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  • Using FFmpeg in c#?

    - by daniel
    So i know its a fairly big challenge but i want to write a basic movie player/converter in c# using the FFmpeg library. However the first obstacle i need to overcome is wrapping the FFmpeg library in c#. I downloaded ffmpeg but couldn't compile it on windows, so i downloaded a precompiled version for me. Ok awesome. Then i started looking for c# wrappers. I have looked around and have found a few wrappers such as SharpFFmpeg (http://sourceforge.net/projects/sharpffmpeg/) and ffmpeg-sharp (http://code.google.com/p/ffmpeg-sharp/). First of all i wanted to use ffmpeg-sharp as its LGPL and SharpFFmpeg is GPL. However it had quite a few compile errors. Turns out it was written for the mono compiler, i tried compiling it with mon but couldn't figure out how. I then started to manually fix the compiler errors myself, but came across a few scary ones and thought i'd better leave those alone. So i gave up on ffmpeg-sharp. Then i looked at SharpFFmpeg and it looks like what i want, all the functions P/Invoked for me. However its GPL? Both the AVCodec.cs and AVFormat.cs files look like ports of avcodec.c and avformat.c which i reckon i could port myself? Then not have to worry about licencing. But i wan't to get this right before i go ahead and start coding. Should I: Write my own c++ library for interacting with ffmpeg, then have my c# program talk to the c++ library in order to play/convert videos etc. OR Port avcodec.h and avformat.h (is that all i need?) to c# by using a whole lot of DllImports and write it entirely in c#? First of all consider that i'm not great at c++ as i rarely use it but i know enough to get around. The reason i'm thinking #1 might be the better option is that most FFmpeg tutorials are in c++ and i'd also have more control over memory management that if i was to do it in c#. What do you think? Also would you happen to have any usefull links (perhaps a tutorial) for using FFmpeg? EDIT: spelling mistakes

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  • Specified key is not a valid size for this algorithm...

    - by phenevo
    Hi, I have with this code: RijndaelManaged rijndaelCipher = new RijndaelManaged(); // Set key and IV rijndaelCipher.Key = Convert.FromBase64String("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz012345678912"); rijndaelCipher.IV = Convert.FromBase64String("1234567890123456789012345678901234567890123456789012345678901234"); I get throws : Specified key is not a valid size for this algorithm. Specified initialization vector (IV) does not match the block size for this algorithm. What's wrong with this strings ? Can I count at some examples strings from You ?

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  • build error with boost spirit grammar (boost 1.43 and g++ 4.4.1)

    - by lurscher
    I'm having issues getting a small spirit/qi grammar to compile. The build stack trace is fugly enought to not make any sense to me (despite some assertion_failed i could notice in there but that didn't brought much information) the input grammar header: inputGrammar.h #include <boost/config/warning_disable.hpp> #include <boost/spirit/include/qi.hpp> #include <boost/spirit/include/phoenix_core.hpp> #include <boost/spirit/include/phoenix_operator.hpp> #include <boost/spirit/include/phoenix_fusion.hpp> #include <boost/spirit/include/phoenix_stl.hpp> #include <boost/fusion/include/adapt_struct.hpp> #include <boost/variant/recursive_variant.hpp> #include <boost/foreach.hpp> #include <iostream> #include <fstream> #include <string> #include <vector> namespace sp = boost::spirit; namespace qi = boost::spirit::qi; using namespace boost::spirit::ascii; //using namespace boost::spirit::arg_names; namespace fusion = boost::fusion; namespace phoenix = boost::phoenix; using phoenix::at_c; using phoenix::push_back; template< typename Iterator , typename ExpressionAST > struct InputGrammar : qi::grammar<Iterator, ExpressionAST(), space_type> { InputGrammar() : InputGrammar::base_type( block ) { tag = sp::lexeme[+(alpha) [sp::_val += sp::_1]];//[+(char_ - '<') [_val += _1]]; block = sp::lit("block") [ at_c<0>(sp::_val) = sp::_1] >> "(" >> *instruction[ push_back( at_c<1>(sp::_val) , sp::_1 ) ] >> ")"; command = tag [ at_c<0>(sp::_val) = sp::_1] >> "(" >> *instruction [ push_back( at_c<1>(sp::_val) , sp::_1 )] >> ")"; instruction = ( command | tag ) [sp::_val = sp::_1]; } qi::rule< Iterator , std::string() , space_type > tag; qi::rule< Iterator , ExpressionAST() , space_type > block; qi::rule< Iterator , ExpressionAST() , space_type > function_def; qi::rule< Iterator , ExpressionAST() , space_type > command; qi::rule< Iterator , ExpressionAST() , space_type > instruction; }; the test build program: i seems the build fails at qi::phrase_parse, i am using boost 1.43 and g++ 4.4.1 #include <iostream> #include <string> #include <vector> using namespace std; //my grammar #include <InputGrammar.h> struct MockExpressionNode { std::string name; std::vector< MockExpressionNode > operands; typedef std::vector< MockExpressionNode >::iterator iterator; typedef std::vector< MockExpressionNode >::const_iterator const_iterator; iterator begin() { return operands.begin(); } const_iterator begin() const { return operands.begin(); } iterator end() { return operands.end(); } const_iterator end() const { return operands.end(); } bool is_leaf() const { return ( operands.begin() == operands.end() ); } }; BOOST_FUSION_ADAPT_STRUCT( MockExpressionNode, (std::string, name) (std::vector<MockExpressionNode>, operands) ) int const tabsize = 4; void tab(int indent) { for (int i = 0; i < indent; ++i) std::cout << ' '; } template< typename ExpressionNode > struct ExpressionNodePrinter { ExpressionNodePrinter(int indent = 0) : indent(indent) { } void operator()(ExpressionNode const& node) const { cout << " tag: " << node.name << endl; for (int i=0 ; i < node.operands.size() ; i++ ) { tab( indent ); cout << " arg "<<i<<": "; ExpressionNodePrinter(indent + 2)( node.operands[i]); cout << endl; } } int indent; }; int test() { MockExpressionNode root; InputGrammar< string::const_iterator , MockExpressionNode > g(); std::string litA = "litA"; std::string litB = "litB"; std::string litC = "litC"; std::string litD = "litD"; std::string litE = "litE"; std::string litF = "litF"; std::string source = litA+"( "+litB+" ,"+litC+" , "+ litD+" ( "+litE+", "+litF+" ) "+ " )"; string::const_iterator iter = source.begin(); string::const_iterator end = source.end(); bool r = qi::phrase_parse( iter , end , g , root , space ); ExpressionNodePrinter< MockExpressionNode > np; np( root ); }; int main() { test(); } finally, the build error is the following: /usr/bin/make -f nbproject/Makefile-linux_amd64_devel.mk SUBPROJECTS= .build-conf make[1]: se ingresa al directorio `/home/mineq/NetBeansProjects/InputParserTests' /usr/bin/make -f nbproject/Makefile-linux_amd64_devel.mk dist/linux_amd64_devel/GNU-Linux-x86/vpuinputparsertests make[2]: se ingresa al directorio `/home/mineq/NetBeansProjects/InputParserTests' mkdir -p build/linux_amd64_devel/GNU-Linux-x86 rm -f build/linux_amd64_devel/GNU-Linux-x86/tests_main.o.d g++ `llvm-config --cxxflags` `pkg-config --cflags unittest-cpp` `pkg-config --cflags boost-1.43` `pkg-config --cflags boost-coroutines` -c -g -I../InputParser -MMD -MP -MF build/linux_amd64_devel/GNU-Linux-x86/tests_main.o.d -o build/linux_amd64_devel/GNU-Linux-x86/tests_main.o tests_main.cpp from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/auto.hpp:16, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi.hpp:15, from /home/mineq/third_party/boost_1_43_0/boost/spirit/include/qi.hpp:16, from ../InputParser/InputGrammar.h:12, from tests_main.cpp:14: /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp: In function ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]’: In file included from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/detail/parse_auto.hpp:14, /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:99: error: no matching function for call to ‘assertion_failed(mpl_::failed************ (boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]::error_invalid_expression::************)(InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode> (*)()))’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:100: error: no matching function for call to ‘assertion_failed(mpl_::failed************ (boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]::error_invalid_expression::************)(MockExpressionNode))’ from /home/mineq/third_party/boost_1_43_0/boost/proto/proto.hpp:12, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/support/meta_compiler.hpp:17, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/meta_compiler.hpp:14, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/action/action.hpp:14, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/action.hpp:14, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi.hpp:14, from /home/mineq/third_party/boost_1_43_0/boost/spirit/include/qi.hpp:16, from ../InputParser/InputGrammar.h:12, from tests_main.cpp:14: /home/mineq/third_party/boost_1_43_0/boost/proto/detail/expr0.hpp: At global scope: /home/mineq/third_party/boost_1_43_0/boost/proto/proto_fwd.hpp: In instantiation of ‘boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()>, 0l>’: In file included from /home/mineq/third_party/boost_1_43_0/boost/proto/core.hpp:13, /home/mineq/third_party/boost_1_43_0/boost/utility/enable_if.hpp:59: instantiated from ‘boost::disable_if<boost::proto::result_of::is_expr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()>, 0l>, void>, void>’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/support/meta_compiler.hpp:200: instantiated from ‘boost::spirit::result_of::compile<boost::spirit::qi::domain, InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), boost::fusion::unused_type, void>’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:107: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/proto/detail/expr0.hpp:64: error: field ‘boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()>, 0l>::child0’ invalidly declared function type from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/auto.hpp:16, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi.hpp:15, from /home/mineq/third_party/boost_1_43_0/boost/spirit/include/qi.hpp:16, from ../InputParser/InputGrammar.h:12, from tests_main.cpp:14: /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp: In function ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]’: In file included from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/detail/parse_auto.hpp:14, /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:107: error: request for member ‘parse’ in ‘boost::spirit::compile [with Domain = boost::spirit::qi::domain, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()](((InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode> (&)())((InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode> (*)())expr)))’, which is of non-class type ‘InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()’ from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/auto.hpp:15, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi.hpp:15, from /home/mineq/third_party/boost_1_43_0/boost/spirit/include/qi.hpp:16, from ../InputParser/InputGrammar.h:12, from tests_main.cpp:14: /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/skip_over.hpp: In function ‘void boost::spirit::qi::skip_over(Iterator&, const Iterator&, const T&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, T = boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]::skipper_type]’: In file included from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/auto/auto.hpp:19, /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:112: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/skip_over.hpp:27: error: ‘const struct MockExpressionNode’ has no member named ‘parse’ make[2]: *** [build/linux_amd64_devel/GNU-Linux-x86/tests_main.o] Error 1 make[2]: se sale del directorio `/home/mineq/NetBeansProjects/InputParserTests' make[1]: *** [.build-conf] Error 2 make[1]: se sale del directorio `/home/mineq/NetBeansProjects/InputParserTests' make: *** [.build-impl] Error 2 BUILD FAILED (exit value 2, total time: 1m 48s)

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  • Objective-C library recommendation for AES-256 in CTR mode

    - by lpfavreau
    Hello, I'm looking for recommendations on an Objective-C library for AES-256 encryption in CTR mode. I have a database full of data encrypted with another library using CTR and seems the included CCCrypt only supports ECB or CBC with PKCS#7. Any idea on the best portable library I should use? I'm not looking to port the original implementation as I don't have the required knowledge in cryptography and hence, that's-a-bad-idea (tm). Thanks!

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  • Connection Timeout and Connection Lifetime

    - by Mark
    What is the advantage and disadvantage of connection timeout=0? And what is the use of Connection Lifetime=0? e.g (Database=TestDB;port=3306;Uid=usernameID;Pwd=myPassword;Server=192.168.10.1;Pooling=false;Connection Lifetime=0;Connection Timeout=0) and what is the use of Connection Pooling?

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  • connect to oracle through socks proxy

    - by Roman
    My application (linux and windows) connects to oracle through OCI interface. Is it possible to connect to oracle through socks proxy? or some other similar proxy method? Simple ssh tunnel is not enough as I need to access multiple services (including oracle) through single port.

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  • Why can't Android find android.graphics.OpenGLContext?

    - by lostInTransit
    I am trying to compile some OpenGL samples available on the net in SDK 1.5. But the import statement for android.graphics.OpenGLContext gives me an error saying the class cannot be found. Can someone please tell me where I can find this class. And if it is no longer supported by the android SDK then how do I port the samples to 1.5.

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  • WCF chunking/streaming - make it transparent for client

    - by bybor
    While developing WCF service i've faced problem of transferring large data as method params ( 4 Mb of raw size, not considering transfer/message overhead). The solution for this problem is to use chunking or streaming, but all the samples i've seen assume client is aware of used method and uses available block size for sending/receiving portions of data, and the problem (for me) is that it's not possible to call just one method, like SaveData(DataInformation info) but write wrapper method which will instead iterate smth like SaveDataChunk(byte[] buffer) Could it be somehow made transparent for client, just calling 'SaveData'?

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  • Download a file with DefaultHTTPClient and preemptive authentication

    - by Nils
    After I had a lot of problems with preemptive authentication , I got it finally working. Now the next problem. I want to get a file with it, but I don't know how. I thought the file data might be in the variable response, but it isn't. Any ideas how this might work? I'm trying it since days without success :( - Basically I'm trying to download an jpeg file, which is on a server protected by prem. auth. // BASIC AUTH /* * ==================================================================== * * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. */ //http://svn.apache.org/repos/asf/httpcomponents/httpclient/branches/4.0.x/httpclient/src/examples/org/apache/http/examples/client/ClientPreemptiveBasicAuthentication.java httpclient = new DefaultHttpClient(); httpclient.getCredentialsProvider().setCredentials( new AuthScope(host, port), new UsernamePasswordCredentials(username, password)); // Generate BASIC scheme object and stick it to the local // execution context BasicHttpContext localcontext = new BasicHttpContext(); BasicScheme basicAuth = new BasicScheme(); localcontext.setAttribute("preemptive-auth", basicAuth); //first request interceptor httpclient.addRequestInterceptor(new PreemptiveAuth(), 0); HttpHost targetHost = new HttpHost(host, port, "http"); //HttpGet httpget = new HttpGet("/"); HttpGet httpget = new HttpGet(http.url); System.out.println("executing request" + httpget.getRequestLine()); /// !!! HttpResponse response = httpclient.execute(targetHost, httpget, localcontext); HttpEntity entity = response.getEntity(); System.out.println("----------------------------------------"); System.out.println("+"+response.getStatusLine()+"+"); ...

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  • Debugging Messaging Exception

    - by rizza
    We have a batch program that incorporates JavaMail 1.2 that sends emails. In our development environment, we haven't got the chance to encounter the above mentioned exception. But in the client's environment, they had experienced this a lot of times with the following error trace: javax.mail.MessagingException: 550 Requested action not taken: NUL characters are not allowed. at com.sun.mail.smtp.SMTPTransport.issueCommand (SMTPTransport.java: 879) at com.sun.mail.smtp.SMTPTransport.finishData (SMTPTransport.java: 820) at com.sun.mail.smtp.SMTPTransport.sendMessage (SMTPTransport.java: 322) ... I'm not sure if this is connected to my problem, http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4697158. But trying JavaMail 1.4.2, I see that the content transfer encoding of the email is still 7bit, so I'm not sure if using JavaMail 1.4.2 could solve the problem. Please take note that I could only do testing in our development environment that hasn't been able to replicate this. With the above exception, how would i know if this is from the sender or the receiver side? What debugging steps could you suggest? EDIT: Here is a DEBUG of the actual sending (masked some information): DEBUG: not loading system providers in &lt;java.home&gt;</a>/lib DEBUG: not loading optional custom providers file: /META-INF/javamail.providers DEBUG: successfully loaded default providers DEBUG: Tables of loaded providers DEBUG: Providers Listed By Class Name: {com.sun.mail.smtp.SMTPTransport=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc], com.sun.mail.imap.IMAPStore=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Sun Microsystems, Inc], com.sun.mail.pop3.POP3Store=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Sun Microsystems, Inc]} DEBUG: Providers Listed By Protocol: {imap=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Sun Microsystems, Inc], pop3=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Sun Microsystems, Inc], smtp=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]} DEBUG: not loading optional address map file: /META-INF/javamail.address.map DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc] DEBUG SMTP: useEhlo true, useAuth false DEBUG: SMTPTransport trying to connect to host "nnn.nnn.n.nnn", port nn DEBUG SMTP RCVD: 220 xxxx.xxxxxxxxxxx.xxx SMTP; Mon, 23 Mar 2009 15:18:57 +0800 DEBUG: SMTPTransport connected to host "nnn.nnn.n.nnn", port: nn DEBUG SMTP SENT: EHLO xxxxxxxxx DEBUG SMTP RCVD: 250 xxxx.xxxxxxxxxxx.xxx Hello DEBUG SMTP: use8bit false DEBUG SMTP SENT: MAIL FROM:<a href="newmsg.cgi?mbx=Main&[email protected]">&lt;[email protected]&gt;</a> DEBUG SMTP RCVD: 250 <a href="newmsg.cgi?mbx=Main&[email protected]">&lt;[email protected]&gt;</a>... Sender ok DEBUG SMTP SENT: RCPT TO:&lt;[email protected]&gt; DEBUG SMTP RCVD: 250 &lt;[email protected]&gt;... Recipient ok Verified Addresses &nbsp;&nbsp;[email protected] DEBUG SMTP SENT: DATA DEBUG SMTP RCVD: 354 Enter mail, end with "." on a line by itself DEBUG SMTP SENT: . DEBUG SMTP RCVD: 550 Requested action not taken: NUL characters are not allowed.

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  • C# XNA: AI Engine?

    - by Rosarch
    I'm developing a game with zombie running around in a swamp. I want AIs to have functionality like "chase this target" or "run away". A major stumbling block is pathfinding. Is there a good pathfinding/AI engine in XNA, or should I roll my own? Does anyone have any experience with this: http://www.codeplex.com/simpleAI?

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  • Snow Leopard upgrade -> reinstalling sqlite3-ruby gem problem

    - by Carl Tessler
    Hi all, I got ruby 1.8.7 (native compiled), rails 2.3.4, OSX 10.6.2 and also sqlite3-ruby. The error I'm getting when accessing the rails app is NameError: uninitialized constant SQLite3::Driver::Native::Driver::API History: I upgraded to snow leopard by migrating my apps with a FW-cable from my old macbook to the new one. Everything was running perfectly for months, but Yesterday I needed to install watir, which was dependant on rb-appscript, which didn't build due a "wrong architecture" error in libsqlite3.dylib. I figured the build was made on the old machine, so i wanted to rebuild sqlite3-ruby: $ sudo gem uninstall sqlite3-ruby $ sudo gem install sqlite3-ruby Building native extensions. This could take a while... ERROR: Error installing sqlite3-ruby: ERROR: Failed to build gem native extension. /usr/local/bin/ruby extconf.rb checking for fdatasync() in -lrt... no checking for sqlite3.h... yes checking for sqlite3_open() in -lsqlite3... no * extconf.rb failed * Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers. Check the mkmf.log file for more details. You may need configuration options. It seems like the sqlite3 libs are not working properly. I've tried to install macports sqlite3 (sudo port install sqlite3) and use that instead, but with same result... so i rebuild sqlite3 from scratch.. download-configure-make-make install. After that, the gem now builds perfectly, but doesn't work in rails, giving the error in the top of this article. I'm not really sure where to go from here because I've tried the following Rebuild sqlite3 from newest source (http://www.sqlite.org/download.html) Reinstalled sqlite3-ruby (sudo gem uninstall sqlite3-ruby && sudo gem install sqlite3-ruby) Used sqlite3 from macports (sudo port install sqlite3 && sudo gem install sqlite3-ruby) Reinstalled rails (sudo gem install rails sqlite3-ruby ) and updated environment.rb to rails 2.3.5. No avail, I still get this error: NameError: uninitialized constant SQLite3::Driver::Native::Driver::AP from /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:105:in const_missing' from /usr/local/lib/ruby/gems/1.8/gems/sqlite3-ruby-1.2.5/lib/sqlite3/driver/native/driver.rb:76:in open' from /usr/local/lib/ruby/gems/1.8/gems/sqlite3-ruby-1.2.5/lib/sqlite3/database.rb:76:in `initialize' Btw, I have Xcode installed from the Snow Leopard CD. What can i do to solve the problem?

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  • Howto - Running Redmine on mongrel as a service on windows

    - by Achilles
    I use Redmine on Mongrel as a project manager and I use a batch file (start-redmine.bat) to start the redmine in mongrel. There are 2 issues with my setup: 1. I have a running IIS on the server that occupies the HTTP port (80) 2. The start-redmine.bat must be periodically checked to see if it's stopped after a restart that is caused by windows update service. for the first issue, I have no choice but running mongrel on a port like 3000 and for the second issue I have to create a windows service that runs automatically in the background when the windows starts; and here comes the trouble! There are at least 3 ways to run redmine as a service that I'm aware of; none of them can satisfy a performance view on this subject. you may read about them on http://stackoverflow.com/questions/877943/how-to-configure-a-rails-app-redmine-to-run-as-a-service-on-windows I tried them all. The easiest way to setup such a service is using mongrel_service approach; in 3 lines of command you're done. but the performance is significantly lower than running that batch file... Now, I wanna show you my approach: First suppose we have ruby installed into c:\ruby and we have issued the command gem install mongrel to get the mongrel gem installed into c:\ruby\bin Also, suppose we have installed the Redmine into a folder like c:\redmine; and we have ruby's path (i.e. c:\ruby\bin) in our PATH environment variable. Now Download and install the Windows NT Resource Kit Tools from microsoft website. Open the command-line tool that comes with the Resource Kit (from start menu). Use instsrv to install a dummy service called Redmine using the following command: "[path-to-instsrv.exe]\instsrv" Redmine "[path-to-srvany.exe]\srvany.exe" in my case (which is the default case) it was something like this: "C:\Program Files\Windows Resource Kits\Tools\instsrv" Redmine "C:\Program Files\Windows Resource Kits\Tools\srvany.exe" Now create the batch file. Open a notepad and paste these instructions into it and then save it as "c:\redmine\start-redmine.bat" @echo off cd c:\redmine\ mongrel_rails start -a 0.0.0.0 -p 3000 -e production Now we need to configure that dummy service we had created before. WATCH OUT WHAT YOU'RE DOING FROM HERE ON, OR YOU MAY CORRUPT YOUR WINDOWS. To configure that service, open windows registry editor (Start - Run - regedit) and navigate to this node: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Redmine Right-Click on "Redmine" node and using the context menu, create a new key called Parameters (New - Key) Right-Click on "Parameters" and create a String Value property called Application. Do this again and create another String Value called AppParameters. Now Double-click on "Application" and put cmd.exe into "Value data" section. Then Double-click on "AppParameters" and put /C "C:\redmine\start-redmine.bat" into Value data section. We're done! issue this command to run the redmine on mongrel as a service: net start Redmine

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  • Mail not being sent when using phpmailer

    - by mithunmo
    I am using the following code to send mail to a smtp server . <?php // example on using PHPMailer with GMAIL include("PHPMailer/class.phpmailer.php"); include("PHPMailer/class.smtp.php"); // note, this is optional - gets called from main class if not already loaded $mail = new PHPMailer(); $mail->IsSMTP(); $mail->SMTPAuth = true; // enable SMTP authentication $mail->Host = "mucse491.eu.xxxxx.com"; // sets GMAIL as the SMTP server $mail->Port = 143; // set the SMTP port $mail->Username = "[email protected]"; // GMAIL username $mail->Password = "xxxx"; // GMAIL password $mail->From = "[email protected]"; $mail->FromName = "mithun"; $mail->Subject = "This is the subject"; $mail->AltBody = "This is the body when user views in plain text format"; //Text Body $mail->WordWrap = 50; // set word wrap $mail->AddAddress("[email protected]","First Last"); $mail->IsHTML(true); // send as HTML if(!$mail->Send()) { echo "Mailer Error: " . $mail->ErrorInfo; } else { echo "Message has been sent"; } ?> When I run it from the command line I get the following error PHP Deprecated: Function eregi() is deprecated in C:\wamp\www\phpmailer\class.p hpmailer.php on line 593 Deprecated: Function eregi() is deprecated in C:\wamp\www\phpmailer\class.phpmai ler.php on line 593 PHP Warning: fputs() expects parameter 1 to be resource, integer given in C:\wa mp\www\phpmailer\class.smtp.php on line 213 Warning: fputs() expects parameter 1 to be resource, integer given in C:\wamp\ww w\phpmailer\class.smtp.php on line 213 Mailer Error: SMTP Error: Could not connect to SMTP host. When i run from the browser I get the following error Deprecated: Function eregi() is deprecated in C:\wamp\www\phpmailer\class.phpmailer.php on line 593 Warning: fsockopen() [function.fsockopen]: php_network_getaddresses: getaddrinfo failed: This is usually a temporary error during hostname resolution and means that the local server did not receive a response from an authoritative server. in C:\wamp\www\phpmailer\class.smtp.php on line 122 Warning: fsockopen() [function.fsockopen]: unable to connect to mucse491.xx.xxxxx.com:143 (php_network_getaddresses: getaddrinfo failed: This is usually a temporary error during hostname resolution and means that the local server did not receive a response from an authoritative server. ) in C:\wamp\www\phpmailer\class.smtp.php on line 122 Mailer Error: SMTP Error: Could not connect to SMTP host. Please someone guide me .

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  • iPhone MapKit problems: viewForAnnotation inconsistently setting pinColor?

    - by blackkettle
    Hi, I'm trying setup a map that displays different pin colors depending on the type/class of the location in question. I know this is a pretty common thing to do, but I'm having trouble getting the viewForAnnotation delegate to consistently update/set the pin color. I have a showThisLocation function that basically cycles through a list of AddressAnnotations and then based on the annotation class (bus stop, hospital, etc.) I set an if( myClass == 1){ [defaults setObject:@"1" forKey:@"currPinColor"]; [defaults synchronize]; NSLog(@"Should be %@!", [defaults objectForKey:@"currPinColor"]); } else if( myClass ==2 ){ [defaults setObject:@"2" forKey:@"currPinColor"]; [defaults synchronize]; NSLog(@"Should be %@!", [defaults objectForKey:@"currPinColor"]); } [_mapView addAnnotation:myCurrentAnnotation]; then my viewForAnnotation delegate looks like this, - (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id )annotation { if( annotation == mapView.userLocation ){ return nil; } NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; MKPinAnnotationView *annView = nil; annView = (MKPinAnnotationView*)[mapView dequeueReusableAnnotationViewWithIdentifier:@"currentloc"]; if( annView == nil ){ annView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"currentloc"]; } annView.pinColor = [defaults integerForKey:@"currPinColor"]; NSLog(@"Pin color: %d", [defaults integerForKey:@"currPinColor"]); annView.animatesDrop=TRUE; annView.canShowCallout = YES; annView.calloutOffset = CGPointMake(-5, 5); return annView; } The problem is that, although the NSLog statements in the "if" block always confirm that the color has been set, the delegate sometimes but not always ends up with the correct color. I've also noticed that what generally happens is that the first search for a new location will set all pins to the last color in the "if" block, but search for the same location again will set the pins to the correct color. I suspect I am not supposed to usen NSUserDefaults in this way, but I also tried to create my own subclass for MKAnnotation which included an additional property "currentPinColor", and while this allowed me to set the "currentPinColor", when I tried to access the "currentPinColor from the delegate method, the compiler complained that it didn't know anything about "currentPinColor in connection with MKAnnotation. Fair enough I guess, but then I tried to revise the delegate method, - (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id )annotation instead of the default - (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id )annotation at which point the compiler complained that it didn't know anything about the protocol for MyCustomMKAnnotation in this delegate context. What is the proper way to set the delegate method and/or MyCustomMKAnnotation, or what is the appropriate way to achieve consistent pinColor settings. I'm just about out of ideas for things to try here.

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  • WebLogic job scheduling

    - by XpiritO
    Hello, overflowers :) I'm trying to implement a WebLogic job scheduling example, to test my cluster capabilities of fail-over on scheduled tasks (to ensure that these tasks are executed on fail over scenario). With this in mind, I've been following this example and trying to configure everything accordingly. Here are the steps I've done so far: Configured a cluster with 1 admin server (AdminServer) and 2 managed instances (Noddy and Snoopy); Set up database tables (using Oracle XE): ACTIVE and WEBLOGIC_TIMERS; Set up data source to access DB and associated it to the scheduling tasks under "Settings for cluster" "Scheduling"; Implemented a job (TimerListener) and a servlet to initialize the job scheduling, as follows: . package timedexecution; import java.io.IOException; import java.io.PrintWriter; import java.io.Serializable; import java.text.SimpleDateFormat; import java.util.Date; import javax.naming.InitialContext; import javax.naming.NamingException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import commonj.timers.Timer; import commonj.timers.TimerListener; import commonj.timers.TimerManager; public class TimerServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected static void logMessage(String message, PrintWriter out){ out.write("<p>"+ message +"</p>"); System.out.println(message); } @Override public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { PrintWriter out = response.getWriter(); // out.println("<html>"); out.println("<head><title>TimerServlet</title></head>"); // try { // logMessage("service() entering try block to intialize the timer from JNDI", out); // InitialContext ic = new InitialContext(); TimerManager jobScheduler = (TimerManager)ic.lookup("weblogic.JobScheduler"); // logMessage("jobScheduler reference " + jobScheduler, out); // jobScheduler.schedule(new ExampleTimerListener(), 0, 30*1000); // logMessage("Timer scheduled!", out); // //execute this job every 30 seconds logMessage("service() started the timer", out); // logMessage("Started the timer - status:", out); // } catch (NamingException ne) { String msg = ne.getMessage(); logMessage("Timer schedule failed!", out); logMessage(msg, out); } catch (Throwable t) { logMessage("service() error initializing timer manager with JNDI name weblogic.JobScheduler " + t,out); } // out.println("</body></html>"); out.close(); } private static class ExampleTimerListener implements Serializable, TimerListener { private static final long serialVersionUID = 8313912206357147939L; public void timerExpired(Timer timer) { SimpleDateFormat sdf = new SimpleDateFormat(); System.out.println( "timerExpired() called at " + sdf.format( new Date() ) ); } } } Then I executed the servlet to start the scheduling on the first managed instance (Noddy server), which returned as expected: (Servlet execution output) service() entering try block to intialize the timer from JNDI jobScheduler reference weblogic.scheduler.TimerServiceImpl@43b4c7 Timer scheduled! service() started the timer Started the timer - status: Which resulted in the creation of 2 rows in my DB tables: WEBLOGIC_TIMERS table state after servlet execution: "EDIT"; "TIMER_ID"; "LISTENER"; "START_TIME"; "INTERVAL"; "TIMER_MANAGER_NAME"; "DOMAIN_NAME"; "CLUSTER_NAME"; ""; "Noddy_1268653040156"; "[datatype]"; "1268653040156"; "30000"; "weblogic.JobScheduler"; "myCluster"; "Cluster" ACTIVE table state after servlet execution: "EDIT"; "SERVER"; "INSTANCE"; "DOMAINNAME"; "CLUSTERNAME"; "TIMEOUT"; ""; "service.SINGLETON_MASTER"; "6382071947583985002/Noddy"; "QRENcluster"; "Cluster"; "10.03.15" Although, the job is not executed as scheduled. It should print a message on the server's log output (Noddy.out file) with a timestamp, saying that the timer had expired. It doesn't. My log files state as follows: Admin server log (myCluster.log file): ####<15/Mar/2010 10H45m GMT> <Warning> <Cluster> <test-ad> <Noddy> <[STANDBY] ExecuteThread: '1' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1268649925727> <BEA-000192> <No currently living server was found that could host TimerMaster. The server will retry in a few seconds.> Noddy server log (Noddy.out file): service() entering try block to intialize the timer from JNDI jobScheduler reference weblogic.scheduler.TimerServiceImpl@43b4c7 Timer scheduled! service() started the timer Started the timer - status: <15/Mar/2010 10H45m GMT> <Warning> <Cluster> <BEA-000192> <No currently living server was found that could host TimerMaster. The server will retry in a few seconds.> (Noddy.log file): ####<15/Mar/2010 11H24m GMT> <Info> <Common> <test-ad> <Noddy> <[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1268652270128> <BEA-000628> <Created "1" resources for pool "TxDataSourceOracle", out of which "1" are available and "0" are unavailable.> ####<15/Mar/2010 11H37m GMT> <Info> <Cluster> <test-ad> <Noddy> <[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'> <<anonymous>> <> <> <1268653040226> <BEA-000182> <Job Scheduler created a job with ID Noddy_1268653040156 for TimerListener with description timedexecution.TimerServlet$ExampleTimerListener@2ce79a> ####<15/Mar/2010 11H39m GMT> <Info> <JDBC> <test-ad> <Noddy> <[ACTIVE] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1268653166307> <BEA-001128> <Connection for pool "TxDataSourceOracle" closed.> Can anyone help me out discovering what's wrong with my configuration? Thanks in advance for your help!

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  • WWW::Mechanize for Objective C / iPhone?

    - by dan
    Hi, I want to port a python app that uses mechanize for the iPhone. This app needs to login to a webpage and using the site cookie to go to other pages on that site to get some data. With my python app I was using mechanize for automatic cookie management. Is there something similar for Objective C that is portable to the iPhone? Thanks for any help.

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  • Java ReentrantReadWriteLocks - how to safely acquire write lock?

    - by Andrzej Doyle
    I am using in my code at the moment a ReentrantReadWriteLock to synchronize access over a tree-like structure. This structure is large, and read by many threads at once with occasional modifications to small parts of it - so it seems to fit the read-write idiom well. I understand that with this particular class, one cannot elevate a read lock to a write lock, so as per the Javadocs one must release the read lock before obtaining the write lock. I've used this pattern successfully in non-reentrant contexts before. What I'm finding however is that I cannot reliably acquire the write lock without blocking forever. Since the read lock is reentrant and I am actually using it as such, the simple code lock.getReadLock().unlock(); lock.getWriteLock().lock() can block if I have acquired the readlock reentrantly. Each call to unlock just reduces the hold count, and the lock is only actually released when the hold count hits zero. EDIT to clarify this, as I don't think I explained it too well initially - I am aware that there is no built-in lock escalation in this class, and that I have to simply release the read lock and obtain the write lock. My problem is/was that regardless of what other threads are doing, calling getReadLock().unlock() may not actually release this thread's hold on the lock if it acquired it reentrantly, in which case the call to getWriteLock().lock() will block forever as this thread still has a hold on the read lock and thus blocks itself. For example, this code snippet will never reach the println statement, even when run singlethreaded with no other threads accessing the lock: final ReadWriteLock lock = new ReentrantReadWriteLock(); lock.getReadLock().lock(); // In real code we would go call other methods that end up calling back and // thus locking again lock.getReadLock().lock(); // Now we do some stuff and realise we need to write so try to escalate the // lock as per the Javadocs and the above description lock.getReadLock().unlock(); // Does not actually release the lock lock.getWriteLock().lock(); // Blocks as some thread (this one!) holds read lock System.out.println("Will never get here"); So I ask, is there a nice idiom to handle this situation? Specifically, when a thread that holds a read lock (possibly reentrantly) discovers that it needs to do some writing, and thus wants to "suspend" its own read lock in order to pick up the write lock (blocking as required on other threads to release their holds on the read lock), and then "pick up" its hold on the read lock in the same state afterwards? Since this ReadWriteLock implementation was specifically designed to be reentrant, surely there is some sensible way to elevate a read lock to a write lock when the locks may be acquired reentrantly? This is the critical part that means the naive approach does not work.

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