the WM KVM’s – of course, the M3G results are completely different. But, again, with real MIDlets, this difference is far less pronounced than one would think based on the synthetic JBenchmark 3D results.

Note that the columns are a bit different from the first chart; now, I’ve also listed the device I’ve run the given MIDlet manager on.
25th October 2007, 01:17 PM |#8  
OP Retired Moderator
Thanks Meter: 139
6. Game compatibility reports

I’ve also thoroughly tested some hundred (!) popular, well-known games; both 2D and 3D titles. (More on these games in THIS article – my previous and, now, slightly outdated article on 3D gaming.)

As has already been emphasized with the benchmarks, there’s no clear winner here either. As a rule of thumb, however, you should always try to run a given title under Jbed first. It’s the least compatible with existing games, but has three real advantages over both the M3G-compliant version of Jeodek and Jblend: if it does work then, generally, it’s the fastest; of the three, it has the best sound emulation and it supports full screen mode.

If you do encounter problems, give a try to alternative MIDlet managers: to IBM J9, TAO Intent, Jeodek M3G or Jblend (or, JblendFullScreen if you don’t need M3G and/or decent music but do need full screen because of, for example, the hard-coded screen size used by the MIDlet). Note that it’s pretty useless to try to run a title not running under Jbed under the non-M3G-capable Jeodek either. Doing the same under the M3G-capable Jeodek version, however, is a completely different issue.

As has already been emphasized, these MIDlet managers can co-exist on the same device and if you’re really into gaming as many MIDlets as possible, you will want to put at least three (Jbed, Jblend and Jeodek M3G) on your handset.

Note that there is an earlier version of this chart HERE. As the chart doesn’t contain for example the Nokia N95, the M3G-capable Jblend (only its full screen, old and pretty much incapable version) and lists far fewer titles than the main games compatibility chart, it’s in no way as important as the main compatibility chart listing the, for gaming, most recommended WM KVM’s (along with Nokia). However, it also contains some info on how different hardware (520 MHz XScale-based VGA HTC Universal vs. 195 MHz TI OMAP-based QVGA Wizard, for example) compare when it comes to running (graphics-intensive) games. As can be seen, the, otherwise, for gaming not really recommended Wizard behaves pretty OK even at the default 195 MHz CPU clock speed.

Highly recommended articles

TUTORIAL: Control issues of Java MIDlets – all secrets of button handling. Crossposts: PPCT, AximSite, XDA-Developers - 1, XDA-Developers - 2, XDA-Developers - 3, FirstLoox, BrightHand, HowardForums, SPT, MoDaCo,,

The Definitive Guide to Running 3D-enabled Java MIDlets on Windows Mobile (note that its discussion of some of the apps is a bit outdated; that is, consider the info in the current Bible of higher priority than in there. Also note that the comments (at the bottom) are really worth checking out, just like with the comments arrived at THIS article. Crossposts: PPCT, AximSite, XDA-Developers, XDA-Developers - 2, FirstLoox, BrightHand, HowardForums, SPT, MoDaCo,,

The Button Enhancer Bible & great button config tips for Opera Mobile / Mini users – it has a LOT of MIDlet-related info. Crossposts: PPCT, AximSite, XDA-Developers - 1, XDA-Developers - 2, FirstLoox, BrightHand, HowardForums, SPT, MoDaCo.

4PDA thread; translations HERE

5 things noobs should know about java mobile games

The MIDlet reviews at Mobile Critic and Midlet Review

The homepages of Fishlabs, Gameloft, Glu and Xendex

My old, outdated, related articles

What TAO Intent versions there are? - this article has been written before Risidoro’s releasing the 1034/1036 versions and the release of the generic SMS / phone.dll hacks. The latter means you don’t need to install the somewhat older version .1023 of the MIDlet manager on your phone-less PPC any more.

Running Motorola-specific Midlet games on the Pocket PC? YES!!

IBM releases new, 6.1.1 version of great Midlet runner J9; now, it’s fully compatible with Google Maps!

Great, Free Java/Midlet Environment IBM J9 New, 6.1 Version is Out – a Full Compliance & Bug Report & Never Before Published Tweaks that Help Using It Much Easier (in there, I’ve also reported on my effort of trying to relocate the IBM J9 deployed MIDlet repository from the main memory).

Java Midlets on the Pocket PC - the Complete Tutorial (outdated, but nice for some additional tips)
25th October 2007, 06:15 PM |#9  
OP Retired Moderator
Thanks Meter: 139
Wowz, thanks for the kind words
25th October 2007, 06:56 PM |#10  
Inactive Recognized Developer
Thanks Meter: 67
Menneisyys, as usual you did an excellent job! Many thanks

I would welcome one addition though: a table which shows which JSR standards are supported by each midlet manager.

I have spent much time to find out that only IBM J9 supports both JSR-75 (accessing PIM database and the File System) and JSR-82 (Java BT API & serial ports). There exist a couple of applications, e.g. MGMaps, which rely on support for both stds.

25th October 2007, 07:31 PM |#11  
OP Retired Moderator
Thanks Meter: 139
Originally Posted by jockyw2001

Menneisyys, as usual you did an excellent job! Many thanks

I would welcome one addition though: a table which shows which JSR standards are supported by each midlet manager.

I have spent much time to find out that only IBM J9 supports both JSR-75 (accessing PIM database and the File System) and JSR-82 (Java BT API & serial ports). There exist a couple of applications, e.g. MGMaps, which rely on support for both stds.


1. Thanks for the kind words

2. JRS-75 (File Connection & PIM) requires an add-on hack (see the "JVM File Connection (part of JSR 75):" row)

3. As far as JSR-82 (BT) is concerned, it did have two third-party BT add-on libraries, but they no longer exist. See for more info.
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