I searched through a couple of questions on the topic "What to use .NET's Windows Workflow for?", (like this and this) and they got me started in grasping the big picture.
But one of the posts mentioned this article, which mentions the term "Process server". More specifically, here's its quote:
It seems like the most obvious use of WF in projects so far is when
you’re building a process server product.
I have been trying to find a clear definition of what a process server is, but did not succeed yet.
One will end up in browsing IBM's WebSphere Process Server, which offers a very short overview of it's purpose, among other links - but I could find no clear and precise definition for Process Server (wikipedia has none).
Could anyone help fill the gap?
The word Process might be closely mapped to something like a Workflow. If you reckon that a workflow needs to be executed, separately, by some entity, you will usually have a Server doing it. So there you go, a process server is something that executes workflows.
Btw, as you can read in one of your links, IBM's WebSphere Process Server at some point changed it's name (and backend apparently) to Business Process Manager. So, continuing with the same line of thinking, and this is me speculating on why they've chosen that name, maybe they thought they were not only executing but also enabling customers to manage workflows. Manage ends up being a more broad and inclusive word (and prettier for the sales guys to use as well :).
WF4 knows how to execute workflows so, yes, it can be used to implement a Process Server.
See, this is my very loose definition of it, it might be greatly improved and completely open to discussion. It really depends on which path you want to take on that discussion.
Related
I have a slow asp.net program running. I would like to profile the production server to see what is going on, but I don't want to slow down the production server noticeably.
In general, is it standard practice to profile a production box or just local dev boxes? Also, what progams do you recommend to accomplish this?
I can recommend you to use "dynatrace Ajax edition 3" for client side profiling (it's free and easy tool) and "JetBrains dotTrace" for server side profiling. This tools does not slow down server as i know.
You can use Tracing and it is recommended to check these things on your local machine, but if you want to check something on server, you can enable tracing for short in your web.config.
ASP.NET tracing enables you to view diagnostic information about a single request for an ASP.NET page. ASP.NET tracing enables you to follow a page's execution path, display diagnostic information at run time, and debug your application. ASP.NET tracing can be integrated with system-level tracing to provide multiple levels of tracing output in distributed and multi-tier applications.
ASP.NET Tracing Overview
Tracing in ASP.NET
I guess the answer is really 'it depends'! I would start by considering whether the program runs slowly just on the production server, or whether it runs slowly on a development environment as well. I would also consider how closely I could get my development/test environment to match the production environment.
Once you've done that, consider whether there are any areas that could represent obvious bottlenecks that you might be able to eliminate. So, for example, is the ASP.NET application backed by some form of database? If it is, you can monitor the performance of the database separately and establish whether that is where the problem lies.
Next, try and be very specific about what you mean by 'slow performance'. Is it consistently slow (compared to what?), or just when you do specific actions. This may give you another clue as to where your problem lies, or at least what questions you should be asking.
Having answered lots of these questions, I'd then bust out ANTS Performance Profiler to try and profile what's going on. It has a fairly minimal overhead when profiling an application, and you should only really be running it for a fairly short time anyway, as you'll hopefully by this point have more specific questions you want to answer, or specific actions that you want to dig into.
Your best option is Prefix (http://www.prefix.io). It will let you see all of your SQL queries, logs, HTTP calls, and a lot more.
Another option is Glimpse or the Mini profiler.
I've had sporadic performance problems with my website for awhile now. 90% of the time the site is very fast. But occasionally it is just really, really slow. I mean like 5-10 seconds load time kind of slow. I thought I had narrowed it down to the server I was on so I migrated everything to a new dedicated server from a completely different web hosting company. But the problems continue.
I guess what I'm looking for is a good tool that'll help me track down the problem, because it's clearly not the hardware. I'd like to be able to log certain events in my ASP.NET code and have that same logger also track server performance/resources at the time. If I can then look back at the logs then I can see what exactly my website was doing at the time of extreme slowness.
Is there a .NET logging system that'll allow me to make calls into it with code while simultaneously tracking performance? What would you recommend?
Every intermittent performance problem I ever had turn out to be caused by something in the database.
You need to check out my blog post Unexplained-SQL-Server-Timeouts-and-Intermittent-Blocking. No, it's not caused by a heavy INSERT or UPDATE process like you would expect.
I would run a database trace for 1/2 a day. Yes, the trace has to be done on production because the problem doesn't usually happen in a low use environment.
Your trace log rows will have a "Duration" column showing how long an event took. You are looking at the long running ones, and the ones before them that might be holding up the long running ones. Once you find the pattern you need to figure out how things are working.
IIS 7.0 has built-in ETW tracing capability. ETW is the fastest and least overhead logging. It is built into Kernel. With respect to IIS it can log every call. The best part of ETW you can include everything in the system and get a holistic picture of the application and the sever. For example you can include , registry, file system, context switching and get call-stacks along with duration.
Here is the basic overview of ETW and specific to IIS and I also have few posts on ETW
I would start by monitoring ASP.NET related performance counters. You could even add your own counters to your application, if you wanted. Also, look to the number of w3wp.exe processes running at the time of the slow down vs normal. Look at their memory usage. Sounds to me like a memory leak that eventually results in a termination of the worker process, which of course fixes the problem, temporarily.
You don't provide specifics of what your application is doing in terms of the resources (database, networking, files) that it is using. In addition to the steps from the other posters, I would take a look at anything that is happening at "out-of-process" such as:
Databases connections
Files opened
Network shares accessed
...basically anything that is not happening in the ASP.NET process.
I would start off with the following list of items:
Turn on ASP.Net Health Monitoring to start getting some metrics & numbers.
Check the memory utilization on the server. Does re-cycling the IIS periodically remove this issue (memory leak??).
ELMAH is a good tool to start looking at the exceptions. Also, go though the logs your application might be generating.
Then, I would look for anti-virus software running at a particular time or some long running processes which might be slowing down the machine etc., a database backup schedule...
HTH.
Of course ultimately I just want to solve the intermittent slowness issues (and I'm not yet sure if I have). But in my initial question I was asking for a rather specific logger.
I never did find an answer for that so I wrote my own stopwatch threshold logging. It's not quite as detailed as my initial idea but it has the benefit of being very easy to apply globally to a web application.
From my experience performance related issues are almost always IO related and is rarely the CPU.
In order to get a gauge on where things are at without writing instrumentation code or installing software is to use Performance Monitor in Windows to see where the time is being spent.
Another quick way to get a sense of where problems might be is to run a small load test locally on your machine while a code profiler (like the one built into VS) is attached to the process to tell you where all the time is going. I usually find a few "quick wins" with that approach.
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I'm developing a RESTful API for a client. The problem is, he's using a rather obscure language called Clarion. It's proprietary and closed, and the docs are not freely available online.
Whenever we discuss passing data from his code to mine, and back again, he starts talking about "ftp file uploads" and direct server-to-server SQL. Needless to say, these ideas bring back visions of the bad old days. I have done some googling, and I can't find any evidence that this language is capable of creating HTTP Post requests at all, let alone using SSL encryption to protect them from prying eyes.
I'm looking for advice specific enough that I can guide him through implementing his end of the bargain. I specifically want to avoid trying to pass XML requests as files via FTP, or by writing them to the disk and calling some script. It should go without saying, but I'm also not interested in running proprietary clarion server code or DLLs on my server.
Is Clarion capable of generating POST requests? Is XML hard to generate in Clarion? Is there a simpler/easier to use format my client may have more sucess with? None of the data is more complex than key/value pairs.
I'm coding in python, but I can deserialize any reasonable data format if there's some way to get the data to my server.
I feel your pain. Communicating between systems can be a major pain. Good news though is that Clarion can do TCP/IP, and XML (with a little help) so there's nothing that should hold your Clarion colleague back.
In the interests of full disclosure I should point out that I'm biased here - I'm about to recommend that the Clarion guy use tools I created - nevertheless there are thousands of Clarion programmers out there using them, and they provide the answer to your question, so please forgive me. Ignore if you like.
In Clarion there are a couple of tools that make TCP/IP communications easy and that enable the use of SSL. The one I make is called NetTalk (http://www.capesoft.com/accessories/netsp.htm).
There is also XML support inside the Clarion box, although it's unnecessarily cumbersome so there are at least 2 xml products he can use - iqXML (which is free) and xFiles (http://www.capesoft.com/accessories/xfilessp.htm) which is designed to be super fast.
Using NetTalk & xFiles together it's trivial to create SOAP servers or clients. (Or plain HTTP servers and clients as you prefer.) There are a LOT of folk doing just this, so there's absolutely no excuse for using shared files, or FTP'ing requests around. I recommend you gently point your Clarion friend in the right direction.
If you'd like to run this question past other Clarion developers then try http://faq.clarionmag.com/ (which is using the StackOverflow engine.) There are also lots of programmers active on the NNTP protocol (news) at news.softvelocity.com (comp.lang.clarion and others).
Cheers
Bruce
Instead of trying to accomplish more in this obscure language, I'd go with the approach that you hinted upon: using the file system as a hand-over mechanism.
Have his code output files to a given folder; then, have a daemon, written in a "normal" language, monitor that folder regularly (cron job, etc). When a new file shows up, upload it through HTTPS / other "normal" means to your other server to do the task.
This approach follows the "localize the crap" philosophy - if you can't get rid of crap, at least make sure that it's "borders" are well defined.
Information wants to be free. The language may be proprietary and closed, but the documentation is published online:
http://www.softvelocity.com/clarion/pdf/LanguageReferenceManual.pdf
Looks like a Windows 3.1 vintage report generating language which has the ability to talk DDE/OLE (!), but seems to have no external communication features other than that.
So no, Clarion cannot do POST requests (except via a third party custom control / DDE conversation). Using the file system might be a safe way to proceed: it keeps the client in familiar territory, and is the easiest to debug. However, if two way communication is required, you might need to blow the dust off the manuals and go the DDE route. It really depends on the exact requirements (e.g. is the program batch or interactive?), but page 935 (Appendix A) in the 1158 page manual is where to start looking!
I came in very late to this post, for I only had Stack Overflow account set today. However, I would like to comment on Bruces answer.
Bruce runs a 3rd party Clarion add on maker company and will always suggest the use of their products. Altough they're really fine an work very well, I can't help pointing that there are standard, open tools for about anything that needs to be done.
For example, the programmer could use "curl" http://curl.haxx.se/ to communicate with a web server from a program. Not only a Clarion program, but any program. Aside from that, Clarion does have access to all the Windows API, and it is just a matter of writing the code, so, sockets, http, mci and whatever are at any programmer's reach.
Need to send e-mail from a program that apparently doesn't have access to smtp functions? use "Blat"! - blat.net
Want to download some file from a web site? wget - gnu.org/software/wget
These are all command line interfaces. And I suggest the ones who don't know what "interface" means, to go get a look at The Free Dictionary - tfd.com/interface
Regards
I think many developers know that uncomfortable feeling when users tell them that "The application is slow (again)."
In a complex web application there can be many possible reasons for a degradation in (perceived) performance: slow database response, bandwidth issues, bad caching etc. There certainly are issues which will never occur in a development or staging environment.
Now my question:
Is there a set of tools and/or methods which would provide a comprehensive "live" state on a IIS/ASP.NET/SQL Server production system in a visually way (not just performance counters):
Current HTTP requests (say the last n minutes)
Exceptions / timeouts
Bandwidth data
Number of open database connections / database calls
...
The primary goal is to see at a glance (or after looking closer) what problem is causing the performance problems.
I think the category of software you're looking for is ".net profiler" or ".net tracer". One such tool that you might consider is JetBrains' dotTrace. It gives you runtime stack traces and an array of counters that indicate possible bottlenecks.
Previously mentioned tools will certainly work. At our shop we needed finer information and built our own solution (long story: it was easier to code than to argue about tools and retrievable data).
I used LogParser to flip through the IIS logs and create output reports of those logs (e.g. result code breakdowns etc).
I used a combination of performance counters and WMI values to get the rest - you can read these using some pretty straightforward C# - this gives you full control that you can then dump to .csv etc for viewing/processing in excel or if you are updating a page as a control center.
I would probably also look at IIS.net as a great resource for IIS tools including debugging, security etc.
I followed urig's advice and found this software called SmartInspect.
Does anybody know this logging/monitoring tool? It seems to be a combination of real time console and developer library.
CLR 4.5 will have some new capabilities that will help you monitor ASP.NET performance live - without restarting your app. Basically you can re-JIT your code to include some monitoring-hooks in it, and then inspect time spent in classes/methods etc.
I'm sure dotTrace and other profiling tools will leverage this automatically, but it's worth checking out: C9 - Inside Re-JIT with David Broman
I've been using WWF for a while as part of an internal call center application (ASP.NET), and while learning it was a good practice in understanding how a state machine based workflow system should work, I am definitely not in love with WWF itself. In my opinion it is:
Overly complex, especially for use within web apps (all that threaded runtime stuff)
Immature (ever worked with that horrible designer?)
Anemic in its current feature set
Does anyone have a suggestion for a better .NET based workflow framework? Specifically, I am looking for the following features:
State machine based (mapping states to available actions)
A focus on user permissions (controlling who has access to what actions)
The ability to run workflows as timed background tasks (for example, to send out reminders for items that have been sitting in a certain state for x days)
That's really all I need. I don't need to be able to "drag and drop" any activities or visually design the flow. I am perfectly comfortable writing actual code once a particular action is triggered.
You could try Simple State Machine. You would have to implement access control and background timers yourself, but that shouldn't be a big deal. SSM was also built out of frustration with WF. There are some other state machine implementations on Codeplex as well. If one of them doesn't fit he bill out of the box, they are open source and should get you close enough.
I wholeheartedly agree with you about state machines in WF - they aren't testable, are too complicated, the threading model is peculiar and hard to follow, and I'm not sure a visual designer could have been more poorly conceived for designing state machines graphically. I think this may be because the state machine concept feels tacked onto the WF runtime, which was designed for sequential state machines, something WF does a much better job with, in my opinion. The problem is that state machines are really not the same animal as a sequential work flow, and should have been given a first class implementation of their own, because the warping of WF to make it seem to support them turned out to be more or less unsupportable, if not actually unusable.
I would stay away from Drools.Net since it's last SVN commit was in September 2007. Looks nice but it seems a bit too risky to make such a big library part of your project when you know it doesn't get any attention anymore.
Try Drools.NET
Have a look at Workflow Engine. It is a lightweight workflow framework for .NET and Java solutions. It has an HTML5 visual designer, version control, a decent UI and supports a wide range of databases.
Do you have the option to consider BizTalk Server?
I quite enjoyed working with Oracle BPEL Process Manager. It's part of JDeveloper.
http://www.oracle.com/technology/bpel/index.html
http://gemsres.com/story/dec06/313602/jellema-fig1.jpg
You may want to take a look at Jazz - http://jazz.codeplex.com/
Try WF4.5. It was completely redesigned since .NET4.0.
First of all you should look for a engine supporting BPMN. BPMN is a standard in Workflow and Process management and well supported from a lot of projects.
Second you should think about the requirements to thus an engine.
When you look for a BPMN Engine, there are two different approaches:
Task-Orientated
These engines (e.g. JBoss BPM - jbpm) are designed to process an input data by a well defined process model. Each task in the model gives the control to a piece of code - either a standard or an individual implementation. The process ends when the process-token reaches the end of the process model (End-Event). This kind of processing takes milliseconds. The engine can be used for batch jobs or processing data with a complex process orientated flow.
Event-Driven
Human-Centric workflow engines are event driven (e.g. Imixs-Workflow). This is a kind of state machine but offers typically much more functionality. You can start a new processinstance by assigning your business object with the initial task (defined by the start event). Than the workflow engine allows you to trigger events assigned to each task, defined in your model. Each event (Intermediate CatchEvent) triggers the workflow engine to transfer the running processinstance to the next task (state). Until no new event is triggered, the processinstance 'waits' in the current task (state). An approval process is an typical example for this kind of human-centric workflow.
You can find a list of engines here.