I'm studying for an exam on Thursday, and in the notes there is a differentiation between incremental development and prototyping. RAD in the notes is said to be an incremental methodology, but anytime I've studied it previously I've referred to it as more of a prototyping method for development.
I'm just wondering whether other people see it as a prototyping methodology?
It should be possible to use an incremental method even for prototyping. Rapid application development is highly suitable for prototyping. The idea is the a.s.a.p. create something "working" on the screen with less of documentation than other development practices.
There is a wikipedia page about this R.A.D. which states the definition and use.
I found rapid application development suitable for developing smaller projects when you are undecided about several factors, for instance language choice, and the programming language of the final product might be another one than what the prototype used.
BTW, the RAD tag you're posting with here stands for IBM Rational Application Developer which is an integrated development environment whose abbreviation also is RAD.
Related
We are evaluating and looking for a workflow engine which support .NET-Core and I'd really appreciate the community input. I would like to hear on the suggestion based on your guys implementation stories.
My main evaluation criteria, so far, are below;
open source and OEM friendly license
production installations (success stories are a great help)
technical support available
open standards support - BPMN
dynamic creation/assembly of the workflow based on input
embeddable
Currently I am evaluating Elsa, Workflow Core, Argo, and Airflow. Elsa seems like a good candidate as well but never used it.
Do you guys have any successful deployments on Elsa workflow engine?
Full disclosure: I am the project lead of Elsa, but I will try and be as objective as I can.
Elsa does not currently support BPMN, so if this is a hard requirement then Elsa might not be suitable for your project. At least not until it implements BPMN in the future.
As for technical support, there is no official paid support available as of yet, but the community is very friendly & helpful, though still relatively small.
Dynamic creation based on input is possible since you can programmatically define workflows. But you cannot update workflows while it executes (which would be more or less similar to being able to update your C# program statements as your program runs). Not sure if this is what you are looking for or not?
Other than that, Elsa is OEM friendly, runs in production successfully at several companies that I know of and is embeddable.
Currently i am working on developing one Warehouse solution from scratch, i am planning to build it in silverlight (as this solution will take around 8-10 months) and the programming will start from Feb 2010.
I need to develop this application for one organization. Certain parts needs to be accessed by public which we are planning to build in ASP .Net 3.5
Now i just wanted to start a thread here for pros and cons of using silverlight, some of them i have already analyzed
Pros :
Rich UI
Excellent user experience
Reduction of scalability concerns
New set of features like data binding, control template etc..
Speed of development (After initial learning curve..my experience says it is faster to develop it in silverlight)
Other rich set of features coming up with SL 4.0 (SL 4.0)
Cons :
Cross platform issues (moonlight is there but it may take some time)
Cross browser issues (Chrome or other browsers)
Learning curve
Any other unknown risk (As there are not many enterprise level application developed in silverlight...or may be i am not aware)
I have also got one link for Pros and cons of silverlight(here) some of the cons might not be relevant with SL 4.0
Also i am having one good link for comparison between ASP .Net Ajax with Silverlight (here)
EDIT :
I have also found Technical Article series in code project (Just Type # google "Adventures while building a Silverlight Enterprise application" and you will get it, i am trying to analyze this series as well)
Please add some pros and cons if you find as i am trying to analyze it from all the angles. It will be of great help if you find any whitepaper on it.
The Pros and Cons have to be weighed against your own requirements.
Rich UI
Compared to what? Its not really a Pro, other tools can deliver Rich UI, where does one draw the line that allows a UI to call itself Rich? A Pro can't be a Pro if can't be measured.
Excellent User Experience
That isn't a Pro either. I wish I could buy product that delvers such a thing out of the box. The reality is it's up to you to deliver the UX. E.g. Stackoverflow delivers an excellent user experience, it doesn't use a tool like SL and it's entirely down to good design not the tool (ASP.NET-MVC+various other tools).
Reduction of Scalability Concerns
Compared to what? Early ASP.NET Forms with extensive use of callbacks then yes. However plain old HTML with Javascript frameworks can deliver this same "Pro".
Speed of Development
Well that depends on how you measure speed and how you weigh the importance of the UX. Currently SL developement isn't any better at ticking off business function points than other tech like poor old ASP.NET Forms and is probably worse. However delivering those same function points with a slick, imaginative UI may tip the balance more in WPF/SL's way. In reality SL allows you deliver more UX with some (but importantly not prohibative) extra effort.
Other Rich Features in SL4
Only a Pro if they would actually add value to your requirement.
Cross Platform
Do you really have a Cross Platform requirement? Within a warehouse business how many Linux and Mac desktops are there? That should answer your cross platform question.
Cross Browser
Is this a Con? Does the company in question allow the use of a variety of browsers? If so which? You can compare that to the browsers SL4 supports and out pops your answer but its your answer not everyones answer. Isn't cross-browser a bigger concern for the Extranet-esq part of the app?
Learning Curve
In all of these factors what are you already versed in is by far and away the most important. I'm guessing its MS tools and in particular .NET, right?
If you're not familiar with WPF already there is some learning curve but its not very steep. However you should definitely make sure you take the time to perform some training projects before you even start designing your real product. That process should help you measure how long it will really take and whether it is really feasable.
Other Known Risks
SL is still very young and it won't sit still. Frustrating "issues" will eat time.
Other questions to ponder
What UX ideas do you have that can't be delivered by a browser?
Why deliver the app via a browser hosted app at all? A WPF application not an option?
Silverlight 4
Considering your timescales if you do choose Silverlight you should target SL4.
Since you are developing solution for the warehouse, you may need consider building a web service with wcf pollDuplex (basically push data from server to the client periodically), just a note on it: it is not (yet) a very scalable and reliable (prior to SL4). Default concurrent connection is 10 (if I remember well), and you have the option to overwrite this default number, however, I haven't find a way to dynamically change this number which turns out to be a scalability issue.
One cool feature I like about SL 4 is the added support of printing, now you have the built-in ability to print the content.
Anyone bulding an Enterprise LOB with a Silverlight client should take a look at John Papa's PDC video.
However, IMHO the initial release of RIA Services was too limited. Now that the next version is buit on top of WCF Services, and the endpoints can be switched out to make them more accessible by more UI clients RIA Service is probably a very sensible investment too.
One of the stated goals of the PureMVC framework is to avoid platform dependencies in order to be portable. Considering that because of language and API differences application code will always be heavily dependent on the platform, and that avoiding platform dependencies makes the framework reinvent the wheel and/or only provide a least-common-denominator feature set, in what way does the portability of the framework benefit me as an application developer?
I've worked with PureMVC. They're trying to implement their stuff in quite a lot of languages. You may be right about the least common denominator, but overall, it's not a bad framework, and I've seen a really nice AS3 app in PureMVC.
I don't think they're talking about portability in terms of porting actual code. The idea there is more that you're using a generalized MVC architecture, which you could apply to other projects and other languages.
They're trying to say that if you become familiar with the PureMVC pattern, you could potentially come into a new PureMVC codebase, even if it's another language, and you would already know the lay of the land.
You might also say that developers who develop good PureMVC skills are likely to develop good habits which will translate as they go from language to language. But then again, maybe not.. for the reasons you mentioned.
We've been using PureMVC on two projects now and in my opinion the attempted language-independence is quite a burden.
The promise of jumping straight in a project because the framework is already know does not seem relevant to me if the languages are not already pretty similar (C# to java would make sense, as3 to php not) -- I agree that it is useful to have known ways of solving things, but for that the 'plain' patterns are good enough.
However, I also don't really agree with the usage of the various patterns the project uses, so our choice to not use it on the next project might be related to both issues, and not just the attempt at language/platform independence.
PureMVC's portability will help you when you migrate to or reimplement in another language.
I can't count the number of platforms and languages I've written code for that are now extinct and for which, even if I still had the source code it would be mostly worthless and have to be rewritten from the ground up today, since the code was usually 100% platform specific.
But all application code need not be heavily dependent upon the platform. View components and services (the boundaries of your application) will necessarily be, but your application logic which is sandwiched between the boundaries need not be.
The scope of PureMVC is really quite narrow; merely to help you split your code into the three tiers proscribed by the MVC meta-pattern. There is no reason why this code has to be tied deeply to your platform in order to be optimal.
When it comes time to migrate, you'll appreciate that the framework actors and their roles, responsibilities and collaborations remain the same. This leaves you to deal with syntactic differences of the language, recreating the view components and services. At least you won't have to completely re-architect.
And for the case of reimplementing in a different language, imagine you're trying to capture a significant part of the mobile market with your app. The market is so fractured, you'll have to implement the same program on 2 or more of Windows Mobile, iPhone, Flash, and Java. Sure you'll probably have separate teams in charge of the apps, but why have a totally different architecture? With PureMVC, you could have a single architecture for all versions of your application.
-=Cliff>
PureMVC is the only real option for Flash Platform developers who choose not to use the Flex Framework. For certain projects the size cost of Flex is too expensive (it happens!).
I like to prototype in Flex and then rip it out and replace my views with custom components when the application is near completion. PureMVC makes this really easy to do with it's Mediator pattern. I'm not sure there is any other framework that would allow me this workflow.
Personally, I think PureMVC went too far with it's portability goals: I enjoy that fact that it works with Flash AND Flex (for the reasons mentioned above), but feel that it should have stopped there, and made use of the native Flash Player event architecture.
Are there examples of people using PureMVC to build and port applications across multiple platforms?
My company is building a Flex application that we may need to port to other platforms:
Silverlight (likely)
Mobile (maybe)
Desktop (maybe -- not just AIR!)
TV sets (maybe eventually)
I am considering PureMVC as a framework if it can ease porting and maintenance. I am curious to know if other people have ported a PureMVC app to a different platform and what their experience was with porting and then having development proceed in parallel for the app on multiple platforms.
Cheers,
Karthik
PureMVC does not rely on a platform for its internal workings (Flash Events etc).
So, while it does not make porting any easier per-say, it can assist simply by showing us its friendly and familiar face wherever we may choose to go ;-)
My company (a large organization) is developing a "road-map" for evolving their rather old, tangled confederation of systems to an SOA model. A few people are pushing hard for using Websphere Integration Developer and Websphere Process Server as the defacto platform for developing future applications...because they feel IBM is a stable vendor, the tools are made for the enterprise, they drank the "business agility" BPEL kool-aid, etc.
Does anyone have positive or negative thoughts on this platform? Do the GUI tools help eliminate monotonous/redundant coding...or just obscure things and make things harder to maintain? Basically, do the benefits justify the complexity?
My experience with the IBM Java tool set is pure pain. Days to install lots of different versions of different components all incompatible with each other, discover a bug in component A get told to update to see if it fixes, updating component A breaks component B and C, get told to update these etc.
I find Eclipse with out the IBM extensions far more stable and quicker and provides more features (as its stable versions are a couple releases ahead of WID/RAD).
I would advise against going the IBM way for development tools. As for process server I have less experience but the people in my team using it seemed to enjoy it as much as I enjoyed WID. not a lot.
So far I havent been impressed by any tools with the "SOA" and/or "BPM" labels on them. My "roadmap" would be very very iterative to see some results with the archetecture as fast as possible while trying to grab some of the easy fruits. That way you gain your feel for what works for you and your people.
I would never let any vendor push me anywhere in the "scuplturing" of the architecture.
I agree with other users complaining about WID. The only reason we are using WID is that a decision was made a while back to use IBM products across the board by our sales department.
That's right, our sales department made the decision to use IBM products.
Development has been painful and frustrating. We have lots of stability problems with Process Server, sometimes it doesn't want to start or shutdown properly. Yeah you can easily draw processes in the IDE, but most any toolset provides that functionality these days. It is nothing special or unique to WID or IBM. IBM is a few iterations behind mainstream.
There are plenty of open source implementations out there that offer great support. Checkout JBoss or RedHat, they are pretty good. If that doesn't float your boat, you can always use Apache tools.
Walter
Developers don't choose WID, WMB, or WPS. Managers do, because IBM is a "stable vendor".
Look at JBoss, or K.I.S.S.
WID/WPS is actually pretty simple. The original intention was for analysts and business people to "compose" services (DO NOT LET THEM DO THIS!) so the UI is simple and easy.
Most of the work will be in defineing and implementing the back end services which depending on the platform will mostly involve wrapping existing code in SOA service.
The most important thing to bear in mind is that SOAP is technoligy and SOA is an architecture and a state of mind.
There is a zen to a succesful SOA implementation. Its all about "business services", if you have a service that you cannot describe to a business user in less than six words you have done it wrong! Ideally the service name alone should be enough to describe the functionality of the service.
If you end up with a service called "MyApp.GetContactData" described as "get name, addresses tel fax etc." then you are there. If You have a service called MyAppGetFaxNoFromOldSys" described as "Retrieve current-fax-nmbr from telephony table in legacy system" you are doomed!
Incidently most of the Websphere tooling for WS* is pretty nice. But I would recommend the very wonderful SAOPUI tool from http://www.eviware.com which is very good for compsing/reading WSDL based messages and also function as a useful test client or server.
Do the GUI tools help eliminate monotonous/redundant coding...or just obscure things and make things harder to maintain? Basically, do the benefits justify the complexity?
As a Developer, I find the tools at varying levels of being bug free. 6.0.1 was a pain, 6.2 is so much better. But once you develop with the tool, there is minimal effort to maintain it. I develop in hours what java developers take days to do. It is also easy to maintain as changes can be made very quickly. I cannot answer your question from the perspective of an architect or a Manager but i would agree with comments of some others here.
I am evaluating WF for use in line of business applications on the web, and I would love to hear some recent first-hand accounts of this technology.
My main interest here is in improving the maintainability of projects and maybe in increasing developer productivity when working on complex processes that change frequently.
I really like the idea of WF, however it seems to be relatively unknown and many older comments I've come across mention that it's overwhelmingly complex once you get into it.
If it's overdesigned to the point that it's unusable (or a bad tradeoff) for a small to medium-sized project, that's something that I need to know.
Of course, it has been out since late 2006, so perhaps it has matured. If that's the case, that's another piece of information that would be very helpful!
Thanks in advance!
Windows Workflow Foundation is a very capable product but still very much in its 1st version :-(
The main reasons for use include:
Visually modeling business requirements.
Separating your business logic from the business rules and externalizing rules as XML files.
Separating your business flow from your application by externalizing your workflows as XML files.
Creating long running processes with the automatic ability to react if nothing has happened for some extended period of time. For example an invoice not being paid.
Automatic persistence of long running workflows to keep resource usage down and allow a process and/or machine to restart.
Automatic tracking of workflows helping with business requirements.
WF comes as a library/framework so most of the time you need to write the host that instantiates the WF runtime. That said, using WCF hosted in IIS is a viable solution and saves a lot of work. However the WCF/WF coupling is less than perfect and needs some serious work. See here http://msmvps.com/blogs/theproblemsolver/archive/2008/08/06/using-a-transactionscopeactivity-with-a-wcf-receiveactivity.aspx for more details. Expect quite a few changes/enhancements in the next version.
WF (and WCF) are pretty central to a lot of the new stuff coming out of Microsoft. You can expect some interesting announcements during the PDC.
BTW keeping multiple versions of a workflow running takes a bit of work but that is mostly standard .NET. I just did a series of blog posts on the subject starting here: http://msmvps.com/blogs/theproblemsolver/archive/2008/09/10/versioning-long-running-workfows.aspx
About visually modeling business requirements.
In theory, this works quite well with a separation of intent and implementation. However, in practice, you will drop quite a few extra activities on a workflow purely for technical reasons, and that sort of defeats the purpose as You have to tell a business analyst to ignore half the shapes and lines.
Related question: When to use Windows Workflow Foundation? My answer there:
You may need WF only if any of the
following is true:
You have a long-running process.
You have a process that changes frequently.
You want a visual model of the process.
For more details, see Paul Andrew's
post: What to use Windows Workflow Foundation for?
Please do not confuse or relate WF
with visual programming of any kind.
It is wrong and can lead to very bad
architecture/design decisions.
So, if you have such requirements, then WF is a good candidate. Of course it is relatively complex, but mention that the problems that is trying to solve is also complex (and sometimes very complex). IMHO, it is very complex for example to dehydrate/rehydrate objects that have event handlers attached (with events that can be triggered when the object is not in memory).
I can not judge what you mean by "small to medium-sized project", but in general I would say that if your project has at least two requirements from the above list, then you can consider WF as a solution.
We've used WF in a large-ish SharePoint application and I can say it's OK. It has lots of power and flexibility. and, as Kevin mentions, once you grok the underlying concepts of workflows, you can do pretty much anything you want with it.
On the other hand, it has some really serious issues, like lack of versioning, which can really hurt your application in the future. We've been forced to deploy up to 3 parallel versions of the same workflow named xxx-v1, xxx-v2 and xxx-v3 to keep older instances running and have new instances use the updated versions. A real pain in the ass. Oh, and there are also some really non-intuitive concepts in there (correlation tokens, wtf??)
We had a project at work that I was involved in using Workflows.
The idea (from management), was that us programmers would write the Workflow Activities along with the "engine" and framework. Then non-programmers would take care of all the rest by compiling their own Workflows into dlls which the engine would automatically load.
Management was sold on this idea of non-programmers using Workflow to help develop software, and it was pretty much a complete waste of time. The problem we were trying to solve with this project was relatively complex and we knew from the very beginning that the software would have to be modified almost constantly (its calculations were dependent on other companies and governements).
The end result was that we were unable to make the Workflow modules generic enough for anyone else to use. So the programmers were the ones who were forced to work with the Workflows, and all the Workflows did was get in our way.
I've been using Workflow 4.0 for the last few months and although mostly impressed, I've found it extremely hard to learn.
For the most recent version (that comes with .NET 4.0 RC), there is next-to-no documentation on the web, in any books or no training courses available. I've only found articles relating to the now defunct 3.0 version. Even the MSDN documenation is light on the ground.
The workflow designer is not as intuitive as it should be by any means so learning is very hard. I've had to rely on answers from a single person on StackOverflow (thanks by the way Maurice!) - and I would be stuffed without his help.
So in summary, I think it has potential but you would be quite mad to learn it yet - wait for more training, documentation and books otherwise you will be going into it blind!
Last year we completed a working application with WF, now used as the backbone of an unbelievably huge system which is used by a very big bank for its mortgage process. The pe process has many steps starting from customer application to approval of credit.
Although it was a success, there were so many problems and crisis all along the way. And it wont worth the trouble for any smaller size projects.
I consider MS WF as a low-level workflow library rather than a fully fledged enterprise workflow product such as K2. It will enable you to build a workflow enabled application, but is not in itself a workflow application. My experiance of it in this capacity has been positive, although we have had to build a lot of our own infrastructure around it (a pub/sub framework, a worlkflow lifetime manager etc). A lot of the documentation out there is fairly simplistic and does not cover building up an enterprise workflow application based on MS WF.
Hard to learn. Quite flexible. Not to be confused with a visual tool for end users, only for programmers. Not sure if I like the dependancy property approach.
It really depends on what you want to do with it. I've only used it a little, but compared to more mature products like MetaStorm (I know technically it's a BPM, but there is still a workflow component), Process Choriographer and IBM MQ workflow, there's no comparison. It's just not mature enough. On the other hand it's free where the others are not and can probably get the job done. I don't know if I would place a multi-million dollar operation on it, but with smaller ones, I'd give it another shot. The real hurdle you are going to face is the change in thought process it requires. If you don't have developers that have worked with state systems before that can be a real hurdle.
Brian, I can't reply to your comment, but anyway, by versioning i mean making changes to the underlying code of the workflow without breaking already running instances, and gracefully applying updates to existing workflows. I'm not sure about 'stock' WF, but at least in SharePoint environment there's no concept of workflow versions so new versions have to be deployed as completely different workflows which becomes a maintenance nightmare.
This has nothing to do with 'rehydration', rehydration is the process by which you bring a 'dormant' workflow back to activity after some event or change in state. That is handled transparently by the workflow runtime.
WF ist integrated into SharePoint (WSS 3.0), and i have created quite a few workflows for various SharePoint-Websites, so i can tell about my experience of WF in SharePoint. Compared with other workflow-frameworks WF scores well. It's stable (i haven't experienced any mysterious errors), workflows are fairly easy to design (thank to the workflow-designer in Visual Studio) and you can use not only sequential but also state-machine workflows.
It's not perfect, of course, and a developer will definitly need some time to understand the concept (of i.e. the Activity Model); but it's definitely useable - even for "small tasks".
Never tried WFF, but I remember reading this article about WFF by Leon Bambrick where he basically says the whole genre of software development tools is nonsense. Might help you decide one way or the other.