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  • iPhone: Try to send html code to a php script (but fail)

    - by Marc-André Weibezahn
    Hello all, I am trying this for an iPhone app in Xcode: create html code for a website on the fly sending it to a php-script and getting the response with this code: NSError * error = [[[NSError alloc]init]autorelease]; NSURL * phpURL = [NSURL URLWithString: @"http://www.mydomain.com/myscript.php?mywebsite= (...websitestring...) ];NSString * myResponse = [NSString stringWithContentsOfURL:phpURL encoding:NSUTF8StringEncoding error:&error]; It does not work. It should not be a problem of the php code because when I replace the websitestring which contains the html code with "hello" or something, this is accepted. (the script then creates a file "test.html" with the content I sent.) But when I put html code in it, I always get the error: Error Domain=NSCocoaErrorDomain Code=256 "The operation couldn’t be completed. (Cocoa error 256.)" UserInfo=0x322ec10 {} It seems that there are some things to consider when sending code to php? Thanks in advance!

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  • MySQL transaction conundrum

    - by David Faitelson
    I need to perform several inserts in a single atomic transaction. For example: start transaction; insert ... insert ... commit; However when MySQL encounters an error it aborts only the particular statement that caused the error. For example, if there is an error in the second insert statement the commit will still take place and the first insert statement will be recorded. Thus, when errors occur a MySQL transaction is not really a transaction. To overcome this problem I have used an error exit handler where I rollback the transaction. Now the transaction is silently aborted but I don't know what was the problem. So here is the conundrum for you: How can I both make MySQL abort a transaction when it encounters an error, and pass the error code on to the caller?

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  • @ExceptionHandler doesn't handle the thrown exceptions

    - by Javi
    Hello, I have a method in my controller which will handle the exceptions thrown by the application. So I have a method like this one. @Controller public class ExceptionController { @RequestMapping(value="/error") @ExceptionHandler(value={Exception.class, NullPointerException.class}) public String showError(Exception e, Model model){ return "tiles:error"; } } And to try I if it works I throw a NullPointerException in another method in other method controller: boolean a = true; if(a){ throw new NullPointerException(); } After the exception is thrown it is printed in the JSP, but it doesn't go throw my showError() method (I've set a breakpoint there and it never enters). showError() method will catch the exception and will show different error pages depending on the exception type (though now it always shows the same error page). If I go to the url /error it shows the error page so the showError() method is OK. I'm using Spring 3. What can be the problem? Thanks.

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  • Rails 2.3.5: How does one add an error when it doesn't make sense to put it in a validation?

    - by randombits
    I recently was trying to add errors.add_to_base code in the middle of some model logic and was wondering why it wasn't showing up in my view that was iterating over all errors. I then ran across this e-mail which explains why: http://groups.google.com/group/rubyonrails-talk/browse_thread/thread/e045ec1dead1ff06?pli=1 The question is then, how does one add errors with add_to_base if it doesn't make sense to put them into a validate method? I have some complex logic. The model needs to talk to a has_many relationship which has its own relationships that go through a myriad of conditionals to figure out if a request makes sense. It's nothing that can be tied to a validate method easily. How does one add errors then accordingly?

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  • CMD Execption Handling C/C++

    - by ciyo
    I will use some CMD commands in my program and these commands might throw some exceptions. And as you know, when an exception accours, CMD writes its own error message the screen. But, I want to write my own error message. My question is this: Is there a way to block CMD messages and write only my own error messages? P.S. This is not a complex program. It executes CMD commands using System(). Example: Let's say, the user can rename and copy any files in the program. As you know, if the user does not enter file's path properly, an error message is showed on the screen. And I want that this error message never appears on the screen. Only my own error message is showed. Thank you!

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  • How to remove .zip file in c on windows? (error: Directory not empty)

    - by ExtremeBlue
    include include include include "win32-dirent.h" include include include define MAXFILEPATH 1024 bool IsDirectory(char* path) { WIN32_FIND_DATA w32fd; HANDLE hFindFile; hFindFile = FindFirstFile((PTCHAR)path, &w32fd); if(hFindFile == INVALID_HANDLE_VALUE) { return false; } return w32fd.dwFileAttributes & (FILE_ATTRIBUTE_DIRECTORY); } int RD(const char* folderName) { DIR *dir; struct dirent *ent; dir = opendir(folderName); if(dir != NULL) { while((ent = readdir(dir)) != NULL) { if(strcmp(ent->d_name , ".") == 0 || strcmp(ent->d_name, "..") == 0) { continue; } char fileName[MAXFILEPATH]; sprintf(fileName,"%s%c%s", folderName, '\\', ent->d_name); if(IsDirectory(fileName)) { RD(fileName); } else { unlink(fileName); } } closedir(dir); //chmod(folderName, S_IWRITE | S_IREAD); if(_rmdir(folderName) != 0)perror(folderName); } else { printf("%s <%s>\n","Could Not Open Directory.", folderName); return -1; } return 0; } int main(int argc, char* argv[]) { if(argc < 2) { printf("usage: ./a.out \n"); return 1; } //RD(argv[1]); //_mkdir("12"); //_mkdir("12\\34"); //_rmdir("12\\34"); //_rmdir("12"); char buf[0xff]; sprintf(buf, "unzip -x -q -d 1234 1234.zip"); system(buf); RD("1234"); //unlink("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\56\\5.txt"); //unlink("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\56\\6.txt"); //unlink("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\1_23.zip"); //unlink("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\4.txt"); //_rmdir("D:\\dev\\c\\project\\removeFolder\\Debug\\1234\\56"); //_rmdir("D:\\dev\\c\\project\\removeFolder\\Debug\\1234"); return 0; } Archive: 1234.zip inflating: 1234/4.txt inflating: 1234/56/5.txt inflating: 1234/56/6.txt inflating: 1234/1_23.zip

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  • how to avoid the error due to missing element from an XML file in Flash Action Script

    - by coderex
    Hi, I have a code which is written for read the xml data. and the xml file contains the optional values, so some time the elements are present there some times not. In this case how can i set a default value for that in action script 3.0. When i tried to trace the value that area is skipping. So is there any other method to trace-out is that element is present or not something like that??

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  • Uploading an image file with Paperclip (in RoR) causing error.

    - by mtay
    This should be a simple thing to do, but I'm running into a wall and I'm not sure how to debug this response. In my Image model, I have: class Image < ActiveRecord::Base has_attached_file :image, :styles => { :display => "500x500>", :thumbnail => "95x95>"} Then in my Views, my form contains this: -form_for @image, :html => { :multipart => true } do |image| %tr %td.woc_left =label_tag :image, 'photo to upload', :class => 'required' %td.woc_center =image.file_field :image In my Mysql table, I have a column called "image_file_name" (string). However, when I try to upload an image and submit it, I see 2 errors prohibited this from being saved There were problems with the following fields: Image Paperclip::CommandNotFoundError Image Paperclip::CommandNotFoundError What am I doing wrong? Thank you for your help!

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  • nested list comprehension using intermediate result

    - by KentH
    I am trying to grok the output of a function which doesn't have the courtesy of setting a result code. I can tell it failed by the "error:" string which is mixed into the stderr stream, often in the middle of a different conversion status message. I have the following list comprehension which works, but scans for the "error:" string twice. Since it is only rescanning the actual error lines, it works fine, but it annoys me I can't figure out how to use a single scan. Here's the working code: errors = [e[e.find('error:'):] for e in err.splitlines() if 'error:' in e] The obvious (and wrong) way to simplify is to save the "find" result errors = [e[i:] for i in e.find('error:') if i != -1 for e in err.splitlines()] However, I get "UnboundLocalError: local variable 'e' referenced before assignment". Blindly reversing the 'for's in the comprehension also fails. How is this done? THanks. Kent

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  • What is wrong in this bit of MyID3 code? (error code is just Exceptions)

    - by user3697621
    Okay, so, this was supposed to get the paths of all mp3 files in a folder, read their metadata and put in an arraylist. public static List<String> OrgMetadata(List<String> rawgenrelist){ File folder = new File("C:\\SOM\\"); File[] listOfFiles = folder.listFiles(); //File path = listOfFiles; for (int i = 0; i < listOfFiles.length; i++) { String pt = listOfFiles[i].getAbsolutePath(); File src = new File(pt); MusicMetadataSet src_set = new MyID3().read(src); if (src_set != null && listOfFiles[i].isFile()) { IMusicMetadata metadata = src_set.getSimplified(); rawgenrelist.add(metadata.getGenreName()); } } List<String> genrelist; genrelist = new ArrayList(new HashSet(rawgenrelist)); return genrelist; }

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  • Error in value of default parameter [Bug in Visual C++ 2008?]

    - by HellBoy
    I am facing following issue while trying to use template in my code I have some C++ code which i call from C functions. Problem is I am getting different values in the following code for statement 1 and 2. Type id : unsigned int statement 1 : 4 statement 2 : 1 C++ Code : template <typename T> void func(T* value, unsigned int len = sizeof(T)) { cout << "Type id : " << typeid(T).name() << endl; cout << "statement 1 " << sizeof(T) << endl; cout << "statement 2 " << len << endl; } template <typename T> void func1(T data) { T val = data; func(&val); } C Code : void test(void *ptr, unsigned int len) { switch(len) { case 1: func1(*(static_cast<uint32_t *>(ptr)) break; } } This happens only on windows. On Linux it works fine.

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  • C: Why does gcc allow char array initialization with string literal larger than array?

    - by Ashwin
    int main() { char a[7] = "Network"; return 0; } A string literal in C is terminated internally with a nul character. So, the above code should give a compilation error since the actual length of the string literal Network is 8 and it cannot fit in a char[7] array. However, gcc (even with -Wall) on Ubuntu compiles this code without any error or warning. Why does gcc allow this and not flag it as compilation error? gcc only gives a warning (still no error!) when the char array size is smaller than the string literal. For example, it warns on: char a[6] = "Network"; [Related] Visual C++ 2012 gives a compilation error for char a[7]: 1>d:\main.cpp(3): error C2117: 'a' : array bounds overflow 1> d:\main.cpp(3) : see declaration of 'a'

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  • How to select Distinct records from SQL without a primary key

    - by Satheesh
    I need to show a Notification on user login if there is any unread messages.So if multiple users send(5 messages each) while the user is in offline these messages should be shown on login.Means have to show the last messages from each user. I use joining to find records. In this scenario Message from User is not a primary key. This is my query SELECT UserMessageConversations.MessageFrom, UserMessageConversations.MessageFromUserName,UserMessages.MessageTo, UserMessageConversations.IsGroupChat, UserMessageConversations.IsLocationChat, UserMessageConversations.Message, UserMessages.UserGroupID,UserMessages.LocationID FROM UserMessageConversations LEFT OUTER JOIN UserMessages ON UserMessageConversations.UserMessageID = UserMessages.UserMessageID ![enter image description here][1]Where UserMessageConversations.MessageTo=743 AND UserMessageConversations.ReadFlag=0 This is the output obtained from above query. MessageFrom -582 appears twice. I need only one record of this User. How is it possible

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  • "The breakpoint will not currently be hit" error while debugging a mixed mode application (c# and unmanaged c++)

    - by user1678403
    While debugging a mixed mode application in VS2010, the breakpoint set on a line of code contained in an unmanaged c++ dll source file (called from a managed c# wrapper class) shows the infamous "The breakpoint will not currently be hit. No symbols have been loaded for this document" info message when hovering the mouse over the breakpoint on the line in question. The breakpoint itself is a red circle with a yellow info triangle instead of the usual solid red orb. Of course, the breakpoint isn't hit when the debugger is executed. Most answers I've found for this warning indicate the breakpoint hasn't been set properly, or that the expected dll is not being loaded, or that the associated pdb file is not located in the correct location, etc. etc. This is not the problem. The application does load and execute the referenced dll correctly. I've verified that the correct pdb file, with the same file date as its dll, is located in the executable's working directory along with the target dll itself. The debugger simply doesn't load the symbols for the dll, and the dll doesn't show in the Modules list. None of the solutions I've found online work for this problem. The dll doesn't show in the modules list available from 'Debug-Windows-Modules' menu selection... even though it is, in fact, loaded. Breakpoints set in the wrapper class work correctly. Deleting the bin and obj directories, cleaning and rebuilding the solution also doesn't help.

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  • php fetch user data from mysql

    - by milodinosaur
    hi, currently i have 2 table in mysql structure: messages id | content | user_id | time submessages id | subcontent | msg_id | user_id | time submessages msg_id is FK for messages id. Now i need to query from php $cur_user = $user->current; // current user id. SELECT * FROM messages WHERE id > '{$_GET['id']}' // problem here how do i query submessages that posted by others not include current user? thank you.

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  • IF statement within WHILE not working

    - by Ds.109
    I am working on a basic messaging system. This is to get all the messages and to make the row of the table that has an unread message Green. In the table, there is a column called 'msgread'. this is set to '0' by default. Therefore it should make any row with the msgread = 0 - green. this is only working for the first row of the table with the code i have - i verified that it is always getting a 0 value, however it only works the first time through in the while statement .. require('./connect.php'); $getmessages = "SELECT * FROM messages WHERE toperson = '" . $userid . "'"; echo $getmessages; $messages = mysql_query($getmessages); if(mysql_num_rows($messages) != 0) { $table = "<table><tr><th>From</th><th>Subject</th><th>Message</th></tr>"; while($results = mysql_fetch_array($messages)) { if(strlen($results[message]) < 30){ $message = $results[message]; } else { $message = substr($results[message], 0 ,30) . "..."; } if($results[msgread] == 0){ $table .= "<tr style='background:#9CFFB6'>"; $table .= "<td>" . $results[from] . "</td><td>" . $results[subject] . "</td><td><a href='viewmessage.php?id=" . $results[message_id] ."'>" . $message . "</a></td></tr>"; } else { $table .= "<tr>"; $table .= "<td>" . $results[from] . "</td><td>" . $results[subject] . "</td><td><a href='viewmessage.php?id=" . $results[message_id] ."'>" . $message . "</a></td></tr>"; } } echo $table ."</table>"; } else { echo "No Messages Found"; } There's all the code, including grabbing the info from the database. Thanks.

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  • Building services with .Net Part 1

    - by Allan Rwakatungu
    On the 26th of May 2010 , I made a presentation to the .NET user group meeting (thanks to Malisa Ncube for organizing this event every month … ). If you missed my presentation , we talked about why we should all be building services … better still using the .NET framework. This blog post is an introduction to services , why you would want to build services and how you can build services using the .NET framework. What is a service? OASIS defines service as "a mechanism to enable access to one or more capabilities, where the access is provided using a prescribed interface and is exercised consistent with constraints and policies as specified by the service description." [1]. If the above definition sounds to academic , you can also define a service as loosely coupled units of functionality that have no calls to each other embedded in the. Instead of services embedding calls to each other in their service code they use defined protocols that describe how services pass and parse messages. This is a good way to think about services if you’re from an objected oriented background. While in object oriented programming functions make calls to each other, in service oriented programming, functions pass messages between each other. Why would you want to use services? 1. If your enterprise architecture looks like this   Services are the building blocks for SOA . With SOA you can move away from the sphaggetti infrastructure that is common in most enterprises. The complexity or lack of visibility of the integration points in your enterprises makes it difficult and costly to implement new initiatives and changes into the business - and even impossible in some cases - as it is not possible to identify the impact a change in one system might have to other systems. With services you can move to an architecture like this Your building blocks from Spaghetti infrastructure to something that is more well-defined and manageable to achieve cost efficiency and not least business agility - enabling you to react to changes in the market with speed and achieve operational efficiency and control are services. 2. If you want to become the Gates or Zuckerburger. Have you heard about Web 2.0 ? Mashups? Software as a service (SAAS) ? Cloud computing ?   They all offer you the opportunity to have scalable but low cost business models and they built using services.  Some of my favorite companies that leverage services for their business models include  https://www.salesforce.com/ (cloud CRM) http://www. twitter.com (more people use twitter clients built by 3rd parties than their official clients) http://www.kayak.com/ (compares data from other travel sites to give information to users in one location) Services with the .NET framework      If you are a .NET developer and you want to develop services, Windows Communication Framework (WCF) is the tool for you. WCF is Microsoft’s unified programming model (service model) for building service oriented applications. ( Before .NET 3.0 you had several models for programming services in .NET including .NET remoting, Web services (ASMX), COM +, Microsoft Messaging queuing (MSMQ) etc, after .NET 3.0 the programming model was unified into one i.e. WCF ). Windows Communication Framework (WCF) provides you 1. An Software Development Kit (SDK) for creating SOA applications 2. A runtime for running services on the Windows platform Why should you use Windows Communication Foundation if you’re programming services?   1. It supports interoperable and open standards e.g. WS* protocols for programming SOAP services 2. It has a unified programming model. Whether you use TCP or Http or Pipes or transmitting using Messaging Queues, programmers need to learn just one way to program. Previously you had .NET remoting, MSMQ, Web services, COM+ and they were all done differently 3. Productive programming model You don’t have to worry about all the plumbing involved to write services. You have a rich declarative programming model to add stuff like logging, transactions, and reliable messages in-built in the Windows Communication Framework. Understanding services in WCF The basic principles of WCF are as easy as ABC A – Address This is where the service is located B- Binding This describes how you communicate with the service e.g. Use TCP, HTTP or both. How to exchange security information with the service etc. C – Contract This defines what the service can do. E.g. Pay water bill, Make a phone call A - Addresses In WCF, an address is a combination of transport, server name, port and path Example addresses may include http://localhost:8001 net.tcp://localhost:8002/MyService net.pipe://localhost/MyPipe net.msmq://localhost/private/MyService net.msmq://localhost/MyService B- Binding   There are numerous ways to communicate with services , different ways that a message can be formatted/sent/secured, that allows you to tailor your service for the compatibility/performance you require for your solution. Transport You can use HTTP TCP MSMQ , Named pipes, Your own custom transport etc Message You  can send a plain text binary, Message Transmission Optimization Mechanism (MTOM) message Communication security No security Transport security Message security Authenticating and authorizing callers etc Behaviour You service can support Transactions Be reliable Use queues Support ajax etc C - Contract You define what your service can do using Service contracts :- Define operations that your service can do, communications and behaviours Data contracts :- Define the messages that are passed from and into your service and how they are formatted Fault contracts :- Defines errors types in your service   As an example, suppose your service service shows money. You define your service contract using a interface [ServiceContract] public interface IShowMeTheMoney {   [OperationContract]    Money Show(); } You define the data contract by annotating a class it with the Data Contract attribute and fields you want to pass in the message as Data Members. (Note:- In the latest versions of WCF you dont have to use attributes if you passing all the objects properties in the message) [DataContract] public Money {   [DataMember]   public string Currency { get; set; }   [DataMember]   public Decimal Amount { get; set; }   public string Comment { get; set; } } Features of Windows Communication Foundation Windows Communication Foundation is not only simple but feature rich , offering you several options to tweak your service to fit your business requirements. Some of the features of WCF include 1. Workflow services You can combine WCF with Windows WorkFlow Foundation (WWF) to write workflow type services 2. Control how your data (messages) are transferred and serialized e.g. you can serialize your business objects as XML or binary 3. control over session management , instance creation and concurrency management without writing code if you like 4. Queues and reliable sessions. You can store messages from the sending client and later forward them to the receiving application. You can also guarantee that messages will arrive at their destincation. 5.Transactions:  You can have different services participate in a transaction operations that can be rolled back if needed 6. Security. WCF has rich features for authorization and authentication  as well as keep audit trails 7. Web programming model. WCF allows developers to expose services as non SOAP endpoints 8. Inbuilt features that you can use to write JSON and services that support AJAX applications And lots more In my next blog I will show you how you can use WCF features to write a real world business service.               Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 ]] /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • BizTalk: History of one project architecture

    - by Leonid Ganeline
    "In the beginning God made heaven and earth. Then he started to integrate." At the very start was the requirement: integrate two working systems. Small digging up: It was one system. It was good but IT guys want to change it to the new one, much better, chipper, more flexible, and more progressive in technologies, more suitable for the future, for the faster world and hungry competitors. One thing. One small, little thing. We cannot turn off the old system (call it A, because it was the first), turn on the new one (call it B, because it is second but not the last one). The A has a hundreds users all across a country, they must study B. A still has a lot nice custom features, home-made features that cannot disappear. These features have to be moved to the B and it is a long process, months and months of redevelopment. So, the decision was simple. Let’s move not jump, let’s both systems working side-by-side several months. In this time we could teach the users and move all custom A’s special functionality to B. That automatically means both systems should work side-by-side all these months and use the same data. Data in A and B must be in sync. That’s how the integration projects get birth. Moreover, the specific of the user tasks requires the both systems must be in sync in real-time. Nightly synchronization is not working, absolutely.   First draft The first draft seems simple. Both systems keep data in SQL databases. When data changes, the Create, Update, Delete operations performed on the data, and the sync process could be started. The obvious decision is to use triggers on tables. When we are talking about data, we are talking about several entities. For example, Orders and Items [in Orders]. We decided to use the BizTalk Server to synchronize systems. Why it was chosen is another story. Second draft   Let’s take an example how it works in more details. 1.       User creates a new entity in the A system. This fires an insert trigger on the entity table. Trigger has to pass the message “Entity created”. This message includes all attributes of the new entity, but I focused on the Id of this entity in the A system. Notation for this message is id.A. System A sends id.A to the BizTalk Server. 2.       BizTalk transforms id.A to the format of the system B. This is easiest part and I will not focus on this kind of transformations in the following text. The message on the picture is still id.A but it is in slightly different format, that’s why it is changing in color. BizTalk sends id.A to the system B. 3.       The system B creates the entity on its side. But it uses different id-s for entities, these id-s are id.B. System B saves id.A+id.B. System B sends the message id.A+id.B back to the BizTalk. 4.       BizTalk sends the message id.A+id.B to the system A. 5.       System A saves id.A+id.B. Why both id-s should be saved on both systems? It was one of the next requirements. Users of both systems have to know the systems are in sync or not in sync. Users working with the entity on the system A can see the id.B and use it to switch to the system B and work there with the copy of the same entity. The decision was to store the pairs of entity id-s on both sides. If there is only one id, the entities are not in sync yet (for the Create operation). Third draft Next problem was the reliability of the synchronization. The synchronizing process can be interrupted on each step, when message goes through the wires. It can be communication problem, timeout, temporary shutdown one of the systems, the second system cannot be synchronized by some internal reason. There were several potential problems that prevented from enclosing the whole synchronization process in one transaction. Decision was to restart the whole sync process if it was not finished (in case of the error). For this purpose was created an additional service. Let’s call it the Resync service. We still keep the id pairs in both systems, but only for the fast access not for the synchronization process. For the synchronizing these id-s now are kept in one main place, in the Resync service database. The Resync service keeps record as: ·       Id.A ·       Id.B ·       Entity.Type ·       Operation (Create, Update, Delete) ·       IsSyncStarted (true/false) ·       IsSyncFinished (true/false0 The example now looks like: 1.       System A creates id.A. id.A is saved on the A. Id.A is sent to the BizTalk. 2.       BizTalk sends id.A to the Resync and to the B. id.A is saved on the Resync. 3.       System B creates id.B. id.A+id.B are saved on the B. id.A+id.B are sent to the BizTalk. 4.       BizTalk sends id.A+id.B to the Resync and to the A. id.A+id.B are saved on the Resync. 5.       id.A+id.B are saved on the B. Resync changes the IsSyncStarted and IsSyncFinished flags accordingly. The Resync service implements three main methods: ·       Save (id.A, Entity.Type, Operation) ·       Save (id.A, id.B, Entity.Type, Operation) ·       Resync () Two Save() are used to save id-s to the service storage. See in the above example, in 2 and 4 steps. What about the Resync()? It is the method that finishes the interrupted synchronization processes. If Save() is started by the trigger event, the Resync() is working as an independent process. It periodically scans the Resync storage to find out “unfinished” records. Then it restarts the synchronization processes. It tries to synchronize them several times then gives up.     One more thing, both systems A and B must tolerate duplicates of one synchronizing process. Say on the step 3 the system B was not able to send id.A+id.B back. The Resync service must restart the synchronization process that will send the id.A to B second time. In this case system B must just send back again also created id.A+id.B pair without errors. That means “tolerate duplicates”. Fourth draft Next draft was created only because of the aesthetics. As it always happens, aesthetics gave significant performance gain to the whole system. First was the stupid question. Why do we need this additional service with special database? Can we just master the BizTalk to do something like this Resync() does? So the Resync orchestration is doing the same thing as the Resync service. It is started by the Id.A and finished by the id.A+id.B message. The first works as a Start message, the second works as a Finish message.     Here is a diagram the whole process without errors. It is pretty straightforward. The Resync orchestration is waiting for the Finish message specific period of time then resubmits the Id.A message. It resubmits the Id.A message specific number of times then gives up and gets suspended. It can be resubmitted then it starts the whole process again: waiting [, resubmitting [, get suspended]], finishing. Tuning up The Resync orchestration resubmits the id.A message with special “Resubmitted” flag. The subscription filter on the Resync orchestration includes predicate as (Resubmit_Flag != “Resubmitted”). That means only the first Sync orchestration starts the Resync orchestration. Other Sync orchestration instantiated by the resubmitting can finish this Resync orchestration but cannot start another instance of the Resync   Here is a diagram where system B was inaccessible for some period of time. The Resync orchestration resubmitted the id.A two times. Then system B got the response the id.A+id.B and this finished the Resync service execution. What is interesting about this, there were submitted several identical id.A messages and only one id.A+id.B message. Because of this, the system B and the Resync must tolerate the duplicate messages. We also told about this requirement for the system B. Now the same requirement is for the Resunc. Let’s assume the system B was very slow in the first response and the Resync service had time to resubmit two id.A messages. System B responded not, as it was in previous case, with one id.A+id.B but with two id.A+id.B messages. First of them finished the Resync execution for the id.A. What about the second id.A+id.B? Where it goes? So, we have to add one more internal requirement. The whole solution must tolerate many identical id.A+id.B messages. It is easy task with the BizTalk. I added the “SinkExtraMessages” subscriber (orchestration with one receive shape), that just get these messages and do nothing. Real design Real architecture is much more complex and interesting. In reality each system can submit several id.A almost simultaneously and completely unordered. There are not only the “Create entity” operation but the Update and Delete operations. And these operations relate each other. Say the Update operation after Delete means not the same as Update after Create. In reality there are entities related each other. Say the Order and Order Items. Change on one of it could start the series of the operations on another. Moreover, the system internals are the “black boxes” and we cannot predict the exact content and order of the operation series. It worth to say, I had to spend a time to manage the zombie message problems. The zombies are still here, but this is not a problem now. And this is another story. What is interesting in the last design? One orchestration works to help another to be more reliable. Why two orchestration design is more reliable, isn’t it something strange? The Synch orchestration takes all the message exchange between systems, here is the area where most of the errors could happen. The Resync orchestration sends and receives messages only within the BizTalk server. Is there another design? Sure. All Resync functionality could be implemented inside the Sync orchestration. Hey guys, some other ideas?

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