nested loops - Page 106

A 3-D grid of regularly spaced points

- by Jack

I want to create a list containing the 3-D coords of a grid of regularly spaced points, each as a 3-element tuple. I'm looking for advice on the most efficient way to do this. In C++ for instance, I simply loop over three nested loops, one for each coordinate. In Matlab, I would probably use the meshgrid function (which would do it in one command). I've read about meshgrid and mgrid in Python, and I've also read that using numpy's broadcasting rules is more efficient. It seems to me that using the zip function in combination with the numpy broadcast rules might be the most efficient way, but zip doesn't seem to be overloaded in numpy.

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Clear All Event subscriptions (Clone linked)

- by mattias

I just implemented Clone from ICloneable and realized that the event subscriptions from my source instance also followed. Is there a good way to clear all those? Currently I am using a couple of these loops for every event I have to clear everything. foreach (var eventhandler in OnIdChanged.GetInvocationList()) { OnIdChanged -= (ItemEventHandler) eventhandler; } foreach (var eventhandler in OnNameChanged.GetInvocationList()) { ... This works fine but clutters the code a bit. Mostly worried to get event dangling.

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Second largest number in list python

- by Manu Lakaster

So I have to find THE SECOND LARGEST NUMBER IN A LIST. I am doing it through simple loops.My approach is I am going to divide a list into two parts and then find the largest number into two parts and then compare two nuumbers. I will choose the smaller number from two of them. I can not use ready functions or different approaches. Basically, this is my code....But it does not run correctly....Help me please to fix it because I spent a lot of time on it :( Thanks....P.S. Can we use indices to "divide" a list ??? #!/usr/local/bin/python2.7 alist=[-45,0,3,10,90,5,-2,4,18,45,100,1,-266,706] largest=alist[0] h=len(alist)/2 m=len(alist)-h print(alist) for i in alist: if alist[h]>largest: largest=alist[h] i=i+1 print(largest)

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C# Making private instance variable accesable (jagged array)

- by Chris

Hello, In a attempt to put some more oop in a program i am looking to make a private instance variable in one class (object) accesable to a class. private byte [][] J; All those code refers to this jagged array with this. Now in the other class i putted all the for loops along with the consolewritlines to display the wanted results. Basicly it says "the name J does not exist in the current context" But how exactly do i make this J accesable? I have tried with get and set but i keep getting 'cannot convert to byte to byte[][]' Also what kind of cyntax would i need with get and set? Something along like this? Or would i need several more steps? : public Byte JArray get { return J; } //can converrt to byte here set { J = value; } //cannnot convert to byte here Kind regards

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Script Doesnt Run All the Way Through

- by Chris

I have a php script that should execute 2 for loops. Both take awhile to run. I have called ignore_user_abort(true) and set_time_limit(0). The interesting thing is, the first for loop completes, then the script dies without calling the next line of code. ignore_user_abort(true); set_time_limit(0); for($i=0; $i<10500; ++$i) { //do work } mail('[email protected]', 'First loop done', 'None'); for($j=0;$j<12500; ++$j) { //do work } mail('[email protected]', 'Second loop done', 'None'); The first loop will finish after about 20 minutes, but the mail function is never called, the script just ends. Any ideas why this might be happening other than a timeout (I have run other scripts for days on my current configuration)?

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Need an efficient algorithm solve this kind of complex structure

- by Rizvan

Problem Statement is : Given 2 Dimensional array, print output for example If 4 rows and 6 columns, output would be: 1 2 3 4 5 6 16 17 18 19 20 7 15 24 23 22 21 8 14 13 12 11 10 9 I tried it is looking like square within square but when I attempted this problem, I put so many while and if loops but didn't got exact answer. If row and columns increases how to handle it? This is not homework. I was learning solving complex structure so I need to understand it by some guidance.

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Javascript function not working with an array

- by Ryan Harvie

Hi, i have this function which loops through an array of check boxes checking if the boxes value is equal to something in a text box, i dont know whats wrong. function checkValue(contain) { var boxes = document.getElementsByTagName("input"); for (var i = 0; i < boxes.length; i++) { if (boxes[i].name == "vote[]") { if (boxes[i].value.indexOf(contain.value) != -1) { boxes[i].checked = true; } } } } and this is how i call it OnClick="uncheckAll(); checkValue(document.getElementsByName("countrylist"));" this code is in side a echo in php which is like this echo ' ';

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how do I repaint an applet while moving a sprite?

- by Nagrom_17

I have a little java applet where I create 2 threads, one thread repaints and the other moves an image from a point to where the user clicks. The problem is that when I call the move function it loops until the image is where the user clicks but it wont repaint until I break out of the loop even though the thread doing the moving and the thread doing the painting are separate. shortened version of key points: my program is an applet using the paint() method I have 2 threads one moves an image and the other paints that image when I am moving the image it is in a while loop the painting thread is still calling repaint() but that is as far as the call goes, it never repaints thank you for your time.

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Python - How can I make this code asynchronous?

- by dave

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

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Sort vector<int>(n) in O(n) time using O(m) space?

- by Adam

I have a vector<unsigned int> vec of size n. Each element in vec is in the range [0, m], no duplicates, and I want to sort vec. Is it possible to do better than O(n log n) time if you're allowed to use O(m) space? In the average case m is much larger than n, in the worst case m == n. Ideally I want something O(n). I get the feeling that there's a bucket sort-ish way to do this: unsigned int aux[m]; aux[vec[i]] = i; Somehow extract the permutation and permute vec. I'm stuck on how to do 3. In my application m is on the order of 16k. However this sort is in the inner loops and accounts for a significant portion of my runtime.

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Python 2.7 creating a multidimensional list

- by poop

I don't know why I am having so much trouble creating a 3 dimensional list. I need the program to create an empty n by n list. So for n = 4: x = [[[],[],[],[]],[[],[],[],[]],[[],[],[],[]],[[],[],[],[]]] I've tried using: y = [n*[n*[]]] y = [[[]]* n for i in range(n)] Which both appear to be creating copies of a reference. I've also tried naieve application of the list builder with little success: y = [[[]* n for i in range(n)]* n for i in range(n)] y = [[[]* n for i in range(1)]* n for i in range(n)] I've also tried building up the array iteratively using loops, with no success. In my rapid flurry of attempts to not post something stupidly easy to SO, I came upon a solution: y = [] for i in range(0,n): y.append([[]*n for i in range(n)]) Is there an easier/ more intuitive way of doing this?

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Is it poor practice to identify objects via an enumeration property, instead of using GetType()?

- by James

I have a collection of objects that all implement one (custom) interface: IAuditEvent. Each object can be stored in a database and a unique numeric id is used for each object type. The method that stores the objects loops around a List<IAuditEvent>, so it needs to know the specific type of each object in order to store the correct numeric id. Is it poor practice to have an enumeration property on IAuditEvent so that each object can identify itself with a unique enumeration value? I can see that the simplest solution would be to write a method that translates a Type into an integer, but what if I need an enumeration of audit events for another purpose? Would it still be wrong to have my enumeration property on IAuditEvent?

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How to return a string from char[] array using recursion loop.(java)

- by Daniel

I am very bed in recursion... I need to convert a char[] array by using recursion loop only, into string. Without using for(),while()... loops. For example if i have char array: a[0]='H', a[1]='e', a[2]='l',a[3]= 'l',a[4]= 'o', it returns H e l l o. What I doing wrong? public String toFormattedString(char[] a) { int temp =a.length; if (a == null) return "null"; if (a.length == 0) return "0"; if( a.length == 1 ) else if( a[0] == a[a.length] ) return toFormattedString (a[a.length -1])+a[a.length];

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Way to kill python thread from inside thread?

- by user859434

I have some python code that currently performs expensive computation by performing the computation in parallel through many threads. For a given time period, many threads are created and started on the fly that share the same code which is explicitly stated within the run method of the thread. My question is how do I stop/kill a thread at the end of its run method? (the run is only called once) I need to do this in order to create more threads for the next batch of computation. #Example class someThread(threading.Thread): def __init__(self): #some init code def run(self): #Explicitly Stated Code without constant loops #Something performed to stop/kill this thread

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Image Preview in ASP.NET MVC

- by imran_ku07

Introduction : Previewing an image is a great way to improve the UI of your site. Also it is always best to check the file type, size and see a preview before submitting the whole form. There are some ways to do this using simple JavaScript but not work in all browsers (like FF3).In this Article I will show you how do this using ASP.NET MVC application. You also see how this will work in case of nested form. Description : Create a new ASP.NET MVC project and then add a file upload and image control into your View. <form id="form1" method="post" action="NerdDinner/ImagePreview/AjaxSubmit"> <table> <tr> <td> <input type="file" name="imageLoad1" id="imageLoad1" onchange="ChangeImage(this,'#imgThumbnail')" /> </td> </tr> <tr> <td align="center"> <img src="images/TempImage.gif" id="imgThumbnail" height="200px" width="200px"> </td> </tr> </table> </form> Note that here NerdDinner is refers to the virtual directory name, ImagePreview is the Controller and ImageLoad is the action name which you will see shortly I will use the most popular jQuery form plug-in, that turns a form into an AJAX form with very little code. Therefore you must get these from Jquery site and then add these files into your page. <script src="NerdDinner/Scripts/jquery-1.3.2.js" type="text/javascript"></script> <script src="NerdDinner/Scripts/jquery.form.js" type="text/javascript"></script> Then add the javascript function. <script type="text/javascript">function ChangeImage(fileId,imageId){ $("#form1").ajaxSubmit({success: function(responseText){ var d=new Date(); $(imageId)[0].src="NerdDinner/ImagePreview/ImageLoad?a="+d.getTime(); } });}</script> This function simply submit the form named form1 asynchronously to ImagePreviewController's method AjaxSubmit and after successfully receiving the response, it will set the image src property to the action method ImageLoad. Here I am also adding querystring, preventing the browser to serve the cached image. Now I will create a new Controller named ImagePreviewController. public class ImagePreviewController : Controller { [AcceptVerbs(HttpVerbs.Post)] public ActionResult AjaxSubmit(int? id) { Session["ContentLength"] = Request.Files[0].ContentLength; Session["ContentType"] = Request.Files[0].ContentType; byte[] b = new byte[Request.Files[0].ContentLength]; Request.Files[0].InputStream.Read(b, 0, Request.Files[0].ContentLength); Session["ContentStream"] = b; return Content( Request.Files[0].ContentType+";"+ Request.Files[0].ContentLength ); } public ActionResult ImageLoad(int? id) { byte[] b = (byte[])Session["ContentStream"]; int length = (int)Session["ContentLength"]; string type = (string)Session["ContentType"]; Response.Buffer = true; Response.Charset = ""; Response.Cache.SetCacheability(HttpCacheability.NoCache); Response.ContentType = type; Response.BinaryWrite(b); Response.Flush(); Session["ContentLength"] = null; Session["ContentType"] = null; Session["ContentStream"] = null; Response.End(); return Content(""); } } The AjaxSubmit action method will save the image in Session and return content type and content length in response. ImageLoad action method will return the contents of image in response.Then clear these Sessions. Just run your application and see the effect. Checking Size and Content Type of File: You may notice that AjaxSubmit action method is returning both content type and content length. You can check both properties before submitting your complete form. $(myform).ajaxSubmit({success: function(responseText) { var contentType=responseText.substring(0,responseText.indexOf(';')); var contentLength=responseText.substring(responseText.indexOf(';')+1); // Here you can do your validation var d=new Date(); $(imageId)[0].src="http://weblogs.asp.net/MoneypingAPP/ImagePreview/ImageLoad?a="+d.getTime(); } }); Handling Nested Form Case: The above code will work if you have only one form. But this is not the case always.You may have a form control which wraps all the controls and you do not want to submit the whole form, just for getting a preview effect. In this case you need to create a dynamic form control using JavaScript, and then add file upload control to this form and submit the form asynchronously function ChangeImage(fileId,imageId) { var myform=document.createElement("form"); myform.action="NerdDinner/ImagePreview/AjaxSubmit"; myform.enctype="multipart/form-data"; myform.method="post"; var imageLoad=document.getElementById(fileId).cloneNode(true); myform.appendChild(imageLoad); document.body.appendChild(myform); $(myform).ajaxSubmit({success: function(responseText) { var contentType=responseText.substring(0,responseText.indexOf(';')); var contentLength=responseText.substring(responseText.indexOf(';')+1); var d=new Date(); $(imageId)[0].src="http://weblogs.asp.net/MoneypingAPP/ImagePreview/ImageLoad?a="+d.getTime(); document.body.removeChild(myform); } }); } You also need append the child in order to send request and remove them after receiving response.

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"const char *" is incompatible with parameter of type "LPCWSTR" error

- by N0xus

I'm trying to incorporate some code from Programming an RTS Game With Direct3D into my game. Before anyone says it, I know the book is kinda old, but it's the particle effects system he creates that I'm trying to use. With his shader class, he intialise it thusly: void SHADER::Init(IDirect3DDevice9 *Dev, const char fName[], int typ) { m_pDevice = Dev; m_type = typ; if(m_pDevice == NULL)return; // Assemble and set the pixel or vertex shader HRESULT hRes; LPD3DXBUFFER Code = NULL; LPD3DXBUFFER ErrorMsgs = NULL; if(m_type == PIXEL_SHADER) hRes = D3DXCompileShaderFromFile(fName, NULL, NULL, "Main", "ps_2_0", D3DXSHADER_DEBUG, &Code, &ErrorMsgs, &m_pConstantTable); else hRes = D3DXCompileShaderFromFile(fName, NULL, NULL, "Main", "vs_2_0", D3DXSHADER_DEBUG, &Code, &ErrorMsgs, &m_pConstantTable); } How ever, this generates the following error: Error 1 error C2664: 'D3DXCompileShaderFromFileW' : cannot convert parameter 1 from 'const char []' to 'LPCWSTR' The compiler states the issue is with fName in the D3DXCompileShaderFromFile line. I know this has something to do with the character set, and my program was already running with a Unicode Character set on the go. I read that to solve the above problem, I need to switch to a multi-byte character set. But, if I do that, I get other errors in my code, like so: Error 2 error C2664: 'D3DXCreateEffectFromFileA' : cannot convert parameter 2 from 'const wchar_t *' to 'LPCSTR' With it being accredited to the following line of code: if(FAILED(D3DXCreateEffectFromFile(m_pD3DDevice9,effectFileName.c_str(),NULL,NULL,0,NULL,&m_pCurrentEffect,&pErrorBuffer))) This if is nested within another if statement checking my effectmap list. Though it is the FAILED word with the red line. Like wise I get the another error with the following line of code: wstring effectFileName = TEXT("Sky.fx"); With the error message being: Error 1 error C2440: 'initializing' : cannot convert from 'const char [7]' to 'std::basic_string<_Elem,_Traits,_Ax' If I change it back to a Uni code character set, I get the original (fewer) errors. Leaving as a multi-byte, I get more errors. Does anyone know of a way I can fix this issue?

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BizTalk 2009 - Naming Guidelines

- by StuartBrierley

The following is effectively a repost of the BizTalk 2004 naming guidlines that I have previously detailed. I have posted these again for completeness under BizTalk 2009 and to allow an element of separation in case I find some reason to amend these for BizTalk 2009. These guidlines should be universal across any version of BizTalk you may wish to apply them to. General Rules All names should be named with a Pascal convention. Project Namespaces For message schemas: [CompanyName].XML.Schemas.[FunctionalName]* Examples: ABC.XML.Schemas.Underwriting DEF.XML.Schemas.MarshmellowTradingExchange * Donates potential for multiple levels of functional name, such as Underwriting.Dictionary.Valuation For web services: [CompanyName].Web.Services.[FunctionalName] Examples: ABC.Web.Services.OrderJellyBeans For the main BizTalk Projects: [CompanyName].BizTalk.[AssemblyType].[FunctionalName]* Examples: ABC.BizTalk.Mappings.Underwriting ABC.BizTalk.Orchestrations.Underwriting * Donates potential for multiple levels of functional name, such as Mappings.Underwriting.Valuations Assemblies BizTalk Assembly names should match the associated Project Namespace, such as ABC.BizTalk.Mappings.Underwriting. This pertains to the formal assembly name and the DLL name. The Solution name should take the name of the main project within the solution, and also therefore the namespace for that project. Although long names such as this can be unwieldy to work with, the benefits of having the full scope available when the assemblies are installed on the target server are generally judged to outweigh this inconvenience. Messaging Artifacts Artifact Standard Notes Example Schema <DescriptiveName>.xsd .NET Type name should match, without file extension. .NET Namespace will likely match assembly name. PurchaseOrderAcknowledge_FF.xsd or FNMA100330_FF.xsd Property Schema <DescriptiveName>.xsd Should be named to reflect possible common usage across multiple schemas IspecMessagePropertySchema.xsd UnderwritingOrchestrationKeys.xsd Map <SourceSchema>2<DestinationSchema>.btm Exceptions to this may be made where the source and destination schemas share the majority of the name, such as in mainframe web service maps InstructionResponse2CustomEmailRequest.btm (exception example) AccountCustomerAddressSummaryRequest2MainframeRequest.btm Orchestration <DescriptiveName>.odx GetValuationReports.odx SendMTEDecisionResponse.odx Send/Receive Pipeline <DescriptiveName>.btp ValidatingXMLReceivePipeline.btp FlatFileAssembler.btp Receive Port A plainly worded phrase that will clearly explain the function. FraudPreventionServices LetterProcessing Receive Location A plainly worded phrase that will clearly explain the function. ? Do we want to include the transport type here ? Arrears Web Service Send Port Group A plainly worded phrase that will clearly explain the function. Customer Updates Send Port A plainly worded phrase that will clearly explain the function. ABCProductUpdater LogLendingPolicyOutput Parties A meaningful name for a Trading Partner. If dealing with multiple entities within a Trading Partner organization, the Organization name could be used as a prefix. Roles A meaningful name for the role that a Trading Partner plays. Orchestration Workflow Shapes Shape Standard Notes Example Scopes <DescriptionOfContainedWork> or <DescOfcontainedWork><TxType> Including info about transaction type may be appropriate in some situations where it adds significant documentation value to the diagram. HandleReportResponse Receive Receive<MessageName> Typically, MessageName will be the same as the name of the message variable that is being received “into”. ReceiveReportResponse Send Send<MessageName> Typically, MessageName will be the same as the name of the message variable that is being sent. SendValuationDetailsRequest Expression <DescriptionOfEffect> Expression shapes should be named to describe the net effect of the expression, similar to naming a method. The exception to this is the case where the expression is interacting with an external .NET component to perform a function that overlaps with existing BizTalk functionality – use closest BizTalk shape for this case. CreatePrintXML Decide <DescriptionOfDecision> A description of what will be decided in the “if” branch Report Type? Perform MF Save? If-Branch <DescriptionOfDecision> A (potentially abbreviated) description of what is being decided Mortgage Valuation Yes Else-Branch Else Else-branch shapes should always be named “Else” Else Construct Message (Assign) Create<Message> (for Construct) <ExpressionDescription> (for expression) If a Construct shape contains a message assignment, it should be prefixed with “Create” followed by an abbreviated name of the message being assigned. The actual message assignment shape contained should be named to describe the expression that is contained. CreateReportDataMV which contains expression: ExtractReportData Construct Message (Transform) Create<Message> (for Construct) <SourceSchema>2<DestSchema> (for transform) If a Construct shape contains a message transform, it should be prefixed with “Create” followed by an abbreviated name of the message being assigned. The actual message transform shape contained should generally be named the same as the called map. CreateReportDataMV which contains transform: ReportDataMV2ReportDataMV Construct Message (containing multiple shapes) If a Construct Message shape uses multiple assignments or transforms, the overall shape should be named to communicate the net effect, using no prefix. Call/Start Orchestration Call<OrchestrationName> Start<OrchestrationName> Throw Throw<ExceptionType> The corresponding variable name for the exception type should (often) be the same name as the exception type, only camel-cased. ThrowRuleException, which references the “ruleException” variable. Parallel <DescriptionOfParallelWork> Parallel shapes should be named by a description of what work will be done in parallel Delay <DescriptionOfWhatWaitingFor> Delay shapes should be named by a description of what is being waited for. POAcknowledgeTimeout Listen <DescriptionOfOutcomes> Listen shapes should be named by a description that captures (to the degree possible) all the branches of the Listen shape POAckOrTimeout FirstShippingBid Loop <DescriptionOfLoop> A (potentially abbreviated) description of what the loop is. ForEachValuationReport WhileErrorFlagTrue Role Link See “Roles” in messaging naming conventions above. Suspend <ReasonDescription> Describe what action an administrator must take to resume the orchestration. More detail can be passed to error property – and should include what should be done by the administrator before resuming the orchestration. ReEstablishCreditLink Terminate <ReasonDescription> Describe why the orchestration terminated. More detail can be passed to error property. TimeoutsExpired Call Rules Call<PolicyName> The policy name may need to be abbreviated. CallLendingPolicy Compensate Compensate or Compensate<TxName> If the shape compensates nested transactions, names should be suffixed with the name of the nested transaction – otherwise it should simple be Compensate. CompensateTransferFunds Orchestration Types Type Standard Notes Example Multi-Part Message Types <LogicalDocumentType> Multi-part types encapsulate multiple parts. The WSDL spec indicates “parts are a flexible mechanism for describing the logical abstract content of a message.” The name of the multi-part type should correspond to the “logical” document type, i.e. what the sum of the parts describes. InvoiceReceipt (which might encapsulate an invoice acknowledgement and a payment voucher.) Multi-Part Messsage Part <SchemaNameOfPart> Should be named (most often) simply for the schema (or simple type) associated with the part. InvoiceHeader Messages <SchemaName> or <MuliPartMessageTypeName> Should be named based on the corresponding schema type or multi-part message type. If there is more than one variable of a type, name for its use within the orchestration. ReportDataMV UpdatedReportDataMV Variables <DescriptiveName> TargetFilePath StringProcessor Port Types <FunctionDescription>PortType Should be named to suggest the nature of an endpoint, with pascal casing and suffixed with “PortType”. If there will be more than one Port for a Port Type, the Port Type should be named according to the abstract service supplied. The WSDL spec indicates port types are “a named set of abstract operations and the abstract messages involved” that also encapsulates the message pattern (i.e. one-way, request-response, solicit-response) that all operations on the port type adhere to. ReceiveReportResponsePortType or CallEAEPortType (This is a two way port, so Receove or Send alone would not be appropriate. Could have been ProcessEAERequestPortType etc....) Ports <FunctionDescription>Port Should be named to suggest a grouping of functionality, with pascal casing and suffixed with “Port.” ReceiveReportResponsePort CallEAEPort Correlation types <DescriptiveName> Should be named based on the logical name of what is being used to correlate. PurchaseOrderNumber Correlation sets <DescriptiveName> Should be named based on the corresponding correlation type. If there is more than one, it should be named to reflect its specific purpose within the orchestration. PurchaseOrderNumber Orchestration parameters <DescriptiveName> Should be named to match the caller’s names for the corresponding variables where appropriate.

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SQL SERVER – Copy Statistics from One Server to Another Server

- by pinaldave

I was recently working on a performance tuning project in Dubai (yeah I was able to see the tallest tower from the window of my work place). I had a very interesting learning experience there. There was a situation where we wanted to receive the schema of original database from a certain client. However, the client was not able to provide us any data due to privacy issues. The schema was very important because without having an access to underlying data, it was a bit difficult to judge the queries etc. For example, without any primary data, all the queries are running in 0 (zero) milliseconds and all were using nested loop as there were no data to be returned. Even though we had CPU offending queries, they were not doing anything without the data in the tables. This was really a challenge as I did not have access to production server data and I could not recreate the scenarios as production without data. Well, I was confused but Ruben from Solid Quality Mentors, Spain taught me new tricks. He suggested that when table schema is generated, we can create the statistics consequently. Here is how we had done that: Once statistics is created along with the schema, without data in the table, all the queries will work as how they will work on production server. This way, without access to the data, we were able to recreate the same scenario as production server on development server. When observed at the script, you will find that the statistics were also generated along with the query. You will find statistics included in WITH STATS_STREAM clause. What a very simple and effective script. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology Tagged: SQL Statistics, Statistics

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Scripting with the Sun ZFS Storage 7000 Appliance

- by Geoff Ongley

The Sun ZFS Storage 7000 appliance has a user friendly and easy to understand graphical web based interface we call the "BUI" or "Browser User Interface".This interface is very useful for many tasks, but in some cases a script (or workflow) may be more appropriate, such as:Repetitive tasksTasks which work on (or obtain information about) a large number of shares or usersTasks which are triggered by an alert threshold (workflows)Tasks where you want a only very basic input, but a consistent output (workflows)The appliance scripting language is based on ECMAscript 3 (close to javascript). I'm not going to cover ECMAscript 3 in great depth (I'm far from an expert here), but I would like to show you some neat things you can do with the appliance, to get you started based on what I have found from my own playing around.I'm making the assumption you have some sort of programming background, and understand variables, arrays, functions to some extent - but of course if something is not clear, please let me know so I can fix it up or clarify it.Variable Declarations and ArraysVariablesECMAScript is a dynamically and weakly typed language. If you don't know what that means, google is your friend - but at a high level it means we can just declare variables with no specific type and on the fly.For example, I can declare a variable and use it straight away in the middle of my code, for example:projects=list();Which makes projects an array of values that are returned from the list(); function (which is usable in most contexts). With this kind of variable, I can do things like:projects.length (this property on array tells you how many objects are in it, good for for loops etc). Alternatively, I could say:projects=3;and now projects is just a simple number.Should we declare variables like this so loosely? In my opinion, the answer is no - I feel it is a better practice to declare variables you are going to use, before you use them - and given them an initial value. You can do so as follows:var myVariable=0;To demonstrate the ability to just randomly assign and change the type of variables, you can create a simple script at the cli as follows (bold for input):fishy10:> script("." to run)> run("cd /");("." to run)> run ("shares");("." to run)> var projects;("." to run)> projects=list();("." to run)> printf("Number of projects is: %d\n",projects.length);("." to run)> projects=152;("." to run)> printf("Value of the projects variable as an integer is now: %d\n",projects);("." to run)> .Number of projects is: 7Value of the projects variable as an integer is now: 152You can also confirm this behaviour by checking the typeof variable we are dealing with:fishy10:> script("." to run)> run("cd /");("." to run)> run ("shares");("." to run)> var projects;("." to run)> projects=list();("." to run)> printf("var projects is of type %s\n",typeof(projects));("." to run)> projects=152;("." to run)> printf("var projects is of type %s\n",typeof(projects));("." to run)> .var projects is of type objectvar projects is of type numberArraysSo you likely noticed that we have already touched on arrays, as the list(); (in the shares context) stored an array into the 'projects' variable.But what if you want to declare your own array? Easy! This is very similar to Java and other languages, we just instantiate a brand new "Array" object using the keyword new:var myArray = new Array();will create an array called "myArray".A quick example:fishy10:> script("." to run)> testArray = new Array();("." to run)> testArray[0]="This";("." to run)> testArray[1]="is";("." to run)> testArray[2]="just";("." to run)> testArray[3]="a";("." to run)> testArray[4]="test";("." to run)> for (i=0; i < testArray.length; i++)("." to run)> {("." to run)> printf("Array element %d is %s\n",i,testArray[i]);("." to run)> }("." to run)> .Array element 0 is ThisArray element 1 is isArray element 2 is justArray element 3 is aArray element 4 is testWorking With LoopsFor LoopFor loops are very similar to those you will see in C, java and several other languages. One of the key differences here is, as you were made aware earlier, we can be a bit more sloppy with our variable declarations.The general way you would likely use a for loop is as follows:for (variable; test-case; modifier for variable){}For example, you may wish to declare a variable i as 0; and a MAX_ITERATIONS variable to determine how many times this loop should repeat:var i=0;var MAX_ITERATIONS=10;And then, use this variable to be tested against some case existing (has i reached MAX_ITERATIONS? - if not, increment i using i++);for (i=0; i < MAX_ITERATIONS; i++){ // some work to do}So lets run something like this on the appliance:fishy10:> script("." to run)> var i=0;("." to run)> var MAX_ITERATIONS=10;("." to run)> for (i=0; i < MAX_ITERATIONS; i++)("." to run)> {("." to run)> printf("The number is %d\n",i);("." to run)> }("." to run)> .The number is 0The number is 1The number is 2The number is 3The number is 4The number is 5The number is 6The number is 7The number is 8The number is 9While LoopWhile loops again are very similar to other languages, we loop "while" a condition is met. For example:fishy10:> script("." to run)> var isTen=false;("." to run)> var counter=0;("." to run)> while(isTen==false)("." to run)> {("." to run)> if (counter==10) ("." to run)> { ("." to run)> isTen=true; ("." to run)> } ("." to run)> printf("Counter is %d\n",counter);("." to run)> counter++; ("." to run)> }("." to run)> printf("Loop has ended and Counter is %d\n",counter);("." to run)> .Counter is 0Counter is 1Counter is 2Counter is 3Counter is 4Counter is 5Counter is 6Counter is 7Counter is 8Counter is 9Counter is 10Loop has ended and Counter is 11So what do we notice here? Something has actually gone wrong - counter will technically be 11 once the loop completes... Why is this?Well, if we have a loop like this, where the 'while' condition that will end the loop may be set based on some other condition(s) existing (such as the counter has reached 10) - we must ensure that we terminate this iteration of the loop when the condition is met - otherwise the rest of the code will be followed which may not be desirable. In other words, like in other languages, we will only ever check the loop condition once we are ready to perform the next iteration, so any other code after we set "isTen" to be true, will still be executed as we can see it was above.We can avoid this by adding a break into our loop once we know we have set the condition - this will stop the rest of the logic being processed in this iteration (and as such, counter will not be incremented). So lets try that again:fishy10:> script("." to run)> var isTen=false;("." to run)> var counter=0;("." to run)> while(isTen==false)("." to run)> {("." to run)> if (counter==10) ("." to run)> { ("." to run)> isTen=true; ("." to run)> break;("." to run)> } ("." to run)> printf("Counter is %d\n",counter);("." to run)> counter++; ("." to run)> }("." to run)> printf("Loop has ended and Counter is %d\n", counter);("." to run)> .Counter is 0Counter is 1Counter is 2Counter is 3Counter is 4Counter is 5Counter is 6Counter is 7Counter is 8Counter is 9Loop has ended and Counter is 10Much better!Methods to Obtain and Manipulate DataGet MethodThe get method allows you to get simple properties from an object, for example a quota from a user. The syntax is fairly simple:var myVariable=get('property');An example of where you may wish to use this, is when you are getting a bunch of information about a user (such as quota information when in a shares context):var users=list();for(k=0; k < users.length; k++){ user=users[k]; run('select ' + user); var username=get('name'); var usage=get('usage'); var quota=get('quota');...Which you can then use to your advantage - to print or manipulate infomation (you could change a user's information with a set method, based on the information returned from the get method). The set method is explained next.Set MethodThe set method can be used in a simple manner, similar to get. The syntax for set is:set('property','value'); // where value is a string, if it was a number, you don't need quotesFor example, we could set the quota on a share as follows (first observing the initial value):fishy10:shares default/test-geoff> script("." to run)> var currentQuota=get('quota');("." to run)> printf("Current Quota is: %s\n",currentQuota);("." to run)> set('quota','30G');("." to run)> run('commit');("." to run)> currentQuota=get('quota');("." to run)> printf("Current Quota is: %s\n",currentQuota);("." to run)> .Current Quota is: 0Current Quota is: 32212254720This shows us using both the get and set methods as can be used in scripts, of course when only setting an individual share, the above is overkill - it would be much easier to set it manually at the cli using 'set quota=3G' and then 'commit'.List MethodThe list method can be very powerful, especially in more complex scripts which iterate over large amounts of data and manipulate it if so desired. The general way you will use list is as follows:var myVar=list();Which will make "myVar" an array, containing all the objects in the relevant context (this could be a list of users, shares, projects, etc). You can then gather or manipulate data very easily.We could list all the shares and mountpoints in a given project for example:fishy10:shares another-project> script("." to run)> var shares=list();("." to run)> for (i=0; i < shares.length; i++)("." to run)> {("." to run)> run('select ' + shares[i]);("." to run)> var mountpoint=get('mountpoint');("." to run)> printf("Share %s discovered, has mountpoint %s\n",shares[i],mountpoint);("." to run)> run('done');("." to run)> }("." to run)> .Share and-another discovered, has mountpoint /export/another-project/and-anotherShare another-share discovered, has mountpoint /export/another-project/another-shareShare bob discovered, has mountpoint /export/another-projectShare more-shares-for-all discovered, has mountpoint /export/another-project/more-shares-for-allShare yep discovered, has mountpoint /export/another-project/yepWriting More Complex and Re-Usable CodeFunctionsThe best way to be able to write more complex code is to use functions to split up repeatable or reusable sections of your code. This also makes your more complex code easier to read and understand for other programmers.We write functions as follows:function functionName(variable1,variable2,...,variableN){}For example, we could have a function that takes a project name as input, and lists shares for that project (assuming we're already in the 'project' context - context is important!):function getShares(proj){ run('select ' + proj); shares=list(); printf("Project: %s\n", proj); for(j=0; j < shares.length; j++) { printf("Discovered share: %s\n",shares[i]); } run('done'); // exit selected project}Commenting your CodeLike any other language, a large part of making it readable and understandable is to comment it. You can use the same comment style as in C and Java amongst other languages.In other words, sngle line comments use://at the beginning of the comment.Multi line comments use:/*at the beginning, and:*/ at the end.For example, here we will use both:fishy10:> script("." to run)> // This is a test comment("." to run)> printf("doing some work...\n");("." to run)> /* This is a multi-line("." to run)> comment which I will span across("." to run)> three lines in total */("." to run)> printf("doing some more work...\n");("." to run)> .doing some work...doing some more work...Your comments do not have to be on their own, they can begin (particularly with single line comments this is handy) at the end of a statement, for examplevar projects=list(); // The variable projects is an array containing all projects on the system.Try and Catch StatementsYou may be used to using try and catch statements in other languages, and they can (and should) be utilised in your code to catch expected or unexpected error conditions, that you do NOT wish to stop your code from executing (if you do not catch these errors, your script will exit!):try{ // do some work}catch(err) // Catch any error that could occur{ // do something here under the error condition}For example, you may wish to only execute some code if a context can be reached. If you can't perform certain actions under certain circumstances, that may be perfectly acceptable.For example if you want to test a condition that only makes sense when looking at a SMB/NFS share, but does not make sense when you hit an iscsi or FC LUN, you don't want to stop all processing of other shares you may not have covered yet.For example we may wish to obtain quota information on all shares for all users on a share (but this makes no sense for a LUN):function getShareQuota(shar) // Get quota for each user of this share{ run('select ' + shar); printf(" SHARE: %s\n", shar); try { run('users'); printf(" %20s %11s %11s %3s\n","Username","Usage(G)","Quota(G)","Quota(%)"); printf(" %20s %11s %11s %4s\n","--------","--------","--------","----"); users=list(); for(k=0; k < users.length; k++) { user=users[k]; getUserQuota(user); } run('done'); // exit user context } catch(err) { printf(" SKIPPING %s - This is NOT a NFS or CIFs share, not looking for users\n", shar); } run('done'); // done with this share}Running Scripts Remotely over SSHAs you have likely noticed, writing and running scripts for all but the simplest jobs directly on the appliance is not going to be a lot of fun.There's a couple of choices on what you can do here:Create scripts on a remote system and run them over sshCreate scripts, wrapping them in workflow code, so they are stored on the appliance and can be triggered under certain circumstances (like a threshold being reached)We'll cover the first one here, and then cover workflows later on (as these are for the most part just scripts with some wrapper information around them).Creating a SSH Public/Private SSH Key PairLog on to your handy Solaris box (You wouldn't be using any other OS, right? :P) and use ssh-keygen to create a pair of ssh keys. I'm storing this separate to my normal key:[geoff@lightning ~] ssh-keygen -t rsa -b 1024Generating public/private rsa key pair.Enter file in which to save the key (/export/home/geoff/.ssh/id_rsa): /export/home/geoff/.ssh/nas_key_rsaEnter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /export/home/geoff/.ssh/nas_key_rsa.Your public key has been saved in /export/home/geoff/.ssh/nas_key_rsa.pub.The key fingerprint is:7f:3d:53:f0:2a:5e:8b:2d:94:2a:55:77:66:5c:9b:14 geoff@lightningInstalling the Public Key on the ApplianceOn your Solaris host, observe the public key:[geoff@lightning ~] cat .ssh/nas_key_rsa.pub ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAvYfK3RIaAYmMHBOvyhKM41NaSmcgUMC3igPN5gUKJQvSnYmjuWG6CBr1CkF5UcDji7v19jG3qAD5lAMFn+L0CxgRr8TNaAU+hA4/tpAGkjm+dKYSyJgEdMIURweyyfUFXoerweR8AWW5xlovGKEWZTAfvJX9Zqvh8oMQ5UJLUUc= geoff@lightningNow, copy and paste everything after "ssh-rsa" and before "user@hostname" - in this case, geoff@lightning. That is, this bit:AAAAB3NzaC1yc2EAAAABIwAAAIEAvYfK3RIaAYmMHBOvyhKM41NaSmcgUMC3igPN5gUKJQvSnYmjuWG6CBr1CkF5UcDji7v19jG3qAD5lAMFn+L0CxgRr8TNaAU+hA4/tpAGkjm+dKYSyJgEdMIURweyyfUFXoerweR8AWW5xlovGKEWZTAfvJX9Zqvh8oMQ5UJLUUc=Logon to your appliance and get into the preferences -> keys area for this user (root):[geoff@lightning ~] ssh [email protected]: Last login: Mon Dec 6 17:13:28 2010 from 192.168.0.2fishy10:> configuration usersfishy10:configuration users> select rootfishy10:configuration users root> preferences fishy10:configuration users root preferences> keysOR do it all in one hit:fishy10:> configuration users select root preferences keysNow, we create a new public key that will be accepted for this user and set the type to RSA:fishy10:configuration users root preferences keys> createfishy10:configuration users root preferences key (uncommitted)> set type=RSASet the key itself using the string copied previously (between ssh-rsa and user@host), and set the key ensuring you put double quotes around it (eg. set key="<key>"):fishy10:configuration users root preferences key (uncommitted)> set key="AAAAB3NzaC1yc2EAAAABIwAAAIEAvYfK3RIaAYmMHBOvyhKM41NaSmcgUMC3igPN5gUKJQvSnYmjuWG6CBr1CkF5UcDji7v19jG3qAD5lAMFn+L0CxgRr8TNaAU+hA4/tpAGkjm+dKYSyJgEdMIURweyyfUFXoerweR8AWW5xlovGKEWZTAfvJX9Zqvh8oMQ5UJLUUc="Now set the comment for this key (do not use spaces):fishy10:configuration users root preferences key (uncommitted)> set comment="LightningRSAKey" Commit the new key:fishy10:configuration users root preferences key (uncommitted)> commitVerify the key is there:fishy10:configuration users root preferences keys> lsKeys:NAME MODIFIED TYPE COMMENT key-000 2010-10-25 20:56:42 RSA cycloneRSAKey key-001 2010-12-6 17:44:53 RSA LightningRSAKey As you can see, we now have my new key, and a previous key I have created on this appliance.Running your Script over SSH from a Remote SystemHere I have created a basic test script, and saved it as test.ecma3:[geoff@lightning ~] cat test.ecma3 script// This is a test script, By Geoff Ongley 2010.printf("Testing script remotely over ssh\n");.Now, we can run this script remotely with our keyless login:[geoff@lightning ~] ssh -i .ssh/nas_key_rsa root@fishy10 < test.ecma3Pseudo-terminal will not be allocated because stdin is not a terminal.Testing script remotely over sshPutting it Together - An Example Completed Quota Gathering ScriptSo now we have a lot of the basics to creating a script, let us do something useful, like, find out how much every user is using, on every share on the system (you will recognise some of the code from my previous examples): script/************************************** Quick and Dirty Quota Check script ** Written By Geoff Ongley ** 25 October 2010 **************************************/function getUserQuota(usr){ run('select ' + usr); var username=get('name'); var usage=get('usage'); var quota=get('quota'); var usage_g=usage / 1073741824; // convert bytes to gigabytes var quota_g=quota / 1073741824; // as above var quota_percent=0 if (quota > 0) { quota_percent=(usage / quota)*(100/1); } printf(" %20s %8.2f %8.2f %d%%\n",username,usage_g,quota_g,quota_percent); run('done'); // done with this selected user}function getShareQuota(shar){ //printf("DEBUG: selecting share %s\n", shar); run('select ' + shar); printf(" SHARE: %s\n", shar); try { run('users'); printf(" %20s %11s %11s %3s\n","Username","Usage(G)","Quota(G)","Quota(%)"); printf(" %20s %11s %11s %4s\n","--------","--------","--------","--------"); users=list(); for(k=0; k < users.length; k++) { user=users[k]; getUserQuota(user); } run('done'); // exit user context } catch(err) { printf(" SKIPPING %s - This is NOT a NFS or CIFs share, not looking for users\n", shar); } run('done'); // done with this share}function getShares(proj){ //printf("DEBUG: selecting project %s\n",proj); run('select ' + proj); shares=list(); printf("Project: %s\n", proj); for(j=0; j < shares.length; j++) { share=shares[j]; getShareQuota(share); } run('done'); // exit selected project}function getProjects(){ run('cd /'); run('shares'); projects=list(); for (i=0; i < projects.length; i++) { var project=projects[i]; getShares(project); } run('done'); // exit context for all projects}getProjects();.Which can be run as follows, and will print information like this:[geoff@lightning ~/FISHWORKS_SCRIPTS] ssh -i ~/.ssh/nas_key_rsa root@fishy10 < get_quota_utilisation.ecma3Pseudo-terminal will not be allocated because stdin is not a terminal.Project: another-project SHARE: and-another Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- nobody 0.00 0.00 0% geoffro 0.05 0.00 0% Billy 0.10 0.00 0% root 0.00 0.00 0% testing-user 0.05 0.00 0% SHARE: another-share Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- root 0.00 0.00 0% nobody 0.00 0.00 0% geoffro 0.05 0.49 9% testing-user 0.05 0.02 249% Billy 0.10 0.29 33% SHARE: bob Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- nobody 0.00 0.00 0% root 0.00 0.00 0% SHARE: more-shares-for-all Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- Billy 0.10 0.00 0% testing-user 0.05 0.00 0% nobody 0.00 0.00 0% root 0.00 0.00 0% geoffro 0.05 0.00 0% SHARE: yep Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- root 0.00 0.00 0% nobody 0.00 0.00 0% Billy 0.10 0.01 999% testing-user 0.05 0.49 9% geoffro 0.05 0.00 0%Project: default SHARE: Test-LUN SKIPPING Test-LUN - This is NOT a NFS or CIFs share, not looking for users SHARE: test-geoff Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- geoffro 0.05 0.00 0% root 3.18 10.00 31% uucp 0.00 0.00 0% nobody 0.59 0.49 119%^CKilled by signal 2.Creating a WorkflowWorkflows are scripts that we store on the appliance, and can have the script execute either on request (even from the BUI), or on an event such as a threshold being met.Workflow BasicsA workflow allows you to create a simple process that can be executed either via the BUI interface interactively, or by an alert being raised (for some threshold being reached, for example).The basics parameters you will have to set for your "workflow object" (notice you're creating a variable, that embodies ECMAScript) are as follows (parameters is optional):name: A name for this workflowdescription: A Description for the workflowparameters: A set of input parameters (useful when you need user input to execute the workflow)execute: The code, the script itself to execute, which will be function (parameters)With parameters, you can specify things like this (slightly modified sample taken from the System Administration Guide): ...parameters: variableParam1: { label: 'Name of Share', type: 'String' }, variableParam2 { label: 'Share Size', type: 'size' },execute: ....}; Note the commas separating the sections of name, parameters, execute, and so on. This is important!Also - there is plenty of properties you can set on the parameters for your workflow, these are described in the Sun ZFS Storage System Administration Guide.Creating a Basic Workflow from a Basic ScriptTo make a basic script into a basic workflow, you need to wrap the following around your script to create a 'workflow' object:var workflow = {name: 'Get User Quotas',description: 'Displays Quota Utilisation for each user on each share',execute: function() {// (basic script goes here, minus the "script" at the beginning, and "." at the end)}};However, it appears (at least in my experience to date) that the workflow object may only be happy with one function in the execute parameter - either that or I'm doing something wrong. As far as I can tell, after execute: you should only have a basic one function context like so:execute: function(){}To deal with this, and to give an example similar to our script earlier, I have created another simple quota check, to show the same basic functionality, but in a workflow format:var workflow = {name: 'Get User Quotas',description: 'Displays Quota Utilisation for each user on each share',execute: function () { run('cd /'); run('shares'); projects=list(); for (i=0; i < projects.length; i++) { run('select ' + projects[i]); shares=list('filesystem'); printf("Project: %s\n", projects[i]); for(j=0; j < shares.length; j++) { run('select ' +shares[j]); try { run('users'); printf(" SHARE: %s\n", shares[j]); printf(" %20s %11s %11s %3s\n","Username","Usage(G)","Quota(G)","Quota(%)"); printf(" %20s %11s %11s %4s\n","--------","--------","--------","-------"); users=list(); for(k=0; k < users.length; k++) { run('select ' + users[k]); username=get('name'); usage=get('usage'); quota=get('quota'); usage_g=usage / 1073741824; // convert bytes to gigabytes quota_g=quota / 1073741824; // as above quota_percent=0 if (quota > 0) { quota_percent=(usage / quota)*(100/1); } printf(" %20s %8.2f %8.2f %d%%\n",username,usage_g,quota_g,quota_percent); run('done'); } run('done'); // exit user context } catch(err) { // printf(" %s is a LUN, Not looking for users\n", shares[j]); } run('done'); // exit selected share context } run('done'); // exit project context } }};SummaryThe Sun ZFS Storage 7000 Appliance offers lots of different and interesting features to Sun/Oracle customers, including the world renowned Analytics. Hopefully the above will help you to think of new creative things you could be doing by taking advantage of one of the other neat features, the internal scripting engine!Some references are below to help you continue learning more, I'll update this post as I do the same! Enjoy...More information on ECMAScript 3A complete reference to ECMAScript 3 which will help you learn more of the details you may be interested in, can be found here:http://www.ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262,%203rd%20edition,%20December%201999.pdfMore Information on Administering the Sun ZFS Storage 7000The Sun ZFS Storage 7000 System Administration guide can be a useful reference point, and can be found here:http://wikis.sun.com/download/attachments/186238602/2010_Q3_2_ADMIN.pdf

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How do I make complex SQL queries easier to write?

- by DragonLord

I'm finding it very difficult to write complex SQL queries involving joins across many (at least 3-4) tables and involving several nested conditions. The queries I'm being asked to write are easily described by a few sentences, but can require a deceptive amount of code to complete. I'm finding myself often using temporary views to write these queries, which seem like a bit of a crutch. What tips can you provide that I can use to make these complex queries easier? More specifically, how do I break these queries down into the steps I need to use to actually write the SQL code? Note that I'm the SQL I'm being asked to write is part of homework assignments for a database course, so I don't want software that will do the work for me. I want to actually understand the code I'm writing. More technical details: The database is hosted on a PostgreSQL server running on the local machine. The database is very small: there are no more than seven tables and the largest table has less than about 50 rows. The SQL queries are being passed unchanged to the server, via LibreOffice Base.

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How to implement early exit / return in Haskell?

- by Giorgio

I am porting a Java application to Haskell. The main method of the Java application follows the pattern: public static void main(String [] args) { if (args.length == 0) { System.out.println("Invalid number of arguments."); System.exit(1); } SomeDataType d = getData(arg[0]); if (!dataOk(d)) { System.out.println("Could not read input data."); System.exit(1); } SomeDataType r = processData(d); if (!resultOk(r)) { System.out.println("Processing failed."); System.exit(1); } ... } So I have different steps and after each step I can either exit with an error code, or continue to the following step. My attempt at porting this to Haskell goes as follows: main :: IO () main = do a <- getArgs if ((length args) == 0) then do putStrLn "Invalid number of arguments." exitWith (ExitFailure 1) else do -- The rest of the main function goes here. With this solution, I will have lots of nested if-then-else (one for each exit point of the original Java code). Is there a more elegant / idiomatic way of implementing this pattern in Haskell? In general, what is a Haskell idiomatic way to implement an early exit / return as used in an imperative language like Java?

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5 Ways Microsoft Can Improve the Windows 8 Start Screen

- by Matt Klein

After having used Windows 8 over the past few months, we’ve found a few ways Microsoft could immediately improve the Start Screen to make it less disorienting and more usable, not only for tablets but desktops and laptops as well. It’s safe to say that the one thing Windows 8 doesn’t lack is criticism. Since the Consumer Preview debuted in February, it has proven to be one of the most polarizing Windows releases ever. But regardless of whether you love or hate it, Windows 8 is where Microsoft’s venerable operating system is headed. Portable computing is here to stay and if the company is to survive, let alone remain relevant, it has to change, adapt, embrace, and extend. Perhaps the single most universally controversial change to Windows is Microsoft’s decision to remove the Start button (or orb, if you’ve moved beyond XP) and with it, what we know to be the Start Menu. In their place we now have a Start hot corner (a workable alternative) and the newly redesigned Metro Start Screen. The Start Screen is, if nothing else, different. Beyond a doubt, there has not been such a radical redesign of Windows’ Start functionality since it went to a two-column design with a nested “All Programs” menu in Windows XP. The Start Screen can be a little jarring because it requires users to not only relearn what they’ve known for nearly two decades but to also rethink the way they interact with Windows. However, the Start Screen maintains its core elements: a Start “menu”, a place for all installed programs (All apps), and a search pane. The Start Screen is attractive, clean, bold, and very imperfect. Here are five changes we’d like to see in the Start Screen before Windows 8 goes gold … How to Make Your Laptop Choose a Wired Connection Instead of Wireless HTG Explains: What Is Two-Factor Authentication and Should I Be Using It? HTG Explains: What Is Windows RT and What Does It Mean To Me?

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CodePlex Daily Summary for Tuesday, October 22, 2013

CodePlex Daily Summary for Tuesday, October 22, 2013Popular ReleasesLINQ to Twitter: LINQ to Twitter v2.1.10: Supports .NET 3.5, .NET 4.0, .NET 4.5, Silverlight 4.0, Windows Phone 7.1, Windows Phone 8, Client Profile, Windows 8, and Windows Azure. 100% Twitter API coverage. Also supports Twitter API v1.1! Also on NuGet.Grauers Hide Ribbon Items: Grauers Hide Ribbon Items: Hiding ribbon items in a SharePoint libraryMedia Companion: Media Companion MC3.584b: IMDB changes fixed. Fixed* mc_com.exe - Fixed to using new profile entries. * Movie - fixed rename movie and folder if use foldername selected. * Movie - Alt Edit Movie, trailer url check if changed and confirm valid. * Movie - Fixed IMDB poster scraping * Movie - Fixed outline and Plot scraping, including removal of Hyperlink's. * Movie Poster refactoring, attempts to catch gdi+ errors Revision HistoryJayData -The unified data access library for JavaScript: JayData 1.3.4: JayData is a unified data access library for JavaScript to CRUD + Query data from different sources like WebAPI, OData, MongoDB, WebSQL, SQLite, HTML5 localStorage, Facebook or YQL. The library can be integrated with KendoUI, Angular.js, Knockout.js or Sencha Touch 2 and can be used on Node.js as well. See it in action in this 6 minutes video KendoUI examples: JayData example site Examples for map integration JayData example site What's new in JayData 1.3.4 For detailed release notes check ...TerrariViewer: TerrariViewer v7.2 [Terraria Inventory Editor]: Added "Check for Update" button Hopefully fixed Windows XP issue You can now backspace in Item stack fieldsIsWiX: IsWiX 2.2.13293.1: This a minor enhancement of the 2.1 release. IsWiX Merge Module projects now include a second wxs fragment file that is useful for inserting `custom` components not supposed by the IsWiX UI.Simple Injector: Simple Injector v2.3.6: This patch releases fixes one bug concerning resolving open generic types that contain nested generic type arguments. Nested generic types were handled incorrectly in certain cases. This affects RegisterOpenGeneric and RegisterDecorator. (work item 20332)Virtual Wifi Hotspot for Windows 7 & 8: Virtual Router Plus 2.6.0: Virtual Router Plus 2.6.0Fast YouTube Downloader: Fast YouTube Downloader 2.3.0: Fast YouTube DownloaderMagick.NET: Magick.NET 6.8.7.101: Magick.NET linked with ImageMagick 6.8.7.1. Breaking changes: - Renamed Matrix classes: MatrixColor = ColorMatrix and MatrixConvolve = ConvolveMatrix. - Renamed Depth method with Channels parameter to BitDepth and changed the other method into a property.VidCoder: 1.5.9 Beta: Added Rip DVD and Rip Blu-ray AutoPlay actions for Windows: now you can have VidCoder start up and scan a disc when you insert it. Go to Start -> AutoPlay to set it up. Added error message for Windows XP users rather than letting it crash. Removed "quality" preset from list for QSV as it currently doesn't offer much improvement. Changed installer to ignore version number when copying files over. Should reduce the chances of a bug from me forgetting to increment a version number. Fixed ...MSBuild Extension Pack: October 2013: Release Blog Post The MSBuild Extension Pack October 2013 release provides a collection of over 480 MSBuild tasks. A high level summary of what the tasks currently cover includes the following: System Items: Active Directory, Certificates, COM+, Console, Date and Time, Drives, Environment Variables, Event Logs, Files and Folders, FTP, GAC, Network, Performance Counters, Registry, Services, Sound Code: Assemblies, AsyncExec, CAB Files, Code Signing, DynamicExecute, File Detokenisation, GUI...VG-Ripper & PG-Ripper: VG-Ripper 2.9.49: changes NEW: Added Support for "ImageTeam.org links NEW: Added Support for "ImgNext.com" links NEW: Added Support for "HostUrImage.com" links NEW: Added Support for "3XVintage.com" linksMoreTerra (Terraria World Viewer): MoreTerra 1.11.3.1: Release 1.11.3.1 ================ = New Features = ================ Added markers for Copper Cache, Silver Cache and the Enchanted Sword. ============= = Bug Fixes = ============= Use Official Colors now no longer tries to change the Draw Wires option instead. World reading was breaking for people with a stock 1.2 Terraria version. Changed world name reading so it does not crash the program if you load MoreTerra while Terraria is saving the world. =================== = Feature Removal = =...patterns & practices - Windows Azure Guidance: Cloud Design Patterns: 1st drop of Cloud Design Patterns project. It contains 14 patterns with 6 related guidance.Player Framework by Microsoft: Player Framework for Windows and WP (v1.3): Includes all changes in v1.3 beta 1 and v1.3 beta 2 Support for Windows 8.1 RTM and VS2013 RTM Xaml: New property: AutoLoadPluginTypes to help control which stock plugins are loaded by default (requires AutoLoadPlugins = true). Support for SystemMediaTransportControls on Windows 8.1 JS: Support for visual markers in the timeline. JS: Support for markers collection and markerreached event. JS: New ChaptersPlugin to automatically populate timeline with chapter tracks. JS: Audio an...Json.NET: Json.NET 5.0 Release 8: Fix - Fixed not writing string quotes when QuoteName is falsePowerShell Community Extensions: 3.1 Production: PowerShell Community Extensions 3.1 Release NotesOct 17, 2013 This version of PSCX supports Windows PowerShell 3.0 and 4.0 See the ReleaseNotes.txt download above for more information.Social Network Importer for NodeXL: SocialNetImporter(v.1.9): This new version includes: - Download latest status update and use it as vertex tooltip - Limit the timelines to parse to me, my friends or both - Fixed some reported bugs about the fan page and group importer - Fixed the login bug reported latelyPython Tools for Visual Studio: 2.0: PTVS 2.0 We’re pleased to announce the release of Python Tools for Visual Studio 2.0 RTM. Python Tools for Visual Studio (PTVS) is an open-source plug-in for Visual Studio which supports programming with the Python language. PTVS supports a broad range of features including CPython/IronPython, Edit/Intellisense/Debug/Profile, Cloud, IPython, and cross platform and cross language debugging support. QUICK VIDEO OVERVIEW For a quick overview of the general IDE experience, please watch this v...New Projects40FINGERS NB_Store Menumanipulator: This component allows you to add the categories of your NB_Store webshop to your DotNetNuke website's menu.ABCat: ??????? ?????????? ???????????? ????????, ?????????????? ??????? ??? ????????? ????????? ?????????? ? ?????????? ????? ?????????.AUTOFIX: This is a project related to Web Application development for University of HertfordshireAutomated service accounts creation for SharePoint 2010 and 2013 and SQL Server: Purpose of this project is just to automate the creation of SharePoint Service accounts in Active Directory.BeatportPro: Windows version of Beatport ProCasaNet: CasaNetFree Cascaded Dropdown lists JQuery Plugin for SharePoint Forms: SPCascade lets you create multi-level cascaded dropdown lists on a SharePoint form using easy JQuery code.GODspeed - FTP client for JTAG/RGH Xbox 360 consoles: Total Commander like FTP client designed to fasten and clarify file management of JTAG/RGH/DevKit Xbox 360 consoles.HCI Web Search: This project seaches for using alternative ways to handle and to visualize Web search results in a 3D environment, by interacting with gestures and speech reco.HengbeiVillage: ASP.Net + EF + AjaxToolkit ControlsIntegração Cielo Nopcommerce: Realizar a integração nopcommerce com a Cielo. Maiores detalhes são bem vindo.juzgadosdelaciudad: Mapa con Juzgados de la ciudad de buenos airesLeapJanken: LeapMotion?????、Windows Store Apps??????????????????。Looking tester for Template Engine: -VALIDATE TEMPLATE SYNTAX - no template parsing overhead, only compiles once. - unlimited nesting of sections, conditionals, etc.MQTT Broker for .NET: Project to develop a broker (server) for the MQTT protocol, an M2M Internet-of-Things communication protocol.NC MKT DNT: NC MKTNet Imobiliaria: Projeto Integrador IV SenacNewBiz: NewBiz Java Web ApplicationOAuthServer: OAuthServer is an Open Authentication server that allows you to securely authenticate your Active Directory users directly on the internet.QlikBar SDK for .NET 2.0: QlikBar SDK for .NET 2.0RainNoise - The Sound of Rain, without the wet feet.: Making some rain noise for Android device.Redsys / Sermepa gateway for Asp.Net MVC4: Coming soon....Restore Exchange 2003 Data to Exchange 2010: SysTools Exchange Recovery tool which proffers efficient and beneficial features in order to restore or migrate Exchange mailboxes from one server to anotherTimely: A library to fluently work with DateTime and TimeSpan objectstutorials_online: This is a project that is associated with my progress in tutorials in Web Scripting and Application Development in for the University of HertfordshireUQBuy ?????: ??????，?????，????，??????Voxel To Mesh Converter: Converts voxel models into mesh models.

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Using XML as data storage

- by Kian Mayne

I was thinking about the XML format and the following quote: “XML is not a database. It was never meant to be a database. It is never going to be a database. Relational databases are proven technology with more than 20 years of implementation experience. They are solid, stable, useful products. They are not going away. XML is a very useful technology for moving data between different databases or between databases and other programs. However, it is not itself a database. Don't use it like one.“ -Effective XML: 50 Specific Ways to Improve Your XML by Elliotte Rusty Harold (page 230, Part 4, Item 41, 2nd paragraph) This seems to really stress that XML should not be used for data storage and should only be used for program to program interoperability. Personally, I disagree and .NET's app.config file that's used to store a program's settings is an example of data storage in an XML file. However for databases rather than configurations etc XML should not be used. To develop my point, I will use two examples: A) Data about customers with fields that are all on one level i.e. there are a number of fields all relating to one customer with no children B) Data about configuration of an application where nested fields and properties make a lot of sense So my question is, Is this still a valid statement and is it now acceptable to store data using XML? EDIT: I've sent an email to the author of that quote to ask for his input/extra context.

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Would you refactor this and if so, would you charge your client?

- by Julius

I am working on a freelance job at home. The client wants me to write some new functionality for his CMS, but it is taking me a lot of time to figure out what the code is doing, because it is written in a very unreadable style. Below is just an example of what I mean. The previous programmer made extensive use of anonymous functions, of eval(), he uses deeply nested ternary operators, he didn't indent code, didn't use comments, and he uses funny constructions like misusing the behaviour of logical operators || and && for creating if/else conditions (the second condition of && only gets tested if the first one is true, opening the possibility to use && as an if/else construction). All in all it's insane code and it's costing me a lot of time to find out how the current code works. return ($this->main->context != "ajax" || in_array($this->type, $this->definition->ajax)) ? eval('return method_exists($this,"Show'.ucfirst($this->type).'") ? $this->Show'.ucfirst($this->type).'('.(count($args) ? join(",",array_map(create_function('$a','return (is_numeric($a) || preg_match("/^array/",$a)) ? $a : "\"".$a."\"";'),$args)) : "").') : null;') : ''; Would you refactor this code and how would you handle this sort of thing with your client, I mean financially?

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