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  • How to convert datatable to json string using json.net?

    - by Pandiya Chendur
    How to convert datatable to json using json.net? Any suggestion... I ve downloaded the necessary binaries... Which class should i use to get the conversion of my datatable to json? Thus far used this method to get json string by passing my datatable... public string GetJSONString(DataTable table) { StringBuilder headStrBuilder = new StringBuilder(table.Columns.Count * 5); //pre-allocate some space, default is 16 bytes for (int i = 0; i < table.Columns.Count; i++) { headStrBuilder.AppendFormat("\"{0}\" : \"{0}{1}¾\",", table.Columns[i].Caption, i); } headStrBuilder.Remove(headStrBuilder.Length - 1, 1); // trim away last , StringBuilder sb = new StringBuilder(table.Rows.Count * 5); //pre-allocate some space sb.Append("{\""); sb.Append(table.TableName); sb.Append("\" : ["); for (int i = 0; i < table.Rows.Count; i++) { string tempStr = headStrBuilder.ToString(); sb.Append("{"); for (int j = 0; j < table.Columns.Count; j++) { table.Rows[i][j] = table.Rows[i][j].ToString().Replace("'", ""); tempStr = tempStr.Replace(table.Columns[j] + j.ToString() + "¾", table.Rows[i][j].ToString()); } sb.Append(tempStr + "},"); } sb.Remove(sb.Length - 1, 1); // trim last , sb.Append("]}"); return sb.ToString(); } Now i thought of using json.net but dont know where to get started....

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  • iPhone Audio Queue Service sample units

    - by pion
    I am looking at Audio Queue Services document specifically on the following code: // Writing an audio queue buffer to disk AudioFileWritePackets ( // 1 pAqData->mAudioFile, // 2 false, // 3 inBuffer->mAudioDataByteSize, // 4 inPacketDesc, // 5 pAqData->mCurrentPacket, // 6 &inNumPackets, // 7 inBuffer->mAudioData // 8 ); inBuffer-mAudioDataByteSize is the number of bytes of audio data being written. inBuffer-mAudioData is the new audio data to write to the audio file. Assuming the sample rate is 44100. AudioStreamBasicDescription mDataFormat; mDataFormat.mSampleRate = 44100.0f; mDataFormat.mBitsPerChannel = 16; ... NSInteger numberSamples = inBuffer->mAudioDataByteSize / 2; SInt16 *audioSample = (SInt16 *)inBuffer->mAudioData; I use core-plot to plot the above where x axis is number of sample [1 .. numberSamples] and the y axis is audioSample[0] .. audioSample[numberSamples]. I can see the chart in "real-time" where the y axis goes up and down depending the loudness of my voice. Beginner questions: What does the audioSample represent? What am I looking at here? What is the unit of audioSample? What do I need to do if I just want to plot the range between 50 - 100 Hz? Thanks in advance for your help.

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  • How to stream partial content with ASP.NET MVC FileStreamResult

    - by o_o
    We're using a FileStreamResult to provide video data to a Silverlight MediaElement based video player: public ActionResult Preview(Guid id) { return new FileStreamResult( Services.AssetStore.GetStream(id, ContentType.Preview), "application/octet-stream"); } Unfortunately, the Silverlight video player downloads the entire video file before it starts playing. This behavior is expected as our Preview Action does not support downloading partial content. (side note: if the file is hosted in an IIS virtual directory we can start playback at any location in the video while it is still downloading. however for security and auditing reasons we can't provide a direct download link. so this is not an option.) How can we improve the Controller Action to support partial HTTP content? I assume we first have to inform the client that we support it (adding an "Accept-Ranges:bytes" header to a HEAD request), then we have to evaluate the HTTP "Range" header and stream the requested file range with a response code of 206. Will that work with ASP.NET MVC hosted on IIS6? Is there already some code available? Also see: http://en.wikipedia.org/wiki/List_of_HTTP_headers http://blogs.msdn.com/anilkumargupta/archive/2009/04/29/downloadprogress-downloadprogressoffset-and-bufferprogress-of-the-mediaelement.aspx http://benramsey.com/archives/206-partial-content-and-range-requests/

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  • How to override ATTR_DEFAULT_IDENTIFIER_OPTIONS in Models in Doctrine?

    - by user309083
    Here someone explained that setting a 'primary' attribute for any row in your Model will override Doctrine_Manager's ATTR_DEFAULT_IDENTIFIER_OPTIONS attribute: http://stackoverflow.com/questions/2040675/how-do-you-override-a-constant-in-doctrines-models This works, however if you have a many to many relation whereby the intermediate table is created, even if you have set both columns in the intermediate to primary an error still results when Doctrine tries to place an index on the nonexistant 'id' column upon table creation. Here's my code: //Bootstrap // set the default primary key to be named 'id', integer, 4 bytes Doctrine_Manager::getInstance()->setAttribute( Doctrine_Core::ATTR_DEFAULT_IDENTIFIER_OPTIONS, array('name' => 'id', 'type' => 'integer', 'length' => 4)); //User Model class User extends Doctrine_Record { public function setTableDefinition() { $this->setTableName('users'); } public function setUp() { $this->hasMany('Role as roles', array( 'local' => 'id', 'foreign' => 'user_id', 'refClass' => 'UserRole', 'onDelete' => 'CASCADE' )); } } //Role Model class Role extends Doctrine_Record { public function setTableDefinition() { $this->setTableName('roles'); } public function setUp() { $this->hasMany('User as users', array( 'local' => 'id', 'foreign' => 'role_id', 'refClass' => 'UserRole' )); } } //UserRole Model class UserRole extends Doctrine_Record { public function setTableDefinition() { $this->setTableName('roles_users'); $this->hasColumn('user_id', 'integer', 4, array('primary'=>true)); $this->hasColumn('role_id', 'integer', 4, array('primary'=>true)); } } Resulting error: SQLSTATE[42000]: Syntax error or access violation: 1072 Key column 'id' doesn't exist in table. Failing Query: "CREATE TABLE roles_users (user_id INT UNSIGNED NOT NULL, role_id INT UNSIGNED NOT NULL, INDEX id_idx (id), PRIMARY KEY(user_id, role_id)) ENGINE = INNODB". Failing Query: CREATE TABLE roles_users (user_id INT UNSIGNED NOT NULL, role_id INT UNSIGNED NOT NULL, INDEX id_idx (id), PRIMARY KEY(user_id, role_id)) ENGINE = INNODB I'm creating my tables using Doctrine::createTablesFromModels();

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  • Sync Vs. Async Sockets Performance in C#

    - by Michael Covelli
    Everything that I read about sockets in .NET says that the asynchronous pattern gives better performance (especially with the new SocketAsyncEventArgs which saves on the allocation). I think this makes sense if we're talking about a server with many client connections where its not possible to allocate one thread per connection. Then I can see the advantage of using the ThreadPool threads and getting async callbacks on them. But in my app, I'm the client and I just need to listen to one server sending market tick data over one tcp connection. Right now, I create a single thread, set the priority to Highest, and call Socket.Receive() with it. My thread blocks on this call and wakes up once new data arrives. If I were to switch this to an async pattern so that I get a callback when there's new data, I see two issues The threadpool threads will have default priority so it seems they will be strictly worse than my own thread which has Highest priority. I'll still have to send everything through a single thread at some point. Say that I get N callbacks at almost the same time on N different threadpool threads notifying me that there's new data. The N byte arrays that they deliver can't be processed on the threadpool threads because there's no guarantee that they represent N unique market data messages because TCP is stream based. I'll have to lock and put the bytes into an array anyway and signal some other thread that can process what's in the array. So I'm not sure what having N threadpool threads is buying me. Am I thinking about this wrong? Is there a reason to use the Async patter in my specific case of one client connected to one server?

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  • A catalogue of Cassandra log messages: What is the correct interpretation?

    - by knorv
    The following is a complete catalogue of all log messages generated by Cassandra 0.6 when stress-testing a Cassandra installation over an extended period of time: AntiEntropyService: Sending AEService tree for (,) to: [] CassandraDaemon: Binding thrift service to localhost/N.N.N.N:N CassandraDaemon: Cassandra starting up... ColumnFamilyStore: has reached its threshold; switching in a fresh Memtable at CommitLogContext(file='.../cassandra/commitlog/CommitLog-N.log', position=N) ColumnFamilyStore: Enqueuing flush of Memtable()@N CommitLog: Discarding obsolete commit log:CommitLogSegment(.../cassandra/commitlog/CommitLog-N.log) CommitLog: Log replay complete CommitLog: Replaying .../cassandra/commitlog/CommitLog-N.log, ... CommitLogSegment: Creating new commitlog segment .../cassandra/commitlog/CommitLog-N.log CompactionManager: Compacted to .../cassandra/data//-N-Data.db. N/N bytes for N keys. Time: Nms. CompactionManager: Compacting [org.apache.cassandra.io.SSTableReader(path='.../cassandra/data//-N-Data.db'), ...] DatabaseDescriptor: Auto DiskAccessMode determined to be mmap GCInspector: GC for ConcurrentMarkSweep: N ms, N reclaimed leaving N used; max is N GCInspector: GC for ParNew: N ms, N reclaimed leaving N used; max is N Memtable: Completed flushing .../cassandra/data//-N-Data.db Memtable: Writing Memtable()@N SSTable: Deleted .../cassandra/data//-N-Data.db SSTableDeletingReference: Deleted .../cassandra/data//-N-Data.db SSTableReader: Sampling index for .../cassandra/data//-N-Data.db StorageService: Starting up server gossip SystemTable: Saved ClusterName found: Test Cluster SystemTable: Saved ClusterName not found. Using Test Cluster SystemTable: Saved Token found: N SystemTable: Saved Token not found. Using N For each of the log messages listed - what is the correct interpretation of the log message?

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  • Using Freepascal\Lazarus JSON Libraries

    - by Gizmo_the_Great
    I'm hoping for a bit of a "simpletons" demo\explanation for using Lazarus\Freepascal JSON parsing. I've asked a question here but all the replies are "read this" and none of them are really helping me get a grasp because the examples are bit too in-depth and I'm seeking a very simple example to help me understand how it works. In brief, my program reads an untyped binary file in chunks of 4096 bytes. The raw data then gets converted to ASCII and stored in a string. It then goes through the variable looking for certain patterns, which, it turned out, are JSON data structures. I've currently coded the parsing the hard way using Pos and ExtractANSIString etc. But I'vesince learnt that there are JSON libraries for Lazarus & FPC, namely fcl-json, fpjson, jsonparser, jsonscanner etc. https://bitbucket.org/reiniero/fpctwit/src http://fossies.org/unix/misc/fpcbuild-2.6.0.tar.gz:a/fpcbuild-2.6.0/fpcsrc/packages/fcl-json/src/ http://svn.freepascal.org/cgi-bin/viewvc.cgi/trunk/packages/fcl-json/examples/ However, I still can't quite work out HOW I read my string variable and parse it for JSON data and then access those JSON structures. Can anyone give me a very simple example, to help getting me going? My code so far (without JSON) is something like this: try SourceFile.Position := 0; while TotalBytesRead < SourceFile.Size do begin BytesRead := SourceFile.Read(Buffer,sizeof(Buffer)); inc(TotalBytesRead, BytesRead); StringContent := StripNonAsciiExceptCRLF(Buffer); // A custom function to strip out binary garbage leaving just ASCII readable text if Pos('MySearchValue', StringContent) > 0 then begin // Do the parsing. This is where I need to do the JSON stuff ...

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  • django+uploadify - don't working

    - by Erico
    Hi, I'm trying to use an example posted on the "github" the link is http://github.com/tstone/django-uploadify. And I'm having trouble getting work. can you help me? I followed step by step, but does not work. Accessing the "URL" / upload / the only thing is that returns "True" part of settings.py import os PROJECT_ROOT_PATH = os.path.dirname(os.path.abspath(file)) MEDIA_ROOT = os.path.join(PROJECT_ROOT_PATH, 'media') TEMPLATE_DIRS = ( os.path.join(PROJECT_ROOT_PATH, 'templates')) urls.py from django.conf.urls.defaults import * from django.conf import settings from teste.uploadify.views import * from django.contrib import admin admin.autodiscover() urlpatterns = patterns('', (r'^admin/', include(admin.site.urls)), url(r'upload/$', upload, name='uploadify_upload'), ) views.py from django.http import HttpResponse import django.dispatch upload_received = django.dispatch.Signal(providing_args=['data']) def upload(request, *args, **kwargs): if request.method == 'POST': if request.FILES: upload_received.send(sender='uploadify', data=request.FILES['Filedata']) return HttpResponse('True') models.py from django.db import models def upload_received_handler(sender, data, **kwargs): if file: new_media = Media.objects.create( file = data, new_upload = True, ) new_media.save() upload_received.connect(upload_received_handler, dispatch_uid='uploadify.media.upload_received') class Media(models.Model): file = models.FileField(upload_to='images/upload/', null=True, blank=True) new_upload = models.BooleanField() uploadify_tags.py from django import template from teste import settings register = template.Library() @register.inclusion_tag('uploadify/multi_file_upload.html', takes_context=True) def multi_file_upload(context, upload_complete_url): """ * filesUploaded - The total number of files uploaded * errors - The total number of errors while uploading * allBytesLoaded - The total number of bytes uploaded * speed - The average speed of all uploaded files """ return { 'upload_complete_url' : upload_complete_url, 'uploadify_path' : settings.UPLOADIFY_PATH, # checar essa linha 'upload_path' : settings.UPLOADIFY_UPLOAD_PATH, } template - uploadify/multi_file_upload.html {% load uploadify_tags }{ multi_file_upload '/media/images/upload/' %} <script type="text/javascript" src="{{ MEDIA_URL }}js/swfobject.js"></script> <script type="text/javascript" src="{{ MEDIA_URL }}js/jquery.uploadify.js"></script> <div id="uploadify" class="multi-file-upload"><input id="fileInput" name="fileInput" type="file" /></div> <script type="text/javascript">// <![CDATA[ $(document).ready(function() { $('#fileInput').uploadify({ 'uploader' : '/media/swf/uploadify.swf', 'script' : '{% url uploadify_upload %}', 'cancelImg' : '/media/images/uploadify-remove.png/', 'auto' : true, 'folder' : '/media/images/upload/', 'multi' : true, 'onAllComplete' : allComplete }); }); function allComplete(event, data) { $('#uploadify').load('{{ upload_complete_url }}', { 'filesUploaded' : data.filesUploaded, 'errorCount' : data.errors, 'allBytesLoaded' : data.allBytesLoaded, 'speed' : data.speed }); // raise custom event $('#uploadify') .trigger('allUploadsComplete', data); } // ]]</script>

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  • solve a classic map-reduce problem with opencl?

    - by liuliu
    I am trying to parallel a classic map-reduce problem (which can parallel well with MPI) with OpenCL, namely, the AMD implementation. But the result bothers me. Let me brief about the problem first. There are two type of data that flow into the system: the feature set (30 parameters for each) and the sample set (9000+ dimensions for each). It is a classic map-reduce problem in the sense that I need to calculate the score of every feature on every sample (Map). And then, sum up the overall score for every feature (Reduce). There are around 10k features and 30k samples. I tried different ways to solve the problem. First, I tried to decompose the problem by features. The problem is that the score calculation consists of random memory access (pick some of the 9000+ dimensions and do plus/subtraction calculations). Since I cannot coalesce memory access, it costs. Then, I tried to decompose the problem by samples. The problem is that to sum up overall score, all threads are competing for few score variables. It keeps overwriting the score which turns out to be incorrect. (I cannot carry out individual score first and sum up later because it requires 10k * 30k * 4 bytes). The first method I tried gives me the same performance on i7 860 CPU with 8 threads. However, I don't think the problem is unsolvable: it is remarkably similar to ray tracing problem (for which you carry out calculation that millions of rays against millions of triangles). Any ideas?

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  • How to use the buffer on SocketAsyncEventArgs object

    - by Rob
    We're stuck with using buffers on the SocketAsyncEventArgs object. With the old socket method we'd cast our state object, like this: clientState cs = (clientState)asyncResult.AsyncState; However, the 3.5 framework is different. With have strings arriving from the client in chunks and we can't seem to work out how the buffers work so we can process an entire string when we find a char3. Code at the moment: private void ProcessReceive(SocketAsyncEventArgs e) { string content = string.Empty; // Check if the remote host closed the connection. if (e.BytesTransferred > 0) { if (e.SocketError == SocketError.Success) { Socket s = e.UserToken as Socket; //asyncResult.AsyncState; Int32 bytesTransferred = e.BytesTransferred; // Get the message received from the listener. content += Encoding.ASCII.GetString(e.Buffer, e.Offset, bytesTransferred); if (content.IndexOf(Convert.ToString((char)3)) > -1) { e.BufferList = null; // Increment the count of the total bytes receive by the server. Interlocked.Add(ref this.totalBytesRead, bytesTransferred); } else { content += Encoding.ASCII.GetString(e.Buffer, e.Offset, bytesTransferred); ProcessReceive(e); } } else { this.CloseClientSocket(e); } } }

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  • What's the recommended implemenation for hashing OLE Variants?

    - by Barry Kelly
    OLE Variants, as used by older versions of Visual Basic and pervasively in COM Automation, can store lots of different types: basic types like integers and floats, more complicated types like strings and arrays, and all the way up to IDispatch implementations and pointers in the form of ByRef variants. Variants are also weakly typed: they convert the value to another type without warning depending on which operator you apply and what the current types are of the values passed to the operator. For example, comparing two variants, one containing the integer 1 and another containing the string "1", for equality will return True. So assuming that I'm working with variants at the underlying data level (e.g. VARIANT in C++ or TVarData in Delphi - i.e. the big union of different possible values), how should I hash variants consistently so that they obey the right rules? Rules: Variants that hash unequally should compare as unequal, both in sorting and direct equality Variants that compare as equal for both sorting and direct equality should hash as equal It's OK if I have to use different sorting and direct comparison rules in order to make the hashing fit. The way I'm currently working is I'm normalizing the variants to strings (if they fit), and treating them as strings, otherwise I'm working with the variant data as if it was an opaque blob, and hashing and comparing its raw bytes. That has some limitations, of course: numbers 1..10 sort as [1, 10, 2, ... 9] etc. This is mildly annoying, but it is consistent and it is very little work. However, I do wonder if there is an accepted practice for this problem.

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  • Hibernate: OutOfMemoryError persisting Blob when printing log message

    - by paul
    I have a Hibernate Entity: @Entity class Foo { //... @Lob public byte[] getBytes() { return bytes; } //.... } My VM is configured with a maximum heap size of 512 MB. When I try to persist an object which has a 75 MB large object, I get an OutOfMemoryError. The names of the methods in the stack trace (StringBuilder, ByteArrayBlobType.toLoggableString, pretty.Printer.toString) suggest that hibernate is trying to write a very large log message that contains my object. Am I correct about why hibernate is using so much memory? What is the simplest way to work around this problem? java.lang.OutOfMemoryError: Java heap space at java.lang.AbstractStringBuilder.<init>(AbstractStringBuilder.java:44) at java.lang.StringBuilder.<init>(StringBuilder.java:81) at org.hibernate.type.ByteArrayBlobType.toString(ByteArrayBlobType.java:117) at org.hibernate.type.ByteArrayBlobType.toLoggableString(ByteArrayBlobType.java:127) at org.hibernate.pretty.Printer.toString(Printer.java:53) at org.hibernate.pretty.Printer.toString(Printer.java:90) at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:97) at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:26) at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000) at org.jboss.seam.persistence.HibernateSessionProxy.flush(HibernateSessionProxy.java:181)

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  • FileDialog DoubleClick Behavior

    - by Shaun Hamman
    While developing a WinForms application, I came across what I believe is a bug in the OpenFileDialog and SaveFileDialog controls. A Google search turned up a single other person who noticed the same issue, but neither a solution nor a workaround was provided. You can view this thread at: http://bytes.com/topic/visual-basic-net/answers/389470-open-file-dialog-picturebox-click-event. I have a custom control on my form that handles the MouseDown event. If I doubleclick a file in a FileDialog control while the mouse is over this control (with the dialog between them, obviously), the MouseDown event gets triggered. I don't think this is an issue with my control, because the person I mentioned before noticed this happening with a PictureBox control. It would seem that even though the mouse button was pressed down (for the second click to open the file) while on the dialog box, the event passed through to the form and my control when the dialog closed. I have tried disabling my control while the dialog box is active, but that didn't stop it from capturing the event. I assume this is because the event is passed down after the dialog closes, so my control would be re-enabled. Does anyone know of a way to prevent that click from reaching the form and, in turn, my control? Also, can anyone confirm if this really is a bug in the FileDialog controls, or if I just have some setting configured incorrectly?

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  • How to reproduce System.Security.Cryptography.SHA1Managed result in Python

    - by joetyson
    Here's the deal: I'm moving a .NET website to Python. I have a database with passwords hashed using the System.Security.Cryptography.SHA1Managed utility. I'm creating the hash in .NET with the following code: string hashedPassword = Cryptographer.CreateHash("MYHasher", userInfo.Password); The MYHasher block looks like this: <add algorithmType="System.Security.Cryptography.SHA1Managed, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=blahblahblah" saltEnabled="true" type="Microsoft.Practices.EnterpriseLibrary.Security.Cryptography.HashAlgorithmProvider, Microsoft.Practices.EnterpriseLibrary.Security.Cryptography, Version=3.0.0.0, Culture=neutral, PublicKeyToken=daahblahdahdah" name="MYHasher" /> So for a given password, I get back and store in the database a 48 byte salted sha1. I assume the last 8 bytes are the salt. I have tried to reproduce the hashing process in python by doing a sha1(salt + password) and sha1(password + salt) but I'm having no luck. My question to you: How are the public keys being used? How is the password rehashed using the salt. How is the salt created? (e.g., When I say saltEnabled="true", what extra magic happens?) I need specific details that don't just reference other .NET libraries, I'm looking for the actual operational logic that happens in the blackbox. Thanks!

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  • java converting int to short

    - by changed
    Hi I am calculating 16 bit checksum on my data which i need to send to server where it has to recalculate and match with the provided checksum. Checksum value that i am getting is in int but i have only 2 bytes for sending the value.So i am casting int to short while calling shortToBytes method. This works fine till checksum value is less than 32767 thereafter i am getting negative values. Thing is java does not have unsigned primitives, so i am not able to send values greater than max value of signed short allowed. How can i do this, converting int to short and send over the network without worrying about truncation and signed & unsigned int. Also on both the side i have java program running. private byte[] shortToBytes(short sh) { byte[] baValue = new byte[2]; ByteBuffer buf = ByteBuffer.wrap(baValue); return buf.putShort(sh).array(); } private short bytesToShort(byte[] buf, int offset) { byte[] baValue = new byte[2]; System.arraycopy(buf, offset, baValue, 0, 2); return ByteBuffer.wrap(baValue).getShort(); }

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  • Character set issues with Oracle Gateways, SQL Server, and Application Express

    - by Brian Deterling
    I am migrating data from a Oracle on VMS that accesses data on SQL Server using heterogeneous services (over ODBC) to Oracle on AIX accessing the SQL Server via Oracle Gateways (dg4msql). The Oracle VMS database used the WE8ISO8859P1 character set. The AIX database uses WE8MSWIN1252. The SQL Server database uses "Latin1-General, case-insensitive, accent-sensitive, kanatype-insensitive, width-insensitive for Unicode Data, SQL Server Sort Order 52 on Code Page 1252 for non-Unicode Data" according to sp_helpsort. The SQL Server databases uses nchar/nvarchar or all string columns. In Application Express, extra characters are appearing in some cases, for example 123 shows up as %001%002%003. In sqlplus, things look ok but if I use Oracle functions like initcap, I see what appear as spaces between each letter of a string when I query the sql server database (using a database link). This did not occur under the old configuration. I'm assuming the issue is that an nchar has extra bytes in it and the character set in Oracle can't convert it. It appears that the ODBC solution didn't support nchars so must have just cast them back to char and they showed up ok. I only need to view the sql server data so I'm open to any solution such as casting, but I haven't found anything that works. Any ideas on how to deal with this? Should I be using a different character set in Oracle and if so, does that apply to all schemas since I only care about one of them.

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  • Still about SSD potentials...write and read speed

    - by Macroideal
    HI Gurus, I have been working on SSD(solid state disk) for several months..Problems and Questions hit my head unexpectedly..Coz i am a virgin in ssd... Esp these days i was testing the write-read speed of ssd, which I was always caring.... however result turned out not good as I expected, or even worse Three kinds of read-write were implemented in my test 1. read and write directly from and into ssd, with openning ssd as a whole device. in windows: _open("\\:g", ***).. It can be very tricky and hairy that you'd write a data with size of folds of 512, at the disk position of folds of 512bytes... So, If you wanto write just a byte or 4 bytes, you'v to write at least a whole sector one time. 2. Read and write data from and into files located in SSD... 3. Read and Write data from and into files in mechanical Disk I compared the pratices below...I found ssd sucks...the ssd performs worse than mechanical disk... so i am wondering where i can get the potential performance of ssd, since ssd is said to a substitute for mechanical disk in the future.. Nevertheless, I test ssd with a pro-hard-disk tools..ssd is like twice speedier than mechanical disk. So, why? Thanx very much...If you know tips of ssd...follow me

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  • Create Zip File In Windows and Extract Zip File In Linux

    - by Yan Cheng CHEOK
    I had created a zip file (together with directory) under Windows as follow : package sandbox; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.util.zip.ZipEntry; import java.util.zip.ZipOutputStream; /** * * @author yan-cheng.cheok */ public class Main { /** * @param args the command line arguments */ public static void main(String[] args) { // These are the files to include in the ZIP file String[] filenames = new String[]{"MyDirectory" + File.separator + "MyFile.txt"}; // Create a buffer for reading the files byte[] buf = new byte[1024]; try { // Create the ZIP file String outFilename = "outfile.zip"; ZipOutputStream out = new ZipOutputStream(new FileOutputStream(outFilename)); // Compress the files for (int i=0; i<filenames.length; i++) { FileInputStream in = new FileInputStream(filenames[i]); // Add ZIP entry to output stream. out.putNextEntry(new ZipEntry(filenames[i])); // Transfer bytes from the file to the ZIP file int len; while ((len = in.read(buf)) > 0) { out.write(buf, 0, len); } // Complete the entry out.closeEntry(); in.close(); } // Complete the ZIP file out.close(); } catch (IOException e) { e.printStackTrace(); } } } The newly created zip file can be extracted without problem under Windows, by using http://www.exampledepot.com/egs/java.util.zip/GetZip.html However, I realize if I extract the newly created zip file under Linux, using http://www.exampledepot.com/egs/java.util.zip/GetZip.html, I will get a file named "MyDirectory\MyFile.txt" instead of MyFile.txt being placed under folder MyDirectory. I try to solve the problem by changing the zip file creation code to String[] filenames = new String[]{"MyDirectory" + "/" + "MyFile.txt"}; But, is this an eligible solution, by hard-coded the seperator? Will it work under Mac OS? (I do not have a Mac to try out)

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  • File extensions and MIME Types in .NET

    - by Marc Climent
    I want to get a MIME Content-Type from a given extension (preferably without accessing the physical file). I have seen some questions about this and the methods described to perform this can be resumed in: Use registry information. Use urlmon.dll's FindMimeFromData. Use IIS information. Roll your own MIME mapping function. Based on this table, for example. I've been using no.1 for some time but I realized that the information provided by the registry is not consistent and depends on the software installed on the machine. Some extensions, like .zip don't use to have a Content-Type specified. Solution no.2 forces me to have the file on disk in order to read the first bytes, which is something slow but may get good results. The third method is based on Directory Services and all that stuff, which is something I don't like much because I have to add COM references and I'm not sure it's consistent between IIS6 and IIS7. Also, I don't know the performance of this method. Finally, I didn't want to use my own table but at the end seems the best option if I want a decent performance and consistency of the results between platforms (even Mono). Do you think there's a better option than using my own table or one of other described methods are better? What's your experience?

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  • SQLite table does not exist exception for existing SQLite database (and table)

    - by SK9
    I've followed the instructions given here for introducing an existing SQLite database to your Android app. When I query the table "android_metadata" this is fine. But when I run a similar query on my own table "words" (which has _id for primary integer key) I get a table does not exist exception and the app crashes. Why is that? Code: Cursor c = myDatabase.query("android_metadata", null, null, null, null, null, null, null); works but Cursor c = myDatabase.query("words", null, null, null, null, null, null, null); returns a table does not exist exception. This is how I'm creating the database (the references to paths and filenames are correct): private void copyDatabase() throws IOException{ //Open local db as the input stream InputStream myInput = mContext.getAssets().open(DB_NAME); //Path to the just created empty db String outFileName = DB_PATH + DB_NAME; //Open the empty db as the output stream OutputStream myOutput = new FileOutputStream(outFileName); //Transfer bytes from the inputfile to the outputfile byte[] buffer = new byte[1024]; int length; while ((length = myInput.read(buffer))>0){ myOutput.write(buffer, 0, length); } //Close the streams myOutput.flush(); myOutput.close(); myInput.close(); } (Note: To my eyes, the table is there. I'm looking right at it in my SQLite browser.)

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  • BCP task hangs while executing

    - by user350374
    Hey guys, We have a HPC node that runs some of our tasks in it. I have a task in my .net project that kicks the bcp utility on the HPC node and the output of the query that I have runs into 9 Mb. When the HPC node runs this task the output of the query is dumped into a file and then after it dumps around 5mb of data it suddenly stops dumping any more data and this happens all the time. (Please note this isnt any data issue as its not crashing on a particular row every time). this may or may not be of significance but I dump the data into a different server which has adequate permissions set. I have run the command with the same query directly on the hpc node and on other comps and it gives the right output. I'm running the bcp command as follows: var processInfo = new ProcessStartInfo("bcp.exe", argument) { RedirectStandardOutput = true, RedirectStandardError = true, CreateNoWindow = true, UseShellExecute = false }; var proc = new Process { StartInfo = processInfo, EnableRaisingEvents = true }; proc.Exited += new EventHandler(bcp_log); proc.Start(); proc.WaitForExit(); So my code actually waits for each bcp task to run before it goes ahead as I call it multiple times. FYI to remind you again it only fails when my o/p exceeds a certain no of bytes in this case approx 5mb. Any help is much appreciated.

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  • maintaining a large list in python

    - by Oren
    I need to maintain a large list of python pickleable objects that will quickly execute the following algorithm: The list will have 4 pointers and can: Read\Write each of the 4 pointed nodes Insert new nodes before the pointed nodes Increase a pointer by 1 Pop nodes from the beginning of the list (without overlapping the pointers) Add nodes at the end of the list The list can be very large (300-400 MB), so it shouldnt be contained in the RAM. The nodes are small (100-200 bytes) but can contain various types of data. The most efficient way it can be done, in my opinion, is to implement some paging-mechanism. On the harddrive there will be some database of a linked-list of pages where in every moment up to 5 of them are loaded in the memory. On insertion, if some max-page-size was reached, the page will be splitted to 2 small pages, and on pointer increment, if a pointer is increased beyond its loaded page, the following page will be loaded instead. This is a good solution, but I don't have the time to write it, especially if I want to make it generic and implement all the python-list features. Using a SQL tables is not good either, since I'll need to implement a complex index-key mechanism. I tried ZODB and zc.blist, which implement a BTree based list that can be stored in a ZODB database file, but I don't know how to configure it so the above features will run in reasonable time. I don't need all the multi-threading\transactioning features. No one else will touch the database-file except for my single-thread program. Can anyone explain me how to configure the ZODB\zc.blist so the above features will run fast, or show me a different large-list implementation?

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  • git push error 'remote rejected] master -> master (branch is currently checked out)'

    - by hap497
    Hi, Yesterday, I post a question regarding how to clone a git repository from 1 of my machine to another. http://stackoverflow.com/questions/2808177/how-can-i-git-clone-from-another-machine/2809612#2809612 I am able to successfully clone a git repository from my src (192.168.1.2) to my dest (192.168.1.1). But when I did an edit to a file and then do a 'git commit -a -m "test"' and then do a git push. I get this error on my dest (192.168.1.1): git push [email protected]'s password: Counting objects: 21, done. Compressing objects: 100% (11/11), done. Writing objects: 100% (11/11), 1010 bytes, done. Total 11 (delta 9), reused 0 (delta 0) error: refusing to update checked out branch: refs/heads/master error: By default, updating the current branch in a non-bare repository error: is denied, because it will make the index and work tree inconsistent error: with what you pushed, and will require 'git reset --hard' to match error: the work tree to HEAD. error: error: You can set 'receive.denyCurrentBranch' configuration variable to error: 'ignore' or 'warn' in the remote repository to allow pushing into error: its current branch; however, this is not recommended unless you error: arranged to update its work tree to match what you pushed in some error: other way. error: error: To squelch this message and still keep the default behaviour, set error: 'receive.denyCurrentBranch' configuration variable to 'refuse'. To git+ssh://[email protected]/media/LINUXDATA/working ! [remote rejected] master -> master (branch is currently checked out) error: failed to push some refs to 'git+ssh://[email protected]/media/LINUXDATA/working' I have 2 version of git, will that causes this problem? I have git 1.7 on 192.168.1.2 (src) but git 1.5 on 192.168.1.1 (dest). I appreciate if someone can help me with this. Thank you.

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  • Android: writing a file to sdcard

    - by Sumit M Asok
    I'm trying to write a file from an Http post reply to a file on the sdcard. Everything works fine until the byte array of data is retrieved. I've tried setting WRITE_EXTERNAL_STORAGE permission in the manifest and tried many different combinations of tutorials I found on the net. All I could find was using the openFileOutput("",MODE_WORLD_READABLE) method, of the activity but how my app writes file is by using a thread. Specifically, a thread is invoked from another thread when a file has to be written, so giving an activity object didn't work even though I tried it. The app has come a long way and I cannot change how the app is currently written. Please, someone help me? CODE: File file = new File(bgdmanip.savLocation); FileOutputStream filecon = null; filecon = new FileOutputStream(file); // bgdmanip.savLocation holds the whole files path byte[] myByte; myByte = Base64Coder.decode(seReply); Log.d("myBytes", String.valueOf(myByte)); bos.write(myByte); filecon.write(myByte); myvals = x * 11024; seReply is a string reply from HttpPost response. the second set of code is looped with reference to x. the file is created but remains 0 bytes

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  • KeepAlive packets over a Soap request

    - by Nycto
    I've been debugging some Soap requests we are making between two servers on the same VLAN. The app on one server is written in PHP, the app on the other is written in Java. I can control and make changes to the PHP code, but I can't affect the Java server. The PHP app forms the XML using the DOMDocument objects, then sends the request using the cURL extension. When the soap request took longer than 5 minutes to complete, it would always wait until the max timeout limit and exit with a message like this: Operation timed out after 900000 milliseconds with 0 bytes received After sniffing the packets that were being sent, it turns out that the problem was caused by a 5 minute timeout in the network that was closing what it thought was a stale connection. There were two ways to fix it: bump up the timeout in iptables, or start sending KeepAlive packets over the request. To be thorough, I would like to implement both solutions. Bumping up the timeout was easy for ops to do, but sending KeepAlive packets is turning out to be difficult. The cURL library itself supports this (see the --keepalive-time flag for the CLI app), but it doesn't appear that this has been implemented in the PHP cURL library. I even checked the source to make sure it wasn't an undocumented feature. So my question is this: How the heck can I get these packets sent? I see a few clear options, but I don't like any of them: Write a wrapper that will kick off the request by shell_execing the CLI app. This is a hack that I just don't like Update the cURL extension to support this. This is a non-option according to Ops. Open the socket myself. I know just enough to be dangerous. I also haven't seen a way to do this with fsockopen, but I could be missing something. Switch to another library. What exists that supports this? Thanks for any help you can offer.

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