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  • Application Architecture using WCF and System.AddIn

    - by Silverhalide
    A little background -- we're designing an application that uses a client/server architecture consisting of: A server which loads server-side modules, potentially developed by other teams. A client which loads corresponding client-side modules (also potentially developed by those other teams; each client module corresponds with a server module). The client side communicates with the server side for general coordination, and as well as module specific tasks. (At this point, I think that means client talks to server, client modules talk to server modules.) Environment is .NET 3.5, and client side is WPF. The deployment scenario introduces the potential to upgrade the server, any server-side module, the client, and any client-side module independently. However, being able to "work" using mismatched versions is required. I'm therefore concerned about versioning issues. My thinking so far: A Windows Service for the server. Using System.AddIn for the server to load and communicate with the server modules will give us the greatest flexibility in terms of version compatability between server and server modules. The server and each server module vend WCF services for communication to the client side; communication between the server and a server module, or between two server modules use the AddIn contracts. (One advantage of this is that a module can expose a different interface within the server and outside it.) Similarly, the client uses System.AddIn to find, load, and communicate with the client modules. Client communications with client modules is via the AddIn interface; communications from the client and from client modules to the server side are via WCF. For maximum resilience, each module will run in a separate app-domain. In general, the system has modest performance requirements, so marshalling and crossing process boundaries is not expected to be a performance concern. (Performance requirement is basically summed up by: don't get in the way of the other parts of the system not described here.) My questions are around the idea of having two different communication and versioning models to work with which will be an added burden on our developers. System.AddIn seems quite powerful, but also a little unwieldly. (I'm also unsure of Microsoft's commitment to it in the future.) On the other hand, I'm not thrilled with WCF's versioning capabilities. I have a feeling that it would be possible to implement the System.AddIn view/adapter/contract system within WCF, but being fairly new to both technologies, I would have no idea of where to start. So... Am I on the right track here? Am I doing this the hard way? Are there gotchas I need to be aware of on this road? Thanks.

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  • European Interoperability Framework - a new beginning?

    - by trond-arne.undheim
    The most controversial document in the history of the European Commission's IT policy is out. EIF is here, wrapped in the Communication "Towards interoperability for European public services", and including the new feature European Interoperability Strategy (EIS), arguably a higher strategic take on the same topic. Leaving EIS aside for a moment, the EIF controversy has been around IPR, defining open standards and about the proper terminology around standardization deliverables. Today, as the document finally emerges, what is the verdict? First of all, to be fair to those among you who do not spend your lives in the intricate labyrinths of Commission IT policy documents on interoperability, let's define what we are talking about. According to the Communication: "An interoperability framework is an agreed approach to interoperability for organisations that want to collaborate to provide joint delivery of public services. Within its scope of applicability, it specifies common elements such as vocabulary, concepts, principles, policies, guidelines, recommendations, standards, specifications and practices." The Good - EIF reconfirms that "The Digital Agenda can only take off if interoperability based on standards and open platforms is ensured" and also confirms that "The positive effect of open specifications is also demonstrated by the Internet ecosystem." - EIF takes a productive and pragmatic stance on openness: "In the context of the EIF, openness is the willingness of persons, organisations or other members of a community of interest to share knowledge and stimulate debate within that community, the ultimate goal being to advance knowledge and the use of this knowledge to solve problems" (p.11). "If the openness principle is applied in full: - All stakeholders have the same possibility of contributing to the development of the specification and public review is part of the decision-making process; - The specification is available for everybody to study; - Intellectual property rights related to the specification are licensed on FRAND terms or on a royalty-free basis in a way that allows implementation in both proprietary and open source software" (p. 26). - EIF is a formal Commission document. The former EIF 1.0 was a semi-formal deliverable from the PEGSCO, a working group of Member State representatives. - EIF tackles interoperability head-on and takes a clear stance: "Recommendation 22. When establishing European public services, public administrations should prefer open specifications, taking due account of the coverage of functional needs, maturity and market support." - The Commission will continue to support the National Interoperability Framework Observatory (NIFO), reconfirming the importance of coordinating such approaches across borders. - The Commission will align its internal interoperability strategy with the EIS through the eCommission initiative. - One cannot stress the importance of using open standards enough, whether in the context of open source or non-open source software. The EIF seems to have picked up on this fact: What does the EIF says about the relation between open specifications and open source software? The EIF introduces, as one of the characteristics of an open specification, the requirement that IPRs related to the specification have to be licensed on FRAND terms or on a royalty-free basis in a way that allows implementation in both proprietary and open source software. In this way, companies working under various business models can compete on an equal footing when providing solutions to public administrations while administrations that implement the standard in their own software (software that they own) can share such software with others under an open source licence if they so decide. - EIF is now among the center pieces of the Digital Agenda (even though this demands extensive inter-agency coordination in the Commission): "The EIS and the EIF will be maintained under the ISA Programme and kept in line with the results of other relevant Digital Agenda actions on interoperability and standards such as the ones on the reform of rules on implementation of ICT standards in Europe to allow use of certain ICT fora and consortia standards, on issuing guidelines on essential intellectual property rights and licensing conditions in standard-setting, including for ex-ante disclosure, and on providing guidance on the link between ICT standardisation and public procurement to help public authorities to use standards to promote efficiency and reduce lock-in.(Communication, p.7)" All in all, quite a few good things have happened to the document in the two years it has been on the shelf or was being re-written, depending on your perspective, in any case, awaiting the storms to calm. The Bad - While a certain pragmatism is required, and governments cannot migrate to full openness overnight, EIF gives a bit too much room for governments not to apply the openness principle in full. Plenty of reasons are given, which should maybe have been put as challenges to be overcome: "However, public administrations may decide to use less open specifications, if open specifications do not exist or do not meet functional interoperability needs. In all cases, specifications should be mature and sufficiently supported by the market, except if used in the context of creating innovative solutions". - EIF does not use the internationally established terminology: open standards. Rather, the EIF introduces the notion of "formalised specification". How do "formalised specifications" relate to "standards"? According to the FAQ provided: The word "standard" has a specific meaning in Europe as defined by Directive 98/34/EC. Only technical specifications approved by a recognised standardisation body can be called a standard. Many ICT systems rely on the use of specifications developed by other organisations such as a forum or consortium. The EIF introduces the notion of "formalised specification", which is either a standard pursuant to Directive 98/34/EC or a specification established by ICT fora and consortia. The term "open specification" used in the EIF, on the one hand, avoids terminological confusion with the Directive and, on the other, states the main features that comply with the basic principle of openness laid down in the EIF for European Public Services. Well, this may be somewhat true, but in reality, Europe is 30 year behind in terminology. Unless the European Standardization Reform gets completed in the next few months, most Member States will likely conclude that they will go on referencing and using standards beyond those created by the three European endorsed monopolists of standardization, CEN, CENELEC and ETSI. Who can afford to begin following the strict Brussels rules for what they can call open standards when, in reality, standards stemming from global standardization organizations, so-called fora/consortia, dominate in the IT industry. What exactly is EIF saying? Does it encourage Member States to go on using non-ESO standards as long as they call it something else? I guess I am all for it, although it is a bit cumbersome, no? Why was there so much interest around the EIF? The FAQ attempts to explain: Some Member States have begun to adopt policies to achieve interoperability for their public services. These actions have had a significant impact on the ecosystem built around the provision of such services, e.g. providers of ICT goods and services, standardisation bodies, industry fora and consortia, etc... The Commission identified a clear need for action at European level to ensure that actions by individual Member States would not create new electronic barriers that would hinder the development of interoperable European public services. As a result, all stakeholders involved in the delivery of electronic public services in Europe have expressed their opinions on how to increase interoperability for public services provided by the different public administrations in Europe. Well, it does not take two years to read 50 consultation documents, and the EU Standardization Reform is not yet completed, so, more pragmatically, you finally had to release the document. Ok, let's leave some of that aside because the document is out and some people are happy (and others definitely not). The Verdict Considering the controversy, the delays, the lobbying, and the interests at stake both in the EU, in Member States and among vendors large and small, this document is pretty impressive. As with a good wine that has not yet come to full maturity, let's say that it seems to be coming in in the 85-88/100 range, but only a more fine-grained analysis, enjoyment in good company, and ultimately, implementation, will tell. The European Commission has today adopted a significant interoperability initiative to encourage public administrations across the EU to maximise the social and economic potential of information and communication technologies. Today, we should rally around this achievement. Tomorrow, let's sit down and figure out what it means for the future.

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  • Webcast Q&A: Qualcomm Provides a Seamless Experience for Customers with Oracle WebCenter

    - by kellsey.ruppel
    Last Thursday we had the second webcast in our WebCenter in Action webcast series, "Qualcomm Provides a Seamless Experience for Customers with Oracle WebCenter, where customer Michael Chander from Qualcomm and Vince Casarez & Gourav Goyal from Oracle Partner Keste shared how Oracle WebCenter is powering Qualcomm’s externally facing website and providing a seamless experience for their customers. In case you missed it, here's a recap of the Q&A.   Mike Chandler, Qualcomm Q: Did you run into any issues when integrating all of the different applications together?A: Definitely, our main challenges were in the area of user provisioning and security propagation, all the standard stuff you might expect when hooking up SSO for authentication and authorization. In addition, we spent several iterations getting the UI’s in sync. While everyone was given the same digital material to build too, each team interpreted and implemented it their own way. Initially as a user navigated, if you were looking for it, you could slight variations in color or font or width , stuff like that. So we had to pull all the developers responsible for the UI together and get pixel level agreement on a lot of things so we could ensure seamless transitions across applications. Q: What has been the biggest benefit your end users have seen?A: Wow, there have been several. An SSO enabled environment was huge a win for our users. The portal application that this replaced had not really been invested in by the business. With this project, we had full business participation and backing, and it really showed in some key areas like the shopping experience. For example, while ordering in the previous site, the items did not have any pictures or really usable descriptions. A tremendous amount of work was done to try and make the site more intuitive and user friendly. Site performance has also drastically improved thanks to new hardware, improved database design, and of course the fact that ADF has made great strides in runtime performance. Q: Was there any resistance internally when implementing the solution? If so, how did you overcome that?A: Within a large company, I’m sure there is always going to be competition for large projects, as there was here. Once we got through the technical analysis and settled on the technology choices, it was actually no resistance to implementing the solution. This project was fully driven by the business with the aim of long term growth. I can confidently say that the fact that this project was given the utmost importance by both the business and IT really help put down any resistance that you would typically see while implementing a new solution. Q: Given the performance, what do you estimate to be the top end capacity of the system? A:I think our top end capacity is really only limited by our hardware. I’m comfortable saying we could grow 10x on our current hardware, both in terms of transactions and users. We can easily spin up new JVM instances if needed. We already use less JVM’s than we had planned. In addition, ADF is doing a very good job with his connection pooling and application module pooling, so we see a very good ratio of users connected to the systems vs db connections, without impacting performace. Q: What's the overview or summary of feedback from the users interacting with the site?A: Feedback has been overwhelmingly positive from both the business and our customers. They’re very happy with the new SSO environment , the new LAF, and the performance of the site. Of course, it’s not all roses. No matter what, there are always going to be people that don’t like the layout or the color scheme, etc. By and large though, customers are happy and the business is happy. Q: Can you describe the impressions about the site before and after the project within Qualcomm?A: Before the project, the site worked and people were using it, but most people were not happy with it. It was slow and tended to be a bit tempermental, for example a user would perform a transaction and the system would throw and unexpected error. The user could back up and retry the steps and things would work fine, so why didn’t work the first time?. From a UI perspective, we’d hear comments like it looked like it was built by a high school student.  Vince Casarez & Gourav Goyal, Keste Q: Did you run into any obstacles when implementing the solution?A: It's interesting some people call them "obstacles" on this project we just called them "dependencies".  There were both technical and business related dependencies that we had to work out. Mike points out the SSO dependencies and the coordination and synchronization between the teams to have a seamless login experience and a seamless end user experience.  There was also a set of dependencies on the User Acceptance testing to make sure that everyone understood the use cases for how the system would be used.  With a branching into a new market and trying to match a simple user experience as many consumer sites have today, there was always a tendency for the team members to provide their suggestions on how things could be simpler.  But with all the work up front on the user design and getting the business driving this set of experiences, this minimized the downstream suggestions that tend to distract a team.  In this case, all the work up front allowed us to enumerate the "dependencies" and keep the distractions to a minimum. Q: Was there a lot of custom work that needed to be done for this particular solution?A: The focus for this particular solution was really on the custom processes. The interesting thing is that with the data flows and the integration with applications, there are some pre-built integrations, but realistically for the process flow, we had to build those. The framework and tooling we used made things easier so we didn’t have to implement core functionality, like transitioning from screen to screen or from flow to flow. The design feature of Task Flows really helped speed the development and keep the component infrastructure in line with the dynamic processes.  Task flows and other elements like Skins are core to the infrastructure or technology stack of Oracle. This then allowed the team to center the project focus around the business flows and use cases to meet the core requirements and keep the project on time. Q: What do you think were the keys to success for rolling out WebCenter?A:  The 5 main keys to success were: 1) Sponsorship from the whole organization around this project from senior executive agreement, business owners driving functionality, and IT development alignment; 2) Upfront design planning and use case definition to clearly define the project scope and requirements; 3) Focussed development and project management aligned with the top level goals and drivers; 4) User acceptance and usability testing along the way to identify potential issues and direct resolution of the issues;  and 5) Constant prioritization of the issues for development to fix by the business.  It also helps to have great team chemistry and really smart people working on the project. If you missed the webcast, be sure to catch the replay to see a live demonstration of WebCenter in action!  Qualcomm Provides a Seamless Experience for Customers with Oracle WebCenter from Oracle WebCenter

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  • Spring Security: session expiration without redirect to expired-url?

    - by Kdeveloper
    I'm using Spring Security 3.0.2 form based authentication. But I can't figure out how I can configure it so that when a session expires that the request is not redirect to an other page (expired-url) or displays a 'session expires' message. I don't want any redirect or messages, I want that a anonymous session is started just like when a user without a session enters the website. My current configuration: <http> <intercept-url pattern="/login.action*" filters="none"/> <intercept-url pattern="/admin/**" access="ROLE_ADMIN" /> <intercept-url pattern="/**" access="IS_AUTHENTICATED_ANONYMOUSLY"/> <form-login login-page="/login.action" authentication-failure-url="/login.action?error=failed" login-processing-url="/login-handler.action"/> <logout logout-url="/logoff-execute.action" logout-success-url="/logoff.action?done=1"/> <remember-me key="remember-me-security" services-ref="rememberMeServices"/> <session-management > <concurrency-control max-sessions="1" error-if-maximum-exceeded="false" expired-url="/login.action?error=expired.url"/> </session-management> </http>

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  • EF 4, POCO and AddOrUpdate

    - by Eric J.
    I'm trying to create a method on an EF 4 POCO repository called AddOrUpdate. The idea is that the business layer can pass in a POCO object and the persistence framework will add the object if it is new (not yet in the database), else will update the database (once SaveChanges() is called) with the new value. This is similar to some other questions I have asked about EF, but I'm only about 80% there in understanding this so please forgive partial duplication. The part I'm missing is how to update the object graph in my ObjectContext/associated ObjectSet for the passed-in business object once I have determined that the business object indeed already exists in the database (and now has been loaded thanks to TryGetObjectByKey). ApplyCurrentValues sounds sort of like what I want, but it only copies scalar values and doesn't seem intended to update the object graph in the ObjectContext/ObjectSet. Because of my particular use case I don't care about concurrency right now. public void AddOrUpdate(BO biz) { object obj; EntityKey ek = Ctx.CreateEntityKey(mySetName, biz); bool found = Ctx.TryGetObjectByKey(ek, out obj); if (found) { // How do I do what this method name implies? Biz is a parent with children. mySet.TellTheSetToUpdateThisObject(biz); } else { mySet.AddObject(biz); } Ctx.DetectChanges(); }

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  • How can I beta test web Perl modules under Apache/mod_perl on production web server?

    - by DVK
    We have a setup where most code, before being promoted to full production, is deployed in BETA mode - meaning, it runs in full production environment (using production database - usually production data; and production web server). We call that stage BETA testing. One of the main requirements is that BETA code promotion to production must be a simple "cp" command from beta to production directory - no code/filename changes. For non-web Perl code, achieving seamless BETA test is quite doable (see details here): Perl programs live in a standard location under production root (/usr/code/scripts) with production perl modules living under the same root (/usr/code/lib/perl) The BETA code has 100% same code paths except under beta root (/usr/code/beta/) A special module manipulates @INC of any script based on whether the script was called from /usr/code/scripts or /usr/code/test/scripts, to include beta libraries for beta scripts. This setup works fine up till we need to beta test our web Perl code (the setup is EmbPerl and Apache/mod_perl). The hang-up is as follows: if both a production Perl module and BETA Perl module have the same name (e.g. /usr/code/lib/perl/MyLib1.pm and /usr/code/beta/lib/perl/MyLib1.pm), then mod_perl will only be able to load ONE of these modules into memory - and there's no way we are aware of for a particular web page to affect which version of the module is currently loaded due to concurrency issues. Leaving aside the obvious non-programming solution (get a bloody BETA web server) which for political/organizational reasons is not feasible, is there any way we can somehow hack around this problem in either Perl or mod_perl? I played around with various approaches to unloading Perl modules that %INC has listed, but the problem remains that another user might load a beta page at just the right (or rather wrong) moment and have the beta module loaded which will be used for my production page.

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  • Atomic UPSERT in SQL Server 2005

    - by rabidpebble
    What is the correct pattern for doing an atomic "UPSERT" (UPDATE where exists, INSERT otherwise) in SQL Server 2005? I see a lot of code on SO (e.g. see http://stackoverflow.com/questions/639854/tsql-check-if-a-row-exists-otherwise-insert) with the following two-part pattern: UPDATE ... FROM ... WHERE <condition> -- race condition risk here IF @@ROWCOUNT = 0 INSERT ... or IF (SELECT COUNT(*) FROM ... WHERE <condition>) = 0 -- race condition risk here INSERT ... ELSE UPDATE ... where will be an evaluation of natural keys. None of the above approaches seem to deal well with concurrency. If I cannot have two rows with the same natural key, it seems like all of the above risk inserting rows with the same natural keys in race condition scenarios. I have been using the following approach but I'm surprised not to see it anywhere in people's responses so I'm wondering what is wrong with it: INSERT INTO <table> SELECT <natural keys>, <other stuff...> FROM <table> WHERE NOT EXISTS -- race condition risk here? ( SELECT 1 FROM <table> WHERE <natural keys> ) UPDATE ... WHERE <natural keys> (Note: I'm assuming that rows will not be deleted from this table. Although it would be nice to discuss how to handle the case where they can be deleted -- are transactions the only option? Which level of isolation?) Is this atomic? I can't locate where this would be documented in SQL Server documentation.

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  • Suggestions for doing async I/O with Task Parallel Library

    - by anelson
    I have some high performance file transfer code which I wrote in C# using the Async Programming Model (APM) idiom (eg, BeginRead/EndRead). This code reads a file from a local disk and writes it to a socket. For best performance on modern hardware, it's important to keep more than one outstanding I/O operation in flight whenever possible. Thus, I post several BeginRead operations on the file, then when one completes, I call a BeginSend on the socket, and when that completes I do another BeginRead on the file. The details are a bit more complicated than that but at the high level that's the idea. I've got the APM-based code working, but it's very hard to follow and probably has subtle concurrency bugs. I'd love to use TPL for this instead. I figured Task.Factory.FromAsync would just about do it, but there's a catch. All of the I/O samples I've seen (most particularly the StreamExtensions class in the Parallel Extensions Extras) assume one read followed by one write. This won't perform the way I need. I can't use something simple like Parallel.ForEach or the Extras extension Task.Factory.Iterate because the async I/O tasks don't spend much time on a worker thread, so Parallel just starts up another task, resulting in potentially dozens or hundreds of pending I/O operations; way too much! You can work around that by Waiting on your tasks, but that causes creation of an event handle (a kernel object), and a blocking wait on a task wait handle, which ties up a worker thread. My APM-based implementation avoids both of those things. I've been playing around with different ways to keep multiple read/write operations in flight, and I've managed to do so using continuations that call a method that creates another task, but it feels awkward, and definitely doesn't feel like idiomatic TPL. Has anyone else grappled with an issue like this with the TPL? Any suggestions?

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  • WinForms DataGridView - update database

    - by Geo Ego
    I know this is a basic function of the DataGridView, but for some reason, I just can't get it to work. I just want the DataGridView on my Windows form to submit any changes made to it to the database when the user clicks the "Save" button. I populate the DataGridView according to a function triggered by a user selection in a DropDownList as follows: using (SqlConnection con = new SqlConnection(conString)) { con.Open(); SqlDataAdapter ruleTableDA = new SqlDataAdapter("SELECT rule.fldFluteType AS [Flute], rule.fldKnife AS [Knife], rule.fldScore AS [Score], rule.fldLowKnife AS [Low Knife], rule.fldMatrixScore AS [Matrix Score], rule.fldMatrix AS [Matrix] FROM dbo.tblRuleTypes rule WHERE rule.fldMachine_ID = '1003'", con); DataSet ruleTableDS = new DataSet(); ruleTableDA.Fill(ruleTableDS); RuleTable.DataSource = ruleTableDS.Tables[0]; } In my save function, I basically have the following (I've trimmed out some of the code around it to get to the point): using (SqlDataAdapter ruleTableDA = new SqlDataAdapter("SELECT rule.fldFluteType AS [Flute], rule.fldKnife AS [Knife], rule.fldScore AS [Score], rule.fldLowKnife AS [Low Knife], rule.fldMatrixScore AS [Matrix Score], rule.fldMatrix AS [Matrix] FROM dbo.tblRuleTypes rule WHERE rule.fldMachine_ID = '1003'", con)) { SqlCommandBuilder commandBuilder = new SqlCommandBuilder(ruleTableDA); DataTable dt = new DataTable(); dt = RuleTable.DataSource as DataTable; ruleTableDA.Fill(dt); ruleTableDA.Update(dt); } Okay, so I edited the code to do the following: build the commands, create a DataTable based on the DataGridView (RuleTable), fill the DataAdapter with the DataTable, and update the database. Now ruleTableDA.Update(dt) is throwing the exception "Concurrency violation: the UpdateCommand affected 0 of the expected 1 records."

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  • Can I tell Castle Windsor to create a component in a separate AppDomain?

    - by Michael L Perry
    I've created a multi-threaded service that uses Castle Windsor to create components to run on separate threads. I Resolve an component by name with parameters for each thread. I'm running into concurrency problems with a 3rd party library used by the components. I suspect that isolating those components in separate AppDomains will resolve the problem. Is there a way to have Resolve create the component using a different AppDomain? private ActivityThread NewActivityThread(ActivityInstance activityInstance) { // Set up the creation arguments. System.Collections.IDictionary arguments = new Dictionary<string, string>(); activityInstance.Parameters.ForEach(p => arguments.Add(p.Name, p.Value)); // Get the activity handler from the container. IActivity activity = Program.Container.Resolve<IActivity>(activityInstance.Name, arguments); // Create a thread for the activity. ActivityThread thread = new ActivityThread(activity, activityInstance, _nextActivityID++); return thread; } public ActivityThread(IActivity activity, ActivityInstance instance, int id) { _activity = activity; _instance = instance; _id = id; } public void Start() { if (_thread == null) { // Create a new thread to run this activity. _thread = new Thread(delegate() { _activity.Run(); }); _thread.Name = _activity.ToString(); _thread.SetApartmentState(ApartmentState.STA); _thread.Start(); } }

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  • Implementation review for a MVC.NET app with custom membership

    - by mrjoltcola
    I'd like to hear if anyone sees any problems with how I implemented the security in this Oracle based MVC.NET app, either security issues, concurrency issues or scalability issues. First, I implemented a CustomOracleMembershipProvider to handle the database interface to the membership store. I implemented a custom Principal named User which implements IPrincipal, and it has a hashtable of Roles. I also created a separate class named AuthCache which has a simple cache for User objects. Its purpose is simple to avoid return trips to the database, while decoupling the caching from either the web layer or the data layer. (So I can share the cache between MVC.NET, WCF, etc.) The MVC.NET stock MembershipService uses the CustomOracleMembershipProvider (configured in web.config), and both MembershipService and FormsService share access to the singleton AuthCache. My AccountController.LogOn() method: 1) Validates the user via the MembershipService.Validate() method, also loads the roles into the User.Roles container and then caches the User in AuthCache. 2) Signs the user into the Web context via FormsService.SignIn() which accesses the AuthCache (not the database) to get the User, sets HttpContext.Current.User to the cached User Principal. In global.asax.cs, Application_AuthenticateRequest() is implemented. It decrypts the FormsAuthenticationTicket, accesses the AuthCache by the ticket.Name (Username) and sets the Principal by setting Context.User = user from the AuthCache. So in short, all these classes share the AuthCache, and I have, for thread synchronization, a lock() in the cache store method. No lock in the read method. The custom membership provider doesn't know about the cache, the MembershipService doesn't know about any HttpContext (so could be used outside of a web app), and the FormsService doesn't use any custom methods besides accessing the AuthCache to set the Context.User for the initial login, so it isn't dependent on a specific membership provider. The main thing I see now is that the AuthCache will be sharing a User object if a user logs in from multiple sessions. So I may have to change the key from just UserId to something else (maybe using something in the FormsAuthenticationTicket for the key?).

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  • Ruby - Immutable Objects

    - by Chris Bunch
    I've got a highly multithreaded app written in Ruby that shares a few instance variables. Writes to these variables are rare (1%) while reads are very common (99%). What is the best way (either in your opinion or in the idiomatic Ruby fashion) to ensure that these threads always see the most up-to-date values involved? Here's some ideas so far that I had (although I'd like your input before I overhaul this): Have a lock that most be used before reading or writing any of these variables (from Java Concurrency in Practice). The downside of this is that it puts a lot of synchronize blocks in my code and I don't see an easy way to avoid it. Use Ruby's freeze method (see here), although it looks equally cumbersome and doesn't give me any of the synchronization benefits that the first option gives. These options both seem pretty similar but hopefully anyone out there will have a better idea (or can argue well for one of these ideas). I'd also be fine with making the objects immutable so they aren't corrupted or altered in the middle of an operation, but I don't know Ruby well enough to make the call on my own and this question seems to argue that objects are highly mutable.

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  • Updating multiple related tables in SQLite

    - by PerryJ
    Just some background, sorry so long winded. I'm using the System.Data.SQLite ADO.net adapter to create a local sqlite database and this will be the only process hitting the database, so I don't need to worry about concurrency. I'm building the database from various sources and don't want to build this all in memory using datasets or dataadapters or anything like that. I want to do this using SQL (DdCommands). I'm not very good with SQL and complete noob in sqlite. I'm basically using sqlite as a local database / save file structure. The database has a lot of related tables and the data has nothing to do with People or Regions or Districts, but to use a simple analogy, imagine: Region table with auto increment RegionID, RegionName column and various optional columns. District table with auto increment DistrictID, DistrictName, RegionId, and various optional columns Person table with auto increment PersonID, PersonName, DistrictID, and various optional columns So I get some data representing RegionName, DistrictName,PersonName, and other Person related data. The Region, District and/or Person may or may not be created at this point. Once again, not being the greatest with this, my thoughts would be something like: Check to see if Region exists and if so get the RegionID else create it and get RegionID Check to see if District exists and if so get the DistrictID else create it adding in RegionID from above and get DistrictID Check to see if Person exists and if so get the PersonID else create it adding in DistrictID from above and get PersonID Update Person with rest of data. In MS SQL Server I would create a stored procedure to handle all this. Only way I can see to do this with sqlite is a lot of commands. So I'm sure I'm not getting this. I've spent hours looking around on various sites but just don't feel like I'm going down the right road. Any suggestions would be greatly appreciated.

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  • Retrieve input entered in a JDialog

    - by Jules Olléon
    I extended JDialog to create a custom dialog where the user must fill some fields : How should I retrieve the data entered ? I came up with a solution that works. It mimics JOptionPane but the way I do it looks ugly to me because of the static fields involved... Here is roughly my code : public class FObjectDialog extends JDialog implements ActionListener { private static String name; private static String text; private JTextField fName; private JTextArea fText; private JButton bAdd; private JButton bCancel; private FObjectDialog(Frame parentFrame) { super(parentFrame,"Add an object",true); // build the whole dialog buildNewObjectDialog(); setVisible(true); } @Override public void actionPerformed(ActionEvent ae) { if(ae.getSource()==bAdd){ name=fName.getText(); text=fText.getText(); } else { name=null; text=null; } setVisible(false); dispose(); } public static String[] showCreateDialog(Frame parentFrame){ new FObjectDialog(parentFrame); String[] res={name,text}; if((name==null)||(text==null)) res=null; return res; } } As I said, that works properly, but I guess that might raise serious concurrency issues... Is there a cleaner way to do that ? How is it done in JOptionPane ?

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  • Execute remote Lua Script

    - by Bruno Lee
    Hi, I want to make an application that executes a remote script. The user can create a script (probabily a LUA script) then stores it in the server. Then he can uses an API for execute the script. I was thinking that API could be a webservice. So my questions are: I need high performance to execute the script. So my first choice was LUA script. Someone has another sugestion? Cause I need high perfomance, I was thinking if the webservice is the best solution. Maybe I could create a TCP/IP Windows Service that hold the users request. It is important to say that I will have many user executing scripts at the same time. So I will have a concurrency problem. My scripts will query in a database. I will use Tokyo Cabinet or Tokio Tyrant. I think Tokio Tyrant is the only solution cause I will have many requests. For perfomance, Do I need to make a connection pooling? Is there anyway to share variables between webservices requests? To make the webservice or the Windows service i was thinking to use C++. Can someone help with these questions? thanks

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  • Using StringBuilder to process csv files to save heap space

    - by portoalet
    I am reading a csv file that has about has about 50,000 lines and 1.1MiB in size (and can grow larger). In Code1, I use String to process the csv, while in Code2 I use StringBuilder (only one thread executes the code, so no concurrency issues) Using StringBuilder makes the code a little bit harder to read that using normal String class. Am I prematurely optimizing things with StringBuilder in Code2 to save a bit of heap space and memory? Code1 fr = new FileReader(file); BufferedReader reader = new BufferedReader(fr); String line = reader.readLine(); while ( line != null ) { int separator = line.indexOf(','); String symbol = line.substring(0, seperator); int begin = separator; separator = line.indexOf(',', begin+1); String price = line.substring(begin+1, seperator); // Publish this update publisher.publishQuote(symbol, price); // Read the next line of fake update data line = reader.readLine(); } Code2 fr = new FileReader(file); StringBuilder stringBuilder = new StringBuilder(reader.readLine()); while( stringBuilder.toString() != null ) { int separator = stringBuilder.toString().indexOf(','); String symbol = stringBuilder.toString().substring(0, separator); int begin = separator; separator = stringBuilder.toString().indexOf(',', begin+1); String price = stringBuilder.toString().substring(begin+1, separator); publisher.publishQuote(symbol, price); stringBuilder.replace(0, stringBuilder.length(), reader.readLine()); }

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  • How do people know so much about programming?

    - by Luciano
    I see people in this forums with a lot of points, so I assume they know about a lot of different programming stuff. When I was young I knew about basic (commodore) and the turbo pascal (pc). Then in college I learnt about C, memory management, x86 set, loop invariants, graphs, db query optimization, oop, functional, lambda calculus, prolog, concurrency, polymorphism, newton method, simplex, backtracking, dynamic programming, heuristics, np completeness, LR, LALR, neural networks, static & dynamic typing, turing, godel, and more in between. Then in industry I started with Java several years ago and learnt about it, and its variety of frameworks, and also design patterns, architecture patterns, web development, server development, mobile development, tdd, bdd, uml, use cases, bug trackers, process management, people management if you are a tech lead, profiling, security concerns, etc. I started to forget what I learnt in college... And then there is the stuff I don't know yet, like python, .net, perl, JVM stuff like groovy or scala.. Of course Google is a must for rapid documentation access to know if a problem has been solved already and how, and to keep informed about new stuff by blogs and places like this one. It's just too much or I just have a bad memory.. how do you guys manage it?

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  • Updating multiple related tables in SQLite with C#

    - by PerryJ
    Just some background, sorry so long winded. I'm using the System.Data.SQLite ADO.net adapter to create a local sqlite database and this will be the only process hitting the database, so I don't need to worry about concurrency. I'm building the database from various sources and don't want to build this all in memory using datasets or dataadapters or anything like that. I want to do this using SQL (DdCommands). I'm not very good with SQL and complete noob in sqlite. I'm basically using sqlite as a local database / save file structure. The database has a lot of related tables and the data has nothing to do with People or Regions or Districts, but to use a simple analogy, imagine: Region table with auto increment RegionID, RegionName column and various optional columns. District table with auto increment DistrictID, DistrictName, RegionId, and various optional columns Person table with auto increment PersonID, PersonName, DistrictID, and various optional columns So I get some data representing RegionName, DistrictName,PersonName, and other Person related data. The Region, District and/or Person may or may not be created at this point. Once again, not being the greatest with this, my thoughts would be something like: Check to see if Region exists and if so get the RegionID else create it and get RegionID Check to see if District exists and if so get the DistrictID else create it adding in RegionID from above and get DistrictID Check to see if Person exists and if so get the PersonID else create it adding in DistrictID from above and get PersonID Update Person with rest of data. In MS SQL Server I would create a stored procedure to handle all this. Only way I can see to do this with sqlite is a lot of commands. So I'm sure I'm not getting this. I've spent hours looking around on various sites but just don't feel like I'm going down the right road. Any suggestions would be greatly appreciated.

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  • How should I go about implementing a points-to analysis in Maude?

    - by reprogrammer
    I'm going to implement a points-to analysis algorithm. I'd like to implement this analysis mainly based on the algorithm by Whaley and Lam. Whaley and Lam use a BDD based implementation of Datalog to represent and compute the points-to analysis relations. The following lists some of the relations that are used in a typical points-to analysis. Note that D(w, z) :- A(w, x),B(x, y), C(y, z) means D(w, z) is true if A(w, x), B(x, y), and C(y, z) are all true. BDD is the data structure used to represent these relations. Relations input vP0 (variable : V, heap : H) input store (base : V, field : F, source : V) input load (base : V, field : F, dest : V) input assign (dest : V, source : V) output vP (variable : V, heap : H) output hP (base : H, field : F, target : H) Rules vP(v, h) :- vP0(v, h) vP(v1, h) :- assign(v1, v2), vP(v2, h) hP(h1, f,h2) :- store(v1, f, v2), vP(v1, h1), vP(v2, h2) vP(v2, h2) :- load(v1, f, v2), vP(v1, h1), hP(h1, f, h2) I need to understand if Maude is a good environment for implementing points-to analysis. I noticed that Maude uses a BDD library called BuDDy. But, it looks like that Maude uses BDDs for a different purpose, i.e. unification. So, I thought I might be able to use Maude instead of a Datalog engine to compute the relations of my points-to analysis. I assume Maude propagates independent information concurrently. And this concurrency could potentially make my points-to analysis faster than sequential processing of rules. But, I don't know the best way to represent my relations in Maude. Should I implement BDD in Maude myself, or Maude's internal unification based on BDD has the same effect?

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  • Returning from dll (Asynchronous sockets)

    - by Juha
    I am trying to do a simple http-server in (c++) dll-file that I can use from managed (C#) application with P/Invoke. I was trying to do this with asynchronous functions (WSAAsyncSelect() and stuff), so that I could manage server by calling functions inside dll whenever needed and after that it would return to my main program. Now I'm not sure if that is even possible. It seems that "main function" in dll, the function that starts the server, has to include message loop or something and since it's a loop, it doesn't return from dll ever. Could I somehow do this message stuff in my managed application and call some function in dll when there is something to do? Or is it even possible to do this stuff in one thred? I would really like to avoid all concurrency stuff. The dll looks now basicly the same as here, main function is the one that I call from managed C# program and would like to return to there after calling the function. http://www.winsocketdotnetworkprogramming.com/winsock2programming/winsock2advancediomethod5b.html I'm quite noob in windows programming, and never even heard of this message-queue or message-loop.

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  • Testing system where App-level and Request-level IoC containers exist

    - by Bobby
    My team is in the process of developing a system where we're using Unity as our IoC container; and to provide NHibernate ISessions (Units of work) over each HTTP Request, we're using Unity's ChildContainer feature to create a child container for each request, and sticking the ISession in there. We arrived at this approach after trying others (including defining per-request lifetimes in the container, but there are issues there) and are now trying to decide on a unit testing strategy. Right now, the application-level container itself is living in the HttpApplication, and the Request container lives in the HttpContext.Current. Obviously, neither exist during testing. The pain increases when we decided to use Service Location from our Domain layer, to "lazily" resolve dependencies from the container. So now we have more components wanting to talk to the container. We are also using MSTest, which presents some concurrency dilemmas during testing as well. So we're wondering, what do the bright folks out there in the SO community do to tackle this predicament? How does one setup an application that, during "real" runtime, relies on HTTP objects to hold the containers, but during test has the flexibility to build-up and tear-down the containers consistently, and have the ServiceLocation bits get to those precise containers. I hope the question is clear, thanks!

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  • A business Case for Enterprise Python

    - by Srirangan
    Hi all, This will not be a "programming" question but more technology / platform related question. I'm trying to figure out whether Python can be a suitable Java alternative for enterprise / web applications. Which are the ideal cases where you would prefer to use Python instead of Java? How would a typical Python web application (databases/sessions/concurrency) perform as compared to a typical Java application? How do specific Python frameworks square up against Java based frameworks (Spring, SEAM, Grails etc.)? For businesses, switching from the Java infrastructure to a Python infrastructure .. is it too hard/expensive/resource intensive/not viable? Also shed some light on the business case for providing a Python + Google AppEngine based solution to the end customer. Will it be cost effective in an typical scenario? Sorry if I am asking too wide a question, I would have liked to keep it specific, but I need your help to evaluate Python as a whole from the perspectives of the programmers, service providing company and end business customer. For an SME, a Python/GoogleAppEngine based technology stack is a clear scalable and affordable platform. But what about a large MNC that already has a lot invested in Java. Thank you so much. I am researching this myself and will gladly share my conclusions here! Thank you, Srirangan

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  • What specific features of LabView are frustrating to you?

    - by Underflow
    Please bear with me: this isn't a language debate or a flame. It's a real request for opinions. Occasionally, I have to help educate a traditional text coder in how to think in LabVIEW (LV). Often during this process, I get to hear about how LV sucks. Rarely is this insight accompanied by rational observations other than "Language X is just so much better!". While this statement is satisfying to them, it doesn't help me understand what is frustrating them. So, for those of you with LabVIEW and text language experience, what specific things about LV drive you nuts? ------ Summaries ------- Thanks for all the answers! Some of the issues are answered in the comments below, some exist on other sites, and some are just genuine problems with LV. In the spirit of the original question, I'm not going to try to answer all of these here: check LAVA or NI's website, and you'll be pleasantly surprised at how many of these things can be overcome. Unintentional concurrency No access to tradition text manipulation tools Binary-only source code control Difficult to branch and merge Too many open windows Text has cleaner/clearer/more expressive syntax Clean coding requires a lot of time and manipulation Large, difficult to access API/palette system Mouse required File namespacing: no duplicate files with the same name in memory LV objects are natively by-value only Requires dev environment to view code Lack of zoom Slow startup Memory pig "Giant" code is difficult to work with UI lockup is easy to do Trackpads and LV don't mix well String manipulation is graphically bloated Limited UI customization "Hidden" primitives (yes, these exist) Lack of official metaprogramming capability (not for much longer, though) Lack of unicode support [1]: http://www.lavag.org LAVA

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  • Executing remote script - Architecture

    - by Bruno Lee
    Hi, I want to make an application that executes a remote script. The user can create a script (probabily a LUA script) then stores it in the server. Then he can uses an API for execute the script. I was thinking that API could be a webservice. So my questions are: I need high performance to execute the script. So my first choice was LUA script. Someone has another sugestion? Cause I need high perfomance, I was thinking if the webservice is the best solution. Maybe I could create a TCP/IP Windows Service that hold the users request. It is important to say that I will have many user executing scripts at the same time. So I will have a concurrency problem. My scripts will query in a database. I will use Tokyo Cabinet or Tokio Tyrant. I think Tokio Tyrant is the only solution cause I will have many requests. For perfomance, Do I need to make a connection pooling? Is there anyway to share variables between webservices requests? To make the webservice or the Windows service i was thinking to use C++. Can someone help with these questions? thanks

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  • How to pass binary data between two apps using Content Provider?

    - by Viktor
    I need to pass some binary data between two android apps using Content Provider (sharedUserId is not an option). I would prefer not to pass the data (a savegame stored as a file, small in size < 20k) as a file (ie. overriding openFile()) since this would necessitate some complicated temp-file scheme to cope with concurrency with several content provider accesses and a running game. I would like to read the file into memory under a mutex lock and then pass the binary array in the simplest way possible. How do I do this? It seems creating a file in memory is not a possibility due to the return type of openFile(). query() needs to return a Cursor. Using MatrixCursor is not possible since it applies toString() to all stored objects when reading it. What do I need to do? Implement a custom Cursor? This class has 30 abstract methods. Do I read the file, put it in a SQLite db and return the cursor? The complexity of this seemingly simple task is mindboggling.

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