catch all - Page 31 - Developer IT

Need help making this code more efficient

- by Rendicahya

I always use this method to easily read the content of a file. Is it efficient enough? Is 1024 good for the buffer size? public static String read(File file) { FileInputStream stream = null; StringBuilder str = new StringBuilder(); try { stream = new FileInputStream(file); } catch (FileNotFoundException e) { } FileChannel channel = stream.getChannel(); ByteBuffer buffer = ByteBuffer.allocate(1024); try { while (channel.read(buffer) != -1) { buffer.flip(); while (buffer.hasRemaining()) { str.append((char) buffer.get()); } buffer.rewind(); } } catch (IOException e) { } finally { try { channel.close(); stream.close(); } catch (IOException e) { } } return str.toString(); }

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Whether to check for null

- by coffeeaddict

I know that you should always check incoming params to a method for null. But what if I have this scenario with a try/catch referring to a local variable. Do I really need to check for null below? Because it's gonna catch it anyway if it's null and the next line of code tries to use the refundResponse variable: public string DoRefund(...) { try { ...... string refundTransactionID = string.Empty; ...... RefundTransactionResponseType refundResponse = transaction.DoRefund(...); if (refundResponse != null) refundTransactionID = refundResponse.RefundTransactionID; ..... } catch (Exception ex) { LogError(ex); return ex.ToString(); } }

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I set a global bug catcher in my application for unhandled exceptions and it is picking up all exceptions

- by user1632018

I am trying to figure out why this is happing. In my vb.net application I set a global handler in the ApplicationEvents.vb which I thought would only pick up any unhandled exceptions, although it is picking up every exception that happens in my application whether or not they are handled with try catch blocks. Here is my code in applicationevents Private Sub MyApplication_UnhandledException(ByVal _ sender As Object, ByVal e As _ Microsoft.VisualBasic.ApplicationServices.UnhandledExceptionEventArgs) _ Handles Me.UnhandledException e.ExitApplication = _ MessageBox.Show(e.Exception.Message & _ vbCrLf & "The application has encountered a bug, would you like to Continue?", "An Error has occured.", _ MessageBoxButtons.YesNo, _ MessageBoxIcon.Question) _ = DialogResult.No End Sub In the rest of my application I set normal try catch blocks like this: Try Catch ex as exception End Try Can anyone tell me why this is happening?

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response from server

- by john

When I create request to the server: <script language="javascript" type="text/javascript"> function ajaxFunction() var ajaxRequest; try{ ajaxRequest = new XMLHttpRequest(); } catch (e){ try{ } catch (e) { try{ ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e){ alert("Your browser broke!"); return false; } } } ajaxRequest.onreadystatechange = function(){ if(ajaxRequest.readyState == 4){ document.write(ajaxRequest.responseText); document.myForm.time.value = ajaxRequest.responseText; } } ajaxRequest.open("GET", "http://www.bbc.co.uk", true); ajaxRequest.send(null); } </script> Why response is nothing? Why response isnt html code of this web site?

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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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Get data from MySQL to Android application

- by Mona

I want to get data from MySQL database using PHP and display it in Android activity. I code it and pass JSON Array but there is a problem i dont know how to connect to server and my all database is on local server. I code it Kindly tell me where i go wrong so I can get exact results. I'll be very thankful to you. My PHP code is: <?php $response = array(); require_once __DIR__ . '/db_connect.php'; $db = new DB_CONNECT(); if (isset($_GET["cid"])) { $cid = $_GET['cid']; // get a product from products table $result = mysql_query("SELECT *FROM my_task WHERE cid = $cid"); if (!empty($result)) { // check for empty result if (mysql_num_rows($result) > 0) { $result = mysql_fetch_array($result); $task = array(); $task["cid"] = $result["cid"]; $task["cus_name"] = $result["cus_name"]; $task["contact_number"] = $result["contact_number"]; $task["ticket_no"] = $result["ticket_no"]; $task["task_detail"] = $result["task_detail"]; // success $response["success"] = 1; // user node $response["task"] = array(); array_push($response["my_task"], $task); // echoing JSON response echo json_encode($response); } else { // no task found $response["success"] = 0; $response["message"] = "No product found"; // echo no users JSON echo json_encode($response); } } else { // no task found $response["success"] = 0; $response["message"] = "No product found"; echo json_encode($response); } } else { $response["success"] = 0; $response["message"] = "Required field(s) is missing"; // echoing JSON response echo json_encode($response);} ?> My Android code is: public class My_Task extends Activity { TextView cus_name_txt, contact_no_txt, ticket_no_txt, task_detail_txt; EditText attend_by_txtbx, cus_name_txtbx, contact_no_txtbx, ticket_no_txtbx, task_detail_txtbx; Button btnSave; Button btnDelete; String cid; // Progress Dialog private ProgressDialog tDialog; // Creating JSON Parser object JSONParser jParser = new JSONParser(); ArrayList<HashMap<String, String>> my_taskList; // single task url private static final String url_read_mytask = "http://198.168.0.29/mobile/read_My_Task.php"; // url to update product private static final String url_update_mytask = "http://198.168.0.29/mobile/update_mytask.php"; // url to delete product private static final String url_delete_mytask = "http://198.168.0.29/mobile/delete_mytask.php"; // JSON Node names private static String TAG_SUCCESS = "success"; private static String TAG_MYTASK = "my_task"; private static String TAG_CID = "cid"; private static String TAG_NAME = "cus_name"; private static String TAG_CONTACT = "contact_number"; private static String TAG_TICKET = "ticket_no"; private static String TAG_TASKDETAIL = "task_detail"; private static String attend_by_txt; // task JSONArray JSONArray my_task = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.my_task); cus_name_txt = (TextView) findViewById(R.id.cus_name_txt); contact_no_txt = (TextView)findViewById(R.id.contact_no_txt); ticket_no_txt = (TextView)findViewById(R.id.ticket_no_txt); task_detail_txt = (TextView)findViewById(R.id.task_detail_txt); attend_by_txtbx = (EditText)findViewById(R.id.attend_by_txt); attend_by_txtbx.setText(My_Task.attend_by_txt); Spinner severity = (Spinner) findViewById(R.id.severity_spinner); // Create an ArrayAdapter using the string array and a default spinner layout ArrayAdapter<CharSequence> adapter3 = ArrayAdapter.createFromResource(this, R.array.Severity_array, android.R.layout.simple_dropdown_item_1line); // Specify the layout to use when the list of choices appears adapter3.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); // Apply the adapter to the spinner severity.setAdapter(adapter3); // save button btnSave = (Button) findViewById(R.id.btnSave); btnDelete = (Button) findViewById(R.id.btnDelete); // getting product details from intent Intent i = getIntent(); // getting product id (pid) from intent cid = i.getStringExtra(TAG_CID); // Getting complete product details in background thread new GetProductDetails().execute(); // save button click event btnSave.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View arg0) { // starting background task to update product new SaveProductDetails().execute(); } }); // Delete button click event btnDelete.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View arg0) { // deleting product in background thread new DeleteProduct().execute(); } }); } /** * Background Async Task to Get complete product details * */ class GetProductDetails extends AsyncTask<String, String, String> { /** * Before starting background thread Show Progress Dialog * */ @Override protected void onPreExecute() { super.onPreExecute(); tDialog = new ProgressDialog(My_Task.this); tDialog.setMessage("Loading task details. Please wait..."); tDialog.setIndeterminate(false); tDialog.setCancelable(true); tDialog.show(); } /** * Getting product details in background thread * */ protected String doInBackground(String... params) { // updating UI from Background Thread runOnUiThread(new Runnable() { public void run() { // Check for success tag int success; try { // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("cid", cid)); // getting product details by making HTTP request // Note that product details url will use GET request JSONObject json = JSONParser.makeHttpRequest( url_read_mytask, "GET", params); // check your log for json response Log.d("Single Task Details", json.toString()); // json success tag success = json.getInt(TAG_SUCCESS); if (success == 1) { // successfully received product details JSONArray my_taskObj = json .getJSONArray(TAG_MYTASK); // JSON Array // get first product object from JSON Array JSONObject my_task = my_taskObj.getJSONObject(0); // task with this cid found // Edit Text // display task data in EditText cus_name_txtbx = (EditText) findViewById(R.id.cus_name_txt); cus_name_txtbx.setText(my_task.getString(TAG_NAME)); contact_no_txtbx = (EditText) findViewById(R.id.contact_no_txt); contact_no_txtbx.setText(my_task.getString(TAG_CONTACT)); ticket_no_txtbx = (EditText) findViewById(R.id.ticket_no_txt); ticket_no_txtbx.setText(my_task.getString(TAG_TICKET)); task_detail_txtbx = (EditText) findViewById(R.id.task_detail_txt); task_detail_txtbx.setText(my_task.getString(TAG_TASKDETAIL)); } else { // task with cid not found } } catch (JSONException e) { e.printStackTrace(); } } }); return null; } /** * After completing background task Dismiss the progress dialog * **/ protected void onPostExecute(String file_url) { // dismiss the dialog once got all details tDialog.dismiss(); } } /** * Background Async Task to Save product Details * */ class SaveProductDetails extends AsyncTask<String, String, String> { /** * Before starting background thread Show Progress Dialog * */ @Override protected void onPreExecute() { super.onPreExecute(); tDialog = new ProgressDialog(My_Task.this); tDialog.setMessage("Saving task ..."); tDialog.setIndeterminate(false); tDialog.setCancelable(true); tDialog.show(); } /** * Saving product * */ protected String doInBackground(String... args) { // getting updated data from EditTexts String cus_name = cus_name_txt.getText().toString(); String contact_no = contact_no_txt.getText().toString(); String ticket_no = ticket_no_txt.getText().toString(); String task_detail = task_detail_txt.getText().toString(); // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair(TAG_CID, cid)); params.add(new BasicNameValuePair(TAG_NAME, cus_name)); params.add(new BasicNameValuePair(TAG_CONTACT, contact_no)); params.add(new BasicNameValuePair(TAG_TICKET, ticket_no)); params.add(new BasicNameValuePair(TAG_TASKDETAIL, task_detail)); // sending modified data through http request // Notice that update product url accepts POST method JSONObject json = JSONParser.makeHttpRequest(url_update_mytask, "POST", params); // check json success tag try { int success = json.getInt(TAG_SUCCESS); if (success == 1) { // successfully updated Intent i = getIntent(); // send result code 100 to notify about product update setResult(100, i); finish(); } else { // failed to update product } } catch (JSONException e) { e.printStackTrace(); } return null; } /** * After completing background task Dismiss the progress dialog * **/ protected void onPostExecute(String file_url) { // dismiss the dialog once product uupdated tDialog.dismiss(); } } /***************************************************************** * Background Async Task to Delete Product * */ class DeleteProduct extends AsyncTask<String, String, String> { /** * Before starting background thread Show Progress Dialog * */ @Override protected void onPreExecute() { super.onPreExecute(); tDialog = new ProgressDialog(My_Task.this); tDialog.setMessage("Deleting Product..."); tDialog.setIndeterminate(false); tDialog.setCancelable(true); tDialog.show(); } /** * Deleting product * */ protected String doInBackground(String... args) { // Check for success tag int success; try { // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("cid", cid)); // getting product details by making HTTP request JSONObject json = JSONParser.makeHttpRequest( url_delete_mytask, "POST", params); // check your log for json response Log.d("Delete Task", json.toString()); // json success tag success = json.getInt(TAG_SUCCESS); if (success == 1) { // product successfully deleted // notify previous activity by sending code 100 Intent i = getIntent(); // send result code 100 to notify about product deletion setResult(100, i); finish(); } } catch (JSONException e) { e.printStackTrace(); } return null; } /** * After completing background task Dismiss the progress dialog * **/ protected void onPostExecute(String file_url) { // dismiss the dialog once product deleted tDialog.dismiss(); } } public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) { // An item was selected. You can retrieve the selected item using // parent.getItemAtPosition(pos) } public void onNothingSelected(AdapterView<?> parent) { // Another interface callback } } My JSONParser code is: public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } // function get json from url // by making HTTP POST or GET mehtod public static JSONObject makeHttpRequest(String url, String method, List<NameValuePair> params) { // Making HTTP request try { // check for request method if(method == "POST"){ // request method is POST // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); httpPost.setEntity(new UrlEncodedFormEntity(params)); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); }else if(method == "GET"){ // request method is GET DefaultHttpClient httpClient = new DefaultHttpClient(); String paramString = URLEncodedUtils.format(params, "utf-8"); url += "?" + paramString; HttpGet httpGet = new HttpGet(url); HttpResponse httpResponse = httpClient.execute(httpGet); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; my all database is in localhost and it is not opening an activity. displays an error "Stopped unexpectedly":( How can i get exact results. Kindly guide me

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trouble running smooth animation in thread only when using key listener

- by heysuse renard

first time using a forum for coding help so sorry if i post this all wrong. i have more than a few classes i don't think screenManger or core holds the problem but i included them just incase. i got most of this code working through a set of tutorials. but a certain point started trying to do more on my own. i want to play the animation only when i'm moving my sprite. in my KeyTest class i am using threads to run the animation it used to work (poorly) but now not at all pluss it really gunks up my computer. i think it's because of the thread. im new to threads so i'm not to sure if i should even be using one in this situation or if its dangerous for my computer. the animation worked smoothly when i had the sprite bouce around the screen forever. the animation loop played with out stopping. i think the main problem is between the animationThread, Sprite, and keyTest classes, but itcould be more indepth. if someone could point me in the right direction for making the animation run smoothly when i push down a key and stop runing when i let off it would be greatly apriciated. i already looked at this Java a moving animation (sprite) obviously we were doing the same tutorial. but i feel my problem is slightly different. p.s. sorry for the typos. import java.awt.*; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import java.util.ArrayList; import javax.swing.ImageIcon; import javax.swing.JFrame; public class KeyTest extends Core implements KeyListener { public static void main(String[] args) { new KeyTest().run(); } Sprite player1; Image hobo; Image background; animation hoboRun; animationThread t1; //init also calls init form superclass public void init() { super.init(); loadImages(); Window w = s.getFullScreenWindow(); w.setFocusTraversalKeysEnabled(false); w.addKeyListener(this); } //load method will go here. //load all pics need for animation and sprite public void loadImages() { background = new ImageIcon("\\\\STUART-PC\\Users\\Stuart\\workspace\\Gaming\\yellow square.jpg").getImage(); Image face1 = new ImageIcon("\\\\STUART-PC\\Users\\Stuart\\workspace\\Gaming\\circle.png").getImage(); Image face2 = new ImageIcon("\\\\STUART-PC\\Users\\Stuart\\workspace\\Gaming\\one eye.png").getImage(); hoboRun = new animation(); hoboRun.addScene(face1, 250); hoboRun.addScene(face2, 250); player1 = new Sprite(hoboRun); this.t1 = new animationThread(); this.t1.setAnimation(player1); } //key pressed public void keyPressed(KeyEvent e) { int keyCode = e.getKeyCode(); if (keyCode == KeyEvent.VK_ESCAPE) { stop(); } if (keyCode == KeyEvent.VK_RIGHT) { player1.setVelocityX(0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1); th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } if (keyCode == KeyEvent.VK_LEFT) { player1.setVelocityX(-0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1); th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } if (keyCode == KeyEvent.VK_DOWN) { player1.setVelocityY(0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1); th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } if (keyCode == KeyEvent.VK_UP) { player1.setVelocityY(-0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1);; th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } else { e.consume(); } } //keyReleased @SuppressWarnings("static-access") public void keyReleased(KeyEvent e) { int keyCode = e.getKeyCode(); if (keyCode == KeyEvent.VK_RIGHT || keyCode == KeyEvent.VK_LEFT) { player1.setVelocityX(0); try { this.t1.setRunning(false); } catch (Exception ex) { } } if (keyCode == KeyEvent.VK_UP || keyCode == KeyEvent.VK_DOWN) { player1.setVelocityY(0); try { this.t1.setRunning(false); } catch (Exception ex) { } } else { e.consume(); } } //last method from interface public void keyTyped(KeyEvent e) { e.consume(); } //draw public void draw(Graphics2D g) { Window w = s.getFullScreenWindow(); g.setColor(w.getBackground()); g.fillRect(0, 0, s.getWidth(), s.getHieght()); g.setColor(w.getForeground()); g.drawImage(player1.getImage(), Math.round(player1.getX()), Math.round(player1.getY()), null); } public void update(long timePassed) { player1.update(timePassed); } } abstract class Core { private static DisplayMode modes[] = { new DisplayMode(1600, 900, 64, 0), new DisplayMode(800, 600, 32, 0), new DisplayMode(800, 600, 24, 0), new DisplayMode(800, 600, 16, 0), new DisplayMode(800, 480, 32, 0), new DisplayMode(800, 480, 24, 0), new DisplayMode(800, 480, 16, 0),}; private boolean running; protected ScreenManager s; //stop method public void stop() { running = false; } public void run() { try { init(); gameLoop(); } finally { s.restoreScreen(); } } //set to full screen //set current background here public void init() { s = new ScreenManager(); DisplayMode dm = s.findFirstCompatibleMode(modes); s.setFullScreen(dm); Window w = s.getFullScreenWindow(); w.setFont(new Font("Arial", Font.PLAIN, 20)); w.setBackground(Color.GREEN); w.setForeground(Color.WHITE); running = true; } //main gameLoop public void gameLoop() { long startTime = System.currentTimeMillis(); long cumTime = startTime; while (running) { long timePassed = System.currentTimeMillis() - cumTime; cumTime += timePassed; update(timePassed); Graphics2D g = s.getGraphics(); draw(g); g.dispose(); s.update(); try { Thread.sleep(20); } catch (Exception ex) { } } } //update animation public void update(long timePassed) { } //draws to screen abstract void draw(Graphics2D g); } class animationThread implements Runnable { String name; boolean playing; Sprite a; //constructor takes input from keyboard public animationThread() { } //The run method for animation public void run() { long startTime = System.currentTimeMillis(); long cumTime = startTime; boolean test = getRunning(); while (test) { long timePassed = System.currentTimeMillis() - cumTime; cumTime += timePassed; test = getRunning(); } } public String getName() { return name; } public void setAnimation(Sprite a) { this.a = a; } public void setName(String name) { this.name = name; } public void setRunning(boolean running) { this.playing = running; } public boolean getRunning() { return playing; } } class animation { private ArrayList scenes; private int sceneIndex; private long movieTime; private long totalTime; //constructor public animation() { scenes = new ArrayList(); totalTime = 0; start(); } //add scene to ArrayLisy and set time for each scene public synchronized void addScene(Image i, long t) { totalTime += t; scenes.add(new OneScene(i, totalTime)); } public synchronized void start() { movieTime = 0; sceneIndex = 0; } //change scenes public synchronized void update(long timePassed) { if (scenes.size() > 1) { movieTime += timePassed; if (movieTime >= totalTime) { movieTime = 0; sceneIndex = 0; } while (movieTime > getScene(sceneIndex).endTime) { sceneIndex++; } } } //get animations current scene(aka image) public synchronized Image getImage() { if (scenes.size() == 0) { return null; } else { return getScene(sceneIndex).pic; } } //get scene private OneScene getScene(int x) { return (OneScene) scenes.get(x); } //Private Inner CLASS////////////// private class OneScene { Image pic; long endTime; public OneScene(Image pic, long endTime) { this.pic = pic; this.endTime = endTime; } } } class Sprite { private animation a; private float x; private float y; private float vx; private float vy; //Constructor public Sprite(animation a) { this.a = a; } //change position public void update(long timePassed) { x += vx * timePassed; y += vy * timePassed; } public void startAnimation(long timePassed) { a.update(timePassed); } //get x position public float getX() { return x; } //get y position public float getY() { return y; } //set x public void setX(float x) { this.x = x; } //set y public void setY(float y) { this.y = y; } //get sprite width public int getWidth() { return a.getImage().getWidth(null); } //get sprite height public int getHeight() { return a.getImage().getHeight(null); } //get horizontal velocity public float getVelocityX() { return vx; } //get vertical velocity public float getVelocityY() { return vx; } //set horizontal velocity public void setVelocityX(float vx) { this.vx = vx; } //set vertical velocity public void setVelocityY(float vy) { this.vy = vy; } //get sprite / image public Image getImage() { return a.getImage(); } } class ScreenManager { private GraphicsDevice vc; public ScreenManager() { GraphicsEnvironment e = GraphicsEnvironment.getLocalGraphicsEnvironment(); vc = e.getDefaultScreenDevice(); } //get all compatible DM public DisplayMode[] getCompatibleDisplayModes() { return vc.getDisplayModes(); } //compares DM passed into vc DM and see if they match public DisplayMode findFirstCompatibleMode(DisplayMode modes[]) { DisplayMode goodModes[] = vc.getDisplayModes(); for (int x = 0; x < modes.length; x++) { for (int y = 0; y < goodModes.length; y++) { if (displayModesMatch(modes[x], goodModes[y])) { return modes[x]; } } } return null; } //get current DM public DisplayMode getCurrentDisplayMode() { return vc.getDisplayMode(); } //checks if two modes match each other public boolean displayModesMatch(DisplayMode m1, DisplayMode m2) { if (m1.getWidth() != m2.getWidth() || m1.getHeight() != m2.getHeight()) { return false; } if (m1.getBitDepth() != DisplayMode.BIT_DEPTH_MULTI && m2.getBitDepth() != DisplayMode.BIT_DEPTH_MULTI && m1.getBitDepth() != m2.getBitDepth()) { return false; } if (m1.getRefreshRate() != DisplayMode.REFRESH_RATE_UNKNOWN && m2.getRefreshRate() != DisplayMode.REFRESH_RATE_UNKNOWN && m1.getRefreshRate() != m2.getRefreshRate()) { return false; } return true; } //make frame full screen public void setFullScreen(DisplayMode dm) { JFrame f = new JFrame(); f.setUndecorated(true); f.setIgnoreRepaint(true); f.setResizable(false); vc.setFullScreenWindow(f); if (dm != null && vc.isDisplayChangeSupported()) { try { vc.setDisplayMode(dm); } catch (Exception ex) { } } f.createBufferStrategy(2); } //sets graphics object = this return public Graphics2D getGraphics() { Window w = vc.getFullScreenWindow(); if (w != null) { BufferStrategy s = w.getBufferStrategy(); return (Graphics2D) s.getDrawGraphics(); } else { return null; } } //updates display public void update() { Window w = vc.getFullScreenWindow(); if (w != null) { BufferStrategy s = w.getBufferStrategy(); if (!s.contentsLost()) { s.show(); } } } //returns full screen window public Window getFullScreenWindow() { return vc.getFullScreenWindow(); } //get width of window public int getWidth() { Window w = vc.getFullScreenWindow(); if (w != null) { return w.getWidth(); } else { return 0; } } //get height of window public int getHieght() { Window w = vc.getFullScreenWindow(); if (w != null) { return w.getHeight(); } else { return 0; } } //get out of full screen public void restoreScreen() { Window w = vc.getFullScreenWindow(); if (w != null) { w.dispose(); } vc.setFullScreenWindow(null); } //create image compatible with monitor public BufferedImage createCopatibleImage(int w, int h, int t) { Window win = vc.getFullScreenWindow(); if (win != null) { GraphicsConfiguration gc = win.getGraphicsConfiguration(); return gc.createCompatibleImage(w, h, t); } return null; } }

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Do not use “using” in WCF Client

- by oazabir

You know that any IDisposable object must be disposed using using. So, you have been using using to wrap WCF service’s ChannelFactory and Clients like this: using(var client = new SomeClient()) {. ..} Or, if you are doing it the hard and slow way (without really knowing why), then: using(var factory = new ChannelFactory<ISomeService>()) {var channel= factory.CreateChannel();...} That’s what we have all learnt in school right? We have learnt it wrong! When there’s a network related error or the connection is broken, or the call is timed out before Dispose is called by the using keyword, then it results in the following exception when the using keyword tries to dispose the channel: failed: System.ServiceModel.CommunicationObjectFaultedException : The communication object, System.ServiceModel.Channels.ServiceChannel, cannot be used for communication because it is in the Faulted state. Server stack trace: at System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout) Exception rethrown at [0]: at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) at System.ServiceModel.ICommunicationObject.Close(TimeSpan timeout) at System.ServiceModel.ClientBase`1.System.ServiceModel.ICommunicationObject.Close(TimeSpan timeout) at System.ServiceModel.ClientBase`1.Close() at System.ServiceModel.ClientBase`1.System.IDisposable.Dispose() There are various reasons for which the underlying connection can be at broken state before the using block is completed and the .Dispose() is called. Common problems like network connection dropping, IIS doing an app pool recycle at that moment, some proxy sitting between you and the service dropping the connection for various reasons and so on. The point is, it might seem like a corner case, but it’s a likely corner case. If you are building a highly available client, you need to treat this properly before you go-live. So, do NOT use using on WCF Channel/Client/ChannelFactory. Instead you need to use an alternative. Here’s what you can do: First create an extension method. public static class WcfExtensions{ public static void Using<T>(this T client, Action<T> work) where T : ICommunicationObject { try { work(client); client.Close(); } catch (CommunicationException e) { client.Abort(); } catch (TimeoutException e) { client.Abort(); } catch (Exception e) { client.Abort(); throw; } }} Then use this instead of the using keyword: new SomeClient().Using(channel => { channel.Login(username, password);}); Or if you are using ChannelFactory then: new ChannelFactory<ISomeService>().Using(channel => { channel.Login(username, password);}); Enjoy!

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MVP Summit 2011 summary and thoughts: The “I hope I don’t cross a line and lose my MVP status” post

- by George Clingerman

I've been wanting to write this post summarizing my thoughts about the MVP summit but have been dragging my feet since it's a very difficult one to write. However seeing Andy (http://forums.create.msdn.com/forums/t/77625.aspx) and Catalin (http://www.catalinzima.com/2011/03/mvp-summit-2011/) and Chris (http://geekswithblogs.net/cwilliams/archive/2011/03/07/144229.aspx) post about it has encouraged me to finally take the plunge. I'm going to have to write carefully though because I'm going to be dancing around a ton of NDA mine fields as well as having to walk the tight-rope of not sending the wrong message or having people read too much into what I'm saying. I want to note that most of what I'm about to say is just based on my observations, they're not thoughts that Microsoft has asked me to pass along and they're not things I heard Microsoft say. It's just me sharing what I think after going to the MVP summit. Let's start off with a short imaginary question and answer session. Has the App Hub forums and XBLIG management been rather poor by Microsoft? Yes. Do I think we're going to see changes to that overnight? No. Will it continue to look bad from the outside? Somewhat. Confusing right? Well that's kind of how things are right now. Lots of confusion. XNA is doing AWESOME. Like, really, really awesome. As a result of that awesomeness, XNA is on three major platforms: Xbox 360, WP7 and PC. This means that internally Microsoft is really excited and invested in the technology. That's fantastic for XNA and really should show you the future the framework has. It's here to stay. So why are Xbox LIVE Indie Game developers feeling so much pain? The ironic thing is that pain is being caused by the success of XNA. When XNA was just a small thing, there was more freedom and more focus. It was just us and them. We were an only child. Now our family has grown and everyone has and wants some time with XNA. This gets XNA pulled in all directions and as it moves onto new platforms, it plays catch up trying to get those platforms up to speed to where Xbox LIVE Indie Games has grown. Forums, documentation, educational content. They all need to be there because Xbox LIVE Indie Games has all of that and more. Along with the catch up in features/documentation/awesomeness there's the catch up that the people on the team have to play. New platforms and new areas of development mean new players and those new guys don't have the history of being around from the beginning. This leads to a lack of understanding at times just how important some things are because they seem so small and insignificant (Rich Text defaulting for new forum profiles would be one things that jumps to mind). If you're not aware that the forums have become more than just a basic Q&A, if you're not aware that they're a central hub to a very active community, then you don't understand why that small change should be prioritized over something else. New people have to get caught up and figure out how to make a framework and central forum site work for everyone it's now serving. So yeah, a lot of our pain this last year has been simply that XNA is doing well and XBLIG is doing well so the focus was shifted to catch other things up. It hurts when a parent seems to not have any time for you and they're spending some much time with your new baby brother. Growing pains. All families and in our case our product family experience it to some degree. I think as WP7 matures we'll see the team figuring out how to give everyone the right amount of attention. While we're talking about some of our growing pains, it is also important to note (although not really an excuse) that the Xbox LIVE Arcade developers complain about many of the same things that we do. If you paid attention to talks and information coming out of GDC 2011, most of the the XBLA guys were saying things that sounded eerily similar to what the XBLIG developers are saying (Scott Nichols from GayGamer.net noticed http://twitter.com/#!/NaviFairyGG/status/43540379206811650). Does this mean we should just accept the status quo since we're being treated exactly the same? No way. However it DOES show that the way we're being treated is no indication of the stability and future of the platform, it's just Microsoft dropping the communication ball on two playing fields. We're not alone and we're not even being treated worse. Not great, but also in a weird way a very good sign. Now on to a few tidbits I think I CAN share from the summit (I'm really crossing my fingers I'm not stepping over some NDA line I shouldn't be). First, I discovered that the XBLIG user base is bigger than I personally had originally estimated. I won't give the exact numbers (although we did beg Microsoft to release some of these numbers so maybe someday?) but it was much larger than my original guestimates and I was pleasantly surprised. Maybe some of you guys had the right number when you were guessing, but I know that mine was much too low. And even MORE importantly the number of users/shoppers is growing at a steady pace as well. Our market is growing! That was fantastic news and really something that I had to share. On to the community manager discussion. It was mentioned. I was mentioned. I blushed. Nothing more to report there than the blush in my cheeks was a light crimson color. If I ever see a job description posted for that position I have a resume waiting in the wings. I can't deny that I think that would be my dream job... ...so after I finished blushing, the MVPs did make it very, very clear that the communication has to improve. Community manager or not the single biggest pain point with the Xbox LIVE Indie Game community has been a lack of communication. I have seen dramatic improvement in the team responding to MVPs and I'm even seeing more communication from them on the forums so I'm hoping that's a long term change. I really think they understood the issue, the problem remains how to open that communication channel in a way that was sustainable. I think they'll get it figured out and hopefully that's sooner rather than later. During the summit, you may have seen me tweeting about how I was "that guy" (http://twitter.com/#!/clingermangw/status/42740432471470081). You also may have noticed that Andy and Catalin both mentioned me in their summit write ups. I may have come on a bit strong while I was there...went a little out of character for myself. I've been agitated for a while with the way things have been and I've been listening to you guys and hearing you guys be agitated. I'm also watching some really awesome indie game developers looking elsewhere and leaving the platform. Some of them we might not have been able to keep even with changes, but others are only leaving because of perceptions and lack of communication from Microsoft. And that pisses me off. And I let Microsoft know that I was pissed off. You made your list and I took that list and verbalized it. I verbalized the hell out of it. [It was actually mentioned that I'm a lot nicer on the forums and in email than I am in person...I felt bad about that, but I couldn't stay silent]. Hopefully it did something guys, I really did try hard to get the message across. Along with my agitation, I also brought some pride. I mentioned several things in person to the team that I was particularly proud of. From people in the community that are doing an awesome job, to the re-launch of XboxIndies that was going on that week and even gamers like Steven Hurdle (http://writingsofmassdeduction.com/) who have purchased one XBLIG every day for over 100 days now. The community is freaking rocking it and I made sure to highlight that. So in conclusion, I'd just like to say hang in there (you know, like that picture of the cat). If you've been worried about investing in Xbox LIVE Indie Games because you think it's on shaky ground. It's not. Dream Build Play being about the Xbox 360 should have helped a little to point that out. The team is really scrambling around trying to figure things out and make improvements all around. There’s quite a few new gals and guys and it's going to take them time to catch up and there are a lot of constantly shifting priorities. We all have one toy, one team and we're fighting for time with it. It's also time for the community to continue spreading our wings and going out on our own more often. The Indie Game Winter Uprising was a fantastic example of that. We took things into our own hands and it got noticed and Microsoft got behind it. They do every time we stand up and do something (look at how many Microsoft employees tweeted, wrote about the re-launch of XboxIndies.com or the support I've gotten from them for my weekly XNA Notes). XNA is here to stay, it's time for us to stop being scared of that and figure out how to make our own games the successes they should be. There's definitely a list of things that need to be fixed, things that should be improved and I think we should definitely keep vocal about that with Microsoft. Keep it short, focused and prioritized. There's also a lot of things we can do ourselves while we're waiting on them to fix and change things. Lots of ways we can compensate for particular weaknesses in the channel. The kind of stuff that we can step up and do ourselves. Do it on our own, you know, the way Indies always do. And I'm really looking forward to watching us do just that.

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Subterranean IL: Filter exception handlers

- by Simon Cooper

Filter handlers are the second type of exception handler that aren't accessible from C#. Unlike the other handler types, which have defined conditions for when the handlers execute, filter lets you use custom logic to determine whether the handler should be run. However, similar to a catch block, the filter block does not get run if control flow exits the block without throwing an exception. Introducing filter blocks An example of a filter block in IL is the following: .try { // try block } filter { // filter block endfilter }{ // filter handler } or, in v1 syntax, TryStart: // try block TryEnd: FilterStart: // filter block HandlerStart: // filter handler HandlerEnd: .try TryStart to TryEnd filter FilterStart handler HandlerStart to HandlerEnd In the v1 syntax there is no end label specified for the filter block. This is because the filter block must come immediately before the filter handler; the end of the filter block is the start of the filter handler. The filter block indicates to the CLR whether the filter handler should be executed using a boolean value on the stack when the endfilter instruction is run; true/non-zero if it is to be executed, false/zero if it isn't. At the start of the filter block, and the corresponding filter handler, a reference to the exception thrown is pushed onto the stack as a raw object (you have to manually cast to System.Exception). The allowed IL inside a filter block is tightly controlled; you aren't allowed branches outside the block, rethrow instructions, and other exception handling clauses. You can, however, use call and callvirt instructions to call other methods. Filter block logic To demonstrate filter block logic, in this example I'm filtering on whether there's a particular key in the Data dictionary of the thrown exception: .try { // try block } filter { // Filter starts with exception object on stack // C# code: ((Exception)e).Data.Contains("MyExceptionDataKey") // only execute handler if Contains returns true castclass [mscorlib]System.Exception callvirt instance class [mscorlib]System.Collections.IDictionary [mscorlib]System.Exception::get_Data() ldstr "MyExceptionDataKey" callvirt instance bool [mscorlib]System.Collections.IDictionary::Contains(object) endfilter }{ // filter handler // Also starts off with exception object on stack callvirt instance string [mscorlib]System.Object::ToString() call void [mscorlib]System.Console::WriteLine(string) } Conclusion Filter exception handlers are another exception handler type that isn't accessible from C#, however, just like fault handlers, the behaviour can be replicated using a normal catch block: try { // try block } catch (Exception e) { if (!FilterLogic(e)) throw; // handler logic } So, it's not that great a loss, but it's still annoying that this functionality isn't directly accessible. Well, every feature starts off with minus 100 points, so it's understandable why something like this didn't make it into the C# compiler ahead of a different feature.

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SQL SERVER – Weekly Series – Memory Lane – #049

- by Pinal Dave

Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Two Connections Related Global Variables Explained – @@CONNECTIONS and @@MAX_CONNECTIONS @@CONNECTIONS Returns the number of attempted connections, either successful or unsuccessful since SQL Server was last started. @@MAX_CONNECTIONS Returns the maximum number of simultaneous user connections allowed on an instance of SQL Server. The number returned is not necessarily the number currently configured. Query Editor – Microsoft SQL Server Management Studio This post may be very simple for most of the users of SQL Server 2005. Earlier this year, I have received one question many times – Where is Query Analyzer in SQL Server 2005? I wrote small post about it and pointed many users to that post – SQL SERVER – 2005 Query Analyzer – Microsoft SQL SERVER Management Studio. Recently I have been receiving similar question. OUTPUT Clause Example and Explanation with INSERT, UPDATE, DELETE SQL Server 2005 has a new OUTPUT clause, which is quite useful. OUTPUT clause has access to insert and deleted tables (virtual tables) just like triggers. OUTPUT clause can be used to return values to client clause. OUTPUT clause can be used with INSERT, UPDATE, or DELETE to identify the actual rows affected by these statements. OUTPUT clause can generate a table variable, a permanent table, or temporary table. Even though, @@Identity will still work with SQL Server 2005, however I find the OUTPUT clause very easy and powerful to use. Let us understand the OUTPUT clause using an example. Find Name of The SQL Server Instance Based on database server stored procedures has to run different logic. We came up with two different solutions. 1) When database schema is very much changed, we wrote completely new stored procedure and deprecated older version once it was not needed. 2) When logic depended on Server Name we used global variable @@SERVERNAME. It was very convenient while writing migrating script which depended on the server name for the same database. Explanation of TRY…CATCH and ERROR Handling With RAISEERROR Function One of the developers at my company thought that we can not use the RAISEERROR function in new feature of SQL Server 2005 TRY… CATCH. When asked for an explanation he suggested SQL SERVER – 2005 Explanation of TRY… CATCH and ERROR Handling article as excuse suggesting that I did not give example of RAISEERROR with TRY…CATCH. We all thought it was funny. Just to keep records straight, TRY… CATCH can sure use RAISEERROR function. Different Types of Cache Objects Serveral kinds of objects can be stored in the procedure cache: Compiled Plans: When the query optimizer finishes compiling a query plan, the principal output is compiled plan. Execution contexts: While executing a compiled plan, SQL Server has to keep track of information about the state of execution. Cursors: Cursors track the execution state of server-side cursors, including the cursor’s current location within a resultset. Algebrizer trees: The Algebrizer’s job is to produce an algebrizer tree, which represents the logic structure of a query. Open SSMS From Command Prompt – sqlwb.exe Example This article is written by request and suggestion of Sr. Web Developer at my organization. Due to the nature of this article most of the content is referred from Book On-Line. sqlwbcommand prompt utility which opens SQL Server Management Studio. Squib command does not run queries from the command prompt. sqlcmd utility runs queries from command prompt, read for more information. 2008 Puzzle – Solution – Computed Columns Datatype Explanation Just a day before I wrote article SQL SERVER – Puzzle – Computed Columns Datatype Explanation which was inspired by SQL Server MVP Jacob Sebastian. I suggest that before continuing this article read the original puzzle question SQL SERVER – Puzzle – Computed Columns Datatype Explanation.The question was if the computed column was of datatype TINYINT how to create a Computed Column of datatype INT? 2008 – Find If Index is Being Used in Database It is very often I get a query that how to find if any index is being used in the database or not. If any database has many indexes and not all indexes are used it can adversely affect performance. If the number of indices are higher it reduces the INSERT / UPDATE / DELETE operation but increase the SELECT operation. It is recommended to drop any unused indexes from table to improve the performance. 2009 Interesting Observation – Execution Plan and Results of Aggregate Concatenation Queries If you want to see what’s going on here, I think you need to shift your point of view from an implementation-centric view to an ANSI point of view. ANSI does not guarantee processing the order. Figure 2 is interesting, but it will be potentially misleading if you don’t understand the ANSI rule-set SQL Server operates under in most cases. Implementation thinking can certainly be useful at times when you really need that multi-million row query to finish before the backup fire off, but in this case, it’s counterproductive to understanding what is going on. SQL Server Management Studio and Client Statistics Client Statistics are very important. Many a times, people relate queries execution plan to query cost. This is not a good comparison. Both parameters are different, and they are not always related. It is possible that the query cost of any statement is less, but the amount of the data returned is considerably larger, which is causing any query to run slow. How do we know if any query is retrieving a large amount data or very little data? 2010 I encourage all of you to go through complete series and write your own on the subject. If you write an article and send it to me, I will publish it on this blog with due credit to you. If you write on your own blog, I will update this blog post pointing to your blog post. SQL SERVER – ORDER BY Does Not Work – Limitation of the View 1 SQL SERVER – Adding Column is Expensive by Joining Table Outside View – Limitation of the View 2 SQL SERVER – Index Created on View not Used Often – Limitation of the View 3 SQL SERVER – SELECT * and Adding Column Issue in View – Limitation of the View 4 SQL SERVER – COUNT(*) Not Allowed but COUNT_BIG(*) Allowed – Limitation of the View 5 SQL SERVER – UNION Not Allowed but OR Allowed in Index View – Limitation of the View 6 SQL SERVER – Cross Database Queries Not Allowed in Indexed View – Limitation of the View 7 SQL SERVER – Outer Join Not Allowed in Indexed Views – Limitation of the View 8 SQL SERVER – SELF JOIN Not Allowed in Indexed View – Limitation of the View 9 SQL SERVER – Keywords View Definition Must Not Contain for Indexed View – Limitation of the View 10 SQL SERVER – View Over the View Not Possible with Index View – Limitations of the View 11 SQL SERVER – Get Query Running in Session I was recently looking for syntax where I needed a query running in any particular session. I always remembered the syntax and ha d actually written it down before, but somehow it was not coming to mind quickly this time. I searched online and I ended up on my own article written last year SQL SERVER – Get Last Running Query Based on SPID. I felt that I am getting old because I forgot this really simple syntax. Find Total Number of Transaction on Interval In one of my recent Performance Tuning assignments I was asked how do someone know how many transactions are happening on a server during certain interval. I had a handy script for the same. Following script displays transactions happened on the server at the interval of one minute. You can change the WAITFOR DELAY to any other interval and it should work. 2011 Here are two DMV’s which are newly introduced in SQL Server 2012 and provides vital information about SQL Server. DMV – sys.dm_os_volume_stats – Information about operating system volume DMV – sys.dm_os_windows_info – Information about Operating System SQL Backup and FTP – A Quick and Handy Tool I have used this tool extensively since 2009 at numerous occasion and found it to be very impressive. What separates it from the crowd the most – it is it’s apparent simplicity and speed. When I install SQLBackupAndFTP and configure backups – all in 1 or 2 minutes, my clients are always impressed. Quick Note about JOIN – Common Questions and Simple Answers In this blog post we are going to talk about join and lots of things related to the JOIN. I recently started office hours to answer questions and issues of the community. I receive so many questions that are related to JOIN. I will share a few of the same over here. Most of them are basic, but note that the basics are of great importance. 2012 Importance of User Without Login Question: “In recent version of SQL Server we can create user without login. What is the use of it?” Great question indeed. Let me first attempt to answer this question but after reading my answer I need your help. I want you to help him as well with adding more value to it. Preserve Leading Zero While Coping to Excel from SSMS Earlier I wrote two articles about how to efficiently copy data from SSMS to Excel. Since I wrote that post there are plenty of interest generated on this subject. There are a few questions I keep on getting over this subject. One of the question is how to get the leading zero preserved while copying the data from SSMS to Excel. Well it is almost the same way as my earlier post SQL SERVER – Excel Losing Decimal Values When Value Pasted from SSMS ResultSet. The key here is in EXCEL and not in SQL Server. Solution – 2 T-SQL Puzzles – Display Star and Shortest Code to Display 1 Earlier on this blog we had asked two puzzles. The response from all of you is nothing but Amazing. I have received 350+ responses. Many are valid and many were indeed something I had not thought about it. I strongly suggest you read all the puzzles and their answers here - trust me if you start reading the comments you will not stop till you read every single comment. Seriously trust me on it. Personally I have learned a lot from it. Identify Most Resource Intensive Queries – SQL in Sixty Seconds #028 – Video http://www.youtube.com/watch?v=TvlYy-TGaaA Importance of User Without Login – T-SQL Demo Script Earlier I wrote a blog post about SQL SERVER – Importance of User Without Login and my friend and SQL Expert Vinod Kumar has written excellent follow up blog post about Contained Databases inside SQL Server 2012. Now lots of people asked me if I can also explain the same concept again so here is the small demonstration for it. Let me show you how login without user can help. Before we continue on this subject I strongly recommend that you read my earlier blog post here. In following demo I am going to demonstrate following situation. Login using the System Admin account Create a user without login Checking Access Impersonate the user without login Checking Access Revert Impersonation Give Permission to user without login Impersonate the user without login Checking Access Revert Impersonation Clean up Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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SQLOS and Cloud Infrastructure sessions at PASS Summit 2012

- by SQLOS Team

The SQL Pass Summit 2012, the largest yet, is in full swing. Here's a summary of the sessions this week on cloud infrastructure and SQLOS topics. Some of these were today, and you can catch the recordings. One more session takes place on Friday covering SQL Server solution patterns in Windows Azure VMs... Also, catch Thursday's keynote with Quentin Clark which will feature a cool IaaS demo! SQL Server in Windows Azure VM Sessions CLD-309-A SQLCAT: Best Practices and Lessons Learned on SQL Server in an Azure VM Steve Howard, Arvind Ranasaria - Wednesday 11/6 10:15 This session looked at some best practices to optimize Networking, Memory, Disk IO and high availability based on lessons learned during SQLCat work with customer deployments. Well worth catching the recording. SQL Server in Azure VM patterns: Hybrid Disaster Recovery, data movement and BI Guy Bowerman, Peter Saddow, Michael Washam, Ross LoForte - Friday 11/9 9:45 Rm 613 [Note: In the guides this has an outdated title.] This session has a focus on SQL Server Azure VM solutions. Starting with the basics and then going deeper into: - New features in the Microsoft Assessment and Planning Toolkit 8.0 to help plan and size SQL VM migrations.- A Look at a Windows Azure VM SQL Server app making use of load balancing and SQL Server high availability features.- A BI case study running SQL BI components in Azure VMs and making use of Windows 8 tiles.- A training class in a VM case study. SQLOS Sessions DBA-500-HD Inside SQLOS 2012 (half-day session) Bob Ward - Wednesday 11/6 1:30pm Bob Ward from CSS applies his wealth of experience to look at the internals of SQLOS and what's changed in the various SQL 2012 components, including memory, resource governor, scheduler. DBA-403-M: SQLCAT: Memory Manager Changes in SQL Server 2012 Gus Apostol, Jerome Halmans - 1:30pm Covers the redesigned SQLOS memory manager in SQL Server 2012 including the new page allocator for any size pages (and all that implies), DMVs, demo's. Not sure why this was placed at the same time as the SQLOS half-day session, but since it's recorded it's available for catch-up. - Guy Originally posted at http://blogs.msdn.com/b/sqlosteam/

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Voice echo in UDP based voice transmission [closed]

- by Meherzad

I have coded a java application for voice transmission between to ip in LAN. Here the code. public static Boolean flag= true; public static Boolean recFlag=true; DatagramSocket UDPSocket=null; AudioFormat format = null; TargetDataLine microphone=null; byte[] buffer=null; DatagramPacket UDPPacket=null; public void startChat(String ipAddress){ try{ buffer = new byte[1000]; UDPSocket=new DatagramSocket(1987); Thread th=new Thread(new Listener()); th.start(); microphone = AudioSystem.getTargetDataLine(format); format= new AudioFormat(8000.0f, 16, 1, true, true); UDPPacket = new DatagramPacket(buffer, buffer.length, InetAddress.getByName(ipAddress), 1988); microphone.open(format); microphone.start(); while (flag) { microphone.read(buffer, 0, buffer.length); UDPSocket.send(UDPPacket); } } catch(Exception e){ System.out.println(" ssss "+e.getMessage()); } } public class Listener extends Thread{ byte[] buff=new byte[1000]; DatagramSocket UDPSocket1=null; DatagramPacket recPacket=null; DataLine.Info info = new DataLine.Info(SourceDataLine.class, format); SourceDataLine line=null; @Override public void run(){ try{ UDPSocket1=new DatagramSocket(1988); format= new AudioFormat(8000.0f, 16, 1, true, true); line = (SourceDataLine) AudioSystem.getLine(info); line.open(format); line.start(); } catch(Exception e){ System.out.println("list "+ e.getMessage()); } recPacket=new DatagramPacket(buff, buff.length); while(recFlag){ try{ UDPSocket1.receive(recPacket); buff = (byte[])recPacket.getData(); line.write(buff, 0, buff.length); } catch(Exception e){ System.out.println("errr "+e.getMessage()); } } line.drain(); line.close(); } } Main problem which I am facing that I am getting only echo of my own voice. I am unable to hear voice from the other end only I am hearing is my own voice. Please suggest any solution.

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Methods of learning / teaching programming

- by Mark Avenius

When I was in school, I had a difficult time getting into programming because of a catch-22 in the learning process: I didn't know how to write anything because I didn't know what keywords and commands meant. For example (as a student, I would think), "what does this using namespace std; thing do anyway? I didn't know what keywords and commands meant because I hadn't written anything. This basically led me to spending countless long night cursing the compiler as I made minor tweaks to my assignments until they would compile (and hopefully perform whatever operation they were supposed to). Is there a teaching/learning method that anyone uses that gets around this catch-22? I am trying to make this non-argumentative, which is why I don't want to know the 'best' method, but rather which methods exist.

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Oracle OpenWorld 2012, Live From The Show Floor Videos

- by Chris Kawalek

At shows like Oracle OpenWorld, we like to catch up with the session speakers and other experts with short video clips that we post on our YouTube channel. For Oracle OpenWorld 2012, we put together this handy playlist of server and desktop virtualization related videos: We were also able to catch up with a few Oracle Linux partners at the Oracle Linux Pavillion. You can find those videos here: And if you'd like to look at the slides for any of our virtualization presentations or any other Oracle OpenWorld session, have a look at the Oracle OpenWorld 2012 content catalog. There's a lot of great information there! -Chris

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manage spam and catchalls on google apps?

- by acidzombie24

I use google apps as my email system for my website. I have a catch all which fowards mail to some_account which forwards mail to my peronal account bc its rare to receive mail on my sites. Problem is emails that are caught by the catch all ALWAYS goes to junk. Junk emails are never forwarded so i dont receive them in my main gmail account thus i dont receive emails sent to the wrong [email protected]. So i wrote a filter that on my catch_all_user to never send to spam, which worked as i get those emails. But on my main account those emails dont show up as spam/junk. How do i get it forwarding but still marked as spam so its in its own junk folder instead of mixed up in my real mail?

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Why unhandled exceptions are useful

- by Simon Cooper

It’s the bane of most programmers’ lives – an unhandled exception causes your application or webapp to crash, an ugly dialog gets displayed to the user, and they come complaining to you. Then, somehow, you need to figure out what went wrong. Hopefully, you’ve got a log file, or some other way of reporting unhandled exceptions (obligatory employer plug: SmartAssembly reports an application’s unhandled exceptions straight to you, along with the entire state of the stack and variables at that point). If not, you have to try and replicate it yourself, or do some psychic debugging to try and figure out what’s wrong. However, it’s good that the program crashed. Or, more precisely, it is correct behaviour. An unhandled exception in your application means that, somewhere in your code, there is an assumption that you made that is actually invalid. Coding assumptions Let me explain a bit more. Every method, every line of code you write, depends on implicit assumptions that you have made. Take this following simple method, that copies a collection to an array and includes an item if it isn’t in the collection already, using a supplied IEqualityComparer: public static T[] ToArrayWithItem( ICollection<T> coll, T obj, IEqualityComparer<T> comparer) { // check if the object is in collection already // using the supplied comparer foreach (var item in coll) { if (comparer.Equals(item, obj)) { // it's in the collection already // simply copy the collection to an array // and return it T[] array = new T[coll.Count]; coll.CopyTo(array, 0); return array; } } // not in the collection // copy coll to an array, and add obj to it // then return it T[] array = new T[coll.Count+1]; coll.CopyTo(array, 0); array[array.Length-1] = obj; return array; } What’s all the assumptions made by this fairly simple bit of code? coll is never null comparer is never null coll.CopyTo(array, 0) will copy all the items in the collection into the array, in the order defined for the collection, starting at the first item in the array. The enumerator for coll returns all the items in the collection, in the order defined for the collection comparer.Equals returns true if the items are equal (for whatever definition of ‘equal’ the comparer uses), false otherwise comparer.Equals, coll.CopyTo, and the coll enumerator will never throw an exception or hang for any possible input and any possible values of T coll will have less than 4 billion items in it (this is a built-in limit of the CLR) array won’t be more than 2GB, both on 32 and 64-bit systems, for any possible values of T (again, a limit of the CLR) There are no threads that will modify coll while this method is running and, more esoterically: The C# compiler will compile this code to IL according to the C# specification The CLR and JIT compiler will produce machine code to execute the IL on the user’s computer The computer will execute the machine code correctly That’s a lot of assumptions. Now, it could be that all these assumptions are valid for the situations this method is called. But if this does crash out with an exception, or crash later on, then that shows one of the assumptions has been invalidated somehow. An unhandled exception shows that your code is running in a situation which you did not anticipate, and there is something about how your code runs that you do not understand. Debugging the problem is the process of learning more about the new situation and how your code interacts with it. When you understand the problem, the solution is (usually) obvious. The solution may be a one-line fix, the rewrite of a method or class, or a large-scale refactoring of the codebase, but whatever it is, the fix for the crash will incorporate the new information you’ve gained about your own code, along with the modified assumptions. When code is running with an assumption or invariant it depended on broken, then the result is ‘undefined behaviour’. Anything can happen, up to and including formatting the entire disk or making the user’s computer sentient and start doing a good impression of Skynet. You might think that those can’t happen, but at Halting problem levels of generality, as soon as an assumption the code depended on is broken, the program can do anything. That is why it’s important to fail-fast and stop the program as soon as an invariant is broken, to minimise the damage that is done. What does this mean in practice? To start with, document and check your assumptions. As with most things, there is a level of judgement required. How you check and document your assumptions depends on how the code is used (that’s some more assumptions you’ve made), how likely it is a method will be passed invalid arguments or called in an invalid state, how likely it is the assumptions will be broken, how expensive it is to check the assumptions, and how bad things are likely to get if the assumptions are broken. Now, some assumptions you can assume unless proven otherwise. You can safely assume the C# compiler, CLR, and computer all run the method correctly, unless you have evidence of a compiler, CLR or processor bug. You can also assume that interface implementations work the way you expect them to; implementing an interface is more than simply declaring methods with certain signatures in your type. The behaviour of those methods, and how they work, is part of the interface contract as well. For example, for members of a public API, it is very important to document your assumptions and check your state before running the bulk of the method, throwing ArgumentException, ArgumentNullException, InvalidOperationException, or another exception type as appropriate if the input or state is wrong. For internal and private methods, it is less important. If a private method expects collection items in a certain order, then you don’t necessarily need to explicitly check it in code, but you can add comments or documentation specifying what state you expect the collection to be in at a certain point. That way, anyone debugging your code can immediately see what’s wrong if this does ever become an issue. You can also use DEBUG preprocessor blocks and Debug.Assert to document and check your assumptions without incurring a performance hit in release builds. On my coding soapbox… A few pet peeves of mine around assumptions. Firstly, catch-all try blocks: try { ... } catch { } A catch-all hides exceptions generated by broken assumptions, and lets the program carry on in an unknown state. Later, an exception is likely to be generated due to further broken assumptions due to the unknown state, causing difficulties when debugging as the catch-all has hidden the original problem. It’s much better to let the program crash straight away, so you know where the problem is. You should only use a catch-all if you are sure that any exception generated in the try block is safe to ignore. That’s a pretty big ask! Secondly, using as when you should be casting. Doing this: (obj as IFoo).Method(); or this: IFoo foo = obj as IFoo; ... foo.Method(); when you should be doing this: ((IFoo)obj).Method(); or this: IFoo foo = (IFoo)obj; ... foo.Method(); There’s an assumption here that obj will always implement IFoo. If it doesn’t, then by using as instead of a cast you’ve turned an obvious InvalidCastException at the point of the cast that will probably tell you what type obj actually is, into a non-obvious NullReferenceException at some later point that gives you no information at all. If you believe obj is always an IFoo, then say so in code! Let it fail-fast if not, then it’s far easier to figure out what’s wrong. Thirdly, document your assumptions. If an algorithm depends on a non-trivial relationship between several objects or variables, then say so. A single-line comment will do. Don’t leave it up to whoever’s debugging your code after you to figure it out. Conclusion It’s better to crash out and fail-fast when an assumption is broken. If it doesn’t, then there’s likely to be further crashes along the way that hide the original problem. Or, even worse, your program will be running in an undefined state, where anything can happen. Unhandled exceptions aren’t good per-se, but they give you some very useful information about your code that you didn’t know before. And that can only be a good thing.

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JDK 7 In Action - Learn With Java Tutorials and Developer Guides

- by sowmya

At JavaOne 2012, Stuart Marks, Mike Duigou, and Joe Darcy gave a presentation about JDK 7 In Action. Learn more about using JDK 7 features with the help of Java Tutorials and JDK 7 Developer Guides. Links to relevant information are provided below. If you are considering moving to JDK 7 from a previous release, the JDK 7 Release Notes and JDK 7 Adoption Guide are great resources. Project Coin Features Improved Literals * Literals section in Primitive Datatypes topic. * Binary Literals * Underscores in Numeric Literals Strings In Switch * Strings In Switch Diamond * Type Inference for Generic Instance Creation * Type Inference and Instantiation of Generic Classes Multi-catch and Precise Throw * Catching Multiple Exception Types and Rethrowing Exceptions with Improved Type Checking * Catch Blocks Try-with-resources * The try-with-resources Statement NIO.2 File System API * File I/O for information on path, files, change notification, and more * Zip File System Provider * Zip File System Provider * Developing a Custom File System Provider Fork Join Framework * Fork/Join - Sowmya

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Is possible to write too many asserts?

- by Lex Fridman

I am a big fan of writing assert checks in C++ code as a way to catch cases during development that cannot possibly happen but do happen because of logic bugs in my program. This is a good practice in general. However, I've noticed that some functions I write (which are part of a complex class) have 5+ asserts which feels like it could potentially be a bad programming practice, in terms of readability and maintainability. I think it's still great, as each one requires me to think about pre- and post-conditions of functions and they really do help catch bugs. However, I just wanted to put this out there to ask if there is a better paradigms for catching logic errors in cases when a large number of checks is necessary.

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Feed Reader Fix

- by Geertjan

In the FeedReader sample (available in the New Projects window), there's this piece of code: private static Feed getFeed(Node node) { InstanceCookie ck = node.getLookup().lookup(InstanceCookie.class); if (ck == null) { throw new IllegalStateException("Bogus file in feeds folder: " + node.getLookup().lookup(FileObject.class)); } try { return (Feed) ck.instanceCreate(); } catch (ClassNotFoundException ex) { Exceptions.printStackTrace(ex); } catch (IOException ex) { Exceptions.printStackTrace(ex); } return null; } Since 7.1, for some reason, the above doesn't work. What does work, and is simpler, is this, instead of the above: private static Feed getFeed(Node node) { Feed f = FileUtil.getConfigObject("RssFeeds/sample.instance", Feed.class); if (f == null) { throw new IllegalStateException("Bogus file in feeds folder: " + node.getLookup().lookup(FileObject.class)); } return f; } So, the code needs to be fixed in the sample.

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C# OpenGL problem with animation

- by user3696303

there is a program that simulates a small satellite and requires that a rotation animation of the satellite along the three axes. But when you try to write an animation problem during compilation: the program simply closes (shutdown occurs when swapbuffers, mainloop, redisplay), when you write the easiest programs have the same problem arose. Trying to catch exception by try-catch but here is not exception. How to solve this? I suffer with this a few days. Work in c# visual studio 2008 framework namespace WindowsFormsApplication6 { public partial class Form1 : Form { public Form1() { try { InitializeComponent(); AnT1.InitializeContexts(); } catch(Exception) { Glut.glutDisplayFunc(Draw); Glut.glutTimerFunc(50, Timer, 0); Glut.glutMainLoop(); } } void Timer(int Unused) { Glut.glutPostRedisplay(); Glut.glutTimerFunc(50, Timer, 0); } private void AnT1_Load(object sender, EventArgs e) { Glut.glutInit(); Glut.glutInitDisplayMode(Glut.GLUT_RGB | Glut.GLUT_DOUBLE | Glut.GLUT_DEPTH); Gl.glClearColor(255, 255, 255, 1); Gl.glViewport(0, 0, AnT1.Width, AnT1.Height); Gl.glMatrixMode(Gl.GL_PROJECTION); Gl.glLoadIdentity(); Glu.gluPerspective(45, (float)AnT1.Width / (float)AnT1.Height, 0.1, 200); Gl.glMatrixMode(Gl.GL_MODELVIEW); Gl.glLoadIdentity(); Gl.glEnable(Gl.GL_DEPTH_TEST); Gl.glClear(Gl.GL_COLOR_BUFFER_BIT | Gl.GL_DEPTH_BUFFER_BIT); Gl.glPushMatrix(); double xy = 0.2; Gl.glTranslated(xy, 0, 0); xy += 0.2; Draw(); Glut.glutSwapBuffers(); Glut.glutPostRedisplay(); Gl.glPushMatrix(); Draw(); Gl.glPopMatrix(); } void Draw() { Gl.glLoadIdentity(); Gl.glColor3f(0.502f, 0.502f, 0.502f); Gl.glTranslated(-1, 0, -6); Gl.glRotated(95, 1, 0, 0); Glut.glutSolidCylinder(0.7, 2, 60, 60); Gl.glLoadIdentity(); Gl.glColor3f(0, 0, 0); Gl.glTranslated(-1, 0, -6); Gl.glRotated(95, 1, 0, 0); Glut.glutWireCylinder(0.7, 2, 20, 20); } } }

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Old school trick that I forgot

- by DavidMadden

If you have to support some older Winforms you might like to remember this. When opening a MessageBox to display that the user entered incorrect information, if you are doing so from a dialog, catch the DialogResult of the MessageBox and then set this.DialogResult = DialogResult.None; to prevent the dialog from closing if you want the user to try again. Otherwise, it will close the dialog box and return to the section of code that called it.Note: You do not have to catch the DialogResult from the MessageBox. You can still set this after the return from the call to the MessageBox. Just make sure to do either but exiting the body of the dialog itself.

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Android game scrolling background

- by Stevanicus

Hi There, I'm just trying to figure out the best approach for running a scolling background on an android device. The method I have so far.... its pretty laggy. I use threads, which I believe is not the best bet for android platforms @Override public void run() { // Game Loop while(runningThread){ //Scroll background down bgY += 1; try { this.postInvalidate(); t.sleep(10); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } where postinvalidate in the onDraw function simply pushings the background image down canvas.drawBitmap(backgroundImage, bgX, bgY, null); Thanks in advance

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Missing error handling in Streaming-AJAX-Proxy Log

- by Michael Freidgeim

We are using AjaxProxy(FROM http://www.codeproject.com/KB/ajax/ajaxproxy.aspx) on our web site, but started to notice errors accessing log.txt file. I found that the file is created by Log class and doesn't have ability to switch it off and error handling. I've added reading file name from configuration and try/catch block public static class Log { private static StreamWriter logStream; private static object lockObject = new object (); public static void WriteLine(string msg) { string logFileName = ConfigurationExtensions.GetAppSetting("AjaxStreamingProxy.LogFile" ,""); if (logFileName.IsNullOrEmpty()) return; try { if (logStream == null ) { lock (lockObject) { if (logStream == null ) { logStream = File.AppendText(Path .Combine(AppDomain.CurrentDomain.BaseDirectory, logFileName)); } } } logStream.WriteLine(msg); } catch (Exception exc) { string ignoredMsg = String .Format("The error occured while logging {0}, but processing will continue.\n {1} ", exc); LoggerHelper.LogEvent(ignoredMsg, MyCategorySource, TraceEventType .Warning, true); } }

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spliiting code in java-don't know what's wrong [closed]

- by ???? ?????

I'm writing a code to split a file into many files with a size specified in the code, and then it will join these parts later. The problem is with the joining code, it doesn't work and I can't figure what is wrong! This is my code: import java.io.*; import java.util.*; public class StupidSplit { static final int Chunk_Size = 10; static int size =0; public static void main(String[] args) throws IOException { String file = "b.txt"; int chunks = DivideFile(file); System.out.print((new File(file)).delete()); System.out.print(JoinFile(file, chunks)); } static boolean JoinFile(String fname, int nChunks) { /* * Joins the chunks together. Chunks have been divided using DivideFile * function so the last part of filename will ".partxxxx" Checks if all * parts are together by matching number of chunks found against * "nChunks", then joins the file otherwise throws an error. */ boolean successful = false; File currentDirectory = new File(System.getProperty("user.dir")); // File[] fileList = currentDirectory.listFiles(); /* populate only the files having extension like "partxxxx" */ List<File> lst = new ArrayList<File>(); // Arrays.sort(fileList); for (File file : fileList) { if (file.isFile()) { String fnm = file.getName(); int lastDot = fnm.lastIndexOf('.'); // add to list which match the name given by "fname" and have //"partxxxx" as extension" if (fnm.substring(0, lastDot).equalsIgnoreCase(fname) && (fnm.substring(lastDot + 1)).substring(0, 4).equals("part")) { lst.add(file); } } } /* * sort the list - it will be sorted by extension only because we have * ensured that list only contains those files that have "fname" and * "part" */ File[] files = (File[]) lst.toArray(new File[0]); Arrays.sort(files); System.out.println("size ="+files.length); System.out.println("hello"); /* Ensure that number of chunks match the length of array */ if (files.length == nChunks-1) { File ofile = new File(fname); FileOutputStream fos; FileInputStream fis; byte[] fileBytes; int bytesRead = 0; try { fos = new FileOutputStream(ofile,true); for (File file : files) { fis = new FileInputStream(file); fileBytes = new byte[(int) file.length()]; bytesRead = fis.read(fileBytes, 0, (int) file.length()); assert(bytesRead == fileBytes.length); assert(bytesRead == (int) file.length()); fos.write(fileBytes); fos.flush(); fileBytes = null; fis.close(); fis = null; } fos.close(); fos = null; } catch (FileNotFoundException fnfe) { System.out.println("Could not find file"); successful = false; return successful; } catch (IOException ioe) { System.out.println("Cannot write to disk"); successful = false; return successful; } /* ensure size of file matches the size given by server */ successful = (ofile.length() == StupidSplit.size) ? true : false; } else { successful = false; } return successful; } static int DivideFile(String fname) { File ifile = new File(fname); FileInputStream fis; String newName; FileOutputStream chunk; //int fileSize = (int) ifile.length(); double fileSize = (double) ifile.length(); //int nChunks = 0, read = 0, readLength = Chunk_Size; int nChunks = 0, read = 0, readLength = Chunk_Size; byte[] byteChunk; try { fis = new FileInputStream(ifile); StupidSplit.size = (int)ifile.length(); while (fileSize > 0) { if (fileSize <= Chunk_Size) { readLength = (int) fileSize; } byteChunk = new byte[readLength]; read = fis.read(byteChunk, 0, readLength); fileSize -= read; assert(read==byteChunk.length); nChunks++; //newName = fname + ".part" + Integer.toString(nChunks - 1); newName = String.format("%s.part%09d", fname, nChunks - 1); chunk = new FileOutputStream(new File(newName)); chunk.write(byteChunk); chunk.flush(); chunk.close(); byteChunk = null; chunk = null; } fis.close(); System.out.println(nChunks); // fis = null; } catch (FileNotFoundException fnfe) { System.out.println("Could not find the given file"); System.exit(-1); } catch (IOException ioe) { System.out .println("Error while creating file chunks. Exiting program"); System.exit(-1); }System.out.println(nChunks); return nChunks; } } }

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