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THE CONTEXT:
I should develop a software to calculate billing for a lot of customers
The software should be used by different local administrations, each one with its own rules to calculate the billing to its citizens.
At first i've thought to a workflow engine in order to "design" different calculation flows and apply then to the customers.
In the past i had a little experience with a workflow manager product (i worked a little with IBM BPM) and i had a lot of difficult to debug what happens when something went wrong and i found a lot of performance issue (respect to a simple OOP software).
Maybe these difficulties went caused by my poor knowledge of the tool, or maybe IBM BPM is not as good as IBM says.
Anyway, respect to my objective (produce a custom billing, and make it as flexible as possible in therm of configuration and process) is a workflow engine a suitable product?
Any suggestion about tools, frameworks and above all how to approach the problem.
My initial idea of the architecture is to develop a main software in c# (where i'm more confident) and using a workflow engine (like JBpm) as a black box, invoking previously configured flows into the bpm.
I would recommend using Cadence Workflow for your use case. It records all events that are related to your workflow in an execution history. It makes troubleshooting of production issues very straightforward.
As workflow is essentially a program in Java (or Go) you have unlimited flexibility on implementation. The performance is also not an issue as Cadence was built from ground up for high scalability. It was tested to over hundred million open workflows and tens of thousands of events per second.
See the presentation that goes over Cadence programming model.
I need to come up with a CM process for PLC code.
Currently, the system is developed using RSLogix 5000. The build product is a monolithic file that can be loaded onto a PLC for execution and edited directly in the development environment. With multiple developers, this has become a problem. They're stepping on each others changes.
As an analogy, it's as if, when doing Java development, the only wway to edit and save the source would be to load up a *.jar file into your IDE, make the change, and then save it back to the jar file. This is less than ideal.
How can I coordinate changes between multiple developers working with PLC's?
If we are talking about one big binary files, then a VCS (centralized or decentralized) is not the best tool for the job.
An external referencial (a shared disk for instance) where a batch will copy and label the current PCL state is better.
See "Tracking Software History"
To avert discontinuities in the historical record of revisions, old versions of programs must be stored.
“We take it a step further, though. Using our MDT AutoSave, we actually go out and interrogate the equipment. Overnight or at whatever frequency is specified, the software reads the programs in the PLCs and then compares that information to the last known program. The version-control software will copy the new program and store it and [then] compare it to the last one.
Launching version control is fairly simple. Required is software installation and then hardware configuration. “You would need a server and a couple of weeks of engineering and you’re good to go,” Perysyn says. However, his company uses a “shrink-wrap approach” that involves installing the software and then customization by users filling in the blanks.
That being said, when you have multiple changes from multiple developers, you need an integration environment where a first delivery can be done and validated, before pushing it to the actual server.
See also this post.
I use Unity Pro, so this may not apply for other brands.
Unity can export an "archive" file which is XML which describes the PLC program and IO setup in its entirety. After commissioning changes, I create an export and check it in to my local Git repo. This gets me an annotated history of changes, but no visual comparison. I can always use UnityDiff for comparison.
Check out http://www.mdtsoft.com/ also
You need specialized versioning system for PLCs like VersionDog.
From the manufacturer:
"Special support with Smart Compares for SIMATIC S5, SIMATIC S7,
SIMATIC PCS 7, WinCC, WinCC flexible, InTouch, CoDeSys, TwinCAT,
Phoenix PC WORX, RSLogix, Schneider Modsoft, Schneider Concept,
Schneider Unity, SINUMERIK 840D, Bosch IndraWorks and more. Also robot
programs from ABB and Kuka and office related data formats like
Microsoft Word, Microsoft Excel and Adobe PDF are perfectly supported
by versiondog.
Update: Here is a screenshot showing ladder version compare. I guess that's what most PLC folks are interested in. We also use it to schedule e-mail report if PLC offline and online application versions are a match, as an alarm that something has been changed in PLC but not put into version control server.
About RSLogix5000 specifically, I have seen developers use an emulated PLC and make their changes online. The final product once developed is then put together with all the comments (as they are not contained in the PLC) and then commissioned. There are issues with changes that cannot be done online, such as AOIs. There are tools in place to stop two people editing the same logic online at once and to take ownership of sections. Backups can be done in the form of uploads, but there isn't any way to track changes.
It is a messy problem, messier still for when you are maintaining a system as you want an .ACD that you can go online with, as unless you are somehow doing a diff with the RSLogix compare tool you just see unreadable machine code like "+|Éû³´¬ÙÆW×晵‚>Ù,"
The most common revision control I have seen (sadly) is just saving the the latest file, then taking a copy and adding the current date to the file name, like the recommended control.com post described.
RSLogix5000 has always prohibited multiple users from opening and editing on the same .ACD simultaneously. However, if multiple users have identical .ACD files, open them, and all make connections to the same target controller, they each can edit on the controller simultaneously, but only if they are working on different routines. Other's edits appear automatically, if they were to look at another programmers routine.
Note that working online like this is usually done with the PLC running, even sometimes with the target system (some kind of machine) operating. This kind of arrangement for the purpose of completing work faster, or in some cases because the system is huge. No one develops like this, as it is really a debug tool and impractical for significant changes.
If one programmer finishes, and another is not done, the unfinished work of the other will be saved to the first programmer's .ACD when they save. Whoever saves last will have everyone's work.
Like others have mentioned in this thread, using file date is fairly reasonable. Some companies use a version control variable that is usually displayed on a connected HMI. Other companies use a separate document that documents who and what changes. Sometimes version notes are placed in a lengthy rung comment in the main routine.
My company uses a separate change log, and dated archive copies are maintained. Multiple programmers are only used in the most extreme cases. Someone is always designated to maintain the offline file integrity, usually the person who will be working the longest, or the project manager.
It is important to note that rung comments are not carried from one user to another before RSLogix5000 v21 because previous versions didn't store comments on the controller.
All this said, you might be trying to manage offline development. I haven't seen any sophisticated methods for this. Usually programmers write the needed routines separately, and a project manager will assemble them into a single project. The cleanest approach I've seen is where a project manager will create an architecture with global functionality, and assign routine work to others, giving them a copy of the .ACD to work with. They return the .ACD with changes, and the project manager copies and pastes their routines into the "master" project.
This is a very good question and it really depends on what you want it to do.
If you are only using Rockwell equipment it might be helpfull to look at their solution, I think it's called FactoryTalk AssetCentre.
Currently I am looking into using Bazaar from Canonical.
One thing that VonC pointed out is that a piece of software that can interogate the PLC is a deffinate plus, not a must in my oppinion but it sure as hell helps.
Am I reading your question properly and you have multiple developers working on the same PLC code at the same time? It's a scary thought but I know it sometimes needs to happen, Siemens PLC's are a bit easier to program with multiple developers but I would assign one person to consolidate and test all the changes before committing to the PLC. Any CVS system will let you create branches for every developer but how you would get them to consolidate their changes is the million dolar question.
Bart.
A simple thing to do would be to do a text diff on the .l5k files so you can easily see whether a developer has been messing with part of the file that is outside of their scope.
I saw this question just now from a link at stack exchange: Are There Realistic/Useful Solutions for Source Control for Ladder Logic Programs. Rather than have a link only answer, I'll dupe my answer here:
There is actually a canned solution - from GE-IP of all places. Check out Proficy Change Management. This product does version control from a PLC control systems point of view, rather than a pure version control of files point of view - it works as a layer sitting on top of a VCS (the scary part is that originally this VCS was Visual SourceSafe) and handles rights management, reporting and checkout/checkin.
While the product is from GE-IP, it is designed to support a variety of PLC and HMI systems out of the box.
Full disclosure, I used for work for a company selling and installing PCM (but that was 7 years ago). So if you ask me what it was like back then I'm likely to tell you where it all went wrong!
In my company we just started a trial with Copia.io
Check it out. Our first tests look very promising!
It brings, branching, merging, ladder diff etc... for multiple PLC platforms (Rockwell, Siemens, Codesys)..
PS. I work for a company that builds machines, we were looking for version-dog alike solutions with a bit more power in collaboration and diffing capabilities. I used tools like Mercurial, Git, Tortoise in past companies (not for PLC though).
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I'm currently a developer at my first job right out of college. I work for a large company, and the trend I notice with them is that they tend to go with more expensive, closed source software about 99% of the time, while there are perfectly good open source alternatives that are available, most of which are vastly superior to their closed-source counterparts. For example, we use this absolutely awful source control software that cost a ton of money, while there are quite a few open source and/or free options that in my experience, albiet limited, are much better and offer basically the exact same functionality.
I guess my question is: How would an experienced developer approach management about using more free software?
It appears there is another question very similar to this that did not show up when I made this one: How can I convince IT that F/OSS software isn't evil?
EDIT: Just come clarification. I'm not necessarily trying to change the company's procedure, I'm looking for advice on how to approach management about the subject.
Start using it in small utilities and things which are throwaway and don't need management buyin. This can prove the worth of an open source solution and put a crack in
the door for using it in other
projects.
Present articles from trade magazines showing that other people are using the open source solution.
Go with products which have commercial support options, such as MySQL, which enterprises seem to have an easier time swallowing.
Pick your battles carefully. Wait until they are suffering. If they are happy with what they have, they will not switch, no matter how much cheaper or superior the alternative is. You need to catch them while they're trying to think of ways to save money, or while they're disgusted with the problems of the current system.
Be very careful with what you refer to as free. There is a very large corpus of products that would be perfectly valid for a student to use without paying that an enterprise would have to pay for. Also never forget Total Cost of Ownership (TCO). A lot of relatively expensive software is expensive because you get things like configuration and help support for them whereas that may not be the case for free software.
I think you are not asking the right question. To me, the challenge is to have my Big Corp to buy the BEST softwares for me, be it free softwares or not.
Paying for Windows or paying for Linux is not important (what is 100 $ for a Big Corp ?).
But having things done better is really important.
I think that your request to your boss should not be : "Hey, it's free and it's as good as XYZ, why are we using XYZ ?"
Why you boss would risk something trying the product you told when XYZ seems to be ok ?
It would be much more better to ask : "Hey, here is what I cannot do with XYZ : (your list). With my product, I would be able to do that and much more so fast than I would have a lot of spare time to test our own software !".
Small money is usually not a show stopper. Being able to work faster in order to do much more testing (or any other things that could help your boss have a better image) is definitely an excellent argument !
Best wishes,
Sylvain.
I work in a big company that has recently moved into being more enthusiastic about open source solutions. There have been a few big hurdles:
Customer won't support it - we're defense contractors. We do almost nothing without customer say-so. As the customer's opinions have changed we've been able to change our architectures and tool usage. That said, there are still scenarios were open source is unacceptable and we don't use it.
No tech support = scary - in several cases, it's been possible to make the point that open source may not have a single point of company tech support, but it does have huge communities that will support questios for free, and that there are consultants available as needed for the really hard stuff. Plus many, many releases of new versions for bug fixes. And, several competing expensive products have not been able to service tech support needs. Being able to point to specific internal examples with long. well documented, histories of support problems, has been key.
Fear of security issues - we had to develop a process for scrutinizing and controlling every peice of open source introduced. We've managed to find criteria for what we deem risky, versus what we deem relatively benign based on info-sec policy.
Fear of lawsuit - Being large, and profitable, we fear lawsuits, we're great targets. We now have a process for the legal team to scrutinize every open source license. This has proved to be a win - since the legal team now has briefings on every major version of the typical open source licenses, and they can quickly review most stuff.
Version control - fear that if those wacky developers can just download anything they like the world will self destruct. OK, well, practically speaking, the concept of "how do we know what's in a given product" - being able to show a FOSS version control process that is managed internally has been important.
It was definitely a slow process - small projects proved profitable and customers started encouraging it in proposals. That made it useful for executive management. It's helped that those that support it have been williing to put in some extra time to making the business case in terms of efficiency/cost savings, and have been willing to negotiate repeatedly with various parts of the corporate infrastructure.
Making open source work has taken the effort of IT, the info security folks, the legal team, the procurement team, and technical management. Knowing that before you talk to your manager is probably a key to success.
There's also some political savy - for a first project, don't encroach on any sacred cows - ie, those projects that may not be successful, but are high profile and owned by someone with lots of political power. Instead, choose some wacky new thing that isn't available right now and prove the cost savings in a way that is unlikely to provoke a defensive reaction.
When you try to introduce open source software to a big company (or even a small one, in many cases), the biggest counter-argument you're going to hear is "There's no tech support." Companies tend to be wary of using software that's supported by the community, because there's no guarantee (or in some cases, service agreement) that questions about the software will be answered within a reasonable time frame, or at all. In many cases, you can find a company that will provide support for the open-source package you want to use (for example, Red Hat does this for its Linux distribution, even though the contents of the distribution is mainly open source). Showing management a business entity that can support the software will often go a long way.
The other counter-argument to using open source software that I've heard the most often is "Open source software is buggy." This is a tough one; this opinion is pretty ingrained in some corporate cultures. Two possible responses are "The open-source community fixes bugs quickly" and "Since we have the source code, our engineers can fix bugs"--but that's often not what managers want to hear.
So, in essence, it depends on the company, their attitudes, and how much they trust you to make business-critical recommendations. I've used all of the arguments above with different levels of success in different companies.
Of course, in these economic times, the "free" part may go a long way. :-)
"Free software" doesn't necessarily mean your company is going to get software for free. Many successful open-source projects are also offered with licenses and services that cost real money and are geared to organizations that want or need to be assured of good support. MySQL is an example
The reason for a lot of big companies using closed software is that they can call support and the vendor will issue a hotfix, patch or cumulative update
Changing a large company's habits are often like turning an Oil tanker around... it takes a long time and uses a lot of energy.
If the company were in the process of evaluating the purchase of new software for a specific task, Then I would make sure to write a concise opinion memo about why my choice is better.
If the software is something I would use personally and not a server product that multiple developers are forced to use, then I would just ask my manager to use it.
If the software is in place, does the job (even if I don't like the way it does it), i'd learn as much as I can about it to give it as much chance of work for me, or at least make my life easier. If it still sucks really bad, I probably wouldn't try to change it until it was time for the company to pay for an upgrade.
If the software works but is just annoying... I'd do as above, learning all there is to know about it just to make my life easier and then deal with it.
You're probably right that the system you'd recommend is better than the one currently in place. But like some other posters said, choose your battles, especially when this is your first job out in the real world. You may become expendable quickly.
It's not really so much a matter of what's better, even if your way IS better, it's a matter of the culture and the way things are done and the cost of switching. Even if, hypothetically, their system can be magically transported to your OSS system, with no loss of data, dates, records, or anything, you're still going to have people who say "I liked the old way better."
Remember: Experience is what you get when you don't get what you want. I know it may sound glamorous to be "the new guy who recommended a great new versioning system that everybody loved", but you also could just as easily become "that hotshot who insisted on a new versioning system that everybody hated." It's a much smarter career move to just play by the rules at least for a little while until you have some clout and can make some recommendations. In the meantime you may even learn why the old system is preferred, or learn to like it more the more you use it.
I know what you mean. It took us years to convince our managers that everything would be okay if we moved away from using Interbase (a commercial Relational DB) to it's opensource counterpart Firebird. Mostly it was fear of no support that blocked the move. I think the factors which changed their mind were:
tests showing better performance
that there are companies that provide and charge for supporting the OS alternative
constant pushing of the argument by passionate developers
I think cost savings would have played a part if our company were paying for the site licenses but in fact our customers were.
I look at this question like this. I work with the .NET framework. I could ask my employer to migrate to PHP. This is a disadvantage to me, as well as my company, for many reasons. Let's start with the obvious.
1.) I know PHP, but can do much more, and a lot faster, with .NET.
2.) Paying for a service, usually ensures a better experience. The Visual Studio IDE is second to NONE when developing an application.
3.) I can develop an application much faster in VS than hard-coding PHP.
4.) This is the most important one. If I work with a big company, I want my programmers to develop my app faster, and I expect it to run faster. PHP (an example Open Source language) is fast, and reliable, but if I can spend the money, I'll deploy ASP.NET.
Basically, big business, or even small business, wants to spend their money, as long as it's for a good reason. Your best bet is to say, 'Hey, if you want to deploy ASP.NET (or whatever), send me for some training. Then I'll be able to develop OUR application to my best ability'.
not to sound totally cynical, but:
an experienced developer probably would not approach management about something like this, unless he/she was already an expert with the open source package. Companies like to have a phone number to call and someone to blame when things don't work. Free open source packages do not provide this kind of 'accountability' (yes we know it's a joke, but management doesn't)
it is unlikely that management is going to listen to someone fresh out of college about any major purchasing or technology decision. You have to learn the business and earn everyone's respect first. [sorry!]
Same problem everywhere. Once an organization gets beyond a certain size (e.g., the Dunbar number) it starts to show a certain woodenheaded quality that will confound you. Lots of history, people, agendas that you aren't aware of. And getting everyone to agree on your solution is difficult.
Best to start locally. See if you can persuade your manager or PM to use SVN or CVS or GIT locally for a project and then get it to diffuse.
But that situation is true where I work as well. I use SVN locally for myself, but a commercial product for integrating with others.
Companies will use whatever will ultimately make them the most money. That means whatever software will make their employees more productive. If there is a particular piece of open source software you think they should use then when the time comes to purchase the software to do job X then as long as you can prove it will make the employees more productive and they are able to get reliable support just a phone call away as with commercial software then they will use it.
Big companies need to hire support staff for stuff like that. When they purchase software from a company, they are guaranteed support with the contract. Open source projects can die off a lot easier, whereas a large software vendor can be held responsible for much greater periods of time.
Every company has a culture, and fighting the culture can be something of an uphill battle. But if you're willing to try:
you'll likely have more luck getting BSD and BSD-like projects approved (MIT license, Apache, Boost, etc.); and it doesn't matter if most of the arguments against GPL and LGPL are mainly FUD
you should refer to the projects as "royalty-free"
you should make sure things are approved by somebody that can approve them (your direct manager) because putting the company in a bind -- especially when you're new -- (even if the "bind" is only in their head) is not conducive to long-term employment
you can probably go a long way by simply asking what the procedure is to choose a library or tool
From a configuration management perspective, having developers add free software stuff willy nilly whenever they feel like is a serious PITA to manage.
I've worked at companies where you were allowed to do it whenever you wanted and others where you could never do it.
There's definitely a balance to be found but if you're in a larger company with multiple projects, you do have to keep in mind that each time you add a new 'tool' it complicates the build process.
I'm looking for a way to give out preview or demo versions of our software to our customers as easy as possible.
The software we are currently developing is a pretty big project. It consists of a client environment, an application server, various databases, web services host etc.
The project is developed incrementally and we want to ship the bits in intervals of one to two months. The first deliveries will not be used in production. They have the puropse of a demo to encourage the customers to give feedback.
We don't want to put burden on the customers to install and configure the system. All in all we are looking for a way to ease the deployment, installation and configuration pain.
What I thought of was to use a virtualizing technique to preinstall and preconfigure a virtual machine with all components that are neccessary. Our customers just have to mount the virtual image and run the application.
I would like to hear from folks who use this technique. I suppose there are some difficulties as well. Especially, what about licensing issues with the installed OS?
Perhaps it is possible to have the virtual machine expire after a certain period of time.
Any experiences out there?
Since you're looking at an entire application stack, you'll need to virtualize the entire server to provide your customers with a realistic demo experience. Thinstall is great for single apps, but not an entire stack....
Microsoft have licensing schemes for this type of situation, since it's only been used for demonstration purposes and not production use a TechNet subscription might just cover you. Give your local Microsoft licensing centre a call to discuss, unlike the offshore support teams they're really helpful and friendly.
For running the 'stack' with the least overhead for your clients, I suggest using VMware. The customers can download the free VMware player, load up the machines (or multiple machines) and get a feel for the system... Microsoft Virtual PC or Virtual Server is going to be a bit more intrusive and not quite the "plug n play" solution that you're looking for.
If you're only looking to ship the application, consider either thinstall or providing Citrix / Terminal services access - customers can remotely login to your own (test) machines and run what they need.
Personally if it's doable, a standalone system would be best - tell your customers install vmware player, then run this app... which launches the various parts of your application stack (maybe off of a DVD) and you've got a fully self contained demo for the marketing guys to pimp out :)
You should take a look at thinstall(It has been bought by vmware and is called thinapp now), its an application virtualizer.
It seems that you're trying to accomplish several competing goals:
"Give" the customer something.
Simplify and ease the customer experience.
Ensure the various components coexist and interact happily.
Accommodate licensing restrictions, both yours and the OS vendor's.
Allow incremental and piecewise upgrades.
Can you achieve all of these by hosting the back end (database, web server, etc.) and providing your customers with a CD (or download) that contains the client? This will give them the "download/upgrade experience" that goes along with client software, without dealing with the complexity of administering the back end.
For a near plug-and-play experience, you might consider placing your demo on a live linux or Windows CD. Note: you need a licensed copy of Windows for the latter.
Perhaps your "serious" customers might be able to request their own demo copies of the back end as well; they'd be more amenable to the additional work on their part.
As far as OS licenses, if your vendor(s) of choice aren't helpful, you might consider free or open-source alternatives such as FreeDOS or linux.
Depending on if you can fit all the needed services into a single OS instance or not...
Vmware Ace or whatever they're calling it nowadays will let you deliver single virtual machines under strict control, with forced updates, expiration and whatnot. But it sounds easier to just set up a demo environment and allow remote access to it.
The issue here I guess is getting several virtual machines to communicate under unknown circumstances - if one is not enough?
An idea then is to ship a physical server preconfigured with virtualisation and whatever amount of virtual servers needed to demonstrate the system.
Using trial versions of the operating system might be good enough for the licensing dilemma - atleast Windows Server is testable for 60 days, extendable to 240 when registering.
Thinstall is great for single apps, but not an entire stack....
I didn't try it yet, but with the new version of thinstall you are able to let different thinstalled application communicate.
But I guess you're right a vm-ware image would be easier
Most of the work I do is with what could be considered enterprise Web applications. These projects have large budgets, longer timelines (from 3-12 months), and heavy customizations. Because as developers we have been touting the idea of the Web as the next desktop OS, customers are coming to expect the software running on this "new OS" to react the same as on the desktop. That includes easy to manage automatic upgrades. In other words, "An update is available. Do you want to upgrade?" Is this even a realistic expectation? Can anyone speak from experience on trying to implement this feature?
At my company we have enterprise installations ranging into the thousands of seats. If we implemented an auto-upgrade, our customers would mutiny!
Large installations have peculiar issues that don't apply to small ones. For example, with 2000 users (not all of whom are, let us say, the most sophisticated of tool users), tool-training is a big deal: training time, internal demos, internal process documents, etc.. They cannot unleash a new feature or UI change without a chance to understand how it fits in their process and therefore what their internal best practices are and how to communicate that to their users.
Also when applications fail, it's the internal IT team who are responsible. Therefore, they want time to install a new version in a test area, beat it up, and deploy on a Saturday only when they're good and ready.
I can see the value in making minor patches more easy to install, particularly when the patch is just for a bug-fix and not for anything that would require retraining, and if the admins still get final say over when it's installed. But even then, I don't believe anyone has ever asked for this! Whether because they don't want it or they are trained to not expect it, it doesn't seem worth it.
Well, it really depends on your business model but for a lot of applications the SaaS model can end up biting you. It's great for a lot of things but for some larger applications the users are not investing as significant amount up front and could possibly move to something else before you've made any money.
See
http://news.zdnet.com/2424-9595_22-218408.html
and here
http://www.25hoursaday.com/weblog/2008/07/21/SoftwareAsAServiceWhenYourBusinessModelBecomesAParadox.aspx
for more information
One of the primary reasons to implement an application as a web application is that you get automatic upgrades for free. Why would users be getting prompted for upgrades on a web app?
For Windows applications, the "update is available, do you want to upgrade?" functionality is provided by Microsoft using ClickOnce, which I have used in an enterprise environment successfully -- there are a few gotchas but for the most part it is a good way to manage automatic deployment and upgrade of Windows apps.
For mobile apps, you can also implement auto-upgrades, although it is a little trickier.
In any case, to answer your question in a broad sense, I don't know if it is expected that all enterprise apps should make upgrading easy, but it certainly is worth the money from an IT support standpoint to architect them to allow for easy upgrading.
If you're providing a hosted solution, I wouldn't bother. Let the upgrade happen silently (perhaps with a notice that you did it). If you're selling an application that's hosted on their servers, let the upgrade decision be made by a single owner, not every user of the app.