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• Offline backup synchronization

  - by Pavan Kumar

  There is a Central Server running Windows Server 2003 and SQL Server 2005 and there are 7 client machines situated in various places and has XP Pro & SQL Server 2005 installed in all of them. They are not interconnected so they are physically seperate. One person goes to each of these centers maybe twice a month and takes the backup (Full database consisting of mdf and ldf files) with a pen drive and brings it to the Central server which contains the central database holding same schema as all the other client databases. I need to synchronize each backup database (belonging to different centers) one by one to update the existing data or inserting new data in the central database . The solution i got was Replication. The pendrive is brought to central server consisting of 7 instances of the databases and then the databases is attached to the central server one by one to the same SQL Server where the central database exists. Then my idea was to replicate the backup database one by one i.e using single subscription (Central Database) and multiple publication ( i.e 7 instances of databases in my case) toplogy by performing replication locally (i.e in the same machine). So i tried to develop a UI in C# .Net to programatically run the Transactional Replication with push subscription using RMO Programming (which is incomplete as of now because there is no point in developing when you already know it is not the solution). Transactional Replication can either be set to initialize with a snapshot or without a snapshot. If i go for the first option i.e with a snapshot , the data whatever is present in Central Database is overwritten by the new data . So the data present initially in the central database is lost. If i try to initialize without snapshot , no data (the data already has the updated and new data) will be sent from the backup database to server. The replication will work in a scenario where any incremental changes is done only after you set the replication . So the initial data whatever was present in the backup database when setting up the replication will not be replicated when running the snapshot agent for the first time to synchronize. Only changes in the backup database thereafter will be reflected to the central database .(Remember I am not going to insert new data or make any changes to the backup database after i attach it to the Central Server. ) So this solution is not feasible. I want a solution for synchronizing from one client database to central database present in the same machine using C#.NET. If you can provide me small example maybe with two databases(with same schema) DB1(Client) to DB2(Server) consisting of one or two tables it will be very helpful. The synchronization is not bidirectional.I want to only update existing data or insert new data from DB1 to DB2 (DB2 may contain some data initially). Thanks and Regards Pavan

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• Rush Hour - Solving the game

  - by Rubys

  Rush Hour if you're not familiar with it, the game consists of a collection of cars of varying sizes, set either horizontally or vertically, on a NxM grid that has a single exit. Each car can move forward/backward in the directions it's set in, as long as another car is not blocking it. You can never change the direction of a car. There is one special car, usually it's the red one. It's set in the same row that the exit is in, and the objective of the game is to find a series of moves (a move - moving a car N steps back or forward) that will allow the red car to drive out of the maze. I've been trying to think how to solve this problem computationally, and I can really not think of any good solution. I came up with a few: Backtracking. This is pretty simple - Recursion and some more recursion until you find the answer. However, each car can be moved a few different ways, and in each game state a few cars can be moved, and the resulting game tree will be HUGE. Some sort of constraint algorithm that will take into account what needs to be moved, and work recursively somehow. This is a very rough idea, but it is an idea. Graphs? Model the game states as a graph and apply some sort of variation on a coloring algorithm, to resolve dependencies? Again, this is a very rough idea. A friend suggested genetic algorithms. This is sort of possible but not easily. I can't think of a good way to make an evaluation function, and without that we've got nothing. So the question is - How to create a program that takes a grid and the vehicle layout, and outputs a series of steps needed to get the red car out? Sub-issues: Finding some solution. Finding an optimal solution (minimal number of moves) Evaluating how good a current state is Example: How can you move the cars in this setting, so that the red car can "exit" the maze through the exit on the right?

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• Should I use Python or Assembly for a super fast copy program

  - by PyNEwbie

  As a maintenance issue I need to routinely (3-5 times per year) copy a repository that is now has over 20 million files and exceeds 1.5 terabytes in total disk space. I am currently using RICHCOPY, but have tried others. RICHCOPY seems the fastest but I do not believe I am getting close to the limits of the capabilities of my XP machine. I am toying around with using what I have read in The Art of Assembly Language to write a program to copy my files. My other thought is to start learning how to multi-thread in Python to do the copies. I am toying around with the idea of doing this in Assembly because it seems interesting, but while my time is not incredibly precious it is precious enough that I am trying to get a sense of whether or not I will see significant enough gains in copy speed. I am assuming that I would but I only started really learning to program 18 months and it is still more or less a hobby. Thus I may be missing some fundamental concept of what happens with interpreted languages. Any observations or experiences would be appreciated. Note, I am not looking for any code. I have already written a basic copy program in Python 2.6 that is no slower than RICHCOPY. I am looking for some observations on which will give me more speed. Right now it takes me over 50 hours to make a copy from a disk to a Drobo and then back from the Drobo to a disk. I have a LogicCube for when I am simply duplicating a disk but sometimes I need to go from a disk to Drobo or the reverse. I am thinking that given that I can sector copy a 3/4 full 2 terabyte drive using the LogicCube in under seven hours I should be able to get close to that using Assembly, but I don't know enough to know if this is valid. (Yes, sometimes ignorance is bliss) The reason I need to speed it up is I have had two or three cycles where something has happened during copy (fifty hours is a long time to expect the world to hold still) that has caused me to have to trash the copy and start over. For example, last week the water main broke under our building and shorted out the power.

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• VS 2008 irritating copy constructor link dependency

  - by Paul Hollingsworth

  Hi guys, I've run into the following annoying and seemingly incorrect behaviour in the Visual Studio 2008 C++ compiler: Suppose I have a class library - Car.lib - that uses a "Car" class, with a header called "Car.h": class Car { public: void Drive() { Accelerate(); } void Accelerate(); }; What I'm actually trying to do is use the Car headers (for some other functions), but without having to link with Car.lib itself (the actual class is not called "Car" but I am sanitising this example). If I #include "Car.h" in the .cpp file used to build a managed C++ .dll, but never refer to Car, everything compiles and links fine. This is because I never instantiate a Car object. However, the following: namespace { class Car { public: Car(const Car& rhs) { Accelerate(); } void Accelerate(); }; } leaves me with the link error: Error 2 error LNK2001: unresolved external symbol "public: void __thiscall `anonymous namespace'::Car::Accelerate(void)" (?Accelerate@Car@?A0xce3bb5ed@@$$FQAEXXZ) CREObjectWrapper.obj CREObjectBuilderWrapper Note I've declared the whole thing inside an anonymous namespace so there's no way that the Car functions could be exported from the .DLL in any case. Declaring the copy constructor out-of-line makes no difference. i.e. the following also fails to link: class Car { public: Car(const Car& rhs); void Accelerate(); }; Car::Car(const Car& rhs) { Accelerate(); } It's something specifically to do with the copy constructor note, because the following, for example, does link: class Car { public: Car() { Accelerate(); } void Accelerate(); }; I am not a C++ standards guru but this doesn't seem correct to me. Surely the compiler still should not have had to even generate any code that calls the Car copy constructor. Can anyone confirm if this behaviour is correct? It's been a while since I used C++ - but I don't think this used to be an issue with Visual Studio 6.0 for example. Can anyone suggest a workaround that allows one to "re-use" the Accelerate method from within the copy constructor and still have the copy constructor declared inline?

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• FASM vc MASM trasnlation problem in mov si, offset msg

  - by Ruben Trancoso

  hi folks, just did my first test with MASM and FASM with the same code (almos) and I falled in trouble. The only difference is that to produce just the 104 bytes I need to write to MBR in FASM I put org 7c00h and in MASM 0h. The problem is on the mov si, offset msg that in the first case transletes it to 44 7C (7c44h) and with masm translates to 44 00 (0044h)! but just when I change org 7c00h to org 0h in MASM. Otherwise it will produce the entire segment from 0 to 7dff. how do I solve it? or in short, how to make MASM produce a binary that begins at 7c00h as it first byte and subsequent jumps remain relative to 7c00h? .model TINY .code org 7c00h ; Boot entry point. Address 07c0:0000 on the computer memory xor ax, ax ; Zero out ax mov ds, ax ; Set data segment to base of RAM jmp start ; Jump to the first byte after DOS boot record data ; ---------------------------------------------------------------------- ; DOS boot record data ; ---------------------------------------------------------------------- brINT13Flag db 90h ; 0002h - 0EH for INT13 AH=42 READ brOEM db 'MSDOS5.0' ; 0003h - OEM name & DOS version (8 chars) brBPS dw 512 ; 000Bh - Bytes/sector brSPC db 1 ; 000Dh - Sectors/cluster brResCount dw 1 ; 000Eh - Reserved (boot) sectors brFATs db 2 ; 0010h - FAT copies brRootEntries dw 0E0h ; 0011h - Root directory entries brSectorCount dw 2880 ; 0013h - Sectors in volume, < 32MB brMedia db 240 ; 0015h - Media descriptor brSPF dw 9 ; 0016h - Sectors per FAT brSPH dw 18 ; 0018h - Sectors per track brHPC dw 2 ; 001Ah - Number of Heads brHidden dd 0 ; 001Ch - Hidden sectors brSectors dd 0 ; 0020h - Total number of sectors db 0 ; 0024h - Physical drive no. db 0 ; 0025h - Reserved (FAT32) db 29h ; 0026h - Extended boot record sig brSerialNum dd 404418EAh ; 0027h - Volume serial number (random) brLabel db 'OSAdventure' ; 002Bh - Volume label (11 chars) brFSID db 'FAT12 ' ; 0036h - File System ID (8 chars) ;------------------------------------------------------------------------ ; Boot code ; ---------------------------------------------------------------------- start: mov si, offset msg call showmsg hang: jmp hang msg db 'Loading...',0 showmsg: lodsb cmp al, 0 jz showmsgd push si mov bx, 0007 mov ah, 0eh int 10h pop si jmp showmsg showmsgd: retn ; ---------------------------------------------------------------------- ; Boot record signature ; ---------------------------------------------------------------------- dw 0AA55h ; Boot record signature END

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• Dojo - How to position tooltip close to text?

  - by user244394

  Like the title says i want to be able to display the tooltip close to the text, currently it is displayed far away in the cell. Tobe noted the tooltip positions correctly for large text, only fails for small text. In DOJO How can i position the tooltip close to the text? I have this bit of code snippet that display the tooltip in the grid cells. Screenshot attached, html <div class="some_app claro"></div> ... com.c.widget.EnhancedGrid = function ( aParent, options ) { var grid, options; this.theParentApp = aParent; dojo.require("dojox.grid.EnhancedGrid"); dojo.require("dojox.grid.enhanced.plugins.Menu"); dojo.require("dojox.grid.enhanced.plugins.Selector"); dojo.require("dojox.grid.enhanced.plugins.Pagination"); dojo.require("dojo.store.Memory"); dojo.require("dojo.data.ObjectStore"); dojo.require("dojo._base.xhr"); dojo.require("dojo.domReady!"); dojo.require("dojo.date.locale"); dojo.require("dojo._base.connect"); dojo.require("dojox.data.JsonRestStore"); dojo.require("dojo.data.ItemFileReadStore"); dojo.require("dijit.Menu"); dojo.require("dijit.MenuItem"); dojo.require('dijit.MenuSeparator'); dojo.require('dijit.CheckedMenuItem'); dojo.require('dijit.Tooltip'); dojo.require('dojo/query'); dojo.require("dojox.data.QueryReadStore"); // main initialization function this.init = function( options ) { var me = this; // default options var defaultOptions = { widgetName: ' Enhancedgrid', render: true, // immediately render the grid draggable: true, // disables column dragging containerNode: false, // the Node to hold the Grid (optional) mashupUrl: false, // the URL of the mashup (required) rowsPerPage: 20, //Default number of items per page columns: false, // columns (required) width: "100%", // width of grid height: "100%", // height of grid rowClass: function (rowData) {}, onClick: function () {}, headerMenu: false, // adding a menu pop-up for the header. selectedRegionMenu: false, // adding a menu pop-up for the rows. menusObject: false, //object to start-up the menus using the plug-in. sortInfo: false, // The column default sort infiniteScrolling: false //If true, the enhanced grid will have an infinite scrolling. }; // merge user provided options me.options = jQuery.extend( {}, defaultOptions, options ); // check we have minimum required options if ( ! me.options.mashupUrl ){ throw ("You must supply a mashupUrl"); } if ( ! me.options.columns ){ throw ("You must supply columns"); } // make the column for formatting based on its data type. me.preProcessColumns(); // create the Contextual Menu me.createMenu(); // create the grid object and return me.createGrid(); }; // Loading the data to the grid. this.loadData = function () { var me = this; if (!me.options.infiniteScrolling) { var xhrArgs = { url: me.options.mashupUrl, handleAs: "json", load: function( data ){ var store = new dojo.data.ItemFileReadStore({ data : {items : eval( "data."+me.options.dataRoot)}}); store.fetch({ onComplete : function(items, request) { if (me.grid.selection !== null) { me.grid.selection.clear(); } me.grid.setStore(store); }, onError : function(error) { me.onError(error); } }); }, error: function (error) { me.onError(error); } }; dojo.xhrGet(xhrArgs); } else { dojo.declare('NotificationQueryReadStore', dojox.data.QueryReadStore, { // // hacked -- override to map to proper data structure // from mashup // _xhrFetchHandler : function(data, request, fetchHandler, errorHandler) { // // TODO: need to have error handling here when // data has "error" data structure // // // remap data object before process by super method // var dataRoot = eval ("data."+me.options.dataRoot); var dataTotal = eval ("data."+me.options.dataTotal); data = { numRows : dataTotal, items : dataRoot }; // call to super method to process mapped data and // set rowcount // for proper display this.inherited(arguments); } }); var queryStore = new NotificationQueryReadStore({ url : me.options.mashupUrl, urlPreventCache: true, requestMethod : "get", onError: function (error) { me.onError(error); } }); me.grid.setStore(queryStore); } }; this.preProcessColumns = function () { var me = this; var options = me.options; for (i=0;i<this.options.columns.length;i++) { if (this.options.columns[i].formatter==null) { switch (this.options.columns[i].datatype) { case "string": this.options.columns[i].formatter = me.formatString; break; case "date": this.options.columns[i].formatter = me.formatDate; var todayDate = new Date(); var gmtTime = c.util.Date.parseDate(todayDate.toString()).toString(); var gmtval = gmtTime.substring(gmtTime.indexOf('GMT'),(gmtTime.indexOf('(')-1)); this.options.columns[i].name = this.options.columns[i].name + " ("+gmtval+")"; } } if (this.options.columns[i].sortDefault) { me.options.sortInfo = i+1; } } }; // create GRID object using supplied options this.createGrid = function () { var me = this; var options = me.options; // create a new grid this.grid = new dojox.grid.EnhancedGrid ({ width: options.width, height: options.height, query: { id: "*" }, keepSelection: true, formatterScope: this, structure: options.columns, columnReordering: options.draggable, rowsPerPage: options.rowsPerPage, //sortInfo: options.sortInfo, plugins : { menus: options.menusObject, selector: {"row":"multi", "cell": "disabled" }, }, //Allow the user to decide if a column is sortable by setting sortable = true / false canSort: function(col) { if (options.columns[Math.abs(col)-1].sortable) return true; else return false; }, //Change the row colors depending on severity column. onStyleRow: function (row) { var grid = me.grid; var item = grid.getItem(row.index); if (item && options.rowClass(item)) { row.customClasses += " " +options.rowClass(item); if (grid.selection.selectedIndex == row.index) { row.customClasses += " dojoxGridRowSelected"; } grid.focus.styleRow(row); grid.edit.styleRow(row); } }, onCellMouseOver: function (e){ // var pos = dojo.position(this, true); // alert(pos); console.log( e.rowIndex +" cell node :"+ e.cellNode.innerHTML); // var pos = dojo.position(this, true); console.log( " pos :"+ e.pos); if (e.cellNode.innerHTML!="") { dijit.showTooltip(e.cellNode.innerHTML, e.cellNode); } }, onCellMouseOut: function (e){ dijit.hideTooltip(e.cellNode); }, onHeaderCellMouseOver: function (e){ if (e.cellNode.innerHTML!="") { dijit.showTooltip(e.cellNode.innerHTML, e.cellNode); } }, onHeaderCellMouseOut: function (e){ dijit.hideTooltip(e.cellNode); }, }); // ADDED CODE FOR TOOLTIP var gridTooltip = new Tooltip({ connectId: "grid1", selector: "td", position: ["above"], getContent: function(matchedNode){ var childNode = matchedNode.childNodes[0]; if(childNode.nodeType == 1 && childNode.className == "user") { this.position = ["after"]; this.open(childNode); return false; } if(matchedNode.className && matchedNode.className == "user") { this.position = ["after"]; } else { this.position = ["above"]; } return matchedNode.textContent; } }); ... //Construct the grid this.buildGrid = function(){ var datagrid = new com.emc.widget.EnhancedGrid(this,{ Url: "/dge/api/-resultFormat=json&id="+encodeURIComponent(idUrl), dataRoot: "Root.ATrail", height: '100%', columns: [ { name: 'Time', field: 'Time', width: '20%', datatype: 'date', sortable: true, searchable: true, hidden: false}, { name: 'Type', field: 'Type', width: '20%', datatype: 'string', sortable: true, searchable: true, hidden: false}, { name: 'User ID', field: 'UserID', width: '20%', datatype: 'string', sortable: true, searchable: true, hidden: false } ] }); this.grid = datagrid; };

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• Using JUnit as an acceptance test framework

  - by Chris Knight

  OK, so I work for a company who has openly adopted agile practices for development in recent years. Our unit tests and code quality are improving. One area we still are working on is to find what works best for us in the automated acceptance test arena. We want to take our well formed user stories and use these to drive the code in a test driven manner. This will also give us acceptance level tests for each user story which we can then automate. To date, we've tried Fit, Fitnesse and Selenium. Each have their advantages, but we've also had real issues with them as well. With Fit and Fitnesse, we can't help but feel they overcomplicate things and we've had many technical issues using them. The business haven't fully bought in these tools and aren't particularly keen on maintaining the scripts all the time (and aren't big fans of the table style). Selenium is really good, but slow and relies on real time data and resources. One approach we are now considering is the use of the JUnit framework to provide similiar functionality. Rather than testing just a small unit of work using JUnit, why not use it to write a test (using the JUnit framework) to cover an acceptance level swath of the application? I.e. take a new story ("As a user I would like to see basic details of my policy...") and write a test in JUnit which starts executing application code at the point of entry for the policy details link but covers all code and logic down to the stubbed data access layer and back to the point of forwarding to the next page in the application, asserting on what data the user should see on that page. This seems to me to have the following advantages: Simplicity (no additional frameworks required) Zero effort to integrate with our Continuous Integration build server (since it already handles our JUnit tests) Full skillset already present in the team (its just a JUnit test after all) And the downsides being: Less customer involvement (though they are heavily involved in writing the user stories in the first place from which the acceptance tests will be written) Perhaps more difficult to understand (or make understood) the user story and acceptance criteria in a JUnit class verses a freetext specification ala Fit or Fitnesse So, my question is really, have you ever tried this method? Ever considered it? What are your thoughts? What do you like and dislike about this approach? Finally, please only mention alternative frameworks if you can say why you like or dislike them more than this approach.

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• Error while rendering .rdl file into pdf format

  - by Arka Chatterjee

  Hi, I an generating reports using SQL Server reporting services. I have generated a report and have put .rdl report file in the "E" drive. Now, when I am going to render the .rdl report file into pdf format,I am getting the exception : - "An error occurred during local report processing." The stack trace is follows : - " at Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, CreateAndRegisterStream createStreamCallback, Warning[]& warnings)\r\n at Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, String& mimeType, String& encoding, String& fileNameExtension, String[]& streams, Warning[]& warnings)\r\n at Microsoft.Reporting.WebForms.LocalReport.Render(String format, String deviceInfo, String& mimeType, String& encoding, String& fileNameExtension, String[]& streams, Warning[]& warnings)\r\n at SaltlakeSoft.APEX2.Controllers.TestPageController.RenderReport() in E:\Documents and Settings\Administrator\Desktop\afetbuild15thmayapex2\apex2\Controllers\TestPageController.cs:line 1626\r\n at lambda_method(ExecutionScope , ControllerBase , Object[] )\r\n at System.Web.Mvc.ActionMethodDispatcher.<c_DisplayClass1.b_0(ControllerBase controller, Object[] parameters)\r\n at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)\r\n at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary2 parameters)\r\n at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 parameters)\r\n at System.Web.Mvc.ControllerActionInvoker.<c_DisplayClassa.b_7()\r\n at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)" I am using the following code : - LocalReport report = new LocalReport(); report.ReportPath = @"E:\Report1.rdl"; List employeeCollection = empRepository.FindAll().ToList(); ReportDataSource reportDataSource = new ReportDataSource("dataSource1",employeeCollection); report.DataSources.Clear(); report.DataSources.Add(reportDataSource); report.Refresh(); string reportType = "PDF"; string mimeType; string encoding; string fileNameExtension; string deviceInfo ="" +"PDF" + "8.5in" + "11in" + "0.5in" +"1in" + "1in" +"0.5in" + ""; Warning[] warnings; string[] streams; byte[] renderedBytes; renderedBytes = report.Render(reportType,deviceInfo,out mimeType,out encoding, out fileNameExtension, out streams, out warnings); Response.Clear(); Response.ContentType = mimeType; Response.AddHeader("content-disposition", "attachment; filename=foo." + fileNameExtension); Response.BinaryWrite(renderedBytes); Response.End(); Please help me. Thanks in advance- Arka

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• php , SimpleXML, while loop

  - by Michael

  I'm trying to get some information from ebay api and store it in database . I used simple xml to extract the information but I have a small issue as the information is not displayed for some items . if I make a print to the simple_xml I can see very well that the information is provided by ebay api . I have $items = "220617293997,250645537939,230485306218,110537213815,180519294810"; $number_of_items = count(explode(",", $items)); $xml = $baseClass->getContent("http://open.api.ebay.com/shopping?callname=GetMultipleItems&responseencoding=XML&appid=Morcovar-c74b-47c0-954f-463afb69a4b3&siteid=0&version=525&IncludeSelector=ItemSpecifics&ItemID=$items"); writeDoc($xml, "api.xml"); //echo $xml; $getvalues = simplexml_load_file('api.xml'); // print_r($getvalue); $number = "0"; while($number < 6) { $item_number = $getvalues->Item[$number]->ItemID; $location = $getvalues->Item[$number]->Location; $title = $getvalues->Item[$number]->Title; $price = $getvalues->Item[$number]->ConvertedCurrentPrice; $manufacturer = $getvalues->Item[$number]->ItemSpecifics->NameValueList[3]->Value; $model = $getvalues->Item[$number]->ItemSpecifics->NameValueList[4]->Value; $mileage = $getvalues->Item[$number]->ItemSpecifics->NameValueList[5]->Value; echo "item number = $item_number <br>localtion = $location<br>". "title = $title<br>price = $price<br>manufacturer = $manufacturer". "<br>model = $model<br>mileage = $mileage<br>"; $number++; } the above code returns item number = localtion = title = price = manufacturer = model = mileage = item number = 230485306218 localtion = Coventry, Warwickshire title = 2001 LAND ROVER RANGE ROVER VOGUE AUTO GREEN price = 3635.07 manufacturer = Land Rover model = Range Rover mileage = 76000 item number = 220617293997 localtion = Crawley, West Sussex title = 2004 CITROEN C5 HDI LX RED price = 3115.77 manufacturer = Citroen model = C5 mileage = 76000 item number = 180519294810 localtion = London, London title = 2000 VOLKSWAGEN POLO 1.4 SILVER 16V NEED GEAR BOX price = 905.06 manufacturer = Right-hand drive model = mileage = Standard Car item number = localtion = title = price = manufacturer = model = mileage = As you can see the information is not retrieved for a few items ... If I replace the $number manually like " $item_number = $getvalues-Item[4]-ItemID;" works well for any number .

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• Ideas for multiplatform encrypted java mobile storage system

  - by Fernando Miguélez

  Objective I am currently designing the API for a multiplatform storage system that would offer same interface and capabilities accross following supported mobile Java Platforms: J2ME. Minimum configuration/profile CLDC 1.1/MIDP 2.0 with support for some necessary JSRs (JSR-75 for file storage). Android. No minimum platform version decided yet, but rather likely could be API level 7. Blackberry. It would use the same base source of J2ME but taking advantage of some advaced capabilities of the platform. No minimum configuration decided yet (maybe 4.6 because of 64 KB limitation for RMS on 4.5). Basically the API would sport three kind of stores: Files. These would allow standard directory/file manipulation (read/write through streams, create, mkdir, etc.). Preferences. It is a special store that handles properties accessed through keys (Similar to plain old java properties file but supporting some improvements such as different value data types such as SharedPreferences on Android platform) Local Message Queues. This store would offer basic message queue functionality. Considerations Inspired on JSR-75, all types of stores would be accessed in an uniform way by means of an URL following RFC 1738 conventions, but with custom defined prefixes (i.e. "file://" for files, "prefs://" for preferences or "queue://" for message queues). The address would refer to a virtual location that would be mapped to a physical storage object by each mobile platform implementation. Only files would allow hierarchical storage (folders) and access to external extorage memory cards (by means of a unit name, the same way as in JSR-75, but that would not change regardless of underlying platform). The other types would only support flat storage. The system should also support a secure version of all basic types. The user would indicate it by prefixing "s" to the URL (i.e. "sfile://" instead of "file://"). The API would only require one PIN (introduced only once) to access any kind of secure object types. Implementation issues For the implementation of both plaintext and encrypted stores, I would use the functionality available on the underlying platforms: Files. These are available on all platforms (J2ME only with JSR-75, but it is mandatory for our needs). The abstract File to actual File mapping is straight except for addressing issues. RMS. This type of store available on J2ME (and Blackberry) platforms is convenient for Preferences and maybe Message Queues (though depending on performance or size requirements these could be implemented by means of normal files). SharedPreferences. This type of storage, only available on Android, would match Preferences needs. SQLite databases. This could be used for message queues on Android (and maybe Blackberry). When it comes to encryption some requirements should be met: To ease the implementation it will be carried out on read/write operations basis on streams (for files), RMS Records, SharedPreferences key-value pairs, SQLite database columns. Every underlying storage object should use the same encryption key. Handling of encrypted stores should be the same as the unencrypted counterpart. The only difference (from the user point of view) accessing an encrypted store would be the addressing. The user PIN provides access to any secure storage object, but the change of it would not require to decrypt/re-encrypt all the encrypted data. Cryptographic capabilities of underlying platform should be used whenever it is possible, so we would use: J2ME: SATSA-CRYPTO if it is available (not mandatory) or lightweight BoncyCastle cryptographic framework for J2ME. Blackberry: RIM Cryptographic API or BouncyCastle Android: JCE with integraced cryptographic provider (BouncyCastle?) Doubts Having reached this point I was struck by some doubts about what solution would be more convenient, taking into account the limitation of the plataforms. These are some of my doubts: Encryption Algorithm for data. Would AES-128 be strong and fast enough? What alternatives for such scenario would you suggest? Encryption Mode. I have read about the weakness of ECB encryption versus CBC, but in this case the first would have the advantage of random access to blocks, which is interesting for seek functionality on files. What type of encryption mode would you choose instead? Is stream encryption suitable for this case? Key generation. There could be one key generated for each storage object (file, RMS RecordStore, etc.) or just use one for all the objects of the same type. The first seems "safer", though it would require some extra space on device. In your opinion what would the trade-offs of each? Key storage. For this case using a standard JKS (or PKCS#12) KeyStore file could be suited to store encryption keys, but I could also define a smaller structure (encryption-transformation / key data / checksum) that could be attached to each storage store (i.e. using addition files with the same name and special extension for plain files or embedded inside other types of objects such as RMS Record Stores). What approach would you prefer? And when it comes to using a standard KeyStore with multiple-key generation (given this is your preference), would it be better to use a record-store per storage object or just a global KeyStore keeping all keys (i.e. using the URL identifier of abstract storage object as alias)? Master key. The use of a master key seems obvious. This key should be protected by user PIN (introduced only once) and would allow access to the rest of encryption keys (they would be encrypted by means of this master key). Changing the PIN would only require to reencrypt this key and not all the encrypted data. Where would you keep it taking into account that if this got lost all data would be no further accesible? What further considerations should I take into account? Platform cryptography support. Do SATSA-CRYPTO-enabled J2ME phones really take advantage of some dedicated hardware acceleration (or other advantage I have not foreseen) and would this approach be prefered (whenever possible) over just BouncyCastle implementation? For the same reason is RIM Cryptographic API worth the license cost over BouncyCastle? Any comments, critics, further considerations or different approaches are welcome.

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• When does IE7 recompute styles? Doesn't work reliably when a class is added to the body.

  - by Kid A

  I have an interesting problem here. I'm using a class on the element as a switch to drive a fair amount of layout behavior on my site. If the class is applied, certain things happen, and if the class isn't applied, they don't happen. The relevant CSS is roughly like this: .rightSide { display:none; } .showCommentsRight .rightSide { display:block; width:50%; } .showCommentsRight .leftSide { display:block; width:50%; } And the HTML: <body class="showCommentsRight"> <div class="container"></div> <div class="leftSide"></div> <div class="rightSide"></div> </div> <div class="container"></div> <div class="leftSide"></div> <div class="rightSide"></div> </div> <div class="container"></div> <div class="leftSide"></div> <div class="rightSide"></div> </div> </body> I've simplified things but this is essentially the method. The whole page changes layout (hiding the right side in three different areas) when the flag is set on the body. This works in Firefox and IE8. It does not work in IE8 in compatibility mode. What is fascinating is that if you sit there and refresh the page, the results can vary. It will pick a different section's right side to show. Sometimes it will show only the top section's right side, sometimes it will show the middle. I have tried a validator (to look for malformed html), double css formatting, and making sure my IE7 hack sheet wasn't having an effect. So my question is: * Is there a way that this behavior can be made reliable? * When does IE7 decide to re-do styling? Thanks everyone.

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• Recursive N-way merge/diff algorithm for directory trees?

  - by BobMcGee

  What algorithms or Java libraries are available to do N-way, recursive diff/merge of directories? I need to be able to generate a list of folder trees that have many identical files, and have subdirectories with many similar files. I want to be able to use 2-way merge operations to quickly remove as much redundancy as possible. Goals: Find pairs of directories that have many similar files between them. Generate short list of directory pairs that can be synchronized with 2-way merge to eliminate duplicates Should operate recursively (there may be nested duplicates of higher-level directories) Run time and storage should be O(n log n) in numbers of directories and files Should be able to use an embedded DB or page to disk for processing more files than fit in memory (100,000+). Optional: generate an ancestry and change-set between folders Optional: sort the merge operations by how many duplicates they can elliminate I know how to use hashes to find duplicate files in roughly O(n) space, but I'm at a loss for how to go from this to finding partially overlapping sets between folders and their children. EDIT: some clarification The tricky part is the difference between "exact same" contents (otherwise hashing file hashes would work) and "similar" (which will not). Basically, I want to feed this algorithm at a set of directories and have it return a set of 2-way merge operations I can perform in order to reduce duplicates as much as possible with as few conflicts possible. It's effectively constructing an ancestry tree showing which folders are derived from each other. The end goal is to let me incorporate a bunch of different folders into one common tree. For example, I may have a folder holding programming projects, and then copy some of its contents to another computer to work on it. Then I might back up and intermediate version to flash drive. Except I may have 8 or 10 different versions, with slightly different organizational structures or folder names. I need to be able to merge them one step at a time, so I can chose how to incorporate changes at each step of the way. This is actually more or less what I intend to do with my utility (bring together a bunch of scattered backups from different points in time). I figure if I can do it right I may as well release it as a small open source util. I think the same tricks might be useful for comparing XML trees though.

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• Why is zIndex not working from IE/Javascript?

  - by Vilx-

  <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <meta http-equiv="X-UA-Compatible" content="IE=7" /> <title>Problem demo</title> </head> <body> <div style="background:red; position:relative;" id='div1'>1. <div style="background:lime; position: absolute; width: 300px;height: 300px; top: 3px; left: 30px" id="div2">3.</div> </div> <div style="background:blue;position:relative;color: white" id="div3">2.</div> <script type="text/javascript">/*<![CDATA[*/ window.onload= function() { // The container of the absolute DIV document.getElementById('div1').style.zIndex = 800; // The lowest DIV of all which obscures the absolute DIV document.getElementById('div2').style.zIndex = 1; // The absolute DIV document.getElementById('div3').style.zIndex = 1000; } /*]]>*/</script> </body> </html> In a nutshell, this script has two DIV elements with position:relative and the first of them has a third DIV with position:absolute in it. It's all set to run on IE-7 standards mode (I'm targeting IE7 and above). I know about the separate z-stacks of IE, so by default the third DIV should be beneath the second DIV. To fix this problem there is some Javascript which sets the z-orders of first and third DIV to 1000, and the z-order of the second DIV to 999. Unfortunately this does not help. If the z-indexes were set in markup, this would work, but why not from JS? Note: This problem does not exist in IE8 standards mode, but I'm targetting IE7, so I can't rely on that. Also, if you save this to your hard drive and then open it up, at first IE complains something about ActiveX and stuff. After you wave it away, everything works as expected. But if you refresh the page, the problem is there again.

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• What benefits are there to storing Javascript in external files vs in the <head>?

  - by RenderIn

  I have an Ajax-enabled CRUD application. If I display a record from my database it shows that record's values for each column, including its primary key. For the Ajax actions tied to buttons on the page I am able to set up their calls by printing the ID directly into their onclick functions when rendering the HTML server-side. For example, to save changes to the record I may have a button as follows, with '123' being the primary key of the record. <button type="button" onclick="saveRecord('123')">Save</button> Sometimes I have pages with Javascript generating HTML and Javascript. In some of these cases the primary key is not naturally available at that place in the code. In these cases I took a shortcut and generate buttons like so, taking the primary key from a place it happens to be displayed on screen for visual consumption: ... <td>Primary Key: </td> <td><span id="PRIM_KEY">123</span></td> ... <button type="button" onclick="saveRecord(jQuery('#PRIM_KEY').text())">DoSomething</button> This definitely works, but it seems wrong to drive database queries based on the value of text whose purpose was user consumption rather than method consumption. I could solve this by adding a series of additional parameters to various methods to usher the primary key along until it is eventually needed, but that also seems clunky. The most natural way for me to solve this problem would be to simply situate all the Javascript which currently lives in external files, in the <head> of the page. In that way I could generate custom Javascript methods without having to pass around as many parameters. Other than readability, I'm struggling to see what benefit there is to storing Javascript externally. It seems like it makes the already weak marriage between HTML/DOM and Javascript all the more distant. I've seen some people suggest that I leave the Javascript external, but do set various "custom" variables on the page itself, for example, in PHP: <script type="text/javascript"> var primaryKey = <?php print $primaryKey; ?>; </script> <script type="text/javascript" src="my-external-js-file-depending-on-primaryKey-being-set.js"></script> How is this any better than just putting all the Javascript on the page in the first place? There HTML and Javascript are still strongly dependent on each other.

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• Spring.NET & Immediacy CMS (or how to inject to server side controls without using PageHandlerFactor

  - by Simon Rice

  Is there any way to inject dependencies into an Immediacy CMS control using Spring.NET, ideally without having to use to ContextRegistry when initialising the control? Update, with my own answer The issue here is that Immediacy already has a handler defined in web.config that deals with all aspx pages, & so it's not possible add an entry for Spring.NET's PageHandlerFactory in web.config as per a normal webforms app. That rules out making the control implement ISupportsWebDependencyInjection. Furthermore, most of Immediacy's generated pages are aspx pages that don't physically exist on the drive. I have changed the title of the question to reflect this. What I have done to get Dependency Injection working is: Add the usual entries to web.config for Spring.NET as outlined in the documentation, except for the adding the entry to the <httpHandlers> section. In this case I've got my object definitions in Spring.config. Create the following abstract base class that will deal with all of the Dependency Injection work: DIControl.cs public abstract class DIControl : ImmediacyControl { protected virtual string DIName { get { return this.GetType().Name; } } protected override void OnInit(EventArgs e) { if (ContextRegistry.GetContext().GetObject(DIName, this.GetType()) != null) ContextRegistry.GetContext().ConfigureObject(this, DIName); base.OnInit(e); } } For non-immediacy controls, you can make this server side control inherit from Control or whatever subclass of that you like. For any control with which you wish to use with Spring.NET's Inversion of Control container, define it to inherit from DIControl & add the relelvant entry to Spring.config, for example: SampleControl.cs public class SampleControl : DIControl, INamingContainer { public string Text { get; set; } protected string InjectedText { get; set; } public SampleControl() : base() { Text = "Hello world"; } protected override void RenderContents(HtmlTextWriter output) { output.Write(string.Format("{0} {1}", Text, InjectedText)); } } Spring.config <objects xmlns="http://www.springframework.net"> <object id="SampleControl" type="MyProject.SampleControl, MyAssembly"> <property name="InjectedText" value="from Spring.NET" /> </object> </objects> You can optionally override DIName if you wish to name your entry in Spring.config differently from the name of your class. Provided everything's done correctly, you will have the control writing out "Hello world from Spring.NET!" when used in a page. This solution uses Spring.NET's ContextRegistry from within the control, but I would be surprised if there's no way around that for Immediacy at least since the page objects themselves aren't accessible. However, can this be improved at all from a Spring.NET perspective? Is there maybe an Immediacy plugin that already does this that I'm completely unaware of? Or is there an approach that does this in a more elegant way? I'm open to suggestions.

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• How do I recover from an unchecked exception?

  - by erickson

  Unchecked exceptions are alright if you want to handle every failure the same way, for example by logging it and skipping to the next request, displaying a message to the user and handling the next event, etc. If this is my use case, all I have to do is catch some general exception type at a high level in my system, and handle everything the same way. But I want to recover from specific problems, and I'm not sure the best way to approach it with unchecked exceptions. Here is a concrete example. Suppose I have a web application, built using Struts2 and Hibernate. If an exception bubbles up to my "action", I log it, and display a pretty apology to the user. But one of the functions of my web application is creating new user accounts, that require a unique user name. If a user picks a name that already exists, Hibernate throws an org.hibernate.exception.ConstraintViolationException (an unchecked exception) down in the guts of my system. I'd really like to recover from this particular problem by asking the user to choose another user name, rather than giving them the same "we logged your problem but for now you're hosed" message. Here are a few points to consider: There a lot of people creating accounts simultaneously. I don't want to lock the whole user table between a "SELECT" to see if the name exists and an "INSERT" if it doesn't. In the case of relational databases, there might be some tricks to work around this, but what I'm really interested in is the general case where pre-checking for an exception won't work because of a fundamental race condition. Same thing could apply to looking for a file on the file system, etc. Given my CTO's propensity for drive-by management induced by reading technology columns in "Inc.", I need a layer of indirection around the persistence mechanism so that I can throw out Hibernate and use Kodo, or whatever, without changing anything except the lowest layer of persistence code. As a matter of fact, there are several such layers of abstraction in my system. How can I prevent them from leaking in spite of unchecked exceptions? One of the declaimed weaknesses of checked exceptions is having to "handle" them in every call on the stack—either by declaring that a calling method throws them, or by catching them and handling them. Handling them often means wrapping them in another checked exception of a type appropriate to the level of abstraction. So, for example, in checked-exception land, a file-system–based implementation of my UserRegistry might catch IOException, while a database implementation would catch SQLException, but both would throw a UserNotFoundException that hides the underlying implementation. How do I take advantage of unchecked exceptions, sparing myself of the burden of this wrapping at each layer, without leaking implementation details?

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• Unusually high dentry cache usage

  - by Wolfgang Stengel

  Problem A CentOS machine with kernel 2.6.32 and 128 GB physical RAM ran into trouble a few days ago. The responsible system administrator tells me that the PHP-FPM application was not responding to requests in a timely manner anymore due to swapping, and having seen in free that almost no memory was left, he chose to reboot the machine. I know that free memory can be a confusing concept on Linux and a reboot perhaps was the wrong thing to do. However, the mentioned administrator blames the PHP application (which I am responsible for) and refuses to investigate further. What I could find out on my own is this: Before the restart, the free memory (incl. buffers and cache) was only a couple of hundred MB. Before the restart, /proc/meminfo reported a Slab memory usage of around 90 GB (yes, GB). After the restart, the free memory was 119 GB, going down to around 100 GB within an hour, as the PHP-FPM workers (about 600 of them) were coming back to life, each of them showing between 30 and 40 MB in the RES column in top (which has been this way for months and is perfectly reasonable given the nature of the PHP application). There is nothing else in the process list that consumes an unusual or noteworthy amount of RAM. After the restart, Slab memory was around 300 MB If have been monitoring the system ever since, and most notably the Slab memory is increasing in a straight line with a rate of about 5 GB per day. Free memory as reported by free and /proc/meminfo decreases at the same rate. Slab is currently at 46 GB. According to slabtop most of it is used for dentry entries: Free memory: free -m total used free shared buffers cached Mem: 129048 76435 52612 0 144 7675 -/+ buffers/cache: 68615 60432 Swap: 8191 0 8191 Meminfo: cat /proc/meminfo MemTotal: 132145324 kB MemFree: 53620068 kB Buffers: 147760 kB Cached: 8239072 kB SwapCached: 0 kB Active: 20300940 kB Inactive: 6512716 kB Active(anon): 18408460 kB Inactive(anon): 24736 kB Active(file): 1892480 kB Inactive(file): 6487980 kB Unevictable: 8608 kB Mlocked: 8608 kB SwapTotal: 8388600 kB SwapFree: 8388600 kB Dirty: 11416 kB Writeback: 0 kB AnonPages: 18436224 kB Mapped: 94536 kB Shmem: 6364 kB Slab: 46240380 kB SReclaimable: 44561644 kB SUnreclaim: 1678736 kB KernelStack: 9336 kB PageTables: 457516 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 72364108 kB Committed_AS: 22305444 kB VmallocTotal: 34359738367 kB VmallocUsed: 480164 kB VmallocChunk: 34290830848 kB HardwareCorrupted: 0 kB AnonHugePages: 12216320 kB HugePages_Total: 2048 HugePages_Free: 2048 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 5604 kB DirectMap2M: 2078720 kB DirectMap1G: 132120576 kB Slabtop: slabtop --once Active / Total Objects (% used) : 225920064 / 226193412 (99.9%) Active / Total Slabs (% used) : 11556364 / 11556415 (100.0%) Active / Total Caches (% used) : 110 / 194 (56.7%) Active / Total Size (% used) : 43278793.73K / 43315465.42K (99.9%) Minimum / Average / Maximum Object : 0.02K / 0.19K / 4096.00K OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME 221416340 221416039 3% 0.19K 11070817 20 44283268K dentry 1123443 1122739 99% 0.41K 124827 9 499308K fuse_request 1122320 1122180 99% 0.75K 224464 5 897856K fuse_inode 761539 754272 99% 0.20K 40081 19 160324K vm_area_struct 437858 223259 50% 0.10K 11834 37 47336K buffer_head 353353 347519 98% 0.05K 4589 77 18356K anon_vma_chain 325090 324190 99% 0.06K 5510 59 22040K size-64 146272 145422 99% 0.03K 1306 112 5224K size-32 137625 137614 99% 1.02K 45875 3 183500K nfs_inode_cache 128800 118407 91% 0.04K 1400 92 5600K anon_vma 59101 46853 79% 0.55K 8443 7 33772K radix_tree_node 52620 52009 98% 0.12K 1754 30 7016K size-128 19359 19253 99% 0.14K 717 27 2868K sysfs_dir_cache 10240 7746 75% 0.19K 512 20 2048K filp VFS cache pressure: cat /proc/sys/vm/vfs_cache_pressure 125 Swappiness: cat /proc/sys/vm/swappiness 0 I know that unused memory is wasted memory, so this should not necessarily be a bad thing (especially given that 44 GB are shown as SReclaimable). However, apparently the machine experienced problems nonetheless, and I'm afraid the same will happen again in a few days when Slab surpasses 90 GB. Questions I have these questions: Am I correct in thinking that the Slab memory is always physical RAM, and the number is already subtracted from the MemFree value? Is such a high number of dentry entries normal? The PHP application has access to around 1.5 M files, however most of them are archives and not being accessed at all for regular web traffic. What could be an explanation for the fact that the number of cached inodes is much lower than the number of cached dentries, should they not be related somehow? If the system runs into memory trouble, should the kernel not free some of the dentries automatically? What could be a reason that this does not happen? Is there any way to "look into" the dentry cache to see what all this memory is (i.e. what are the paths that are being cached)? Perhaps this points to some kind of memory leak, symlink loop, or indeed to something the PHP application is doing wrong. The PHP application code as well as all asset files are mounted via GlusterFS network file system, could that have something to do with it? Please keep in mind that I can not investigate as root, only as a regular user, and that the administrator refuses to help. He won't even run the typical echo 2 > /proc/sys/vm/drop_caches test to see if the Slab memory is indeed reclaimable. Any insights into what could be going on and how I can investigate any further would be greatly appreciated. Updates Some further diagnostic information: Mounts: cat /proc/self/mounts rootfs / rootfs rw 0 0 proc /proc proc rw,relatime 0 0 sysfs /sys sysfs rw,relatime 0 0 devtmpfs /dev devtmpfs rw,relatime,size=66063000k,nr_inodes=16515750,mode=755 0 0 devpts /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=000 0 0 tmpfs /dev/shm tmpfs rw,relatime 0 0 /dev/mapper/sysvg-lv_root / ext4 rw,relatime,barrier=1,data=ordered 0 0 /proc/bus/usb /proc/bus/usb usbfs rw,relatime 0 0 /dev/sda1 /boot ext4 rw,relatime,barrier=1,data=ordered 0 0 tmpfs /phptmp tmpfs rw,noatime,size=1048576k,nr_inodes=15728640,mode=777 0 0 tmpfs /wsdltmp tmpfs rw,noatime,size=1048576k,nr_inodes=15728640,mode=777 0 0 none /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0 cgroup /cgroup/cpuset cgroup rw,relatime,cpuset 0 0 cgroup /cgroup/cpu cgroup rw,relatime,cpu 0 0 cgroup /cgroup/cpuacct cgroup rw,relatime,cpuacct 0 0 cgroup /cgroup/memory cgroup rw,relatime,memory 0 0 cgroup /cgroup/devices cgroup rw,relatime,devices 0 0 cgroup /cgroup/freezer cgroup rw,relatime,freezer 0 0 cgroup /cgroup/net_cls cgroup rw,relatime,net_cls 0 0 cgroup /cgroup/blkio cgroup rw,relatime,blkio 0 0 /etc/glusterfs/glusterfs-www.vol /var/www fuse.glusterfs rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072 0 0 /etc/glusterfs/glusterfs-upload.vol /var/upload fuse.glusterfs rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072 0 0 sunrpc /var/lib/nfs/rpc_pipefs rpc_pipefs rw,relatime 0 0 172.17.39.78:/www /data/www nfs rw,relatime,vers=3,rsize=65536,wsize=65536,namlen=255,hard,proto=tcp,port=38467,timeo=600,retrans=2,sec=sys,mountaddr=172.17.39.78,mountvers=3,mountport=38465,mountproto=tcp,local_lock=none,addr=172.17.39.78 0 0 Mount info: cat /proc/self/mountinfo 16 21 0:3 / /proc rw,relatime - proc proc rw 17 21 0:0 / /sys rw,relatime - sysfs sysfs rw 18 21 0:5 / /dev rw,relatime - devtmpfs devtmpfs rw,size=66063000k,nr_inodes=16515750,mode=755 19 18 0:11 / /dev/pts rw,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=000 20 18 0:16 / /dev/shm rw,relatime - tmpfs tmpfs rw 21 1 253:1 / / rw,relatime - ext4 /dev/mapper/sysvg-lv_root rw,barrier=1,data=ordered 22 16 0:15 / /proc/bus/usb rw,relatime - usbfs /proc/bus/usb rw 23 21 8:1 / /boot rw,relatime - ext4 /dev/sda1 rw,barrier=1,data=ordered 24 21 0:17 / /phptmp rw,noatime - tmpfs tmpfs rw,size=1048576k,nr_inodes=15728640,mode=777 25 21 0:18 / /wsdltmp rw,noatime - tmpfs tmpfs rw,size=1048576k,nr_inodes=15728640,mode=777 26 16 0:19 / /proc/sys/fs/binfmt_misc rw,relatime - binfmt_misc none rw 27 21 0:20 / /cgroup/cpuset rw,relatime - cgroup cgroup rw,cpuset 28 21 0:21 / /cgroup/cpu rw,relatime - cgroup cgroup rw,cpu 29 21 0:22 / /cgroup/cpuacct rw,relatime - cgroup cgroup rw,cpuacct 30 21 0:23 / /cgroup/memory rw,relatime - cgroup cgroup rw,memory 31 21 0:24 / /cgroup/devices rw,relatime - cgroup cgroup rw,devices 32 21 0:25 / /cgroup/freezer rw,relatime - cgroup cgroup rw,freezer 33 21 0:26 / /cgroup/net_cls rw,relatime - cgroup cgroup rw,net_cls 34 21 0:27 / /cgroup/blkio rw,relatime - cgroup cgroup rw,blkio 35 21 0:28 / /var/www rw,relatime - fuse.glusterfs /etc/glusterfs/glusterfs-www.vol rw,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072 36 21 0:29 / /var/upload rw,relatime - fuse.glusterfs /etc/glusterfs/glusterfs-upload.vol rw,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072 37 21 0:30 / /var/lib/nfs/rpc_pipefs rw,relatime - rpc_pipefs sunrpc rw 39 21 0:31 / /data/www rw,relatime - nfs 172.17.39.78:/www rw,vers=3,rsize=65536,wsize=65536,namlen=255,hard,proto=tcp,port=38467,timeo=600,retrans=2,sec=sys,mountaddr=172.17.39.78,mountvers=3,mountport=38465,mountproto=tcp,local_lock=none,addr=172.17.39.78 GlusterFS config: cat /etc/glusterfs/glusterfs-www.vol volume remote1 type protocol/client option transport-type tcp option remote-host 172.17.39.71 option ping-timeout 10 option transport.socket.nodelay on # undocumented option for speed # http://gluster.org/pipermail/gluster-users/2009-September/003158.html option remote-subvolume /data/www end-volume volume remote2 type protocol/client option transport-type tcp option remote-host 172.17.39.72 option ping-timeout 10 option transport.socket.nodelay on # undocumented option for speed # http://gluster.org/pipermail/gluster-users/2009-September/003158.html option remote-subvolume /data/www end-volume volume remote3 type protocol/client option transport-type tcp option remote-host 172.17.39.73 option ping-timeout 10 option transport.socket.nodelay on # undocumented option for speed # http://gluster.org/pipermail/gluster-users/2009-September/003158.html option remote-subvolume /data/www end-volume volume remote4 type protocol/client option transport-type tcp option remote-host 172.17.39.74 option ping-timeout 10 option transport.socket.nodelay on # undocumented option for speed # http://gluster.org/pipermail/gluster-users/2009-September/003158.html option remote-subvolume /data/www end-volume volume replicate1 type cluster/replicate option lookup-unhashed off # off will reduce cpu usage, and network option local-volume-name 'hostname' subvolumes remote1 remote2 end-volume volume replicate2 type cluster/replicate option lookup-unhashed off # off will reduce cpu usage, and network option local-volume-name 'hostname' subvolumes remote3 remote4 end-volume volume distribute type cluster/distribute subvolumes replicate1 replicate2 end-volume volume iocache type performance/io-cache option cache-size 8192MB # default is 32MB subvolumes distribute end-volume volume writeback type performance/write-behind option cache-size 1024MB option window-size 1MB subvolumes iocache end-volume ### Add io-threads for parallel requisitions volume iothreads type performance/io-threads option thread-count 64 # default is 16 subvolumes writeback end-volume volume ra type performance/read-ahead option page-size 2MB option page-count 16 option force-atime-update no subvolumes iothreads end-volume

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• Working with friends. Poor career choice?

  - by a_person

  Hi all, Hope you can help me solve somewhat of a moral dilemma. Some time ago, after just a few years of living in U.S. and having to take any job I could get my hands on a friend of mine submitted recommended me for an open position at the company that he was working for. I could have not been happier. I do not have a degree of any sort, however, by being passionate about CS and with constant drive for self education I've became a somewhat of a strong generalist. Every place I worked for recognized me for that quality and used me on various projects where set of technology in hand had no overlap with set of knowledge of the team members. Rapidly I've advanced to Sr. Programmer position and the trend of me following a friend from one place to another have started and continued on for a few years. My friend's goal always been to become an IT Director, mine is to become the best programmer I can be. To my knowledge I've accommodated his goals as much as I could by taking a back seat, and letting him take the lead. Fast forward to today. He's a manager, and I am on his team. I am unhappy and I in considerable amount of suffering. I am not being utilized to my potential, it's almost exact opposite, I am being micromanaged to an unhealthy extent, my decisions, and suggestions are constantly met with negative connotation. Last week I had to hear about how my friend is a better programmer than I am. My ego was ecstatic about this one /s. In addition to that working in the field of BI have exhausted itself for most parts. The only pleasure of my work is being derived from making everything as dynamic and parameter driven as possible. This is the only area where a friend of mine does not feel competent enough to actually micromanage. Because of my situation I feel a fair amount of guilt and ever growing resentment. I need your advice, maybe you've dealt with this expression of ego before, needs of self vs the needs of your friend. Is working with a friend a poor choice? Thank you for reading in.

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• How to obtain the first cluster of the directory's data in FAT using C# (or at least C++) and Win32A

  - by DarkWalker

  So I have a FAT drive, lets say H: and a directory 'work' (full path 'H:\work'). I need to get the NUMBER of the first cluster of that directory. The number of the first cluster is 2-bytes value, that is stored in the 26th and 27th bytes of the folder enty (wich is 32 bytes). Lets say I am doing it with file, NOT a directory. I can use code like this: static public string GetDirectoryPtr(string dir) { IntPtr ptr = CreateFile(@"H:\Work\dover.docx", GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, IntPtr.Zero, OPEN_EXISTING, 0,//FILE_FLAG_BACKUP_SEMANTICS, IntPtr.Zero); try { const uint bytesToRead = 2; byte[] readbuffer = new byte[bytesToRead]; if (ptr.ToInt32() == -1) return String.Format("Error: cannot open direcotory {0}", dir); if (SetFilePointer(ptr, 26, 0, 0) == -1) return String.Format("Error: unable to set file pointer on file {0}", ptr); uint read = 0; // real count of read bytes if (!ReadFile(ptr, readbuffer, bytesToRead, out read, 0)) return String.Format("cant read from file {0}. Error #{1}", ptr, Marshal.GetLastWin32Error()); int result = readbuffer[0] + 16 * 16 * readbuffer[1]; return result.ToString();//ASCIIEncoding.ASCII.GetString(readbuffer); } finally { CloseHandle(ptr); } } And it will return some number, like 19 (quite real to me, this is the only file on the disk). But I DONT need a file, I need a folder. So I am puttin FILE_FLAG_BACKUP_SEMANTICS param for CreateFile call... and dont know what to do next =) msdn is very clear on this issue http://msdn.microsoft.com/en-us/library/aa365258(v=VS.85).aspx It sounds to me like: "There is no way you can get a number of the folder's first cluster". The most desperate thing is that my tutor said smth like "You are going to obtain this or you wont pass this course". The true reason why he is so sure this is possible is because for 10 years (or may be more) he recieved the folder's first cluster number as a HASH of the folder's addres (and I was stupid enough to point this to him, so now I cant do it the same way) PS: This is the most spupid task I have ever had!!! This value is not really used anythere in program, it is only fcking pointless integer.

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• Hibernate3: Self-Referencing Objects

  - by monojohnny

  Need some help on understanding how to do this; I'm going to be running recursive 'find' on a file system and I want to keep the information in a single DB table - with a self-referencing hierarchial structure: This is my DB Table structure I want to populate. DirObject Table: id int NOT NULL, name varchar(255) NOT NULL, parentid int NOT NULL); Here is the proposed Java Class I want to map (Fields only shown): public DirObject { int id; String name; DirObject parent; ... For the 'root' directory was going to use parentid=0; real ids will start at 1, and ideally I want hibernate to autogenerate the ids. Can somebody provide a suggested mapping file for this please; as a secondary question I thought about doing the Java Class like this instead: public DirObject { int id; String name; List<DirObject> subdirs; Could I use the same data model for either of these two methods ? (With a different mapping file of course). --- UPDATE: so I tried the mapping file suggested below (thanks!), repeated here for reference: <hibernate-mapping> <class name="my.proj.DirObject" table="category"> ... <set name="subDirs" lazy="true" inverse="true"> <key column="parentId"/> <one-to-many class="my.proj.DirObject"/> </set> <many-to-one name="parent" class="my.proj.DirObject" column="parentId" cascade="all" /> </class> ...and altered my Java class to have BOTH 'parentid' and 'getSubDirs' [returning a 'HashSet']. This appears to work - thanks, but this is the test code I used to drive this - I think I'm not doing something right here, because I thought Hibernate would take care of saving the subordinate objects in the Set without me having to do this explicitly ? DirObject dirobject=new DirObject(); dirobject.setName("/files"); dirobject.setParent(dirobject); DirObject d1, d2; d1=new DirObject(); d1.setName("subdir1"); d1.setParent(dirobject); d2=new DirObject(); d2.setName("subdir2"); d2.setParent(dirobject); HashSet<DirObject> subdirs=new HashSet<DirObject>(); subdirs.add(d1); subdirs.add(d2); dirobject.setSubdirs(subdirs); session.save(dirobject); session.save(d1); session.save(d2);

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• Uploading multiple files using Spring MVC 3.0.2 after HiddenHttpMethodFilter has been enabled

  - by Tiny

  I'm using Spring version 3.0.2. I need to upload multiple files using the multiple="multiple" attribute of a file browser such as, <input type="file" id="myFile" name="myFile" multiple="multiple"/> (and not using multiple file browsers something like the one stated by this answer, it indeed works I tried). Although no versions of Internet Explorer supports this approach unless an appropriate jQuery plugin/widget is used, I don't care about it right now (since most other browsers support this). This works fine with commons fileupload but in addition to using RequestMethod.POST and RequestMethod.GET methods, I also want to use other request methods supported and suggested by Spring like RequestMethod.PUT and RequestMethod.DELETE in their own appropriate places. For this to be so, I have configured Spring with HiddenHttpMethodFilter which goes fine as this question indicates. but it can upload only one file at a time even though multiple files in the file browser are chosen. In the Spring controller class, a method is mapped as follows. @RequestMapping(method={RequestMethod.POST}, value={"admin_side/Temp"}) public String onSubmit(@RequestParam("myFile") List<MultipartFile> files, @ModelAttribute("tempBean") TempBean tempBean, BindingResult error, Map model, HttpServletRequest request, HttpServletResponse response) throws IOException, FileUploadException { for(MultipartFile file:files) { System.out.println(file.getOriginalFilename()); } } Even with the request parameter @RequestParam("myFile") List<MultipartFile> files which is a List of type MultipartFile (it can always have only one file at a time). I could find a strategy which is likely to work with multiple files on this blog. I have gone through it carefully. The solution below the section SOLUTION 2 – USE THE RAW REQUEST says, If however the client insists on using the same form input name such as ‘files[]‘ or ‘files’ and then populating that name with multiple files then a small hack is necessary as follows. As noted above Spring 2.5 throws an exception if it detects the same form input name of type file more than once. CommonsFileUploadSupport – the class which throws that exception is not final and the method which throws that exception is protected so using the wonders of inheritance and subclassing one can simply fix/modify the logic a little bit as follows. The change I’ve made is literally one word representing one method invocation which enables us to have multiple files incoming under the same form input name. It attempts to override the method protected MultipartParsingResult parseFileItems(List fileItems, String encoding) {} of the abstract class CommonsFileUploadSupport by extending the class CommonsMultipartResolver such as, package multipartResolver; import java.io.UnsupportedEncodingException; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import javax.servlet.ServletContext; import org.apache.commons.fileupload.FileItem; import org.springframework.util.StringUtils; import org.springframework.web.multipart.MultipartException; import org.springframework.web.multipart.MultipartFile; import org.springframework.web.multipart.commons.CommonsMultipartFile; import org.springframework.web.multipart.commons.CommonsMultipartResolver; final public class MultiCommonsMultipartResolver extends CommonsMultipartResolver { public MultiCommonsMultipartResolver() { } public MultiCommonsMultipartResolver(ServletContext servletContext) { super(servletContext); } @Override @SuppressWarnings("unchecked") protected MultipartParsingResult parseFileItems(List fileItems, String encoding) { Map<String, MultipartFile> multipartFiles = new HashMap<String, MultipartFile>(); Map multipartParameters = new HashMap(); // Extract multipart files and multipart parameters. for (Iterator it = fileItems.iterator(); it.hasNext();) { FileItem fileItem = (FileItem) it.next(); if (fileItem.isFormField()) { String value = null; if (encoding != null) { try { value = fileItem.getString(encoding); } catch (UnsupportedEncodingException ex) { if (logger.isWarnEnabled()) { logger.warn("Could not decode multipart item '" + fileItem.getFieldName() + "' with encoding '" + encoding + "': using platform default"); } value = fileItem.getString(); } } else { value = fileItem.getString(); } String[] curParam = (String[]) multipartParameters.get(fileItem.getFieldName()); if (curParam == null) { // simple form field multipartParameters.put(fileItem.getFieldName(), new String[] { value }); } else { // array of simple form fields String[] newParam = StringUtils.addStringToArray(curParam, value); multipartParameters.put(fileItem.getFieldName(), newParam); } } else { // multipart file field CommonsMultipartFile file = new CommonsMultipartFile(fileItem); if (multipartFiles.put(fileItem.getName(), file) != null) { throw new MultipartException("Multiple files for field name [" + file.getName() + "] found - not supported by MultipartResolver"); } if (logger.isDebugEnabled()) { logger.debug("Found multipart file [" + file.getName() + "] of size " + file.getSize() + " bytes with original filename [" + file.getOriginalFilename() + "], stored " + file.getStorageDescription()); } } } return new MultipartParsingResult(multipartFiles, multipartParameters); } } What happens is that the last line in the method parseFileItems() (the return statement) i.e. return new MultipartParsingResult(multipartFiles, multipartParameters); causes a compile-time error because the first parameter multipartFiles is a type of Map implemented by HashMap but in reality, it requires a parameter of type MultiValueMap<String, MultipartFile> It is a constructor of a static class inside the abstract class CommonsFileUploadSupport, public abstract class CommonsFileUploadSupport { protected static class MultipartParsingResult { public MultipartParsingResult(MultiValueMap<String, MultipartFile> mpFiles, Map<String, String[]> mpParams) { } } } The reason might be - this solution is about the Spring version 2.5 and I'm using the Spring version 3.0.2 which might be inappropriate for this version. I however tried to replace the Map with MultiValueMap in various ways such as the one shown in the following segment of code, MultiValueMap<String, MultipartFile>mul=new LinkedMultiValueMap<String, MultipartFile>(); for(Entry<String, MultipartFile>entry:multipartFiles.entrySet()) { mul.add(entry.getKey(), entry.getValue()); } return new MultipartParsingResult(mul, multipartParameters); but no success. I'm not sure how to replace Map with MultiValueMap and even doing so could work either. After doing this, the browser shows the Http response, HTTP Status 400 - type Status report message description The request sent by the client was syntactically incorrect (). Apache Tomcat/6.0.26 I have tried to shorten the question as possible as I could and I haven't included unnecessary code. How could be made it possible to upload multiple files after Spring has been configured with HiddenHttpMethodFilter? That blog indicates that It is a long standing, high priority bug. If there is no solution regarding the version 3.0.2 (3 or higher) then I have to disable Spring support forever and continue to use commons-fileupolad as suggested by the third solution on that blog omitting the PUT, DELETE and other request methods forever. Just curiously waiting for a solution and/or suggestion. Very little changes to the code in the parseFileItems() method inside the class MultiCommonsMultipartResolver might make it to upload multiple files but I couldn't succeed in my attempts (again with the Spring version 3.0.2 (3 or higher)).

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• Running OpenMPI on Windows XP

  - by iamweird

  Hi there. I'm trying to build a simple cluster based on Windows XP. I compiled OpenMPI-1.4.2 successfully, and tools like mpicc and ompi_info work too, but I can't get my mpirun working properly. The only output I can see is Z:\orterun --hostfile z:\hosts.txt -np 2 hostname [host0:04728] Failed to initialize COM library. Error code = -2147417850 [host0:04728] [[8946,0],0] ORTE_ERROR_LOG: Error in file ..\..\openmpi-1.4.2 \orte\mca\ess\hnp\ess_hnp_module.c at line 218 -------------------------------------------------------------------------- It looks like orte_init failed for some reason; your parallel process is likely to abort. There are many reasons that a parallel process can fail during orte_init; some of which are due to configuration or environment problems. This failure appears to be an internal failure; here's some additional information (which may only be relevant to an Open MPI developer): orte_plm_init failed -- Returned value Error (-1) instead of ORTE_SUCCESS -------------------------------------------------------------------------- [host0:04728] [[8946,0],0] ORTE_ERROR_LOG: Error in file ..\..\openmpi-1.4.2 \orte\runtime\orte_init.c at line 132 -------------------------------------------------------------------------- It looks like orte_init failed for some reason; your parallel process is likely to abort. There are many reasons that a parallel process can fail during orte_init; some of which are due to configuration or environment problems. This failure appears to be an internal failure; here's some additional information (which may only be relevant to an Open MPI developer): orte_ess_set_name failed -- Returned value Error (-1) instead of ORTE_SUCCESS -------------------------------------------------------------------------- [host0:04728] [[8946,0],0] ORTE_ERROR_LOG: Error in file ..\..\..\..\openmpi -1.4.2\orte\tools\orterun\orterun.c at line 543 Where z:\hosts.txt appears as follows: host0 host1 Z: is a shared network drive available to both host0 and host1. What my problem is and how do I fix it? Upd: Ok, this problem seems to be fixed. It seems to me that WideCap driver and/or software components causes this error to appear. A "clean" machine runs local task successfully. Anyway, I still cannot run a task within at least 2 machines, I'm getting following message: Z:\mpirun --hostfile z:\hosts.txt -np 2 hostname connecting to host1 username:cluster password:******** Save Credential?(Y/N) y [host0:04728] This feature hasn't been implemented yet. [host0:04728] Could not connect to namespace cimv2 on node host1. Error code =-2147024891 -------------------------------------------------------------------------- mpirun was unable to start the specified application as it encountered an error. More information may be available above. -------------------------------------------------------------------------- I googled a little and did all the things as described here: http://www.open-mpi.org/community/lists/users/2010/03/12355.php but I'm still getting the same error. Can anyone help me? Upd2: Error code -2147024891 might be WMI error WBEM_E_INVALID_PARAMETER (0x80041008) which occures when one of the parameters passed to the WMI call is not correct. Does this mean that the problem is in OpenMPI source code itself? Or maybe it's because of wrong/outdated wincred.h and credui.lib I used while building OpenMPI from the source code?

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• Why isn't my File.Move() working?

  - by yeahumok

  I'm not sure what exactly i'm doing wrong here...but i noticed that my File.Move() isn't renaming any files. Also, does anybody know how in my 2nd loop, i'd be able to populate my .txt file with a list of the path AND sanitized file name? using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; using System.Text.RegularExpressions; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { //recurse through files. Let user press 'ok' to move onto next step string[] files = Directory.GetFiles(@"C:\Documents and Settings\jane.doe\Desktop\~Test Folder for [SharePoint] %testing", "*.*", SearchOption.AllDirectories); foreach (string file in files) { Console.Write(file + "\r\n"); } Console.WriteLine("Press any key to continue..."); Console.ReadKey(true); //End section //Regex -- find invalid chars string pattern = " *[\\~#%&*{}/<>?|\"-]+ *"; string replacement = " "; Regex regEx = new Regex(pattern); string[] fileDrive = Directory.GetFiles(@"C:\Documents and Settings\jane.doe\Desktop\~Test Folder for [SharePoint] %testing", "*.*", SearchOption.AllDirectories); List<string> filePath = new List<string>(); //clean out file -- remove the path name so file name only shows string result; foreach(string fileNames in fileDrive) { result = Path.GetFileName(fileNames); filePath.Add(result); } StreamWriter sw = new StreamWriter(@"C:\Documents and Settings\jane.doe\Desktop\~Test Folder for [SharePoint] %testing\File_Renames.txt"); //Sanitize and remove invalid chars foreach(string Files2 in filePath) { try { string sanitized = regEx.Replace(Files2, replacement); sw.Write(sanitized + "\r\n"); System.IO.File.Move(Files2, sanitized); System.IO.File.Delete(Files2); } catch (Exception ex) { Console.Write(ex); } } sw.Close(); } } } I'm VERY new to C# and trying to write an app that recurses through a specific drive, finds invalid characters (as specified in the RegEx pattern), removes them from the filename and then write a .txt file that has the path name and the corrected filename. Any ideas?

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• Copy image to BLOB from client pc aka Java function in Oracle

  - by mumich

  Hi guys, I've been stuck with this for past two days. I've go java function stored in Oracle system which is supposed to copy image from local drive do remote database and store it in BLOB - it's called CopyBLOB and looks like this: import java.sql.*; import oracle.sql.*; import java.io.*; public class CopyBLOB { static int id; static String fileName = null; static Connection conn = null; public CopyBLOB(int idz, String f) { id = idz; fileName = f; } public static void copy(int ident, String path) throws SQLException, FileNotFoundException { CopyBLOB cpB = new CopyBLOB(ident, path); cpB.getConnection(); cpB.callUpdate(id, fileName); } public void getConnection() throws SQLException { DriverManager.registerDriver (new oracle.jdbc.OracleDriver()); try { conn = DriverManager.getConnection("jdbc:oracle:thin:@oraserv.ms.mff.cuni.cz:1521:db", "xxx", "xxx"); } catch (SQLException sqlex) { System.out.println("SQLException while getting db connection: "+sqlex); if (conn != null) conn.close(); } catch (Exception ex) { System.out.println("Exception while getting db connection: "+ex); if (conn != null) conn.close(); } } public void callUpdate(int id, String file ) throws SQLException, FileNotFoundException { CallableStatement cs = null; try { conn.setAutoCommit(false); File f = new File(file); FileInputStream fin = new FileInputStream(f); cs = (CallableStatement) conn.prepareCall( "begin add_image(?,?); end;" ); cs.setInt(1, id ); cs.setBinaryStream(2, fin, (int) f.length()); cs.execute(); conn.setAutoCommit(true); } catch ( SQLException sqlex ) { System.out.println("SQLException in callUpdateUsingStream method of given status : " + sqlex.getMessage() ); } catch ( FileNotFoundException fnex ) { System.out.println("FileNotFoundException in callUpdateUsingStream method of given status : " + fnex.getMessage() ); } finally { try { if (cs != null) cs.close(); if (conn != null) conn.close(); } catch ( Exception ex ) { System.out.println("Some exception in callUpdateUsingStream method of given status : " + ex.getMessage( ) ); } } } } The wrapper function is defined in package "MyPackage" as folows: procedure image_adder( id varchar2, path varchar2 ) AS language java name 'CopyBLOB.copy(java.lang.String, java.lang.String)'; And the inserting function called image_add is as simple as this: procedure add_image( id numeric(10), pic blob) AS BEGIN insert into pictures values (seq_pic.nextval, id, pic); END add_image; Now the problem: When I type call MyPackage.image_adder(1, 'd:\samples\img.jpg'); I get the ORA-29531 Error: No method copy in class CopyBLOB. Can you help me, please?

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• Is MySQL Replication Appropriate in this case?

  - by MJB

  I have a series of databases, each of which is basically standalone. It initially seemed like I needed a replication solution, but the more I researched it, the more it felt like replication was overkill and not useful anyway. I have not done MySQL replication before, so I have been reading up on the online docs, googling, and searching SO for relevant questions, but I can't find a scenario quite like mine. Here is a brief description of my issue: The various databases almost never have a live connection to each other. They need to be able to "sync" by copying files to a thumb drive and then moving them to the proper destination. It is OK for the data to not match exactly, but they should have the same parent-child relationships. That is, if a generated key differs between databases, no big deal. But the visible data must match. Timing is not critical. Updates can be done a week later, or even a month later, as long as they are done eventually. Updates cannot be guaranteed to be in the proper order, or in any order for that matter. They will be in order from each database; just not between databases. Rather than a set of master-slave relationships, it is more like a central database (R/W) and multiple remote databases (also R/W). I won't know how many remote databases I have until they are created. And the central DB won't know that a database exists until data arrives from it. (To me, this implies I cannot use the method of giving each its own unique identity range to guarantee uniqueness in the central database.) It appears to me that the bottom line is that I don't want "replication" so much as I want "awareness". I want the central database to know what happened in the remote databases, but there is no time requirement. I want the remote databases to be aware of the central database, but they don't need to know about each other. WTH is my question? It is this: Does this scenario sound like any of the typical replication scenarios, or does it sound like I have to roll my own? Perhaps #7 above is the only one that matters, and given that requirement, out-of-the-box replication is impossible. EDIT: I realize that this question might be more suited to ServerFault. I also searched there and found no answers to my questions. And based on the replication questions I did find both on SO and SF, it seemed that the decision was 50-50 over where to put my question. Sorry if I guessed wrong.

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