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  • Inequality joins, Asynchronous transformations and Lookups : SSIS

    - by jamiet
    It is pretty much accepted by SQL Server Integration Services (SSIS) developers that synchronous transformations are generally quicker than asynchronous transformations (for a description of synchronous and asynchronous transformations go read Asynchronous and synchronous data flow components). Notice I said “generally” and not “always”; there are circumstances where using asynchronous transformations can be beneficial and in this blog post I’ll demonstrate such a scenario, one that is pretty common when building data warehouses. Imagine I have a [Customer] dimension table that manages information about all of my customers as a slowly-changing dimension. If that is a type 2 slowly changing dimension then you will likely have multiple rows per customer in that table. Furthermore you might also have datetime fields that indicate the effective time period of each member record. Here is such a table that contains data for four dimension members {Terry, Max, Henry, Horace}: Notice that we have multiple records per customer and that the [SCDStartDate] of a record is equivalent to the [SCDEndDate] of the record that preceded it (if there was one). (Note that I am on record as saying I am not a fan of this technique of storing an [SCDEndDate] but for the purposes of clarity I have included it here.) Anyway, the idea here is that we will have some incoming data containing [CustomerName] & [EffectiveDate] and we need to use those values to lookup [Customer].[CustomerId]. The logic will be: Lookup a [CustomerId] WHERE [CustomerName]=[CustomerName] AND [SCDStartDate] <= [EffectiveDate] AND [EffectiveDate] <= [SCDEndDate] The conventional approach to this would be to use a full cached lookup but that isn’t an option here because we are using inequality conditions. The obvious next step then is to use a non-cached lookup which enables us to change the SQL statement to use inequality operators: Let’s take a look at the dataflow: Notice these are all synchronous components. This approach works just fine however it does have the limitation that it has to issue a SQL statement against your lookup set for every row thus we can expect the execution time of our dataflow to increase linearly in line with the number of rows in our dataflow; that’s not good. OK, that’s the obvious method. Let’s now look at a different way of achieving this using an asynchronous Merge Join transform coupled with a Conditional Split. I’ve shown it post-execution so that I can include the row counts which help to illustrate what is going on here: Notice that there are more rows output from our Merge Join component than on the input. That is because we are joining on [CustomerName] and, as we know, we have multiple records per [CustomerName] in our lookup set. Notice also that there are two asynchronous components in here (the Sort and the Merge Join). I have embedded a video below that compares the execution times for each of these two methods. The video is just over 8minutes long. View on Vimeo  For those that can’t be bothered watching the video I’ll tell you the results here. The dataflow that used the Lookup transform took 36 seconds whereas the dataflow that used the Merge Join took less than two seconds. An illustration in case it is needed: Pretty conclusive proof that in some scenarios it may be quicker to use an asynchronous component than a synchronous one. Your mileage may of course vary. The scenario outlined here is analogous to performance tuning procedural SQL that uses cursors. It is common to eliminate cursors by converting them to set-based operations and that is effectively what we have done here. Our non-cached lookup is performing a discrete operation for every single row of data, exactly like a cursor does. By eliminating this cursor-in-disguise we have dramatically sped up our dataflow. I hope all of that proves useful. You can download the package that I demonstrated in the video from my SkyDrive at http://cid-550f681dad532637.skydrive.live.com/self.aspx/Public/BlogShare/20100514/20100514%20Lookups%20and%20Merge%20Joins.zip Comments are welcome as always. @Jamiet Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • SOA Suite 11g Asynchronous Testing with soapUI

    - by Greg Mally
    Overview The Enterprise Manager test harness that comes bundled with SOA Suite 11g is a great tool for doing smoke tests and some minor load testing. When a more robust testing tool is needed, often times soapUI is leveraged for many reasons ranging from ease of use to cost effective. However, when you want to start doing some more complex testing other than synchronous web services with static content, then the free version of soapUI becomes a bit more challenging. In this blog I will show you how to test asynchronous web services with soapUI free edition. The following assumes that you have a working knowledge of soapUI and will not go into concepts like setting up a project etc. For the basics, please review the documentation for soapUI: http://www.soapui.org/Getting-Started/ Asynchronous Web Service Testing in soapUI When invoking an asynchronous web service, the caller must provide a callback for the response. Since our testing will originate from soapUI, then it is only natural that soapUI would provide the callback mechanism. This mechanism in soapUI is called a MockService. In a nutshell, a soapUI MockService is a simulation of a Web Service (aka, a process listening on a port). We will go through the steps in setting up the MockService for a simple asynchronous BPEL process. After creating your soapUI project based on an asynchronous BPEL process, you will see something like the following: Notice that soapUI created an interface for both the request and the response (i.e., callback). The interface that was created for the callback will be used to create the MockService. Right-click on the callback interface and select the Generate MockService menu item: You will be presented with the Generate MockService dialogue where we will tweak the Path and possibly the port (depends upon what ports are available on the machine where soapUI will be running). We will adjust the Path to include the operation name (append /processResponse in this example) and the port of 8088 is fine: Once the MockService is created, you should have something like the following in soapUI: This window acts as a console/view into the callback process. When the play button is pressed (green triangle in the upper left-hand corner), soapUI will start a process running on the configured Port that will accept web service invocations on the configured Path: At this point we are “almost” ready to try out the asynchronous test. But first we must provide the web service addressing (WS-A) configuration on the request message. We will edit the message for the request interface that was generated when the project was created (SimpleAsyncBPELProcessBinding > process > Request 1 in this example). At the bottom of the request message editor you will find the WS-A configuration by left-clicking on the WS-A label: Here we will setup WS-A by changing the default values to: Must understand: TRUE Add default wsa:Action: Add default wsa:Action (checked) Reply to: ${host where soapUI is running}:${MockService Port}${MockService Path} … in this example: http://192.168.1.181:8088/mockSimpleAsyncBPELProcessCallbackBinding/processResponse We now are ready to run the asynchronous test from soapUI free edition. Make sure that the MockService you created is running and then push the play button for the request (green triangle in the upper left-hand corner of the request editor). If everything is configured correctly, you should see the response show up in the MockService window: To view the response message/payload, just double-click on a response message in the Message Log window of the MockService: At this point you can now expand the project to include a Test Suite for some load balance tests etc. This same topic has been covered in various detail on other sites/blogs, but I wanted to simplify and detail how this is done in the context of SOA Suite 11g. It also serves as a nice introduction to another blog of mine: SOA Suite 11g Dynamic Payload Testing with soapUI Free Edition.

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  • Reminder: True WCF Asynchronous Operation

    - by Sean Feldman
    A true asynchronous service operation is not the one that returns void, but the one that is marked as IsOneWay=true. Without this, client will always wait for valid response from server, blocking execution. Possible work-around is to generate asynchronous methods and subscribe to Completed event, but then it’s a pseudo asynchronous. Real fire-and-forget is with one way operations.

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  • Create an Asynchronous JAX-WS Web Service and call it from Oracle BPEL 11g

    - by Bob Webster
    This posting is the result of a simple requirement to take an existing JAX-WS Web service,convert it to be asynchronous and call it from Oracle BPEL 11g It turned out that this is not a trivial task... BPEL has some very specific expectations about the WSDL for an asynchronous process. One approach is to develop the service starting from a WSDL document that meets BPEL's requirements. This is possible but requires considerable WSDL authoring skills. The other approach is to modify the WSDL generated by Web Service Annotations in Java code (Bottom up development) and instruct JAX-WS to use that WSDL instead of dynamically generating one from annotations. This is the approach taken in this article. This posting details how to: Modify a JAX-WS Web Service developed using a "Bottom up " approach to have an asynchronous method and callback. Call the Asynchronous Service from Oracle BPEL 11g. Read the full posting here.

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  • Button in Update Panel doing full postback?

    - by sah302
    No this isn't a copy of this question: http://stackoverflow.com/questions/654423/button-in-update-panel-is-doing-a-full-postback I've got a drop down inside an update panel, and I am trying to get it to allow the person using the page to add users to a list that is bound to a gridview. The list is a global variable, and on page_load I set that to the gridview's datasource and databind it. However, anytime I click the 'add a user' button, or the button to remove the user from the list. It appears like it is doing a full post back even though all these elements are inside the update Panel. Code Behind: Public accomplishmentTypeDao As New AccomplishmentTypeDao() Public accomplishmentDao As New AccomplishmentDao() Public userDao As New UserDao() Public facultyDictionary As New Dictionary(Of Guid, String) Public facultyList As New List(Of User) Public associatedFaculty As New List(Of User) Public facultyId As New Guid Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Page.Title = "Add a New Faculty Accomplishment" ddlAccomplishmentType.DataSource = accomplishmentTypeDao.getEntireTable() ddlAccomplishmentType.DataTextField = "Name" ddlAccomplishmentType.DataValueField = "Id" ddlAccomplishmentType.DataBind() facultyList = userDao.getListOfUsersByUserGroupName("Faculty") For Each faculty As User In facultyList facultyDictionary.Add(faculty.Id, faculty.LastName & ", " & faculty.FirstName) Next If Not Page.IsPostBack Then ddlFacultyList.DataSource = facultyDictionary ddlFacultyList.DataTextField = "Value" ddlFacultyList.DataValueField = "Key" ddlFacultyList.DataBind() End If gvAssociatedUsers.DataSource = associatedFaculty gvAssociatedUsers.DataBind() End Sub Protected Sub deleteUser(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.CommandEventArgs) facultyId = New Guid(e.CommandArgument.ToString()) associatedFaculty.Remove(associatedFaculty.Find(Function(user) user.Id = facultyId)) gvAssociatedUsers.DataBind() upAssociatedFaculty.Update() End Sub Protected Sub btnAddUser_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnAddUser.Click facultyId = New Guid(ddlFacultyList.SelectedValue) associatedFaculty.Add(facultyList.Find(Function(user) user.Id = facultyId)) gvAssociatedUsers.DataBind() upAssociatedFaculty.Update() End Sub Markup: <asp:ScriptManager ID="ScriptManager1" runat="server"> </asp:ScriptManager> <asp:UpdatePanel ID="upAssociatedFaculty" runat="server" UpdateMode="Conditional"> <ContentTemplate> <p><b>Created By:</b> <asp:Label ID="lblCreatedBy" runat="server"></asp:Label></p> <p><b>Accomplishment Type: </b><asp:DropDownList ID="ddlAccomplishmentType" runat="server"></asp:DropDownList></p> <p><b>Accomplishment Applies To: </b><asp:DropDownList ID="ddlFacultyList" runat="server"></asp:DropDownList> &nbsp;<asp:Button ID="btnAddUser" runat="server" Text="Add Faculty" /></p> <p> <asp:GridView ID="gvAssociatedUsers" runat="server" AutoGenerateColumns="false" GridLines="None" ShowHeader="false"> <Columns> <asp:BoundField DataField="Id" HeaderText="Id" Visible="False" /> <asp:TemplateField ShowHeader="False"> <ItemTemplate> <span style="margin-left: 15px;"> <p><%#Eval("LastName")%>, <%#Eval("FirstName")%> <asp:Button ID="btnUnassignUser" runat="server" CausesValidation="false" CommandArgument='<%# Eval("Id") %>' CommandName="Delete" OnCommand="deleteUser" Text='Remove' /></p> </span> </ItemTemplate> </asp:TemplateField> </Columns> <EmptyDataTemplate> <em>There are currently no faculty associated with this accomplishment.</em> </EmptyDataTemplate> </asp:GridView> </p> </ContentTemplate> </asp:UpdatePanel> Now I thought the point of an update panel was to be able to update things inside of it without doing a full post_back and reloading the page. So if that's the case, why is it calling page_load everytime I click the buttons? I ran this code and debug and I see that even before any of the code associated with button press fires, page_load runs again. I tried putting the gvAssociatedUser.Datasource = associatedFaculty and the line below inside the Page.IsPostBack check, that prevented the page from working. I tried every combination of settings of the update panel for ChildrenAsTriggers and UpdateMode, and none of them worked. I know this is something simple, but all the combinations I've tried won't get it to work. How can I make this thing work?

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  • Get Asynchronous HttpResponse through Silverlight (F#)

    - by jack2010
    I am a newbie with F# and SL and playing with getting asynchronous HttpResponse through Silverlight. The following is the F# code pieces, which is tested on VS2010 and Window7 and works well, but the improvement is necessary. Any advices and discussion, especially the callback part, are welcome and great thanks. module JSONExample open System open System.IO open System.Net open System.Text open System.Web open System.Security.Authentication open System.Runtime.Serialization [<DataContract>] type Result<'TResult> = { [<field: DataMember(Name="code") >] Code:string [<field: DataMember(Name="result") >] Result:'TResult array [<field: DataMember(Name="message") >] Message:string } // The elements in the list [<DataContract>] type ChemicalElement = { [<field: DataMember(Name="name") >] Name:string [<field: DataMember(Name="boiling_point") >] BoilingPoint:string [<field: DataMember(Name="atomic_mass") >] AtomicMass:string } //http://blogs.msdn.com/b/dsyme/archive/2007/10/11/introducing-f-asynchronous-workflows.aspx //http://lorgonblog.spaces.live.com/blog/cns!701679AD17B6D310!194.entry type System.Net.HttpWebRequest with member x.GetResponseAsync() = Async.FromBeginEnd(x.BeginGetResponse, x.EndGetResponse) type RequestState () = let mutable request : WebRequest = null let mutable response : WebResponse = null let mutable responseStream : Stream = null member this.Request with get() = request and set v = request <- v member this.Response with get() = response and set v = response <- v member this.ResponseStream with get() = responseStream and set v = responseStream <- v let allDone = new System.Threading.ManualResetEvent(false) let getHttpWebRequest (query:string) = let query = query.Replace("'","\"") let queryUrl = sprintf "http://api.freebase.com/api/service/mqlread?query=%s" "{\"query\":"+query+"}" let request : HttpWebRequest = downcast WebRequest.Create(queryUrl) request.Method <- "GET" request.ContentType <- "application/x-www-form-urlencoded" request let GetAsynResp (request : HttpWebRequest) (callback: AsyncCallback) = let myRequestState = new RequestState() myRequestState.Request <- request let asyncResult = request.BeginGetResponse(callback, myRequestState) () // easy way to get it to run syncrnously w/ the asynch methods let GetSynResp (request : HttpWebRequest) : HttpWebResponse = let response = request.GetResponseAsync() |> Async.RunSynchronously downcast response let RespCallback (finish: Stream -> _) (asynchronousResult : IAsyncResult) = try let myRequestState : RequestState = downcast asynchronousResult.AsyncState let myWebRequest1 : WebRequest = myRequestState.Request myRequestState.Response <- myWebRequest1.EndGetResponse(asynchronousResult) let responseStream = myRequestState.Response.GetResponseStream() myRequestState.ResponseStream <- responseStream finish responseStream myRequestState.Response.Close() () with | :? WebException as e -> printfn "WebException raised!" printfn "\n%s" e.Message printfn "\n%s" (e.Status.ToString()) () | _ as e -> printfn "Exception raised!" printfn "Source : %s" e.Source printfn "Message : %s" e.Message () let printResults (stream: Stream)= let result = try use reader = new StreamReader(stream) reader.ReadToEnd(); finally () let data = Encoding.Unicode.GetBytes(result); let stream = new MemoryStream() stream.Write(data, 0, data.Length); stream.Position <- 0L let JsonSerializer = Json.DataContractJsonSerializer(typeof<Result<ChemicalElement>>) let result = JsonSerializer.ReadObject(stream) :?> Result<ChemicalElement> if result.Code<>"/api/status/ok" then raise (InvalidOperationException(result.Message)) else result.Result |> Array.iter(fun element->printfn "%A" element) let test = // Call Query (w/ generics telling it you wand an array of ChemicalElement back, the query string is wackyJSON too –I didn’t build it don’t ask me! let request = getHttpWebRequest "[{'type':'/chemistry/chemical_element','name':null,'boiling_point':null,'atomic_mass':null}]" //let response = GetSynResp request let response = GetAsynResp request (AsyncCallback (RespCallback printResults)) () ignore(test) System.Console.ReadLine() |> ignore

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  • The correct way to Fire-and-Forget an asynchronous delegate

    - by Programming Hero
    Consider me rusty on the subject of asynchronous delegates. If I want to call a method asynchronously, in a fire-and-forget style, is this an appropriate way to do it? Action action = DoSomething; action.BeginInvoke(action.EndInvoke, null); The DoSomething() method catches all exceptions and deals with them internally. Is the call to EndInvoke appropriate? Required? Is there a clearer way to achieve the same behaviour?

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  • Callbacks in Thrift Asynchronous Functions?

    - by Roberto Aloi
    Hi all, In Thrift it is possible to use the oneway modifier to specify a call as asynchronous. Apparently, it's not possible to define a callback, though, to be executed when the execution of the function is completed. It seems that the only possibility I have is to give my Thrift client (PHP) some "server" capabilities, so that, when the heavy computation is completed on the server side, I can send a notification to it. This means that I should have a new .thrift file, with new definitions, new services and all the rest and that I should generate php-server side code with Thrift. Even if this is feasible, it looks like an overkill to me and I'm wondering if there's a more clever way to implement the callback. Looking forward for some feedback from you, guys.

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  • Ignoring old multiple asynchronous ajax requests

    - by Travis
    I've got a custom javascript autocomplete script that hits the server with multiple asynchronous ajax requests. (Everytime a key gets pressed.) I've noticed that sometimes an earlier ajax request will be returned after a later requests, which messes things up. The way I handle this now is I have a counter that increments for each ajax request. Requests that come back with a lower count get ignored. I'm wondering: Is this proper? Or is there a better way of dealing with this issue? Thanks in advance, Travis

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  • Asynchronous Silverlight WCF callback

    - by Matt
    I've created my own WCF service and I've successfully been able to talk to it via my Silverlight client. I ran into an interesting problem on my asynchronous callbacks though. When my callback is invoked, I can't update any UI controls with the dreaded invalid cross thread access Here's what my callback function looks like private void GetTimeCallBack( object sender, Talk.ClientBase<IService>.ClientEventArgs e ) { lblDisplay.Text = e.Object.ToString(); } A quick google search showed me that I have to do this instead. private void GetTimeCallBack( object sender, Talk.ClientBase<IService>.ClientEventArgs e ) { Dispatcher.BeginInvoke( () => lblDisplay.Text = e.Object.ToString() ); } Now everything works fine, but I wasn't expecting my callback to be running on a different thread. Will I always have to use the Dispatcher class in order to modify anything within my class or is this just limited to UI elements? I've not familiar with the Dispatcher class at all so I'm looking to understand it more.

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  • Asynchronous Sockets - Handling false socket.AcceptAsync values

    - by David
    The Socket class has a method .AcceptAsync which either returns true or false. I'd thought the false return value was an error condition, but in the samples Microsoft provide for Async sockets they call the callback function synchronously after checking for failure, as shown here: public void StartAccept(SocketAsyncEventArgs acceptEventArg) { if (acceptEventArg == null) { acceptEventArg = new SocketAsyncEventArgs(); acceptEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(AcceptEventArg_Completed); } else { // socket must be cleared since the context object is being reused acceptEventArg.AcceptSocket = null; } m_maxNumberAcceptedClients.WaitOne(); bool willRaiseEvent = listenSocket.AcceptAsync(acceptEventArg); if (!willRaiseEvent) { ProcessAccept(acceptEventArg); } } /// <summary> /// This method is the callback method associated with Socket.AcceptAsync operations and is invoked /// when an accept operation is complete /// </summary> void AcceptEventArg_Completed(object sender, SocketAsyncEventArgs e) { ProcessAccept(e); } Why do they do this? It defeats the purpose of asynchronous sockets and stops the method from returning.

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  • ASP.NET Asynchronous Tasks - Worker Thread Not Releasing?

    - by user296752
    I am having an issue with testing asynchronous tasks in ASP.NET & IIS7. From what I have read, the worker thread should be released back into the thread pool while the I/O thread performs the async work, allowing ASP.NET to server other incoming requests. But when I simulate heavy load on the web application by making 20 simultaneous requests to a page (async.aspx) that performs long running async tasks, I am unable to browse to some other normal aspx page until the requests are just about done. Am I misunderstanding or missing something here? I am running Vista Biz x64, VS2008 + IIS7. I have the Async attribute applied to the Page directive.

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  • Javascript ajax asynchronous question...

    - by Polaris878
    Hello, I'm wondering if anyone can help me understand some asynchronous javascript concepts... Say I make an asynch ajax call like so: xmlhttp=new XMLHttpRequest(); xmlhttp.onreadystatechange= myFoo; xmlhttp.open("GET",url,true); Here is my callback function: function myFoo() { if (xmlhttp.readyState==4) { if (xmlhttp.status==200) { // Success message } else { // some error message } } } Now, where and when does the execution path start again? Once I make the call to open(), does execution continue directly below the open() and another "thread" enters the asynch function once the ajax request has been completed? Or, does the browser wait for the request to complete, make the Asynch call, and then execution continues right after the open? Thanks!

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  • javascript: execute a bunch of asynchronous method with one callback

    - by Samuel Michelot
    I need to execute a bunch of asynchronous methods (client SQLite database), and call only one final callback. Of course, the ugly way is: execAll : function(callBack) { asynch1(function() { asynch2(function() { ... asynchN(function() { callBack(); }) }) }); } But I know there are better ways to do it. Intuitively I would detect when all call back has been called with a counter to call the final callback. I think this is a common design-pattern, so if someone could point me in the right direction... Thanks in advance !

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  • Making an asynchronous interface appear synchronous to mod_python users

    - by Trey
    I have a Python-driven web interface powered by Apache 2.2 with mod_python and Python 2.4. I need to make an asynchronous process appear synchronous to users of this web interface. When users access one module on this website: An external SOAP interface will be contacted with a unique identifier and will respond with a number N The external interface will respond asynchronously by contacting a SOAP server on my machine between 1 and 10 times (the number N tells us how many responses we will receive) I need to somehow aggregate these responses and pass them to the original module which will display the information back to the user. The goal is to make the process appear synchronous to the user. What is the best way to handle this synchronization issue? Is this something Twisted would be well-suited for? I am not restricting myself to Python for the solution, though it is preferred because everything else on the server is in Python. I prefer a solution that is both scalable and will take a minimal amount of programming time (though I understand that these attributes are somewhat at odds).

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  • Dowloading a bunch of files asynchronous wait till last finished

    - by Casper Broeren
    I'm trying to download a lot of files after downloading a sql statement must insert a record. I'm using System.Net.Client to download each file synchronously, still it could be done asynchronous. There's no relation or dependency between each download. At first I just tried to use WebClient.DownloadFileAsync but that shutted the program down and killed all the download processes/threads. Second I tried to create a wait routine something like this; while (processedFiles < totalFiles) Thread.Sleep(1000) This freezed everything. So could someone tell me which aproach to take to implement this Async?

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  • C# Asynchronous Sockets questions.

    - by ccppjava
    Based on my reading and testing, with asynchronous sockets, the socket itself can be passed using state object (IAsyncResult result), also if store the socket as a private field, it would be captured by the callback methods. I am wondering how the IAysnResult is kepted between the BeginXXX and ReceiveXXX? It looks to me that after the BeginXXX call and the method ends, the state object would be disposed by GC if there is no reference to it. In the case of private field, how the private field is shared between threads? (As far as I know, a callback is executed using a thread from the default thread pool, which would be considered as a new thread.) Many thanks, hope the questions themselves are clear.

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  • High performance distributed asynchronous RPC in java

    - by unludo
    I would like to do RPC to a list of clients with the following requirements: the server does not know the clients (implies a kind of broker?) and the cleints do not know the server there may be several clients - they share the load to treat the RPC The RPC is asynchronous very fast (round-trip < 1ms) optional : offers a fail-over mechanism. It can be done with underlying tools which are not really intended for that (Hazelcast is an example). What would you use for such requirements? Thanks!

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  • Python - How can I make this code asynchronous?

    - by dave
    Here's some code that illustrates my problem: def blocking1(): while True: yield 'first blocking function example' def blocking2(): while True: yield 'second blocking function example' for i in blocking1(): print 'this will be shown' for i in blocking2(): print 'this will not be shown' I have two functions which contain while True loops. These will yield data which I will then log somewhere (most likely, to an sqlite database). I've been playing around with threading and have gotten it working. However, I don't really like it... What I would like to do is make my blocking functions asynchronous. Something like: def blocking1(callback): while True: callback('first blocking function example') def blocking2(callback): while True: callback('second blocking function example') def log(data): print data blocking1(log) blocking2(log) How can I achieve this in Python? I've seen the standard library comes with asyncore and the big name in this game is Twisted but both of these seem to be used for socket IO. How can I async my non-socket related, blocking functions?

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  • Multiple asynchronous method calls to method while in a loop

    - by ranabra
    I have spent a whole day trying various ways using 'AddOnPreRenderCompleteAsync' and 'RegisterAsyncTask' but no success so far. I succeeded making the call to the DB asynchronous using 'BeginExecuteReader' and 'EndExecuteReader' but that is missing the point. The asynch handling should not be the call to the DB which in my case is fast, it should be afterwards, during the 'while' loop, while calling an external web-service. I think the simplified pseudo code will explain best: (Note: the connection string is using 'MultipleActiveResultSets') "Select ID, UserName from MyTable" 'Open connection to DB ExecuteReader(); if (DR.HasRows) {     while (DR.Read())     {         'Call external web-service         'and get current Temperature of each UserName - DR["UserName"].ToString()         'Update my local DB         Update MyTable set Temperature = ValueFromWebService where UserName =                                       DR["UserName"]         CmdUpdate.ExecuteNonQuery();     }     'Close connection etc } Accessing the DB is fast. Getting the returned result from the external web-service is slow and that at least should be handled Asynchnously. If each call to the web service takes just 1 second, assuming I have only 100 users it will take minimum 100 seconds for the DB update to complete, which obviously is not an option. There eventually should be thousands of users (currently only 2). Currently everything works, just very synchnously :) Thoughts to myself: Maybe my way of approaching this is wrong? Maybe the entire process should be called Asynchnously Many thanx

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  • Dealing with asynchronous control structures (Fluent Interface?)

    - by Christophe Herreman
    The initialization code of our Flex application is doing a series of asynchronous calls to check user credentials, load external data, connecting to a JMS topic, etc. Depending on the context the application runs in, some of these calls are not executed or executed with different parameters. Since all of these calls happen asynchronously, the code controlling them is hard to read, understand, maintain and test. For each call, we need to have some callback mechanism in which we decide what call to execute next. I was wondering if anyone had experimented with wrapping these calls in executable units and having a Fluent Interface (FI) that would connect and control them. From the top of my head, the code might look something like: var asyncChain:AsyncChain = execute(LoadSystemSettings) .execute(LoadAppContext) .if(IsAutologin) .execute(AutoLogin) .else() .execute(ShowLoginScreen) .etc; asyncChain.execute(); The AsyncChain would be an execution tree, build with the FI (and we could of course also build one without a FI). This might be an interesting idea for environments that run in a single threaded model like the Flash Player, Silverlight, JavaFX?, ... Before I dive into the code to try things out, I was hoping to get some feedback.

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  • Asynchronous background processes in Python?

    - by Geuis
    I have been using this as a reference, but not able to accomplish exactly what I need: http://stackoverflow.com/questions/89228/how-to-call-external-command-in-python/92395#92395 I also was reading this: http://www.python.org/dev/peps/pep-3145/ For our project, we have 5 svn checkouts that need to update before we can deploy our application. In my dev environment, where speedy deployments are a bit more important for productivity than a production deployment, I have been working on speeding up the process. I have a bash script that has been working decently but has some limitations. I fire up multiple 'svn updates' with the following bash command: (svn update /repo1) & (svn update /repo2) & (svn update /repo3) & These all run in parallel and it works pretty well. I also use this pattern in the rest of the build script for firing off each ant build, then moving the wars to Tomcat. However, I have no control over stopping deployment if one of the updates or a build fails. I'm re-writing my bash script with Python so I have more control over branches and the deployment process. I am using subprocess.call() to fire off the 'svn update /repo' commands, but each one is acting sequentially. I try '(svn update /repo) &' and those all fire off, but the result code returns immediately. So I have no way to determine if a particular command fails or not in the asynchronous mode. import subprocess subprocess.call( 'svn update /repo1', shell=True ) subprocess.call( 'svn update /repo2', shell=True ) subprocess.call( 'svn update /repo3', shell=True ) I'd love to find a way to have Python fire off each Unix command, and if any of the calls fails at any time the entire script stops.

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  • Asynchronous event loop design and issues.

    - by Artyom
    Hello, I'm designing event loop for asynchronous socket IO using epoll/devpoll/kqueue/poll/select (including windows-select). I have two options of performing, IO operation: Non-blocking mode, poll on EAGAIN Set socket to non-blocking mode. Read/Write to socket. If operation succeeds, post completion notification to event loop. If I get EAGAIN, add socket to "select list" and poll socket. Polling mode: poll and then execute Add socket to select list and poll it. Wait for notification that it is readable writable read/write Post completion notification to event loop of sucseeds To me it looks like first would require less system calls when using in normal mode, especially for writing to socket (buffers are quite big). Also it looks like that it would be possible to reduce the overhead over number of "select" executions, especially it is nice when you do not have something that scales well as epoll/devpoll/kqueue. Questions: Are there any advantages of the second approach? Are there any portability issues with non-blocking operations on sockets/file descriptors over numerous operating systems: Linux, FreeBSD, Solaris, MacOSX, Windows. Notes: Please do not suggest using existing event-loop/socket-api implementations

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