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• How to Treat Race Condition of Session in Web Application?

  - by Morgan Cheng

  I was in a ASP.NET application has heavy traffic of AJAX requests. Once a user login our web application, a session is created to store information of this user's state. Currently, our solution to keep session data consistent is quite simple and brutal: each request needs to acquire a exclusive lock before being processed. This works fine for tradition web application. But, when the web application turns to support AJAX, it turns to not efficient. It is quite possible that multiple AJAX requests are sent to server at the same time without reloading the web page. If all AJAX requests are serialized by the exclusive lock, the response is not so quick. Anyway, many AJAX requests that doesn't access same session variables are blocked as well. If we don't have a exclusive lock for each requests, then we need to treat all race condition carefully to avoid dead lock. I'm afraid that would make the code complex and buggy. So, is there any best practice to keep session data consistent and keep code simple and clean?

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• Trying to make a plugin system in C++/Qt

  - by Pirate for Profit

  I'm making a task-based program that needs to have plugins. Tasks need to have properties which can be easily edited, I think this can be done with Qt's Meta-Object Compiler reflection capabilities (I could be wrong, but I should be able to stick this in a QtPropertyBrowser?) So here's the base: class Task : public QObject { Q_OBJECT public: explicit Task(QObject *parent = 0) : QObject(parent){} virtual void run() = 0; signals: void taskFinished(bool success = true); } Then a plugin might have this task: class PrinterTask : public Task { Q_OBJECT public: explicit PrinterTask(QObject *parent = 0) : Task(parent) {} void run() { Printer::getInstance()->Print(this->getData()); // fictional emit taskFinished(true); } inline const QString &getData() const; inline void setData(QString data); Q_PROPERTY(QString data READ getData WRITE setData) // for reflection } In a nutshell, here's what I want to do: // load plugin // find all the Tasks interface implementations in it // have user able to choose a Task and edit its specific Q_PROPERTY's // run the TASK It's important that one .dll has multiple tasks, because I want them to be associated by their module. For instance, "FileTasks.dll" could have tasks for deleting files, making files, etc. The only problem with Qt's plugin setup is I want to store X amount of Tasks in one .dll module. As far as I can tell, you can only load one interface per plugin (I could be wrong?). If so, the only possible way to do accomplish what I want is to create a FactoryInterface with string based keys which return the objects (as in Qt's Plug-And-Paint example), which is a terrible boilerplate that I would like to avoid. Anyone know a cleaner C++ plugin architecture than Qt's to do what I want? Also, am I safely assuming Qt's reflection capabilities will do what I want (i.e. able to edit an unknown dynamically loaded tasks' properties with the QtPropertyBrowser before dispatching)?

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• c# - what approach can I use to extend a group of classes that include implemented methods? (see des

  - by Greg

  Hi, I want to create an extendible package I am writing that has Topology, Node & Relationship classes. The idea is these base classes would have the various methods in them necessary to base graph traversal methods etc. I would then like to be able to reuse this by extending the package. For example the base requirements might see Relationship with a parentNode & childNode. Topology would have a List of Nodes and List of Relationships. Topology would have methods like FindChildren(int depth). Then the usage would be to extend these such that additional attributes for Node and Relationships could be added etc. QUESTION - What would be the best approach to package & expose the base level classes/methods? (it's kind of like a custom collection but with multiple facets). Would the following concepts come into play: Interfaces - would this be a good idea to have ITopology, INode etc, or is this not required as the user would extend these classes anyway? Abstract Classes - would the base classes be abstract classes Custom Generic Collection - would some approach using this concept assist (but how would this work if there are the 3 different classes) thanks

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• Where do objects merge/join data in a 3-tier model?

  - by BerggreenDK

  Its probarbly a simple 3-tier problem. I just want to make sure we use the best practice for this and I am not that familiary with the structures yet. We have the 3 tiers: GUI: ASP.NET for Presentation-layer (first platform) BAL: Business-layer will be handling the logic on a webserver in C#, so we both can use it for webforms/MVC + webservices DAL: LINQ to SQL in the Data-layer, returning BusinessObjects not LINQ. DB: The SQL will be Microsoft SQL-server/Express (havent decided yet). Lets think of setup where we have a database of [Persons]. They can all have multiple [Address]es and we have a complete list of all [PostalCode] and corresponding citynames etc. The deal is that we have joined a lot of details from other tables. {Relations}/[tables] [Person]:1 --- N:{PersonAddress}:M --- 1:[Address] [Address]:N --- 1:[PostalCode] Now we want to build the DAL for Person. How should the PersonBO look and when does the joins occure? Is it a business-layer problem to fetch all citynames and possible addressses pr. Person? or should the DAL complete all this before returning the PersonBO to the BAL ? Class PersonBO { public int ID {get;set;} public string Name {get;set;} public List<AddressBO> {get;set;} // Question #1 } // Q1: do we retrieve the objects before returning the PersonBO and should it be an Array instead? or is this totally wrong for n-tier/3-tier?? Class AddressBO { public int ID {get;set;} public string StreetName {get;set;} public int PostalCode {get;set;} // Question #2 } // Q2: do we make the lookup or just leave the PostalCode for later lookup? Can anyone explain in what order to pull which objects? Constructive criticism is very welcome. :o)

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• How to properly implement the Strategy pattern in a web MVC framework?

  - by jboxer

  In my Django app, I have a model (lets call it Foo) with a field called "type". I'd like to use Foo.type to indicate what type the specific instance of Foo is (possible choices are "Number", "Date", "Single Line of Text", "Multiple Lines of Text", and a few others). There are two things I'd like the "type" field to end up affecting; the way a value is converted from its normal type to text (for example, in "Date", it may be str(the_date.isoformat())), and the way a value is converted from text to the specified type (in "Date", it may be datetime.date.fromtimestamp(the_text)). To me, this seems like the Strategy pattern (I may be completely wrong, and feel free to correct me if I am). My question is, what's the proper way to code this in a web MVC framework? In a client-side app, I'd create a Type class with abstract methods "serialize()" and "unserialize()", override those methods in subclasses of Type (such as NumberType and DateType), and dynamically set the "type" field of a newly-instantiated Foo to the appropriate Type subclass at runtime. In a web framework, it's not quite as straightforward for me. Right now, the way that makes the most sense is to define Foo.type as a Small Integer field and define a limited set of choices (0 = "Number", 1 = "Date", 2 = "Single Line of Text", etc.) in the code. Then, when a Foo object is instantiated, use a Factory method to look at the value of the instance's "type" field and plug in the correct Type subclass (as described in the paragraph above). Foo would also have serialize() and unserialize() methods, which would delegate directly to the plugged-in Type subclass. How does this design sound? I've never run into this issue before, so I'd really like to know if other people have, and how they've solved it.

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• How do you populate a NSArrayController with CoreData rows programmatically?

  - by Andrew McCloud

  After several hours/days of searching and diving into example projects i've concluded that I need to just ask. If I bind the assetsView (IKImageBrowserView) directly to an IB instance of NSArrayController everything works just fine. - (void) awakeFromNib { library = [[NSArrayController alloc] init]; [library setManagedObjectContext:[[NSApp delegate] managedObjectContext]]; [library setEntityName:@"Asset"]; NSLog(@"%@", [library arrangedObjects]); NSLog(@"%@", [library content]); [assetsView setDataSource:library]; [assetsView reloadData]; } Both NSLogs are empty. I know i'm missing something... I just don't know what. The goal is to eventually allow multiple instances of this view's "library" filtered programmatically with a predicate. For now i'm just trying to have it display all of the rows for the "Asset" entity. Addition: If I create the NSArrayController in IB and then try to log [library arrangedObjects] or manually set the data source for assetsView I get the same empty results. Like I said earlier, if I bind library.arrangedObjects to assetsView.content (IKImageBrowserView) in IB - with same managed object context and same entity name set by IB - everything works as expected. - (void) awakeFromNib { // library = [[NSArrayController alloc] init]; // [library setManagedObjectContext:[[NSApp delegate] managedObjectContext]]; // [library setEntityName:@"Asset"]; NSLog(@"%@", [library arrangedObjects]); NSLog(@"%@", [library content]); [assetsView setDataSource:library]; [assetsView reloadData]; }

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• Sharing same vector control between different places

  - by Alexander K

  Hi everyone, I'm trying to implement the following: I have an Items Manager, that has an Item class inside. Item class can store two possible visual representations of it - BitmapImage(bitmap) and UserControl(vector). Then later, in the game, I need to share the same image or vector control between all possible places it takes place. For example, consider 10 trees on the map, and all point to the same vector control. Or in some cases this can be bitmap image source. So, the problem is that BitmapImage source can be easily shared in the application by multiple UIElements. However, when I try to share vector control, it fails, and says Child Element is already a Child element of another control. I want to know how to organize this in the best way. For example replace UserControl with other type of control, or storage, however I need to be sure it supports Storyboard animations inside. The code looks like this: if (bi.item.BitmapSource != null) { Image previewImage = new Image(); previewImage.Source = bi.item.BitmapSource; itemPane.ItemPreviewCanvas.Children.Add(previewImage); } else if (bi.item.VectorSource != null) { UserControl previewControl = bi.item.VectorSource; itemPane.ItemPreviewCanvas.Children.Add(previewControl); } Thanks in advance

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• Database structure for ecommerce site

  - by imanc

  Hey Guys, I have been tasked with designing an ecommerce solution. The aspect that is causing me the most problems is the database. Currently the site consists of 10+ country based shops each with their own database (all residing on the same mysql instance). For the new site I'd rather all these shop databases be merged into one database so that all tables (products, orders, customers etc.) have a shop_id field. From a programming perspective this seems to make the most sense as we won't have to manage data across multiple databases. Currently the entire site generates about 120k orders a year, but is experiencing fairly heavy growth and we need to design a solution that will scale. In 5 years there may be more than a million orders per year and a database that contains 5 years order history (archiving maybe a solution here). The question is - do we use a single database, or do we keep the database-per-shop structure? I am currently trying to find supporting evidence for either avenue. The company I am designing the solution for prefer the per-shop database structure because they believe it will allow the sites to scale. But my argument is that the shop's database probably won't get that busy over the next few years that they exceed the capacity of a mysql database and a "no expenses spared" hardware set-up. I am wondering if anyone has any advice either way? Does anyone have experience with websites / ecommerce sites that have tables containing millions of records? I know there is probably not a clear answer here, but at what stage do we have too many records or too large table files to have a fast loading site? Also, if anyone has any advice on sources of information - books, websites, etc. where I can do further research, it would be highly appreciated! Cheers, imanc

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• Passing list of values to django view via jQuery ajax call

  - by finspin

  I'm trying to pass a list of numeric values (ids) from one web page to another with jQuery ajax call. I can't figure out how to pass and read all the values in the list. I can successfully post and read 1 value but not multiple values. Here is what I have so far: jQuery: var postUrl = "http://localhost:8000/ingredients/"; $('li').click(function(){ values = [1, 2]; $.ajax({ url: postUrl, type: 'POST', data: {'terid': values}, traditional: true, dataType: 'html', success: function(result){ $('#ingredients').append(result); } }); }); /ingredients/ view: def ingredients(request): if request.is_ajax(): ourid = request.POST.get('terid', False) ingredients = Ingredience.objects.filter(food__id__in=ourid) t = get_template('ingredients.html') html = t.render(Context({'ingredients': ingredients,})) return HttpResponse(html) else: html = '<p>This is not ajax</p>' return HttpResponse(html) With Firebug I can see that POST contains both ids but probably in the wrong format (terid=1&terid=2). So my ingredients view picks up only terid=2. What am I doing wrong? EDIT: To clarify, I need the ourid variable pass values [1, 2] to the filter in the ingredients view.

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• Dependent Dropdowns with single class element

  - by AJ

  I am trying to create multiple dependent dropdowns (selects) with a unique way. I want to restrict the use of selectors and want to achieve this by using a single class selectors on all SELECTs; by figuring out the SELECT that was changed by its index. Hence, the SELECT[i] that changed will change the SELECT[i+1] only (and not the previous ones like SELECT[i-1]). For html like this: <select class="someclass"> <option value="volvo">Volvo</option> <option value="saab">Saab</option> <option value="mercedes">Mercedes</option> <option value="audi">Audi</option> </select> <select class="someclass"> </select> <select class="someclass"> </select> where the SELECTs other than the first one will get something via AJAX. I see that the following Javascript gives me correct value of the correct SELECT and the value of i also corresponds to the correct SELECT. $(function() { $(".someclass").each(function(i) { $(this).change(function(x) { alert($(this).val() + i); }); }); }); Please note that I really want the minimum selector approach. I just cannot wrap my head around on how to approach this. Should I use Arrays? Like store all the SELECTS in an Array first and then select those? I believe that since the above code already passes the index i, there should be a way without Arrays also. Thanks a bunch. AJ

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• asp.net Can I force every page to inherit from a base page? Also should some of this logic be in my master page?

  - by Bex

  Hi! I have a web app that has a base page. Each page needs to inherit from this base page as it contains properties they all need as well as dealing with the login rights. My base page has some properties, eg: IsRole1, IsRole2, currentUserID, Role1Allowed, Role2Allowed. On the init of each page I set the properties "Role1Allowed" and "Role2Allowed" Private Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init Role1Allowed = True Role2Allowed= False End Sub The basepage then decides if the user needs redirecting. 'Sample code so not exactly what is going to be, bug gives the idea Protected Overridable Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) If Role1Allowed And Not Role1 Then 'Redirect somewhere End If End Sub The page then must override this pageload if they need anything else in it, but making sure they call the base pageload first. Protected Overrides Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load MyBase.Page_Load(sender, e) If Not IsPostBack Then BindGrid() End If End Sub The other properties (IsRole1, IsRole, currentUserID) are also accessible by the page so it can be decided if certain things need doing based on the user. (I hope this makes sense) Ok so I have 2 questions Should this functionality be in the base page or should it somehow be in the master, and if so how would I get access to all the properties if it was? As there are multiple people working on this project and creating pages some are forgetting to inherit from this basepage, or call the base pageload when overriding it. Is there any way to force them to do this? Thanks for any help. bex

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• Going "behind Hibernate's back" to update foreign key values without an associated entity

  - by Alex Cruise

  Updated: I wound up "solving" the problem by doing the opposite! I now have the entity reference field set as read-only (insertable=false updatable=false), and the foreign key field read-write. This means I need to take special care when saving new entities, but on querying, the entity properties get resolved for me. I have a bidirectional one-to-many association in my domain model, where I'm using JPA annotations and Hibernate as the persistence provider. It's pretty much your bog-standard parent/child configuration, with one difference being that I want to expose the parent's foreign key as a separate property of the child alongside the reference to a parent instance, like so: @Entity public class Child { @Id @GeneratedValue Long id; @Column(name="parent_id", insertable=false, updatable=false) private Long parentId; @ManyToOne(cascade=CascadeType.ALL) @JoinColumn(name="parent_id") private Parent parent; private long timestamp; } @Entity public class Parent { @Id @GeneratedValue Long id; @OrderBy("timestamp") @OneToMany(mappedBy="parent", cascade=CascadeType.ALL, fetch=FetchType.LAZY) private List<Child> children; } This works just fine most of the time, but there are many (legacy) cases when I'd like to put an invalid value in the parent_id column without having to create a bogus Parent first. Unfortunately, Hibernate won't save values assigned to the parentId field due to insertable=false, updatable=false, which it requires when the same column is mapped to multiple properties. Is there any nice way to "go behind Hibernate's back" and sneak values into that field without having to drop down to JDBC or implement an interceptor? Thanks!

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• Better way to implement custom views in a listview with simpleadapter?

  - by jonaz

  I have a value called tags which is a comma separated list of words. I want to put this into nicely designed "tag-buttons". The below works. However the line ((LinearLayout) view).removeAllViews(); seems like an ugly fix for not adding the tags multiple times every time adapter.notifyDataSetChanged(); is called after i load more rows with a setOnScrollListener() Any suggestion to "best practice" here, or at least a more good looking solution? adapter = new SimpleAdapter(activity,data, R.layout.list_transactions, new String[] {"comment", "amount","date","tags","category"}, new int[] { R.id.comment, R.id.amount,R.id.date,R.id.tags_container,R.id.category } ); SimpleAdapter.ViewBinder binder = new SimpleAdapter.ViewBinder() { @Override public boolean setViewValue(View view, Object object, String value) { //Log.d(TAG,"view.toString()= "+ view.toString()); if (view.getId() == R.id.tags_container) { String[] tags = value.split(","); ((LinearLayout) view).removeAllViews(); for (String tag : tags) { View v = createTagView(activity.getLayoutInflater(),tag); ((LinearLayout) view).addView(v); } return true; } return false; } };

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• SSRS code variable resetting on new page

  - by edmicman

  In SSRS 2008 I am trying to maintain a SUM of SUMs on a group using custom Code. The reason is that I have a table of data, grouped and returning SUMs of the data. I have a filter on the group to remove lines where group sums are zero. Everything works except I'm running into problems with the group totals - it should be summing the visible group totals but is instead summing the entire dataset. There's tons of articles about how to work around this, usually using custom code. I've made custom functions and variables to maintain a counter: Public Dim GroupMedTotal as Integer Public Dim GrandMedTotal as Integer Public Function CalcMedTotal(ThisValue as Integer) as Integer GroupMedTotal = GroupMedTotal + ThisValue GrandMedTotal = GrandMedTotal + ThisValue Return ThisValue End Function Public Function ReturnMedSubtotal() as Integer Dim ThisValue as Integer = GroupMedTotal GroupMedTotal = 0 Return ThisValue End Function Basically CalcMedTotal is fed a SUM of a group, and maintains a running total of that sum. Then in the group total line I output ReturnMedSubtotal which is supposed to give me the accumulated total and reset it for the next group. This actually works great, EXCEPT - it is resetting the GroupMedTotal value on each page break. I don't have page breaks explicitly set, it's just the natural break in the SSRS viewer. And if I export the results to Excel everything works and looks correctly. If I output Code.GroupMedTotal on each group row, I see it count correctly, and then if a group spans multiple pages on the next page GroupMedTotal is reset and begins counting from zero again. Any help in what's going on or how to work around this? Thanks!

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• Changing property of ItemTemplate controls in ListView

  - by arturito

  I have ListView containig LinkButtons in ItemTemplate. ListView is inside UpdatePanel so it is not doing page refresh. When users click on one the LinkButtons it changes its css property in order to mark the selection: protected void ListView1_ItemCommand1(object sender, ListViewCommandEventArgs e) { ((LinkButton)e.CommandSource).CssClass = "selected"; } That allows multiple selections. But once the page is refreshed the selection disappears, meaning that css property of control goes back to default. <ItemTemplate> <asp:LinkButton ID="local" Text='<%#Eval("Local.Name")%>' runat="server" CommandName="selectLocal" CommandArgument='<%#Eval("Local.Id") %>' CssClass="notSelected" > </asp:LinkButton> <asp:LinkButton ID="guest" Text='<%#Eval("Guest.Name")%>' runat="server" CommandName="selectGuest" CommandArgument='<%#Eval("Guest.Id") %>' CssClass="notSelected" > </asp:LinkButton> </ItemTemplate> How can I select them programatically on page reload? (I'm mainating selection list in session)

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• Enum exeeding the 65535 bytes limit of static initializer... what's best to do?

  - by Daniel Bleisteiner

  I've started a rather large Enum of so called Descriptors that I've wanted to use as a reference list in my model. But now I've come across a compiler/VM limit the first time and so I'm looking for the best solution to handle this. Here is my error : The code for the static initializer is exceeding the 65535 bytes limit It is clear where this comes from - my Enum simply has far to much elements. But I need those elements - there is no way to reduce that set. Initialy I've planed to use a single Enum because I want to make sure that all elements within the Enum are unique. It is used in a Hibernate persistence context where the reference to the Enum is stored as String value in the database. So this must be unique! The content of my Enum can be devided into several groups of elements belonging together. But splitting the Enum would remove the unique safety I get during compile time. Or can this be achieved with multiple Enums in some way? My only current idea is to define some Interface called Descriptor and code several Enums implementing it. This way I hope to be able to use the Hibernate Enum mapping as if it were a single Enum. But I'm not even sure if this will work. And I loose unique safety. Any ideas how to handle that case?

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• Using shared_ptr to implement RCU (read-copy-update)?

  - by yongsun

  I'm very interested in the user-space RCU (read-copy-update), and trying to simulate one via tr1::shared_ptr, here is the code, while I'm really a newbie in concurrent programming, would some experts help me to review? The basic idea is, reader calls get_reading_copy() to gain the pointer of current protected data (let's say it's generation one, or G1). writer calls get_updating_copy() to gain a copy of the G1 (let's say it's G2), and only one writer is allowed to enter the critical section. After the updating is done, writer calls update() to do a swap, and make the m_data_ptr pointing to data G2. The ongoing readers and the writer now hold the shared_ptr of G1, and either a reader or a writer will eventually deallocate the G1 data. Any new readers would get the pointer to G2, and a new writer would get the copy of G2 (let's say G3). It's possible the G1 is not released yet, so multiple generations of data my co-exists. template <typename T> class rcu_protected { public: typedef T type; typedef std::tr1::shared_ptr<type> rcu_pointer; rcu_protected() : m_data_ptr (new type()) {} rcu_pointer get_reading_copy () { spin_until_eq (m_is_swapping, 0); return m_data_ptr; } rcu_pointer get_updating_copy () { spin_until_eq (m_is_swapping, 0); while (!CAS (m_is_writing, 0, 1)) {/* do sleep for back-off when exceeding maximum retry times */} rcu_pointer new_data_ptr(new type(*m_data_ptr)); // as spin_until_eq does not have memory barrier protection, // we need to place a read barrier to protect the loading of // new_data_ptr not to be re-ordered before its construction _ReadBarrier(); return new_data_ptr; } void update (rcu_pointer new_data_ptr) { while (!CAS (m_is_swapping, 0, 1)) {} m_data_ptr.swap (new_data_ptr); // as spin_until_eq does not have memory barrier protection, // we need to place a write barrier to protect the assignments of // m_is_writing/m_is_swapping be re-ordered bofore the swapping _WriteBarrier(); m_is_writing = 0; m_is_swapping = 0; } private: volatile long m_is_writing; volatile long m_is_swapping; rcu_pointer m_data_ptr; };

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• C# DynamicPDF Merging causing "Index out of bounds" error

  - by Dining Philanderer

  Greetings, We use DynamicPDF to merge multiple PDF documents stored in a MSSQL database. The vast majority of times it works wonderfully, but occasionally one of these documents will fail to merge generating the exception message "Index was outside the bounds of the array." I think I have isolated the problem to PDF files that are greater than 8.5 x 11.0. Does anyone know if this is a known issue with DynamicPDF? The merging code is posted here. What would be ideal is if there is a way to resize the PDF files to the correct size so this is not a concern at all... for (int docs = 0; docs < dsPDFInfo.Tables[0].Rows.Count; docs++) { byte[] bytePDFArray = (byte[])dsPDFInfo.Tables[0].Rows[docs]["Content"]; int iContentSize = Convert.ToInt32(dsPDFInfo.Tables[0].Rows[docs]["ContentSize"]); MemoryStream ms = new MemoryStream(bytePDFArray, 0, iContentSize); ceTe.DynamicPDF.Merger.PdfDocument pdfdoc = new ceTe.DynamicPDF.Merger.PdfDocument(ms); ceTe.DynamicPDF.Merger.MergeDocument mergedoc = new ceTe.DynamicPDF.Merger.MergeDocument(pdfdoc); docCombinedPDF.Append(mergedoc); } Thanks....

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• Insert or Update using Oracle and PL/SQL

  - by Shane

  I have a PL/SQL function that performs an update/insert on an Oracle database that maintains a target total and returns the difference between the existing value and the new value. Here is the code I have so far: FUNCTION calcTargetTotal(accountId varchar2, newTotal numeric ) RETURN number is oldTotal numeric(20,6); difference numeric(20,6); begin difference := 0; begin select value into oldTotal from target_total WHERE account_id = accountId for update of value; if (oldTotal != newTotal) then update target_total set value = newTotal WHERE account_id = accountId difference := newTotal - oldTotal; end if; exception when NO_DATA_FOUND then begin difference := newTotal; insert into target_total ( account_id, value ) values ( accountId, newTotal ); -- sometimes a race condition occurs and this stmt fails -- in those cases try to update again exception when DUP_VAL_ON_INDEX then begin difference := 0; select value into oldTotal from target_total WHERE account_id = accountId for update of value; if (oldTotal != newTotal) then update target_total set value = newTotal WHERE account_id = accountId difference := newTotal - oldTotal; end if; end; end; end; return difference end calcTargetTotal; This works as expected in unit tests with multiple threads never failing. However when loaded on a live system we have seen this fail with a stack trace looking like this: ORA-01403: no data found ORA-00001: unique constraint () violated ORA-01403: no data found The line numbers (which I have removed since they are meaningless out of context) verify that the first update fails due to no data, the insert fail due to uniqueness, and the 2nd update is failing with no data, which should be impossible. From what I have read on other thread a MERGE statement is also not atomic and could suffer similar problems. Does anyone have any ideas how to prevent this from occurring?

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• When should we use Views, Temporary Tables and Direct Queries ? What are the Performance issues in a

  - by Shantanu Gupta

  I want to know the performance of using Views, Temp Tables and Direct Queries Usage in a Stored Procedure. I have a table that gets created every time when a trigger gets fired. I know this trigger will be fired very rare and only once at the time of setup. Now I have to use that created table from triggers at many places for fetching data and I confirms it that no one make any changes in that table. i.e ReadOnly Table. I have to use this tables data along with multiple tables to join and fetch result for further queries say select * from triggertable By Using temp table select ... into #tx from triggertable join t2 join t3 and so on select a,b, c from #tx --do something select d,e,f from #tx ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. By Using Views create view viewname ( select ... from triggertable join t2 join t3 and so on ) select a,b, c from viewname --do something select d,e,f from viewname ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. This View can be used in other places as well. So I will be creating at database rather than at sp By Using Direct Query select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something . . --and so on --around 6-7 queries in a row in a stored procedure. Now I can create a view/temporary table/ directly query usage in all upcoming queries. What would be the best to use in this case.

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• Issue with Callback method and maintaining CultureInfo and ASP.Net HttpRuntime

  - by Little Larry Sellers

  Hi All, Here is my issue. I am working on an E-commerce solution that is deployed to multiple European countries. We persist all exceptions within the application to SQL Server and I have found that there are records in the DB that have a DateTime in the future! We define the culture in the web.config, for example pt-PT, and the format expected is DD-MM-YYYY. After debugging I found the issue with these 'future' records in the DB is because of Callback methods we use. For example, in our Caching architecture we use Callbacks, as such - CacheItemRemovedCallback ReloadCallBack = new CacheItemRemovedCallback(OnRefreshRequest); When I check the current threads CultureInfo, on these Callbacks it is en-US instead of pt-PT and also the HttpContext is null. If an exception occurs on the Callback our exception manager reports it as MM-DD-YYYY and thus it is persisted to SQL Server incorrectly. Unfortunately, in the exception manager code, we use DateTime.Now, which is fine if it is not a callback. I can't change this code to be culture specific due to it being shared across other verticals. So, why don't callbacks into ASP.Net maintain context? Is there any way to maintain it on this callback thread? What are the best practices here? Thanks.

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• Issues with simulating cell selection in Excel using PostMessage

  - by DD

  Hi all, So far I've tried drag/drop motion in many applications including Visualization software (moving time slider left/right), Photoshop-Paint (drawing) etc. I need some more testing before I make sure that my system works and it failed in Excel. I'm using the code below to send the input: m.x = 215; m.y = 200 + 36 + 9 * ( currentTime - 1 ); childH = findChild( w->getHandle(), m ); PostMessage( childH, WM_MOUSEMOVE, 0, MAKELPARAM( m.x, m.y ) ); PostMessage( childH, WM_LBUTTONDOWN, MK_LBUTTON, MAKELPARAM( m.x, m.y ) ); m.x = 215; m.y = 200 + 36 + 9 * ( currentTime ); childH = findChild( w->getHandle(), m ); PostMessage( childH, WM_MOUSEMOVE, MK_LBUTTON, MAKELPARAM( m.x, m.y ) ); PostMessage( childH, WM_LBUTTONUP, 0, MAKELPARAM( m.x, m.y ) ); I can click anywhere in Excel and select the cell, or activate buttons/menus anything. I can even drag a plot around (with the code above) but it doesn't work for clicking and dragging the mouse to select multiple cells. It just doesn't do anything. I can't use SendInput because the window doesn't have the focus and is in background. Thanks!

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• Loading Dimension Tables - Methodologies

  - by Nev_Rahd

  Hello, Recently I been working on project, where need to populated Dim Tables from EDW Tables. EDW Tables are of type II which does maintain historical data. When comes to load Dim Table, for which source may be multiple EDW Tables or would be single table with multi level pivoting (on attributes). Mean: There would be 10 records - one for each attribute which need to be pivoted on domain_code to make a single row in Dim. Out of these 10 records there would be some attributes with same domain_code but with different sub_domain_code, which needs further pivoting on subdomain code. Ex: if i got domain code: 01,02, 03 = which are straight pivot on domain code I would also have domain code: 10 with subdomain code / version as 2006,2007,2008,2009 That means I need to split my source table with above attributes into two = one for domain code and other for domain_code + version. so far so good. When it comes to load Dim Table: As per design specs for Dimensions (originally written by third party), what they want is: for every single change in EDW (attribute), it should assemble all the related records (for that NK) mean new one with other attribute values which are current = process them to create a new dim record and insert it. That mean if a single extract contains 100 records updated (one for each NK), it should assemble 100 + (100*9) records to insert / update dim table. How good is this approach. Other way I tried to do is just do a lookup into dim table for that NK get the value's of recent records (attributes which not changed) and insert it and update the current one. What would be the better approach assembling records at source side for one attribute change or looking into dim table's recent record and process it. If this doesn't make sense, would like to elaborate it further. Thanks

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• Save Xml in an Excel cell value causes ComException

  - by mas_oz2k1

  I am trying to save an object (Class1) as string in a cell value. My issue is that from time to time I have a ComException: HRESULT: 0x8007000E (E_OUTOFMEMORY) (It is kind of random but I have not identified any particular pattern yet) when I write the value into a cell. Any ideas will be welcome For illustration purposes: Let Class1 be the class to be converted to an Xml string. (Notice that I removed the xml declaration at the start of the string to avoid having the preamble present- non printable character) <Class1 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" <ElementID HL690375</ElementID </Class1" Class1 myClass = new Class1(); this class is converted to a string s. s= ConvertObjectToXmlString(myClass); then s is assigned to a cell Range r = Application.ActiveCell; r.Value2 = s; Note: (1) If the string is too big, I limit it to 32000 chars and split the string in chunks of 32000 chars and save the chunks in multiple cells. (2) I do not to quote the string before adding to a cell. Do I need to? If so how it can be done? (3) All object contents are English. (4) C# code sample will be great but VB.net code is OK.

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• How to use a string as a delimiter shell script

  - by Dan

  I am reading a line and am using regex to match it in my script. (/bin/bash) echo $line | grep -E '[Ss][Uu][Bb][Jj][Ee][Cc][Tt]: [Hh][Ee][Ll][Pp]' > /dev/null 2>&1 if [[ $? = "0" && -z $subject ]]; then subject=`echo $line | cut -d: -f2` > /dev/null echo "Was able to grab a SUBJECT $line and the actual subject is -> $subject" >> $logfile fi now my problem is that i use the colon as the delimiter. but sometimes the email will have multiple colons in the subject and so I am not able to grab the whole subject because of that. I am looking for a way to grab everything after the colon following subject. even is there is a way to loop through and check for a colon or what. maybe cut allows you to cut with a string as delimiter? Not sure...any ideas? Thanks!

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