Search Results

Search found 14074 results on 563 pages for 'programmers'.

Page 211/563 | < Previous Page | 207 208 209 210 211 212 213 214 215 216 217 218  | Next Page >

• Are There Realistic/Useful Solutions for Source Control for Ladder Logic Programs

  - by Steven A. Lowe

  Version control for ladder logic (LL) programs for programmable logic controllers (PLCs) seems to be virtually non-existent. It may be because LL is a visual language and tends to be stored in binary files, or it may be because source code control hasn't "caught on" in process control engineering circles - or perhaps my Google-Fu is weak tonight. Do you know of any realistic and useful solutions for version control for such systems? Definitions: realistic = changes to the programs are tracked by user and subject to reversion and merges useful = the system integrates with visual LL designers, is not limited to LL from a single PLC manufacturer, and does not cost a ridiculous amount of money? Note: I have heard of people using SVN or Mercurial et al to track the binary files, but I don't think the diff/merge capabilities would display readable differences.

  Read the article

• Exclusive use of a Jini server during long-running call

  - by Matthew Flint

  I'm trying to use Jini, in a "Masters/Workers" arrangement, but the Worker jobs may be long running. In addition, each worker needs to have exclusive access to a singleton resource on that machine. As it stands, if a Worker receives another request while a previous request is running, then the new request is accepted and executed in a second thread. Are there any best-practices to ensure that a Worker accepts no further jobs until the current job is complete? Things I've considered: synchronize the job on the server, with a lock on the singleton resource. This would work, but is far from ideal. A call from a Master would block until the current Worker thread completes, even if other Workers become free in the meantime unregister the Worker from the registry while the job is running, then re-register when it completes. Might work OK, but something doesn't smell right with this idea... Of course, I'm quite happy to be told that there are more appropriate technologies than Jini... but I wouldn't want anything too heavyweight, like rolling out EJB containers all over the place.

  Read the article

• Is event sourcing ready for prime time?

  - by Dakotah North

  Event Sourcing was popularized by LMAX as a means to provide speed, performance scalability, transparent persistence and transparent live mirroring. Before being rebranded as Event Sourcing, this type of architectural pattern was known as System Prevalence but yet I was never familiar with this pattern before the LMAX team went public. Has this pattern proved itself in numerous production systems and therefore even conservative individuals should feel empowered to embrace this pattern or is event sourcing / system prevalence an exotic pattern that is best left for the fearless?

  Read the article

• Instruction vs data cache usage

  - by Nick Rosencrantz

  Say I've got a cache memory where instruction and data have different cache memories ("Harvard architecture"). Which cache, instruction or data, is used most often? I mean "most often" as in time, not amount of data since data memory might be used "more" in terms of amount of data while instruction cache might be used "more often" especially depending on the program. Are there different answers a) in general and b) for a specific program?

  Read the article

• Increase the size of a memory mapped file

  - by sandun dhammika

  I am maintaning a memory mapped file to store my tree like datastructure. When I'm updating the datastructure ,I got this problem. The file is limited on it's size and can't be too long or too small. I have a methods like void mapfile_insert_record(RECORD* /* record*/); void mapfile_modify_record(RECORD* /* record*/); Both operations could lead to exceed the space which is free on memory file. How do I overcome this? What strategy I should use. calculate whether it requires to exceed the file as a pre-condition on both methods. Dynamically exceed it , for a example manage a timer and constantly polling file for it's free avaliable size and then automatically extend it. Any ideas or patterns to overcome this problem?

  Read the article

• How does throwing an ArgumentNullException help?

  - by Scott Whitlock

  Let's say I have a method: public void DoSomething(ISomeInterface someObject) { if(someObject == null) throw new ArgumentNullException("someObject"); someObject.DoThisOrThat(); } I've been trained to believe that throwing the ArgumentNullException is "correct" but an "Object reference not set to an instance of an object" error means I have a bug. Why? I know that if I was caching the reference to someObject and using it later, then it's better to check for nullity when passed in, and fail early. However, if I'm dereferencing it on the next line, why are we supposed to do the check? It's going to throw an exception one way or the other. Edit: It just occurred to me... does the fear of the dereferenced null come from a language like C++ that doesn't check for you (i.e. it just tries to execute some method at memory location zero + method offset)?

  Read the article

• Is there a good book to grok C++?

  - by Paperflyer

  This question got me thinking. I would say I am a pretty experienced C++ programmer. I use it a lot at work, I had some courses on it at the university, I can understand most C++ code I find out there without problems. Other languages you can pretty much learn by using them. But every time I use a new C++ library or check out some new C++ code by someone I did not know before, I discover a new set of idioms C++ has to offer. Basically, this has lead me to believe that there is a lot of stuff in C++ that might be worth knowing but that is not easily discoverable. So, is there a good book for a somewhat experienced C++ programmer to step up the game? You know, to kind of 'get' that language the way you can 'get' Ruby or Objective-C, where everything just suddenly makes sense and you start instinctively knowing 'that C++ way of thing'?

  Read the article

• Which .NET REST approach/technology/tool should I use?

  - by SonOfPirate

  I am implementing a RESTful web service and several client applications that are mostly in Silverlight. I am finding a litany of options for developing both the server-side and client-side of the API but am not sure which is the best approach. I'm concerned about stability as well as a platform that will continue to exist a few months from now. We started using the REST Starter Kit with .NET 3.5 but moved to the new WCF Web API when updating to .NET 4.0. All of their documentation indicates that WCF Web API is the replacement for the RSK. However, Web API is only in Preview 4 and does not include support for Silverlight or Windows Phone 7 clients (yet). WCF Web API looks like a wrapper on top of the WCF WebHttp Services stuff provided in the System.ServiceModel.Web library which makes me think that maybe it would be simpler to just go with the built-in stuff but Web API does offer some nice features. I am specifically tied-up trying to determine the best course for the client-side. My main requirement is that I need to support deserializing into my client-side objects quickly and easily. The Web API offers a nice client library but doesn't have a Silverlight version. I'd like to use the latest approach and the toolset that is being actively developed and supported. Is the REST Starter Kit really obsolete? Has anyone had any success implementing the WCF Web API toolkit? Is there merit to using either of these over the built-in WCF WebHttp Services features found in System.ServiceModel.Web? Is there a single solution that works for any client (web, Silverlight, etc.)? What suggestions do you have?

  Read the article

• How a .NET Programmer learn Big Data/Hadoop? [on hold]

  - by Smith Pascal Jr.

  I have been ASP.NET developer for sometime now and I have been reading a lot about Big Data- Hadoop and its future as to how it is the next technology in IT and how it would be useful to create million of jobs in US and elsewhere in the world. Now since Hadoop is an open source big data tool which is managed by Apache Server Foundation Group, I'm assuming I have to be well aware of JAVA - Correct me if I'm wrong. Moreover, How a .NET programmer can learn Big Data and its related technologies and can work professionally full time into this technology? What challenges and opportunities does a .NET professional face while changing the technology platform? Please advice. Thanks

  Read the article

• What is 'work' in the Pomodoro Technique?

  - by Sachin Kainth

  I have just started to use Pomodoro today and I am trying to work out what I should and should not do during my 25 minute work time. For my 25 minute work stint I started to write some code and realised that I had done something similar in a related project so I opened that solution to copy and paste that existing code. Question is, is this allowed? Also, if during my 25 minutes I realise that there is an important work-related email that I need to send can I do that or should that wait for the next 25 minutes or the break. I am writing this question during my, now extended, 5 minute break. Is this work or is it a break? I really would appreciate some guidance as I really want to use Pomodoro to focus better on my work. Another thing that happened to me was that a Adobe AIR update alert came up on my desktop during the 25 minutes. Should I ignore such things until the break? Sachin

  Read the article

• A way to return multiple return values from a method: put method inside class representing return value. Is it a good design?

  - by john smith optional

  I need to return 2 values from a method. My approach is as follows: create an inner class with 2 fields that will be used to keep those 2 values put the method inside that class instantiate the class and call the method. The only thing that will be changed in the method is that in the end it will assign those 2 values to the fields of the instance. Then I can address those values by referencing to the fields of that object. Is it a good design and why?

  Read the article

• SSO between multiple Flex applications

  - by KarthiPk

  We have three applications developed in Flex and all these use BlazeDS. These applications have their own authentication implementations (Database). Also they will be deployed in tomcat. Deploying all these applications in the same tomcat instance is acceptable for us. We want to bring the authentication credentials of all these applications into a single place and also provide SSO feature between these applications. We also want the authentication module to be configurable. Something like the system administrator can decide if the authentication should be done against a database or LDAP. Say, if the user successfully logs into app1, and when he access app2 in the same browser he should be automatically logged in. Same goes for logout as well. We have been exploring OpenAM, jGuard and JOSSO. I'm not sure if these require lot of customization to work with Flex. I would like to know how people are implementing SSO for Flex applications. Is there a common and simple SSO solution available for Flex based applications ?

  Read the article

• SQLite with two python processes accessing it: one reading, one writing

  - by BBnyc

  I'm developing a small system with two components: one polls data from an internet resource and translates it into sql data to persist it locally; the second one reads that sql data from the local instance and serves it via json and a restful api. I was originally planning to persist the data with postgresql, but because the application will have a very low-volume of data to store and traffic to serve, I thought that was overkill. Is SQLite up to the job? I love the idea of the small footprint and no need to maintain yet another sql server for this one task, but am concerned about concurrency. It seems that with write ahead logging enabled, concurrently reading and writing a SQLite database can happen without locking either process out of the database. Can a single SQLite instance sustain two concurrent processes accessing it, if only one reads and the other writes? I started writing the code but was wondering if this is a misapplication of SQLite.

  Read the article

• Why should I use List<T> over IEnumerable<T>?

  - by Rowan Freeman

  In my ASP.net MVC4 web application I use IEnumerables, trying to follow the mantra to program to the interface, not the implementation. Return IEnumerable(Of Student) vs Return New List(Of Student) People are telling me to use List and not IEnumerable, because lists force the query to be executed and IEumerable does not. Is this really best practice? Is there any alternative? I feel strange using concrete objects where an interface could be used. Is my strange feeling justified?

  Read the article

• Does double-shifting as a PM affect your developer-productivity?

  - by Roopesh Shenoy

  Has it ever happened to you that you are a good developer but suddenly you need to lead a team or are responsible for some PM activities as well? Did you find that it affected your productivity? How did you handle it? I love my job, but I sometimes feel I was much happier as a programmer and the additional burden of being a Project Manager is currently affecting my productivity as a developer. What do you guys suggest as remedies to this? I do not have an alternative currently to quit from my job - basically because Im working for a startup that I co-founded.

  Read the article

• Avoiding Object Oriented Pitfalls, Migrating from C, What Worked for You?

  - by Stephen

  I've been programming in procedural languages for quite some time now, and my first reaction to a problem is to start breaking it down into tasks to perform rather than to consider the different entities (objects) that exist and their relationships. I have had a university course in OOP, and understand the fundamentals of encapsulation, data abstraction, polymorphism, modularity and inheritance. I read Learning to think in the Object Oriented Way and Learning object oriented thinking, and will be looking at some of the books pointed to in those answers. I think that several of my medium to large sized projects will benefit from effective use of OOP but as a novice I would like to avoid time consuming, common errors. Based on your experiences, what are these pitfalls and what are reasonable ways around them? If you could explain why they are pitfalls, and how your suggestion is effective in addressing the issue it'd be appreciated. I'm thinking along the lines of something like "Is it common to have a fair number of observer and modifier methods and use private variables or are there techniques for consolidating/reducing them?" I'm not worried about using C++ as a pure OO language, if there are good reasons to mix methods. (Reminiscent of the reasons to use GOTOs, albeit sparingly.) Thank you!

  Read the article

• Why do people think SOAP is deprecated?

  - by user98q37479

  While browsing SO today I found this question here and it starts with this: Sure, you're gonna tell me that SOAP is depracated and all, well i'm forced to use it Found lots of statement like this one on SO up till now, this one just triggered me to ask this question. REST has its uses, SOAP has its uses, in some places they intersect as functionality but they are not replaceable to one another. So I wonder, why do people think SOAP is "deprecated"? Is it ignorance? Complexity of SOAP and WS-* specs? REST hype? What? If you think SOAP is deprecated please tell me why. I'm curious!

  Read the article

• Naming a predicate: "precondition" or "precondition_is_met"?

  - by RexE

  In my web app framework, each page can have a precondition that needs to be satisfied before it can be displayed to the user. For example, if user 1 and user 2 are playing a back-and-forth role-playing game, user 2 needs to wait for user 1 to finish his turn before he can take his turn. Otherwise, the user is displayed a waiting page. This is implemented with a predicate: def precondition(self): return user_1.completed_turn The simplest name for this API is precondition, but this leads to code like if precondition(): ..., which is not really obvious. Seems to me like it is more accurate to call it precondition_is_met(), but not sure about that either. Is there a best practice for naming methods like this?

  Read the article

• Write a program consisting of a main module and three other modules

  - by user106080

  The owner of a super supermarket would like to have a program that computes the monthly gross pay of their employees as well as the employees’s net pay. The input for this program is the employee id number, hourly rate of pay, and number of regular and overtime hours hours worked. Gross pay is the sum of the wages earnes from regular hours; overtime is 1.5 times the regular rate. Net pay is gross pay hours; overtime is paid at 1.5 times the regular rate. Net pay is the gross pay minus deductions. Assume that deduction are taken for tax withholding (50 percent of gross pay) and parking ($10.00 per month) you will need the following variables: EmployeeID (a string) HourRate is (a float) RegHours (a float) ; GrossPay (a float);Tax (afloat) Parking (a float) OverTimeHours (a float) NetPay (a float) GrossPay = Regularhours* HourRate+OverTimeHours*(HourRate*1.5) NetPay= GrossPay – (GrossPay*Tax) – Parking

  Read the article

• In Scrum, should you split up the backlog in a functional backlog and a technical backlog or not?

  - by Patrick

  In our Scrum teams we use a backlog, which mostly contains functional topics, but also sometimes contains technical topics. The advantage of having 1 backlog is that it becomes easy to choose the topics for the next sprint, but I have some questions: First, to me it seems more logical to have a separate technical backlog, where developers themselves can add pure technical items, like: we could improve performance in this method, this class lacks some technical documentation, ... By having one backlog, all developers always have to pass via the product owner to have their topics added to the backlog, which seems additional, unnecessary work for the product owner. Second, if you have a product owner that only focuses on the pure-functional items, the pure-technical items (like missing technical documentation, code that erodes and should be refactored, classes that always give problems during debugging because they don't have a stable foundation and should be refactored, ...) always end up at the end of the list because "they don't serve the customer directly". By having a separate technical backlog, and time reserved in every sprint for these pure technical items, we can improve the applications functionally, but also keep them healthy inside. What is the best approach? One backlog or two?

  Read the article

• How do I account for changed or forgotten tasks in an estimate?

  - by Andrew

  To handle task-level estimates and time reporting, I have been using (roughly) the technique that Steve McConnell describes in Chapter 10 of Software Estimation. Specifically, when the time comes for me to create task-level estimates (right before coding begins on a project), I determine the tasks at a fairly granular level so that, whenever possible, I have no tasks with a single-point, 50%-confidence estimate greater than four hours. That way, the task estimation process helps with constructing the software while helping me not to forget tasks during estimation. I come up with a range of hours possible for each task also, and using the statistical calculations that McConnell describes along with my historical accuracy data, I can generate estimates at other confidence levels when desired. I feel like this method has been working fairly well for me. We are required to put tasks and their estimates into TFS for tracking, so I use the estimates at the percentage of confidence I am told to use. I am unsure, however, what to do when I do forget a task, or I end up needing to do work that does not neatly fall within one of the tasks I estimated. Of course, trying to avoid this situation is best, but how do I account for forgotten/changed tasks? I want to have the best historical data I can to help me with future estimates, but right now, I basically am just calculating whether I made the 50%-confidence estimate and whether I made it inside the ranged estimate. I'll be happy to clarify what I'm asking if needed -- let me know what is unclear.

  Read the article

• Is there really Object-relational impedance mismatch?

  - by user52763

  It is always stated that it is hard to store applications objects in relational databases - the object-relational impedance mismatch - and that is why Document databases are better. However, is there really an impedance mismatch? And object has a key (albeit it may be hidden away by the runtime as a pointer to memory), a set of values, and foreign keys to other objects. Objects are as much made up of tables as it is a document. Neither really fit. I can see a use for databases to model the data into specific shapes for scenarios in the application - e.g. to speed up database lookup and avoid joins, etc., but won't it be better to keep the data as normalized as possible at the core, and transform as required?

  Read the article

• Can static and dynamically typed languages be seen as different tools for different types of jobs?

  - by Erik Reppen

  Yes, similar questions have been asked but always with the aim of finding out 'which one is better.' I'm asking because I came up as a dev primarily in JavaScript and don't really have any extensive experience writing in statically typed languages. In spite of this I definitely see value in learning C for handling demanding operations at lower levels of code (which I assume has a lot to do with static vs dynamic at the compiler level), but what I'm trying to wrap my head around is whether there are specific project contexts (maybe certain types of dynamic data-intensive operations?) involving things other than performance where it makes a lot more sense to go with Java or C# vs. something like Python.

  Read the article

• Is true multithreading really necessary?

  - by Jonathan Graef

  So yeah, I'm creating a programming language. And the language allows multiple threads. But, all threads are synchronized with a global interpreter lock, which means only one thread is allowed to execute at a time. The only way to get the threads to switch off is to explicitly tell the current thread to wait, which allows another thread to execute. Parallel processing is of course possible by spawning multiple processes, but the variables and objects in one process cannot be accessed from another. However the language does have a fairly efficient IPC interface for communicating between processes. My question is: Would there ever be a reason to have multiple, unsynchronized threads within a single process (thus circumventing the GIL)? Why not just put thread.wait() statements in key positions in the program logic (presuming thread.wait() isn't a CPU hog, of course)? I understand that certain other languages that use a GIL have processor scheduling issues (cough Python), but they have all been resolved.

  Read the article

• How do you organize information?

  - by zvrba

  I have a relatively large collection of useful books (paper and electronic), [academic] papers (mostly electronic) and web bookmarks. However, I don't have an overview of the material. Currently I have most of the electronic (PDF/DJVU) material in a single hierarchical folder and use filename search. Two questions. Do you have a similar problem, and how do you deal with it? Can you recommend some software to help with organizing bibliographic information, including web links. Easy editing of hierarchy and tags is a must. I would also like to be able to write own comments for each entry. [With my current scheme, just using the filesystem, does not provide other metadata.] A plugin for emacs would be perfect, but it's not a must. (org-mode MIGHT be adequate).

  Read the article

< Previous Page | 207 208 209 210 211 212 213 214 215 216 217 218  | Next Page >