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• Setting up a pc bluetooth server for android

  - by Del

  Alright, I've been reading a lot of topics the past two or three days and nothing seems to have asked this. I am writing a PC side server for my andriod device, this is for exchanging some information and general debugging. Eventually I will be connecting to a SPP device to control a microcontroller. I have managed, using the following (Android to pc) to connect to rfcomm channel 11 and exchange data between my android device and my pc. Method m = device.getClass().getMethod("createRfcommSocket", new Class[] { int.class }); tmp = (BluetoothSocket) m.invoke(device, Integer.valueOf(11)); I have attempted the createRfcommSocketToServiceRecord(UUID) method, with absolutely no luck. For the PC side, I have been using the C Bluez stack for linux. I have the following code which registers the service and opens a server socket: int main(int argc, char **argv) { struct sockaddr_rc loc_addr = { 0 }, rem_addr = { 0 }; char buf[1024] = { 0 }; char str[1024] = { 0 }; int s, client, bytes_read; sdp_session_t *session; socklen_t opt = sizeof(rem_addr); session = register_service(); s = socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM); loc_addr.rc_family = AF_BLUETOOTH; loc_addr.rc_bdaddr = *BDADDR_ANY; loc_addr.rc_channel = (uint8_t) 11; bind(s, (struct sockaddr *)&loc_addr, sizeof(loc_addr)); listen(s, 1); client = accept(s, (struct sockaddr *)&rem_addr, &opt); ba2str( &rem_addr.rc_bdaddr, buf ); fprintf(stderr, "accepted connection from %s\n", buf); memset(buf, 0, sizeof(buf)); bytes_read = read(client, buf, sizeof(buf)); if( bytes_read 0 ) { printf("received [%s]\n", buf); } sprintf(str,"to Android."); printf("sent [%s]\n",str); write(client, str, sizeof(str)); close(client); close(s); sdp_close( session ); return 0; } sdp_session_t *register_service() { uint32_t svc_uuid_int[] = { 0x00000000,0x00000000,0x00000000,0x00000000 }; uint8_t rfcomm_channel = 11; const char *service_name = "Remote Host"; const char *service_dsc = "What the remote should be connecting to."; const char *service_prov = "Your mother"; uuid_t root_uuid, l2cap_uuid, rfcomm_uuid, svc_uuid; sdp_list_t *l2cap_list = 0, *rfcomm_list = 0, *root_list = 0, *proto_list = 0, *access_proto_list = 0; sdp_data_t *channel = 0, *psm = 0; sdp_record_t *record = sdp_record_alloc(); // set the general service ID sdp_uuid128_create( &svc_uuid, &svc_uuid_int ); sdp_set_service_id( record, svc_uuid ); // make the service record publicly browsable sdp_uuid16_create(&root_uuid, PUBLIC_BROWSE_GROUP); root_list = sdp_list_append(0, &root_uuid); sdp_set_browse_groups( record, root_list ); // set l2cap information sdp_uuid16_create(&l2cap_uuid, L2CAP_UUID); l2cap_list = sdp_list_append( 0, &l2cap_uuid ); proto_list = sdp_list_append( 0, l2cap_list ); // set rfcomm information sdp_uuid16_create(&rfcomm_uuid, RFCOMM_UUID); channel = sdp_data_alloc(SDP_UINT8, &rfcomm_channel); rfcomm_list = sdp_list_append( 0, &rfcomm_uuid ); sdp_list_append( rfcomm_list, channel ); sdp_list_append( proto_list, rfcomm_list ); // attach protocol information to service record access_proto_list = sdp_list_append( 0, proto_list ); sdp_set_access_protos( record, access_proto_list ); // set the name, provider, and description sdp_set_info_attr(record, service_name, service_prov, service_dsc); int err = 0; sdp_session_t *session = 0; // connect to the local SDP server, register the service record, and // disconnect session = sdp_connect( BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY ); err = sdp_record_register(session, record, 0); // cleanup //sdp_data_free( channel ); sdp_list_free( l2cap_list, 0 ); sdp_list_free( rfcomm_list, 0 ); sdp_list_free( root_list, 0 ); sdp_list_free( access_proto_list, 0 ); return session; } And another piece of code, in addition to 'sdptool browse local' which can verifty that the service record is running on the pc: int main(int argc, char **argv) { uuid_t svc_uuid; uint32_t svc_uuid_int[] = { 0x00000000,0x00000000,0x00000000,0x00000000 }; int err; bdaddr_t target; sdp_list_t *response_list = NULL, *search_list, *attrid_list; sdp_session_t *session = 0; str2ba( "01:23:45:67:89:AB", &target ); // connect to the SDP server running on the remote machine session = sdp_connect( BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY ); // specify the UUID of the application we're searching for sdp_uuid128_create( &svc_uuid, &svc_uuid_int ); search_list = sdp_list_append( NULL, &svc_uuid ); // specify that we want a list of all the matching applications' attributes uint32_t range = 0x0000ffff; attrid_list = sdp_list_append( NULL, &range ); // get a list of service records that have UUID 0xabcd err = sdp_service_search_attr_req( session, search_list, \ SDP_ATTR_REQ_RANGE, attrid_list, &response_list); sdp_list_t *r = response_list; // go through each of the service records for (; r; r = r-next ) { sdp_record_t *rec = (sdp_record_t*) r-data; sdp_list_t *proto_list; // get a list of the protocol sequences if( sdp_get_access_protos( rec, &proto_list ) == 0 ) { sdp_list_t *p = proto_list; // go through each protocol sequence for( ; p ; p = p-next ) { sdp_list_t *pds = (sdp_list_t*)p-data; // go through each protocol list of the protocol sequence for( ; pds ; pds = pds-next ) { // check the protocol attributes sdp_data_t *d = (sdp_data_t*)pds-data; int proto = 0; for( ; d; d = d-next ) { switch( d-dtd ) { case SDP_UUID16: case SDP_UUID32: case SDP_UUID128: proto = sdp_uuid_to_proto( &d-val.uuid ); break; case SDP_UINT8: if( proto == RFCOMM_UUID ) { printf("rfcomm channel: %d\n",d-val.int8); } break; } } } sdp_list_free( (sdp_list_t*)p-data, 0 ); } sdp_list_free( proto_list, 0 ); } printf("found service record 0x%x\n", rec-handle); sdp_record_free( rec ); } sdp_close(session); } Output: $ ./search rfcomm channel: 11 found service record 0x10008 sdptool: Service Name: Remote Host Service Description: What the remote should be connecting to. Service Provider: Your mother Service RecHandle: 0x10008 Protocol Descriptor List: "L2CAP" (0x0100) "RFCOMM" (0x0003) Channel: 11 And for logcat I'm getting this: 07-22 15:57:06.087: ERROR/BTLD(215): ****************search UUID = 0000*********** 07-22 15:57:06.087: INFO//system/bin/btld(209): btapp_dm_GetRemoteServiceChannel() 07-22 15:57:06.087: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Wake, 0x8003 #### 07-22 15:57:06.097: INFO/ActivityManager(88): Displayed activity com.example.socktest/.socktest: 79 ms (total 79 ms) 07-22 15:57:06.697: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Sleep, 0x8004 #### 07-22 15:57:07.517: WARN/BTLD(215): ccb timer ticks: 2147483648 07-22 15:57:07.517: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Wake, 0x8003 #### 07-22 15:57:07.547: WARN/BTLD(215): info:x10 07-22 15:57:07.547: INFO/BTL-IFS(215): send_ctrl_msg: [BTL_IFS CTRL] send BTLIF_DTUN_SIGNAL_EVT (CTRL) 10 pbytes (hdl 14) 07-22 15:57:07.547: DEBUG/DTUN_HCID_BZ4(253): dtun_dm_sig_link_up() 07-22 15:57:07.547: INFO/DTUN_HCID_BZ4(253): dtun_dm_sig_link_up: dummy_handle = 342 07-22 15:57:07.547: DEBUG/ADAPTER(253): adapter_get_device(00:02:72:AB:7C:EE) 07-22 15:57:07.547: ERROR/BluetoothEventLoop.cpp(88): pollData[0] is revented, check next one 07-22 15:57:07.547: ERROR/BluetoothEventLoop.cpp(88): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/253/hci0/dev_00_02_72_AB_7C_EE 07-22 15:57:07.777: WARN/BTLD(215): process_service_search_attr_rsp 07-22 15:57:07.787: INFO/BTL-IFS(215): send_ctrl_msg: [BTL_IFS CTRL] send BTLIF_DTUN_SIGNAL_EVT (CTRL) 13 pbytes (hdl 14) 07-22 15:57:07.787: INFO/DTUN_HCID_BZ4(253): dtun_dm_sig_rmt_service_channel: success=0, service=00000000 07-22 15:57:07.787: ERROR/DTUN_HCID_BZ4(253): discovery unsuccessful! 07-22 15:57:08.497: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Sleep, 0x8004 #### 07-22 15:57:09.507: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Wake, 0x8003 #### 07-22 15:57:09.597: INFO/BTL-IFS(215): send_ctrl_msg: [BTL_IFS CTRL] send BTLIF_DTUN_SIGNAL_EVT (CTRL) 11 pbytes (hdl 14) 07-22 15:57:09.597: DEBUG/DTUN_HCID_BZ4(253): dtun_dm_sig_link_down() 07-22 15:57:09.597: INFO/DTUN_HCID_BZ4(253): dtun_dm_sig_link_down device = 0xf7a0 handle = 342 reason = 22 07-22 15:57:09.597: ERROR/BluetoothEventLoop.cpp(88): pollData[0] is revented, check next one 07-22 15:57:09.597: ERROR/BluetoothEventLoop.cpp(88): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/253/hci0/dev_00_02_72_AB_7C_EE 07-22 15:57:09.597: DEBUG/BluetoothA2dpService(88): Received intent Intent { act=android.bluetooth.device.action.ACL_DISCONNECTED (has extras) } 07-22 15:57:10.107: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Sleep, 0x8004 #### 07-22 15:57:12.107: DEBUG/BluetoothService(88): Cleaning up failed UUID channel lookup: 00:02:72:AB:7C:EE 00000000-0000-0000-0000-000000000000 07-22 15:57:12.107: ERROR/Socket Test(5234): connect() failed 07-22 15:57:12.107: DEBUG/ASOCKWRP(5234): asocket_abort [31,32,33] 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: s 31, how 2 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: fd (-1:31), bta -1, rc 0, wflags 0x0 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): __close_prot_rfcomm: fd 31 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): __close_prot_rfcomm: bind not completed on this socket 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): btlif_signal_event: fd (-1:31), bta -1, rc 0, wflags 0x0 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): btlif_signal_event: event BTLIF_BTS_EVT_ABORT matched 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wrp_close_s_only: wrp_close_s_only [31] (31:-1) [] 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wrp_close_s_only: data socket closed 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wsactive_del: delete wsock 31 from active list [ad3e1494] 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wrp_close_s_only: wsock fully closed, return to pool 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): btsk_free: success 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_write: wrote 1 bytes out of 1 on fd 33 07-22 15:57:12.107: DEBUG/ASOCKWRP(5234): asocket_destroy 07-22 15:57:12.107: DEBUG/ASOCKWRP(5234): asocket_abort [31,32,33] 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: s 31, how 2 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: btsk not found, normal close (31) 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_write: wrote 1 bytes out of 1 on fd 33 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_close: s 33 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_close: btsk not found, normal close (33) 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_close: s 32 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_close: btsk not found, normal close (32) 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_close: s 31 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_close: btsk not found, normal close (31) 07-22 15:57:12.157: DEBUG/Sensors(88): close_akm, fd=151 07-22 15:57:12.167: ERROR/CachedBluetoothDevice(477): onUuidChanged: Time since last connect14970690 07-22 15:57:12.237: DEBUG/Socket Test(5234): -On Stop- Sorry for bombarding you guys with what seems like a difficult question and a lot to read, but I've been working on this problem for a while and I've tried a lot of different things to get this working. Let me reiterate, I can get it to work, but not using service discovery protocol. I've tried a several different UUIDs and on two different computers, although I only have my HTC Incredible to test with. I've also heard some rumors that the BT stack wasn't working on the HTC Droid, but that isn't the case, at least, for PC interaction.

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• Where to put default-servlet-handler in Spring MVC configuration

  - by gigadot

  In my web.xml, the default servlet mapping, i.e. /, is mapped to Spring dispatcher. In my Spring dispatcher configuration, I have DefaultAnnotationHandlerMapping, ControllerClassNameHandlerMapping and AnnotationMethodHandlerAdapter which allows me to map url to controllers either by its class name or its @Requestmapping annotation. However, there are some static resources under the web root which I also want spring dispatcher to serve using default servlet. According to Spring documentation, this can be done using <mvc:default-servlet-handler/> tag. In the configuration below, there are 4 candidate locations that I marked which are possible to insert this tag. Inserting the tag in different location causes the dispatcher to behave differently as following : Case 1 : If I insert it at location 1, the dispatcher will no longer be able to handle mapping by the @RequestMapping and controller class name but it will be serving the static content normally. Cas 2, 3 : It will be able to handle mapping by the @RequestMapping and controller class name as well as serving the static content if other mapping cannot be done successfully. Case 4 : It will not be able to serve the static contents. Therefore, Case 2 and 3 are desirable .According to Spring documentation, this tag configures a handler which precedence order is given to lowest so why the position matters? and Which is the best position to put this tag? <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd"> <context:annotation-config/> <context:component-scan base-package="webapp.controller"/> <!-- Location 1 --> <!-- Enable annotation-based controllers using @Controller annotations --> <bean id="annotationUrlMapping" class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"/> <!-- Location 2 --> <bean id="controllerClassNameHandlerMapping" class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping"/> <!-- Location 3 --> <bean id="annotationMethodHandlerAdapter" class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"/> <!-- Location 4 --> <mvc:default-servlet-handler/> <!-- All views are JSPs loaded from /WEB-INF/jsp --> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/> <property name="prefix" value="/WEB-INF/jsp/"/> <property name="suffix" value=".jsp"/> </bean> </beans>

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• Job conditions conflicting with personal principles on software-development - how much is too much?

  - by Baelnorn

  Sorry for the incoming wall'o'text (and for my probably bad English) but I just need to get this off somehow. I also accept that this question will be probably closed as subjective and argumentative, but I need to know one thing: "how much BS are programmers supposed to put up with before breaking?" My background I'm 27 years old and have a B.Sc. in Computer engineering with a graduation grade of 1.8 from a university of applied science. I went looking for a job right after graduation. I got three offers right away, with two offers paying vastly more than the last one, but that last one seemed more interesting so I went for that. My situation I've been working for the company now for 17 months now, but it feels like a drag more and more each day. Primarily because the company (which has only 5 other developers but me, and of these I work with 4) turned out to be pretty much the anti-thesis of what I expected (and was taught in university) from a modern software company. I agreed to accept less than half of the usual payment appropriate for my qualification for the first year because I was promised a trainee program. However, the trainee program turned out to be "here you got a computer, there's some links on the stuff we use, and now do what you colleagues tell you". Further, during my whole time there (trainee or not) I haven't been given the grace of even a single code-review - apparently nobody's interested in my work as long as it "just works". I was told in the job interview that "Microsoft technology played a central role in the company" yet I've been slowly eroding my congnitive functions with Flex/Actionscript/Cairngorm ever since I started (despite having applied as a C#/.NET developer). Actually, the company's primary projects are based on Java/XSLT and Flex/Actionscript (with some SAP/ABAP stuff here and there but I'm not involved in that) and they've been working on these before I even applied. Having had no experience either with that particular technology nor the framework nor the field (RIA) nor in developing business scale applications I obviously made several mistakes. However, my boss told me that he let me make those mistakes (which ate at least 2 months of development time on their own) on purpose to provide some "learning experience". Even when I was still a trainee I was already tasked with working on a business-critical application. On my own. Without supervision. Without code-reviews. My boss thinks agile methods are a waste of time/money and deems putting more than one developer on any project not efficient. Documentation is not necessary and each developer should only document what he himself needs for his work. Recently he wanted us to do bug tracking with Excel and Email instead of using an already existing Bugzilla, overriding an unanimous decision made by all developers and testers involved in the process - only after another senior developer had another hour-long private discussion with him he agreed to let us use the bugtracker. Project management is basically not present, there are only a few Excel sheets floating around where the senior developer lists some things (not all, mind you) with a time estimate ranging from days to months, trying to at least somehow organize the whole mess. A development process is also basically not present, each developer just works on his own however he wants. There are not even coding conventions in the company. Testing is done manually with a single tester (sometimes two testers) per project because automated testing wasn't given the least thought when the whole project was started. I guess it's not a big surprise when I say that each developer also has his own share of hundreds of overhours (which are, of course, unpaid). Each developer is tasked with working on his own project(s) which in turn leads to a very extensive knowledge monopolization - if one developer was to have an accident or become ill there would be absolutely no one who could even hope to do his work. Considering that each developer has his own business-critical application to work on, I guess that's a pretty bad situation. I've been trying to change things for the better. I tried to introduce a development process, but my first attempt was pretty much shot down by my boss with "I don't want to discuss agile methods". After that I put together a process that at least resembled how most of the developers were already working and then include stuff like automated (or at least organized) testing, coding conventions, etc. However, this was also shot down because it wasn't "simple" enought to be shown on a business slide (actually, I wasn't even given the 15 minutes I'd have needed to present the process in the meeting). My problem I can't stand working there any longer. Seriously, I consider to resign on monday, which still leaves me with 3 months to work there due to the cancelation period. My primary goal since I started studying computer science was being a good computer scientist, working with modern technologies and adhering to modern and proven principles and methods. However, the company I'm working for seems to make that impossible. Some days I feel as if was living in a perverted real-life version of the Dilbert comics. My question Am I overreacting? Is this the reality each graduate from university has to face? Should I betray my sound principles and just accept these working conditions? Or should I gtfo of there? What's the opinion of other developers on this matter. Would you put up with all that stuff?

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• I keep Getting KeyError: 'tried' Whenever I Tried to Run Django Dev Server from Remote Machine

  - by Spikie

  I am running django on python2.6.1, and did start the django web server like this manage.py runserver 192.0.0.1:8000 then tried to connect to the django dev web server on http://192.0.0.1:8000/ keep getting this message on the remote computer Traceback (most recent call last): File "C:\Python26\Lib\site-packages\django\core\servers\basehttp.py", line 279, in run self.result = application(self.environ, self.start_response) File "C:\Python26\Lib\site-packages\django\core\servers\basehttp.py", line 651, in call return self.application(environ, start_response) File "C:\Python26\lib\site-packages\django\core\handlers\wsgi.py", line 241, in call response = self.get_response(request) File "C:\Python26\lib\site-packages\django\core\handlers\base.py", line 115, in get_response return debug.technical_404_response(request, e) File "C:\Python26\Lib\site-packages\django\views\debug.py", line 247, in technical_404_response tried = exception.args[0]['tried'] KeyError: 'tried' what i am doing wrong ? it seen to work ok if i run http://192.0.0.1:8000/ on the computer that runs the Django web server and have that ip 192.0.0.1:8000

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• Postcode and radius lookup recommendations

  - by WestDiscGolf

  I look after a number of divisional websites for a uk based membership organisation and what we want to do is provide, as well as other address functions, is a closest member lookup to a web user from the websites themselves. A few use cases that I want to fill: Case 1: The user puts in their post code and wants to see all the members in a 5/10/15/20/30/40 mile radius from them Case 2: The member puts in an area (city, county, etc.) and gets a list of members in that area. Essentially what I'm looking for is a programmable API which I can code against to do: post code lookup and returns addresses (after picking house number for example). search post code + radius (5miles, 10miles etc) and get a set of applicable post codes to then join onto the membership records in the database Any recommendations? It can be a quarterly update install on the server, it can be a queryable web service. I'm open to suggestions. Thanks in advance

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• Run Windows XP on a usb drive virtually on Windows XP?

  - by Russell

  I am sick of not being able to run and install certain applications on my work computer due to admin restrictions (eg: Adobe AIR) . I have heard of smaller versions of Windows running on a usb thumb drive and have looked into it but can't find anything on running windows virtually from a usb drive. I would like to be able to login to this particular computer, insert my usb drive and then open up another version of windows installed on the thumb drive while still being able to use the windows I logged in on (literally be able to alt+tab between the main desktop and the virtual desktop from the usb drive). Is this even possible? For further clarification: The version of windows has to be Windows XP and there is no other option available for what I want to do. Looking forward to a response.

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• Work Item Link Types in Visual Studio TFS 2010

  - by Ben

  What's the difference between the following work items link types in Visual Studio TFS 2010? Test Case Shared Steps Tests Tested By Thanks,

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• Confusion testing fftw3 - poisson equation 2d test

  - by user3699736

  I am having trouble explaining/understanding the following phenomenon: To test fftw3 i am using the 2d poisson test case: laplacian(f(x,y)) = - g(x,y) with periodic boundary conditions. After applying the fourier transform to the equation we obtain : F(kx,ky) = G(kx,ky) /(kx² + ky²) (1) if i take g(x,y) = sin (x) + sin(y) , (x,y) \in [0,2 \pi] i have immediately f(x,y) = g(x,y) which is what i am trying to obtain with the fft : i compute G from g with a forward Fourier transform From this i can compute the Fourier transform of f with (1). Finally, i compute f with the backward Fourier transform (without forgetting to normalize by 1/(nx*ny)). In practice, the results are pretty bad? (For instance, the amplitude for N = 256 is twice the amplitude obtained with N = 512) Even worse, if i try g(x,y) = sin(x)*sin(y) , the curve has not even the same form of the solution. (note that i must change the equation; i divide by two the laplacian in this case : (1) becomes F(kx,ky) = 2*G(kx,ky)/(kx²+ky²) Here is the code: /* * fftw test -- double precision */ #include <iostream> #include <stdio.h> #include <stdlib.h> #include <math.h> #include <fftw3.h> using namespace std; int main() { int N = 128; int i, j ; double pi = 3.14159265359; double *X, *Y ; X = (double*) malloc(N*sizeof(double)); Y = (double*) malloc(N*sizeof(double)); fftw_complex *out1, *in2, *out2, *in1; fftw_plan p1, p2; double L = 2.*pi; double dx = L/((N - 1)*1.0); in1 = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*(N*N) ); out2 = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*(N*N) ); out1 = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*(N*N) ); in2 = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*(N*N) ); p1 = fftw_plan_dft_2d(N, N, in1, out1, FFTW_FORWARD,FFTW_MEASURE ); p2 = fftw_plan_dft_2d(N, N, in2, out2, FFTW_BACKWARD,FFTW_MEASURE); for(i = 0; i < N; i++){ X[i] = -pi + (i*1.0)*2.*pi/((N - 1)*1.0) ; for(j = 0; j < N; j++){ Y[j] = -pi + (j*1.0)*2.*pi/((N - 1)*1.0) ; in1[i*N + j][0] = sin(X[i]) + sin(Y[j]) ; // row major ordering //in1[i*N + j][0] = sin(X[i]) * sin(Y[j]) ; // 2nd test case in1[i*N + j][1] = 0 ; } } fftw_execute(p1); // FFT forward for ( i = 0; i < N; i++){ // f = g / ( kx² + ky² ) for( j = 0; j < N; j++){ in2[i*N + j][0] = out1[i*N + j][0]/ (i*i+j*j+1e-16); in2[i*N + j][1] = out1[i*N + j][1]/ (i*i+j*j+1e-16); //in2[i*N + j][0] = 2*out1[i*N + j][0]/ (i*i+j*j+1e-16); // 2nd test case //in2[i*N + j][1] = 2*out1[i*N + j][1]/ (i*i+j*j+1e-16); } } fftw_execute(p2); //FFT backward // checking the results computed double erl1 = 0.; for ( i = 0; i < N; i++) { for( j = 0; j < N; j++){ erl1 += fabs( in1[i*N + j][0] - out2[i*N + j][0]/N/N )*dx*dx; cout<< i <<" "<< j<<" "<< sin(X[i])+sin(Y[j])<<" "<< out2[i*N+j][0]/N/N <<" "<< endl; // > output } } cout<< erl1 << endl ; // L1 error fftw_destroy_plan(p1); fftw_destroy_plan(p2); fftw_free(out1); fftw_free(out2); fftw_free(in1); fftw_free(in2); return 0; } I can't find any (more) mistakes in my code (i installed the fftw3 library last week) and i don't see a problem with the maths either but i don't think it's the fft's fault. Hence my predicament. I am all out of ideas and all out of google as well. Any help solving this puzzle would be greatly appreciated. note : compiling : g++ test.cpp -lfftw3 -lm executing : ./a.out output and i use gnuplot in order to plot the curves : (in gnuplot ) splot "output" u 1:2:4 ( for the computed solution )

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• Problem with MIB_IFTABLE & MIB_IFROW

  - by calvin

  Hello there, Im using MIB_IFTABLE & MIB_IFROW to get the no.of bytes transmitted & received. Everything looks fine, and values are correct in case of using WIFI alone. But when i use vpn connection over wifi these values are not correct for wifi adapter, interestingly i'm getting correct values for vpn adapter. And if i see status of any of these adapters(right click and see status), all these values given by windows are correct. here are my questions. 1) is there any other way of getting no.of bytes transferred over adapter? 2) is there a way to tell whether adapter is vpn or not? (as all vpn adapters are shows as Local Area Connection) 3) If you are connected to VPN, is there a possibility of bytes getting transferred through other than this vpn adapter?(forget about split tunneling, consider very simple case) i use vs2005, win7, Im new to these protocols, thanks for any help. -calvin

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• Using xsl:key to store result of boolean expression

  - by hielsnoppe

  In my transformation there is an expression some elements are repeatedly tested against. To reduce redundancy I'd like to encapsulate this in an xsl:key like this (not working): <xsl:key name="td-is-empty" match="td" use="not(./node()[normalize-space(.) or ./node()])" /> The expected behaviour is the key to yield a boolean value of true in case the expression is evaluated successfully and otherwise false. Then I'd like to use it as follows: <xsl:template match="td[not(key('td-is-empty', .))]" /> Is this possible and in case yes, how?

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• binary search and trio

  - by user121196

  given a large list of alphabetically sorted words in a file,I need to write a program that, given a word x, determines if x is in the list. priorties: 1. speed. 2. memory I already know I can use (n is number of words, m is average length of the words) 1. a tri, time is O(log(n)), space(best case) is O(log(n*m)), space(worst case) is O(n*m). 2. load the complete list into memory, then binary search, time is O(log(n)), space is O(n*m) I'm not sure about the complexity on tri, please correct me if they are wrong. Also are there other good approaches?

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• WPF Skin Skinning Security Concerns

  - by Erik Philips

  I'm really new to the WPF in the .Net Framework (get that out of the way). I'm writing an application where the interface is very customizable by simply loading .xaml (at the moment a Page element) files into a frame and then mapping the controls via names as needed. The idea is to have a community of people who are interested in making skins, skin my application however they want (much like Winamp). Now the question arises, due to my lack of Xaml knowledge, is it possible to create malicious Xaml pages that when downloaded and used could have other embedded Iframes or other elements that could have embed html or call remote webpages with malicious content? I believe this could be the case. If this is the case then I two options; either I have an automated process that can remove these types of Xaml files by checking it’s elements prior to allowing download (which I would assume would be most difficult) or have a human review them prior to download. Are there alternatives I’m unaware of that could make this whole process a lot easier?

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• Trouble Extending Network with Apple Airport Extreme (PC won't connect with Ethernet)

  - by 0x783czar

  So I have an Apple Airport Extreme base station that I use to create a wifi network at my house. But on a separate story from this station i have a PC (running Windows 7) that does not have a wireless card. Luckily, I have another Airport Extreme Base Station, so I figured I'd have my second station "extend" the existing network. I asked Apple if this was possible, which it was, and walked through the setup wizard to extend the network. Then I ran an ethernet cable from the Station to my PC. However the PC refuses to connect to the Internet. It says it can access the network, "Unidentified Network (Limited Connectivity)", but that's it. It tells me that my computer does not have an IP address. I tried running the cable to another computer (my Apple MacBook Pro) and got a similar error. Any thoughts?

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• C - floating point rounding

  - by hatorade

  I'm trying to understand how floating point numbers work. I think I'd like to test out what I know / need to learn by evaluating the following: I would like to find the smallest x such that x + 1 = x, where x is a floating point number. As I understand it, this would happen in the case where x is large enough so that x + 1 is closer to x than the next number higher than x representable by floating point. So intuitively it seems it would be the case where I don't have enough digits in the significand. Would this number x then be the number where the significand is all 1's. But then I can't seem to figure out what the exponent would have to be. Obviously it would have to be big (relative to 10^0, anyway).

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• Scaffolding Web Services in Grails

  - by Dan

  I need to implement a web app, but instead of using relational database I need to use different SOAP Web Services as a back-end. An important part of application only calls web services and displays the result. Since Web Services are clearly defined in form of Operation: In parameters and Return Type it seems to me that basic GUI could be easily constructed just like in the case of scaffolding based on Domain Entities. For example in case of SearchProducts web service operation I need to enter search parameters as input, so the search page can be constructed. Operation will return a list of products, so I need a page that will display this list in some kind of table. Is there already some library in grails that let you achieve this. If not, how would you go about creating one?

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• what is order notation f(n)=O(g(n))?

  - by Lopa

  2 questions: question 1: under what circumstances would this[O(f(n))=O(k.f(n))] be the most appropriate form of time-complexity analysis? question 2: working from mathematical definition of O notation, show that O(f(n))=O(k.f(n)), for positive constant k.? My view: For the first one I think it is average case and worst case form of time-complexity. am i right? and what else do i write in that? for the second one I think we need to define the function mathematically, so is the answer something like because the multiplication by a constant just corresponds to a readjustment of value of the arbitrary constant 'k' in definition of O.

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• How beneficial is this subject combination for an undergrad CS student?

  - by Maxood

  I'm an undergrad Computer Science student and studying online. There is a lot of self study, independent research and practice i have to do myself. I wonder how beneficial would it be to choose this subject combination in programming: Data Structures OOP Assembly Language & Computer Architecture Although i also have the option to take DLD (Digital Logic Design) or Data communication courses instead of Assembly Language. My interest lies in programming and i'm also working as a programmer at local software house. Can anyone give me some good advice and suggestions.

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• How do I shim a Excel automation addin that implements IDTExtensibility2 but is not a com add in?

  - by Shane

  I found this article http://blogs.officezealot.com/whitechapel/archive/2005/05/21/4728.aspx but the example given is a straight automation add-in that does not implement IDTExtensibility2. My add in implements IDTExtensibility2 to get access to the excel object model but is not installed as a COM add in so RegisterFunction for example will called when one of the add in functions is first used not when the excel starts as in the case of the a COM add in. Will this method described in the link above work in my case also? I tried version 2.3.1 of the shim wizard which seems to have support for automations add-ins (it has a check box for automation add ins in the metadata import process). The generated shim runs (I can see breakpoints being hit in the debugger), but my functions no longer work (i get #NAME). The shims is installed as a COM add in and loads when excel starts so I suspect it's not doing what I want.

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• What does the term "blocking" mean in programming?

  - by Jackie

  Could someone provide a layman definition and use case?

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• How to extract valid email from larger string in Scala

  - by luigi-prog

  My scala version 2.7.7 Im trying to extract an email adress from a larger string. the string itself follows no format. the code i've got: import scala.util.matching.Regex import scala.util.matching._ val Reg = """\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b""".r "yo my name is joe : [email protected]" match { case Reg(e) => println("match: " + e) case _ => println("fail") } the Regex passes in RegExBuilder but does not pass for scala. Also if there is another way to do this without regex that would be fine also. Thanks!

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• two views ontouchlistener same area how to?

  - by user553465

  I have a two ImageView. 1.ImageView zomeImageMoveable : should zome in,out and moveable. 2.ImageView zomeImageFixed : show zome this is guide line. i want this two views work same touch. { FrameLayout myFrmae = new FrameLayout(this.getContext()); myFrame.addView(zomeImageMoveable); myFrame.addView(zomeImageFixed); } Case 1. below two ImageView have each listener ,but works only one. Case 2. FrameLayout add OnTouchListener and forward. but it doesn't work myFrame.setOnTouchListener(new OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { zomeImageMoveable.onTouchEvent(event); zomeImageFixed.onTouchEvent(event); return false; } }); how do i have to do? thanks for reading.

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• Catch all exceptions in Scala 2.8 RC1

  - by Michel Krämer

  I have the following dummy Scala code in the file test.scala: class Transaction { def begin() {} def commit() {} def rollback() {} } object Test extends Application { def doSomething() {} val t = new Transaction() t.begin() try { doSomething() t.commit() } catch { case _ => t.rollback() } } If I compile this on Scala 2.8 RC1 with scalac -Xstrict-warnings test.scala I'll get the following warning: test.scala:16: warning: catch clause swallows everything: not advised. case _ => t.rollback() ^ one warning found So, if catch-all expressions are not advised, how am I supposed to implement such a pattern instead? And apart from that why are such expressions not advised anyhow?

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• How can I get mounted name and (Drive letter too) on Windows using python

  - by aberry

  I am using Daemon tool to mount an ISO image on Windows XP machine.I do mount using Daemon command (daemon.exe -mount 0,). Above command will mount ISO image to device number. In my case I have 4 partition (C,D,E,F) and G for DVD/CD-RW. Now what happen, ISO gets mounted to drive letter 'H:' with name (as defined while creating ISO) say 'testmount' My queries:- 1) How can I get mount name of mounted ISO image (i.e. 'testmount'). Just another case; if there are already some mount points existing on machine and I created a new one using Daemon tool. Then If I can get latest one using script that will be great. 2) How to get drive letter where it did get mounted. If anyone know python script or command (or even Win command ) to get these info. do let me know. Thanks...

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• list editabale error

  - by ha22109

  Hello all, I m using django 1.1 beta.I m facing porblem in case of list_editable.First it was throughing exception saying need ordering in case of list_editable" then i added ordering in model but know it is giving me error.The code is working fine with django1.1 final. here is my code model.py class User(models.Model): advertiser = models.ForeignKey(WapUser,primary_key=True) status = models.CharField(max_length=20,choices=ADVERTISER_INVITE_STATUS,default='invited') tos_version = models.CharField(max_length=5) contact_email = models.EmailField(max_length=80) contact_phone = models.CharField(max_length=15) contact_mobile = models.CharField(max_length=15) contact_person = models.CharField(max_length=80) feedback=models.BooleanField(choices=boolean_choices,default=0) def __unicode__(self): return self.user.login class Meta: db_table = u'roi_advertiser_info' managed=False ordering=['feedback',] admin.py class UserAdmin(ReadOnlyAdminFields, admin.ModelAdmin): list_per_page = 15 fields = ['advertiser','contact_email','contact_phone','contact_mobile','contact_person'] list_display = ['advertiser','contact_email','contact_phone','contact_mobile','contact_person','status','feedback'] list_editable=['feedback'] readonly = ('advertiser',) search_fields = ['advertiser__login_id'] radio_fields={'approve_auto': admin.HORIZONTAL} list_filter=['status','feedback'] admin.site.register(User,UserADmin)

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• PHP: How to check if query string or POST vars contain same var twice

  - by thomasrutter

  It may sound strange, but in my PHP application I need to check if the same variable name has been declared more than once in the query string or POST variables, and return an error value if this is the case. If my application doesn't return an error in this case, it fails a compliance check. When accessing vars using $_GET, $_POST, etc, PHP only returns the last value given for each variable name. I can't find a way to tell if any variable appeared more than once. I simply need to find out if the query string or the variables in the POST body contained the same variable name more than once, whatever the values.

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