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Closed 9 years ago.
Okay, I will shortly be starting down the path of windows mobile development. I know nothing about the subject really and I am looking for people with experience to let me know of any gottchas you may know of.
Right now I dont even have a breif of what is requied but the assumption is that the application will be very little more than a bunch of CRUD forms for updating data. The only other requirment knowladge I have is that the application will need to support offline storage when there is no signal avaliable. This in turn will obviously require some kind of syncronization when signal returns.
My initial thoughts are that the application will primarily be a front end to interact with a web service layer. Im assuming that WCF will be an appropriate technology for building these services? I also thought that SQL Server CE would be a good route to go down with regards to the offline storage issues.
Any knowlage that you feel is useful within this domain would be appreciated. Advice, links, books anything appreciated.
EDIT: It has been noted that there are two ways to go with off-line synchronization. To either use some form of message queuing or to use SQL synchronization tools. Could anyone offer a good comparison and introduction to these?
EDIT 2: After a little more digging I get the impression that there are basically 3 different approaches I can use here:
Emmbeded Database to query against then syncronization online, when able
MSMQ along with .NET remoting
WCF with ExchangeWebServiceMailTransport bindings using Exchange Server.
Now, there has been a nice few points raised on the first issue, and I think I understand at some level the issues I would face. But I'd like to get a little more information regarding MSMQ implementations and using WCFs new bindings.
Here a few words from my experience so far (about 9 months) of .net Windows Mobile development.
Well you are occasionally connected. (Or more likely occasionally disconnected). You have to choose whether you are going to use messaging with queues (i.e. WCF/SOAP/XML or something like it) or database synchronisation. I choose the SQL synchronisation route so I can't really comment on messaging. The SQL synchronisation route is not hassle free!
If you go down the sync route with SQL compact like me you basically have two choices. SQL Server merge replication or the newer ADO.NET Synchronisation services. If you choose the former you need to be really careful with your DB design to ensure it can be easily partitioned between mobile subscribers and the publisher. You really need to think about conflicts, and splitting tables that wouldn't normally be split in a normalised DB design is one way of doing that. You have to consider situations where a device goes offline for some time and the publisher DB (i.e. main DB) and/or a subscriber alters the same data. What happens when the device comes back online? It might mean resolving conflicts even if you have partitioned things well. This is where I got burnt. But SQL Merge Replication can work well and reduces the amount of code you have to write.
Roll your own DAL. Don't attempt to use datareaders etc. directly from UI code and don't use typed datasets either. There may be third party DALs that work with Windows Mobile (i.e. I know LLBLGEN does, might be worth a look) but Linq-to-SQL is not supported and anyway you need something lightweight. The chances are the DAL won't be too big so roll it yourself.
If you are using .net you'll probably end up wanting some unimplemented platform features. I recommend using this inexpensive framework to give you what your missing (especially as related to connectivity and power management) - http://www.opennetcf.com/Products/SmartDeviceFramework/tabid/65/Default.aspx
Windows Mobile devices partially switch off to save power when not in use. If you are doing a polling type design you'll need to wake them up every x mins. A normal .net timer class won't do this. You'll need to use a platform feature which can be used from OpenNetCF (above). The timer class is called LargeIntervalTimer and is in the OpenNetCF.WindowsCE assembly/namespace (I think).
Good Luck!
SqlCE is only one of the options available for local data storage on a Windows Mobile device, and although it's an excellent database it has limitations. For one thing, SqlCE will not work (period) under encryption (in other words, if your user encrypts the location where your SDF file is, you will no longer be able to access the data).
The second (and most critical) weakness of SqlCE lies in the RDA/Merge Replication tools. SqlCE Merge Replication is not 100% reliable in situations where the network connection can drop during replication (obviously very common in Windows Mobile devices). If you enjoy trying to explain missing or corrupted data to your clients, go ahead and use SqlCE and merge replication.
Oracle Lite is a good alternative to SqlCE, although it too doesn't work properly under encryption. If encryption is a potential problem, you need to find a database engine that works under encryption (I don't know of one) or else write your own persistence component using XML or something.
Writing a WM application as a front end that primarily interacts with a web service in real time will only work in an always-connected environment. A better approach is to write your application as a front end that primarily interacts with local data (SqlCE, Oracle Lite, XML or whatever), and then create a separate Synchronization component that handles pushing and pulling data.
Again, SqlCE merge replication does this pushing and pulling beautifully and elegantly - it just doesn't work all the time. If you want a replication mechanism that works reliably, you'll have to write your own. Oracle Lite has something called a snapshot table that works very well for this purpose. A snapshot table in Olite tracks changes (like adds, updates and deletes) and allows you to query the changes separately and update the central database (through a web service) to match.
This thread I just posted on SO a few days ago has proven to be a great resource for me thus far.
Also the Windows Mobile MSDN WebCasts are a wealth of information on everything from just getting started up to advanced development.
I would suggest Sqlite for local storage. From the last benchmark I ran it was much better than SqlCe and you don't have to do stupid things like retain an open connection for performance improvements.
Trade-offs being that the toolset is less rich and the integration with other MSSql products is nil. :(
you might want to refer to this:
getting-started-with-windows-mobile-development
You shouldn't be intimidated for windows mobile development. It isn't much different from desktop development. I strongly recommend that you use .NET Compact Framework for development and not C++/MFC.
Some useful links:
Mobile section at the Code
Project. You would find a lot of
articles, a little digging is needed
to find the appropriate one.
Smart
Device Framework from OpenNetCF
offer valuable extensions to the
compact framework.
When you install
the Mobile SDK, you will find under the
Community folder links for the
Windows Mobile and CF framework
blogs. These are also valuable
resources.
Regarding your application, you are right about the WCF and the SQL Server CE. These are the proper ways for handling communication and storage.
Some hints for people coming from a desktop world:
You need to have some sort of power management. The device may automatically go to suspend state. Also, you shouldn't consume power when you don't have to.
Network connectivity is a difficult issue. You can register notifications for when a specific network (Wi-Fi, GPRS) becomes available or unavailable. You can also set the preferred means of communication.
Make the UI as simple as possible. The user uses his thumb and/or a pen and he is probably on the move.
Test in a real device as early as possible.
"24 Hours of Windows Mobile Application Development" from the Windows Mobile Team Blog has some good resources
If you can, try to start from the user use cases and work back to the code, rather than vice versa. It's really easy to spend a lot more time working on the tools than working on the business problem. And thinking through user requirements will help you consider alternate strategies, because a lot of the patterns you know from normal .NET don't apply.
I've done lots of intermittent application development of exactly the type you are describing, and an on-board database works just fine. The MSMQ/WCF stuff just adds conceptual overhead without adding much value. You need a logical datastore locally anyway, and replication at this level is a simple concept that you want to keep simple, so the audit trail is easily monitored and debugged. MSMQ and WCF tend to hide things in unfamiliar places.
I upvoted the SqlLite suggestion BTW. MS doesn't have their persistence story stabilized yet for CE.
For the database replication bit I highly recommend Sybase Ultralite. In terms of flexibility and performance it knocks the socks off SQL CE
I had to do this once. Weird setup with Macs for development, and we were all Java programmers. And a short deadline. PowerPC macs too, so no chance to install Windows for Visual Studio development, never mind that the money for this would never have appeared.
We ended up writing applications using Java, running on the IBM J9 virtual machine, with SWT for a user interface. Entirely free development stack. Easy to deploy. Code ran on any platform we desired, not just PocketPC/WinMob.
Most of the work was on the server side anyway - the database, the web service server. The logic. The reporting engine. The client side wasn't totally simple however - would get the form templates from the server (because they changed frequently), the site details (multi-site deployment), generate a UI from the form template (using some SWT GUI components that are wonderful for PocketPC development, like the ExpandBar), gather data with a point and click interface (minimising keyboard entry where possible), and then submit it back to the server.
For offline storage we used XML files on the device itself. More than enough for our needs, but yours may differ. Maybe consider SQLite?
There are a couple links you can check out to start with:
http://developer.windowsmobile.com
http://msdn.microsoft.com/en-us/windowsmobile/default.aspx
If you have a sticking point while developing, there are also Windows Mobile dedicated chats on MSDN that you can attend and ask your questions. The calendar hasn't been updated yet, but the next ones should be in January. You can find the schedule here: http://msdn.microsoft.com/en-us/chats/default.aspx
I am going to add an additional question to this post, as its been active enough and hopefully will be helpful to others as well as me. Ok, so after playing around I now realize that standard class libraries cannot be included in windows mobile applications.
Now the overwhelming advice here seems to be use an embedded database, though I now do have use cases and it appears that I will need to have document synchronization as well as relational data. With this in mind service layer interaction seems inevitable. So my question is how would I share common domain objects and interfaces between the layers?
"Document synchronization" - does that mean bidirectional? Or cumulative write-only? I can think of mobile architectures that would mainly collect and submit transactions for a shared document - if that's your requirement, then we should discuss offline - it's a long (and interesting) conversation.
Owen you can share code from Compact Framework -> Desktop, it's only Desktop -> Compact Framework that has compatability issues if you use certain objects that are not supported by the CF.
While a desktop lib doesn't work on CF a CF lib WILL work on the desktop, you can also run CF.exes on the desktop!
Just create a CF library as the project that defines your base objects / interfaces etc.
This book sshould e essential reading for all Windows Mobile developers: http://www.microsoft.com/learning/en/us/books/10294.aspx
For developing windows mobile applications you must have the basic tools like silverlight, visual studio, windows phone emulator and sqlite as your database storage.
Related
I'm currently trying to find the best message queue solution for an appharbor application. Most of the ones of looked at assume you have a windows environment with MSMQ and DTC installed, which I don't believe the appharbor environment provides.
I would like something that works well with ravendb, as that is the database we are using. Something who's only dependence is on raven would be ideal, especially if it integrates with our existing unit of work. Ie, when save changes is called in our controller action the messages are saved in the same transaction.
It would also need a host that works in a console application for background processing.
Ideally I would like something that "just works" in a development environment also. With raven, for example, we use the embedded mode while developing and I would like something that doesn't require installation.
I've looked at nServicebus, which seems to fail these conditions because it needs a transport (msmq, sql, etc) and much of the documentation is out of date.
I also looked at rhino service bus but there is a distinct lack of documentation and community. I'm also not sure if it can depend entirely on ravendb.
The others I looked at all seemed quite heavyweight and required installation and configuration to run in a development environment.
Edit: the other option, is to implement our own.
First of all, congratulations on being the 1000th NServiceBus question on StackOverflow!
Second, if you were to use SQL for persisting your business data, then you could run NServiceBus on top of that same SQL where all the messages go through tables (instead of queues) and then you wouldn't need the DTC.
Third, if you did want to go with RavenDB as your transport for NServiceBus, you would have to implement the ISendMessages and IReceiveMessages interfaces on top of it, but I believe that somebody in the community has already started working on that, so possibly you could join forces with them.
Finally, I wouldn't recommend writing your own ESB these days - not when there are so many good choices already out there. You mentioned the issues of community and documentation - those tend to be handled the worst when writing your own infrastructure.
I don't have a specific question here but I'm more looking for some guidance regarding a new software project I'm starting at work.
Here is a description of the project:
I am refactoring windows software that was written in Visual Basic 6 and uses MS SQL Server for a database. The code is tightly coupled with SQL queries and references old active X controls.
The software can run in a standalone mode where its only running one instance on one computer or in a distributed mode where it runs on several machines simultaneously all connected to a shared data source.
The users of the software need use of a wide range of USB devices that are integrated with the software on the client side. (I'm assuming this means the new version of the software needs to be a desktop application and can not be a browser based web application.)
The new version of the software is going to be updated to use new technologies in an effort to modernize the code and improve performance.
I would like the architecture of the new software be both logical 3-tiers and to use design patterns if appropriate. Although I am new to design patterns it seem like there is an opportunity to use the abstract factory, observer, and singleton patterns together in the new version of the software.
In a very generic explanation the software has an "employee" database table that stores information about employees. The client side has a grid view that allows the user to view the employee information stored in the database and to make modifications to the data through the grid view. Data can be added to the employee database by the client using forms that have text fields and drop down menus. Employee related data can also be captured by USB devices on the client side and then that data can be added to the employee database as well.
In terms of how this relates to architecture I'm guessing there could be an observable singleton employee object that is observed by data display objects like a grid view object and that these data display objects are created by an abstract factory method. (Does that make sense?)
The new software will be written in Visual Basic using Visual Studio 2010. Aside from that none of the other technologies have been decided upon.
I think we will use windows forms opposed to the windows presentation foundation although I'm not sure as there might be some image handling functionality that we want that is better done with WPF.
From what I've read I like the Entity Framework and Linq but I'm not sure how that works in conjunction with the business logic layer with the design patterns I mentioned above.
Also, I'm trying to understand if we could use the windows communication foundation and web services. This makes sense when the software is running in distributed mode but not much sense in the standalone single machine deployment. Adding web services and using IIS might be overkill for what we are trying to accomplish. I don't know.
So this is what I'm working on and what I've been reading about and researching. I would greatly appreciate your thoughts on this and any guidance you can provide.
Thanks!
Aside from the fact that you will learn a lot during the development process I can give you the following recommendations:
Use Stored Procedures in the database for database access. This will prevent concurrency problems and also allows for transactions. This means if something goes wrong (users computer crashes etc) then no data nor data integrity is lost
Treat the windows forms as simply 'interfaces' between the user and the database. Hence they shouldn't contain anything that keeps track of data (let the database do that) and they're only a means of gathering and showing data
I had a very similar experience.
I tried importing a VB6 database project that ran as a standalone app into VB 2005, and the code was very ugly.
One book that I found very helpful with doing three-tier DB applications using VB.NET (VB 2005, actually) was ADO.NET 2.0 with VB 2005 published by Murach. Got me up to speed very quickly, and it gave direct examples of writing three-tier DB applications (business layer, presentation layer, and DB access layer).
Can't remember for sure if there's a newer version of the book, but I was impressed with the layout of that one. It also deals with web apps.
Beyond that, I did some code generation to streamline hacking out the Object classes and the DB access classes for my project.
I believe this project is really going to have you learn and gain a lot of experience.
Like eddy556 said, use the forms only as interfaces. It works better that way.
Plus, if you have any problems, don't hesitate to ask. That's what we the StackOveflow team are here for anyway.
Good Luck.
I'm wondering if anyone is currently utilizing Microsoft's Master Data Services? How you are utilizing it? Whether you find it useful? When you believe it would be useful? Thanks!
I have been working with MDS since it was first released as part of a feature pack for SQL Server 2008 R2. While MDS has some compelling features - most notably detailed data lineage, I am not confident in recommending it to clients yet.
My reason for this hesitation is the nature of the install and the tendendency to fail on upgrade or system change. I struggled mightily with the both the SQL Server 2012 RC0 MDS and the RTM installs. There are simply too many brittle aspects of the install (such as the hard requirement that the service be installed on a domain-joined machine and the need to install the Silverlight 5.0 SDK for the client to work properly). I also experienced flakiness in the the Excel add-in.
I see where Microsoft is going and I think the product will eventually be useful. Considering it's purpose (master data repository), MDS must be more 'rock solid' before I would use it in production.
We aren't using it currently in our office, however the presentation Microsoft did in town a while back seemed very interesting. I saw it as sort of a competitor to Oracle's OBAW warehouse. You've probably already looked at these, but Microsoft has a decent set of webcasts that cover how to install and use MDS out here:
http://www.msdev.com/Directory/SeriesDescription.aspx?CourseId=155
I'm anxious to see if anyone else is using it as well, we tend to have a hard time talking our management into letting us try these types of services without being able to point to other corporations that have successfully implemented said product.
We're just starting to investigate the use of MDS to support our consulting practice, specifically around data analytics and ETLs to deduplicate, standardize, and sanitize client data. It's probably just scratching the surface of MDS, but we were led to MDS initially for its inclusion of regular expression capabilities in SQL to transform free-form text data.
Before MDS/DQS, part of the sustainability / enduring-success of a custom database application was heavily dependent on one or both of the following items...
Having a full-time technical resource to manually update the master data. Someone who can work with the Business Experts and make the necessary adjustments to the data in the database.
Developing (in addition to the database/application/etc) a custom UI that is intuitive enough for the less-technical Business Experts to use for managing the master data themselves.
Neither of these were ideal from a cost-perspective. With MDS/DQS, a developer/contractor can come in, design an end-to-end Data Warehouse/BI solution including full integration with DQS/MDS (probably via SSIS packages) with relative ease. The Business-Experts can be trained to manage the master data using a UI they are already very familiar with (ex. Excel), and the developer/contractor can move on to the next project/client.
Also, if the business already has other data sources (via acquisitions or silo'd-yet-overlapping efforts or whatever), MDS can be used to manage all the master data in one centralized location.
It might not be the best MDS product available yet however it does come with SQL Server. Compared to most of the bespoke efforts for accommodating meta-data or master data in warehouse loads it's a pretty good option since most of the time is spent concentrating on the warehouse and the mastering of ancillary or other data isn't normally well accommodated for leaving questionable results. I prefer to use it than create some other flaky option that the customers will find it difficult to maintain. If you have budget however I would consider looking around for something more polished.
Like anything though give master data the respect it deserves. If it is going to be used then it's worth spending the time to model the entities, flow of data and usage correctly. The data stewards will need to savvy and will require training (it's not the most usable interface in the world - to say the least).
As we are a small consulting and development company we don't use MDS internally but we do implement it at customers with a focus on managing the Golden Record as the customers have a myriad of databases and applications all using the same data (customer, product …)
I agree with Lynn Langit's comment about installation and SilverLight dependency and the general comments about the UI. There are also a lot of smaller companies that don't run SQL Enterprise Edition but whom could benefit from MDS.
Those are the reasons why we are now developing a modern web application which we will host for our customers (probably on Azure).
If you're thinking about MDS I'd recommend to have a look at the API to replace (parts) of the UI.
Master Data Service is very useful for managing Master Data,
We have used Master Data Services 2012 and 2016, there are not too many features present in 2012 ,2016 is much better than 2012 with some new features , but I think still Microsoft needs to improve Master Data Services, they should include some flexibility in business rule's area.
As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.
Closed 10 years ago.
At work I use mostly the .NET Compact Framework 3.5 for developing applications that run on smart devices. Our devices are not phones or handhelds - they are measurement instruments which you get with a whole punch of features. Our application is pretty advanced - we are even using a N-Layer architecture, a self-made GUI framework and even dependency injection (we built our own as the ones other there are not lightweight enough).
So what's the most advanced things you did with the compact framework?
What's currently missing (for example a mocking framework, as there is no Reflection.Emit on compact framework)?
How are you developing your applications? Are you deploying your application every time to the device. In our case this is very slow, as the solution consists of 30 projects so we have a Win32 Version which runs on the PC.
We've done a plant-floor monitoring system that acts as a data server and a web server collecting data from PLCs and creating dynamic web-based reports all in the CF. We've created a peer-to-peer notification and file sharing system. We've done vehicle tracking and dispatching systems. We've done smart-farming applications that monitor loads of data from a tractor and couple that with location and previous year data, plus quite a few others. So I guess you could say de've written several highly-complex things using the CF.
There are lots of "missing" pieces, but most can be worked around. The most obvious missing piece that can't be worked around is the lack of EE Hosting. Reflection pieces for mocking would be nice, but we can live without - it just makes test more of a bear. The lack of Hosting makes several things simply impossible.
As for deployment, it's all about configuration. The Smart Device Framework itself, when coupled with all of the unit test stuff, is something like 45 projects. Deploying isn't bad as it only recompiled and deploys changes, and I often adjust the configuration of test applications to not deploy all projects, but only the main one. That should auto-deploy all references (eliminating the double-deploys you're probably getting). Also having all projects output to one common directory and setting "Copy Local" to false improves things quite a bit too.
One of the most useful things we do with our .net cf application is work hard to make sure that they can be re-targeted to the full framework. This means you have a second desktop project or a unit test that actually runs your entire application on the desktop. There is a bit of work to do if you are using device specific functionality via pinvokes or device only APIs, but the effort usually pays off because:
You can quickly run/debug your application without having to wait for an emulator or device to spin up
You are forced to architect your code in a way that device specific functionality can be mocked and tested
In many cases you are part way to having a desktop version of your application as well as the device version
It probably goes without saying that in the end, testing will need to be done specifically on the device, but during development and the quick code/debug cycles it is really nice to not wait on the emulator. I remember Daniel Moth posting something about how to actually create a device deployment target that is your desktop computer to achieve this same effect. Maybe someone else can find a link?
I have done Win CE app for industrial PDAs for route sales from pre-loaded inventory and clients list. It gets GPS coordinates, uses scanner to collect data, transmits data over GPRS/EDGE of sales made in the device. The app also prints a receipt (linked to protable printer ober BT).
I wrote an app that monitors the statistics on my self-made blog by interfacing with a WebService.
I have developed a multi-language dictionary. Using one code base on Windows, PDA and via MONO on unix and MAC.
Basically the application is complicated because we use multiple databases that are large. We were able to tweak the data access performance and lookups on large tables are almost instantaenous.
Small devices are not very powerful, but if you design for the way they work you can get good performance out of them.
I made an app to collect measures of any magnitude (for weather), using an n tier app, with MVC and using db4o as a database... Pretty impresive
I work for a large state government agency that is a tad behind the times. Our skill sets are outdated and budgetary freezes prevent any training or hiring of new employees/consultants (firing people is also impossible). Designing business objects, implementing design patterns, establishing code libraries and services, unit testing, source control, etc. are all things that you will not find being done here. We are as much of a 0 on the Joel Test as you can possibly get. The good news is that we can only go up from here!
We develop desktop CRUD applications (in C++, C#, or Java) that hit the Oracle database directly through an ODBC connection. We basically have GUI's littered with SQL statements and patchwork code. We have been told to move towards a service-oriented n-tier architecture to prevent direct access to the database and remove the Oracle Client need on user machines.
Is WCF the path we should be headed down? We've done a few of the n-tier application walkthroughs (like this one) and they seem easy to implement, but we just don't know enough to understand if we are even considering the right technologies. Utilizing the .NET generated typed DataSets seems like a nice stopgap to save us month/years of work (as opposed to creating new business objects from the ground up for numerous projects). Is this canned approach viable for a first step?
I recently started using WCF services for my Data Layer in some web applications and I must say, it's frustrating at the beginning (the first week or so), but it is totally worth it once the code is deployed.
You should first try it out with a small existing app, or maybe a proof of concept to make sure it will fit your needs.
From the description of the environment you are in, I'm sure you'll realize the benefit almost immediately.
The last company I worked for chose WCF for almost the exact reason you describe above. There is lots of good documentation and books for WCF, its relatively easy to get working, and WCF supports a lot of configuration options.
There can be some headaches when you start trying to bend WCF to work in a way not specifically designed out of the box. These are generally configuration issues. But sites like this or IDesign can help you through those.
First of all, I would definitely not (sorry for the emphasis) worry about the time you'll save using typed DataSet's versus creating your own business objects. That is usually not where you will spend most of your development time. I prefer using business objects myself.
In you're situation I would want to implement a proof-of-concept first. One that addresses all issues you may encounter. This proof-of-concept should implement an entire use case, starting on the client, retrieving data from the database and returning it to the client. You should feel confident about your implementation before continuing.
Then about choice of technology. WCF is definitely a good choice for communication between your client applications and the service layer. I suppose that both your clients as well as your service layer will become C# applications? That makes things a lot easier since interoperability between different platforms (Java/C# for example) is still not trivial although it should work in most cases.
Take a look at Entity Framework (as there are a couple Oracle providers available for it already) in conjunction with .NET 3.5 SP1 which enables built-in WCF serialization of your EF generated classes.
Here is a good blog to get started: http://blogs.msdn.com/dsimmons
CSLA might be a good fit for your N-Tier desktop apps. It supports WCF, has a large dev community, and is well documented. It is very object oriented.