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• How to keep group-writeable shares on Samba with OSX clients?

  - by Oliver Salzburg

  I have a FreeNAS server on a network with OSX and Windows clients. When the OSX clients interact with SMB/CIFS shares on the server, they are causing permission problems for all other clients. Update: I can no longer verify any answers because we abandoned the project, but feel free to post any help for future visitors. The details of this behavior seem to also be dependent on the version of OSX the client is running. For this question, let's assume a client running 10.8.2. When I mount the CIFS share on an OSX client and create a new directory on it, the directory will be created with drwxr-x-rx permissions. This is undesirable because it will not allow anyone but me to write to the directory. There are other users in my group which should have write permissions as well. This behavior happens even though the following settings are present in smb.conf on the server: [global] create mask= 0666 directory mask= 0777 [share] force directory mode= 0775 force create mode= 0660 I was under the impression that these settings should make sure that directories are at least created with rwxrwxr-x permissions. But, I guess, that doesn't stop the client from changing the permissions after creating the directory. When I create a folder on the same share from a Windows client, the new folder will have the desired access permissions (rwxrwxrwx), so I'm currently assuming that the problem lies with the OSX client. I guess this wouldn't be such an issue if you could easily change the permissions of the directories you've created, but you can't. When opening the directory info in Finder, I get the old "You have custom access" notice with no ability to make any changes. I'm assuming that this is caused because we're using Windows ACLs on the share, but that's just a wild guess. Changing the write permissions for the group through the terminal works fine, but this is unpractical for the deployment and unreasonable to expect from anyone to do. This is the complete smb.conf: [global] encrypt passwords = yes dns proxy = no strict locking = no read raw = yes write raw = yes oplocks = yes max xmit = 65535 deadtime = 15 display charset = LOCALE max log size = 10 syslog only = yes syslog = 1 load printers = no printing = bsd printcap name = /dev/null disable spoolss = yes smb passwd file = /var/etc/private/smbpasswd private dir = /var/etc/private getwd cache = yes guest account = nobody map to guest = Bad Password obey pam restrictions = Yes # NOTE: read smb.conf. directory name cache size = 0 max protocol = SMB2 netbios name = freenas workgroup = COMPANY server string = FreeNAS Server store dos attributes = yes hostname lookups = yes security = user passdb backend = ldapsam:ldap://ldap.company.local ldap admin dn = cn=admin,dc=company,dc=local ldap suffix = dc=company,dc=local ldap user suffix = ou=Users ldap group suffix = ou=Groups ldap machine suffix = ou=Computers ldap ssl = off ldap replication sleep = 1000 ldap passwd sync = yes #ldap debug level = 1 #ldap debug threshold = 1 ldapsam:trusted = yes idmap uid = 10000-39999 idmap gid = 10000-39999 create mask = 0666 directory mask = 0777 client ntlmv2 auth = yes dos charset = CP437 unix charset = UTF-8 log level = 1 [share] path = /mnt/zfs0 printable = no veto files = /.snap/.windows/.zfs/ writeable = yes browseable = yes inherit owner = no inherit permissions = no vfs objects = zfsacl guest ok = no inherit acls = Yes map archive = No map readonly = no nfs4:mode = special nfs4:acedup = merge nfs4:chown = yes hide dot files force directory mode = 0775 force create mode = 0660

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• SFML 2.0 Too Many Variables in Class Preventing Draw To Screen

  - by Josh

  This is a very strange phenomenon to me. I have a class definition for a game, but when I add another variable to the class, the draw method does not print everything to the screen. It will be easier understood showing the code and output. Code for good draw output: class board { protected: RectangleShape rect; int top, left; int i, j; int rowSelect, columnSelect; CircleShape circleArr[4][10]; CircleShape codeArr[4]; CircleShape keyArr[4][10]; //int pegPresent[4]; public: board(void); void draw(RenderWindow& Window); int mouseOver(RenderWindow& Window); void placePeg(RenderWindow& Window, int pegSelect); }; Screen: Code for missing draw: class board { protected: RectangleShape rect; int top, left; int i, j; int rowSelect, columnSelect; CircleShape circleArr[4][10]; CircleShape codeArr[4]; CircleShape keyArr[4][10]; int pegPresent[4]; public: board(void); void draw(RenderWindow& Window); int mouseOver(RenderWindow& Window); void placePeg(RenderWindow& Window, int pegSelect); }; Screen: As you can see, all I do is un-comment the protected array and most of the pegs are gone from the right hand side. I have checked and made sure that I didn't accidentally created a variable with that name already. I haven't used it anywhere. Why does it not draw the remaining pegs as it should? My only thought is that maybe I am declaring too many variables for the class, but that doesn't really make sense to me. Any thoughts and help is greatly appreciated.

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• Automatically triggering standard spaceship controls to stop its motion

  - by Garan

  I have been working on a 2D top-down space strategy/shooting game. Right now it is only in the prototyping stage (I have gotten basic movement) but now I am trying to write a function that will stop the ship based on it's velocity. This is being written in Lua, using the Love2D engine. My code is as follows (note- object.dx is the x-velocity, object.dy is the y-velocity, object.acc is the acceleration, and object.r is the rotation in radians): function stopMoving(object, dt) local targetr = math.atan2(object.dy, object.dx) if targetr == object.r + math.pi then local currentspeed = math.sqrt(object.dx*object.dx+object.dy*object.dy) if currentspeed ~= 0 then object.dx = object.dx + object.acc*dt*math.cos(object.r) object.dy = object.dy + object.acc*dt*math.sin(object.r) end else if (targetr - object.r) >= math.pi then object.r = object.r - object.turnspeed*dt else object.r = object.r + object.turnspeed*dt end end end It is implemented in the update function as: if love.keyboard.isDown("backspace") then stopMoving(player, dt) end The problem is that when I am holding down backspace, it spins the player clockwise (though I am trying to have it go the direction that would be the most efficient at getting to the angle it would have to be) and then it never starts to accelerate the player in the direction opposite to it's velocity. What should I change in this code to get that to work? EDIT : I'm not trying to just stop the player in place, I'm trying to get it to use it's normal commands to neutralize it's existing velocity. I also changed math.atan to math.atan2, apparently it's better. I noticed no difference when running it, though.

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• parallel_for_each from amp.h – part 1

  - by Daniel Moth

  This posts assumes that you've read my other C++ AMP posts on index<N> and extent<N>, as well as about the restrict modifier. It also assumes you are familiar with C++ lambdas (if not, follow my links to C++ documentation). Basic structure and parameters Now we are ready for part 1 of the description of the new overload for the concurrency::parallel_for_each function. The basic new parallel_for_each method signature returns void and accepts two parameters: a grid<N> (think of it as an alias to extent) a restrict(direct3d) lambda, whose signature is such that it returns void and accepts an index of the same rank as the grid So it looks something like this (with generous returns for more palatable formatting) assuming we are dealing with a 2-dimensional space: // some_code_A parallel_for_each( g, // g is of type grid<2> [ ](index<2> idx) restrict(direct3d) { // kernel code } ); // some_code_B The parallel_for_each will execute the body of the lambda (which must have the restrict modifier), on the GPU. We also call the lambda body the "kernel". The kernel will be executed multiple times, once per scheduled GPU thread. The only difference in each execution is the value of the index object (aka as the GPU thread ID in this context) that gets passed to your kernel code. The number of GPU threads (and the values of each index) is determined by the grid object you pass, as described next. You know that grid is simply a wrapper on extent. In this context, one way to think about it is that the extent generates a number of index objects. So for the example above, if your grid was setup by some_code_A as follows: extent<2> e(2,3); grid<2> g(e); ...then given that: e.size()==6, e[0]==2, and e[1]=3 ...the six index<2> objects it generates (and hence the values that your lambda would receive) are:    (0,0) (1,0) (0,1) (1,1) (0,2) (1,2) So what the above means is that the lambda body with the algorithm that you wrote will get executed 6 times and the index<2> object you receive each time will have one of the values just listed above (of course, each one will only appear once, the order is indeterminate, and they are likely to call your code at the same exact time). Obviously, in real GPU programming, you'd typically be scheduling thousands if not millions of threads, not just 6. If you've been following along you should be thinking: "that is all fine and makes sense, but what can I do in the kernel since I passed nothing else meaningful to it, and it is not returning any values out to me?" Passing data in and out It is a good question, and in data parallel algorithms indeed you typically want to pass some data in, perform some operation, and then typically return some results out. The way you pass data into the kernel, is by capturing variables in the lambda (again, if you are not familiar with them, follow the links about C++ lambdas), and the way you use data after the kernel is done executing is simply by using those same variables. In the example above, the lambda was written in a fairly useless way with an empty capture list: [ ](index<2> idx) restrict(direct3d), where the empty square brackets means that no variables were captured. If instead I write it like this [&](index<2> idx) restrict(direct3d), then all variables in the some_code_A region are made available to the lambda by reference, but as soon as I try to use any of those variables in the lambda, I will receive a compiler error. This has to do with one of the direct3d restrictions, where only one type can be capture by reference: objects of the new concurrency::array class that I'll introduce in the next post (suffice for now to think of it as a container of data). If I write the lambda line like this [=](index<2> idx) restrict(direct3d), all variables in the some_code_A region are made available to the lambda by value. This works for some types (e.g. an integer), but not for all, as per the restrictions for direct3d. In particular, no useful data classes work except for one new type we introduce with C++ AMP: objects of the new concurrency::array_view class, that I'll introduce in the post after next. Also note that if you capture some variable by value, you could use it as input to your algorithm, but you wouldn’t be able to observe changes to it after the parallel_for_each call (e.g. in some_code_B region since it was passed by value) – the exception to this rule is the array_view since (as we'll see in a future post) it is a wrapper for data, not a container. Finally, for completeness, you can write your lambda, e.g. like this [av, &ar](index<2> idx) restrict(direct3d) where av is a variable of type array_view and ar is a variable of type array - the point being you can be very specific about what variables you capture and how. So it looks like from a large data perspective you can only capture array and array_view objects in the lambda (that is how you pass data to your kernel) and then use the many threads that call your code (each with a unique index) to perform some operation. You can also capture some limited types by value, as input only. When the last thread completes execution of your lambda, the data in the array_view or array are ready to be used in the some_code_B region. We'll talk more about all this in future posts… (a)synchronous Please note that the parallel_for_each executes as if synchronous to the calling code, but in reality, it is asynchronous. I.e. once the parallel_for_each call is made and the kernel has been passed to the runtime, the some_code_B region continues to execute immediately by the CPU thread, while in parallel the kernel is executed by the GPU threads. However, if you try to access the (array or array_view) data that you captured in the lambda in the some_code_B region, your code will block until the results become available. Hence the correct statement: the parallel_for_each is as-if synchronous in terms of visible side-effects, but asynchronous in reality.   That's all for now, we'll revisit the parallel_for_each description, once we introduce properly array and array_view – coming next. Comments about this post by Daniel Moth welcome at the original blog.

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• Set up Windows SBS dns server and vpn clients from brench office

  - by mn

  I have got some clients from bench office which connects vpn to main office. The Router from bench office assigned addresses from DHCP 192.168.1.0/255.255.255.0 and remote gateway assigned vpn ip addresses 10.10.20.0/255.255.255.0. There is a DNS server (Active Directory Win SBS 2000) and vpn client are registered with vpn address (10.10.20.0/255.255.255.0 and domain company.com.pl). I would like to register also primary bench subnet 192.168.1.0/255.255.255.0 with domain for example company.vpn.local I want to access vpn hosts for example: dev3.copmany.pkb.local and dev3.company.com using my Win SBS 2000 DNS server.

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• 1.6 or 1.7: Browser side Java version for Oracle VM console

  - by katsumii

  I noticed one of the recent FAQ in OVM forum is about console.OTN Discussion Forums : Oracle VM Server for x86vnc console not running on Oracle VM 3.1.1 One of the variable for running console is Java version. I myself hit the bug below on Windows with JDK1.7 This is Windows only bug. I had success with JDK1.7 on Linux.Bug ID: 7191616 javaws.exe crashes when starting jnlp filejnlp file provided in the steps to reproduce always crashes javaws.exe in Java 7 Update 6.No problems in Update 4

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• Copying a large directory tree locally? cp or rsync?

  - by Rory

  I have to copy a large directory tree, about 1.8 TB. It's all local. Out of habit I'd use rsync, however I wonder if there's much point, and if I should rather use cp. I'm worried about permissions and uid/gid, since they have to be preserved in the clopy (I know rsync does this). As well as thinks like symlinks. The destination is empty, so I don't have to worry about conditionally updating some files. It's all local disk access, so I don't have to worry about ssh or network. The reason I'd be tempted away from rsync, is because rsync might do more than I need. rsync checksums files. I don't need that, and am concerned that it might take longer than cp. So what do you reckon, rsync or cp?

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• Setup a proxy (Not reverse proxy) using Varnish/Squid.

  - by shabda

  I need to setup a proxy server where we can request remote urls and get them served locally. Basically what I need is mysever:8000/varnish/serverfault.com get me serverfault.com served from my local varnish or myserver:8080/squid/serverfault.com get me serverfault.com served from my local squid. (Both should cache the site for 24 hours) I am evaluating if Varnish or Squid will be a good choice for it. Which one will be a better fit? How do I do it. Links to tutorials would be good.

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• Music Art Food Drink: Oracle Social Plaza - Tues 10/2

  - by Bob Rhubart

  Join Oracle's social media mavens plus hundreds of your closest friends at this all-social social… What: Oracle Social Plaza When: Tuesday, October 2, 2012Noon to 8:00 pm Where: Mint Plaza Fifth Street between Mission and Market San Francisco It's a full-on treat for all your senses, featuring music, art, food, and fashion. Music will be provided by indy favs Golden State and dance-rageous local DJ Brandon Arnovick. Watch as artists, including Melanie Alveres, create works of art live, then bid on their creations. Want to do a little creating on your own? Try mugging in the Social PhotoBooth. If you're into fashion, 20 local fashion designers will be on hand with their latest creations. And if you like t-shirts, there'll be live screen printing, with free t-shirts for the first 300 guests. Food and drink? Starting at 4:30 pm there will be two bars, along with munchies from one of those outrageous San Francisco food trucks. And don't worry about missing Larry Ellison's keynote. You can watch if from here.

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• Why does writing a file to an NFS share send a COMMIT operation to the NFS server?

  - by Antonis Christofides

  I have a Debian squeeze (2.6.32-5-amd64) which is at the same time a NFS4 server and client (it mounts itself through NFS4). The local directory that leads directly to disk is /nfs4exports/mydir, whereas /nfs4mounts/mydir is the same thing mounted through NFS, using the machine's external IP address. Here is the line from fstab: 192.168.1.75:/mydir /nfs4mounts/mydir nfs4 soft 0 0 I have an application that writes many small files. If I write directly to /nfs4exports/mydir, it writes thousands of files per second; but if I write to /nfs4mounts/mydir, it writes 4 files per second or so. I can greatly increase speed if I add async to /etc/exports. (Writing a single large file to the NFS-mounted directory goes at more than 100 MB/s.) I examine the server statistics and I see that whenever a file is written, it is "committed" (this also happens with NFSv3): root@debianvboxtest:~# mount -t nfs4 192.168.1.75:/mydir /mnt root@debianvboxtest:~# nfsstat|grep -A 2 'nfs v4 operations' Server nfs v4 operations: op0-unused op1-unused op2-future access close commit 0 0% 0 0% 0 0% 10 4% 1 0% 1 0% root@debianvboxtest:~# echo 'hello' >/mnt/test1056 root@debianvboxtest:~# nfsstat|grep -A 2 'nfs v4 operations' Server nfs v4 operations: op0-unused op1-unused op2-future access close commit 0 0% 0 0% 0 0% 11 4% 2 0% 2 0% Now in the RFC, I read this: The COMMIT operation is similar in operation and semantics to the POSIX fsync(2) system call that synchronizes a file's state with the disk (file data and metadata is flushed to disk or stable storage). COMMIT performs the same operation for a client, flushing any unsynchronized data and metadata on the server to the server's disk or stable storage for the specified file. I don't understand why the client commits. I don't think that the "echo" shell built-in command runs fsync; if echo wrote to a local file and then the machine went down, the file might be lost. In contrast, the NFS client appears to be sending a COMMIT upon completion of the echo. Why? I am reluctant to use the async NFS server option, because it would apparently ignore COMMIT. I feel as if I had a local filesystem and I had to choose between syncing every file upon close and ignoring fsync altogether. What have I understood wrong?

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• What are the requirements to test a website using jquery.get() ? [migrated]

  - by Frankie

  I am working on a simple website. It has to search quite a few text files in different sub-folders. The rest of the page uses jquery, so I would like to use it for this also. The function I am looking at is .get() for downloading the files. So my main question is, can I test this on my local computer (Ubuntu Linux) or do I have to have it uploaded to a server? Also, if there's a better way to go about this, that would be nice to know. However, I'm more worried about getting it working. Thanks, Frankie PS: Heres the JS/jQuery code for downloading the files to an array. g_lists = new Array(); $(":checkbox").each(function(i){ if ($(this).attr("name") != "0") { var path = "../" + $(this).attr("name") + ".txt"; $("#bot").append("<br />" + path); // debug $.get(path, function(data){ g_lists[i] = data; $("#bot").html(data); }); } else { g_lists[i] = ""; } }); Edit: Just a note about the path variable. I think it's correct, but I'm not 100% sure. I'm new to web development. Here's some examples it produces and the directory tree of the site. Maybe it will help, can't hurt. . +-- include ¦   +-- jquery.js ¦   +-- load.js +-- index.xhtml +-- style.css +-- txt    +-- Scripting_Tools    +-- Editors.txt    +-- Other.txt Examples of path: ../txt/Scripting_Tools/Editors.txt ../txt/Scripting_Tools/Other.txt Well I'm a new user, so I can't "answer" my own question, so I'll just post it here: After asking for help on a IRC chat channel specific to jQuery, I was told I could use this on a local host. To do this I installed Apache web server, and copied my site into it's directory. More information on setting it up can be found here: http://www.howtoforge.com/ubuntu_debian_lamp_server Then to run the site I navigated my browser to "localhost" and everything works.

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• Internet Explorer cannot display page from apache with single SSL virtual host

  - by P.scheit

  I have a question that has come up somehow in different questions but I still can't find the solution, yet. My problem is that I'm hosting a site on apache 2.4 on debian with SSL and Internet Explorer 7 on windows xp shows Internet Explorer cannot display the webpage I have only ONE virtual host that uses ssl, but DIFFERENT virtual hosts that use http. Here is my config for the site with SSL enabled (etc/sites-avaible/default-ssl is NOT linked) <Virtualhost xx.yyy.86.193:443> ServerName www.my-certified-domain.de ServerAlias my-certified-domain.de DocumentRoot "/var/local/www/my-certified-domain.de/current/www" Alias /files "/var/local/www/my-certified-domain.de/current/files" CustomLog /var/log/apache2/access.my-certified-domain.de.log combined <Directory "/var/local/www/my-certified-domain.de/current/www"> AllowOverride All </Directory> SSLEngine on SSLCertificateFile /etc/ssl/certs/www.my-certified-domain.de.crt SSLCertificateKeyFile /etc/ssl/private/www.my-certified-domain.de.key SSLCipherSuite HIGH:MEDIUM:!aNULL:+SHA1:+MD5:+HIGH:+MEDIUM SSLCertificateChainFile /etc/apache2/ssl.crt/www.my-certified-domain.de.ca BrowserMatch "MSIE [2-8]" nokeepalive downgrade-1.0 force-response-1.0 </VirtualHost> <VirtualHost *:80> ServerName www.my-certified-domain.de ServerAlias my-certified-domain.de CustomLog /var/log/apache2/access.my-certified-domain.de.log combined Redirect permanent / https://www.my-certified-domain.de/ </VirtualHost> my ports.conf looks like this: NameVirtualHost *:80 Listen 80 <IfModule mod_ssl.c> # If you add NameVirtualHost *:443 here, you will also have to change # the VirtualHost statement in /etc/apache2/sites-available/default-ssl # to <VirtualHost *:443> # Server Name Indication for SSL named virtual hosts is currently not # supported by MSIE on Windows XP. Listen 443 </IfModule> <IfModule mod_gnutls.c> Listen 443 </IfModule> the output from apache2ctl -S is like this: xx.yyy.86.193:443 www.my-certified-domain.de (/etc/apache2/sites-enabled/020-my-certified-domain.de:1) wildcard NameVirtualHosts and _default_ servers: *:80 is a NameVirtualHost default server phpmyadmin.my-certified-domain.de (/etc/apache2/conf.d/phpmyadmin.conf:3) port 80 namevhost phpmyadmin.my-certified-domain.de (/etc/apache2/conf.d/phpmyadmin.conf:3) port 80 namevhost staging.my-certified-domain.de (/etc/apache2/sites-enabled/010-staging.my-certified-domain.de:1) port 80 namevhost testing.my-certified-domain.de (/etc/apache2/sites-enabled/015-testing.my-certified-domain.de:1) port 80 namevhost www.my-certified-domain.de (/etc/apache2/sites-enabled/020-my-certified-domain.de:31) I included the solution for this question: Internet explorer cannot display the page, other browsers can, possibly htaccess / server error And I understand the answer from this question: How to setup Apache NameVirtualHost on SSL? In fakt: I only have one ssl certificate for the domain. And I only want to run ONE virtual host with ssl. So I just want to use the one ip for the ssl virtual host. But still (after rebooting / restarting / testing) internet explorer will still not show the page. When I intepret the apachectl -S as well, I already have only one SSL host and this should response to the initial SSH handshake, shouldn't it? What is wrong in this setup? Thank you so much Philipp

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• Routing tables don't show ppp0 after 12.04 kernel upgrade to 3.5.0: Haier CE682 modem configuration

  - by ubunsteve

  I'm trying to get my Haier CE682 EVDO modem, model number 201e:1022 to work in ubuntu 12.04 kernel 3.5.0-030500-generic #201207211835 . I had it working in a previous 12.04 kernel, using compat-wireless and these instructions http://zulkhamsyahmh.blogspot.com/2012/05/install-smartfren-haier-ce682-on-ubuntu.html, and to get it working had to edit the routing tables so that there was a ppp0 showing up, as suggested at http://www.linuxquestions.org/questions/slackware-14/wvdial-is-connecting-but-im-unable-to-do-anything-714861/ Network manager doesn't work with this modem, so I use either wvdial or gpppon to connect to it, both which work (after I run the command sudo modprobe usbserial vendor=0x201e product=0x1022 ) This is the output of when I connect with gpppon to the modem: Using interface ppp0 Connect: ppp0 <-- /dev/ttyUSB0 sent [LCP ConfReq id=0x1 ] rcvd [LCP ConfAck id=0x1 ] rcvd [LCP ConfReq id=0x2 ] sent [LCP ConfAck id=0x2 ] sent [LCP EchoReq id=0x0 magic=0x819c86db] rcvd [CHAP Challenge id=0x1 <1ac8f12799e953967a3cc222c9254690, name = ""] sent [CHAP Response id=0x1 <6f12a903dc40915ca2761c17b87f8fbd, name = "smart"] rcvd [LCP EchoRep id=0x0 magic=0x0] rcvd [CHAP Success id=0x1 ""] CHAP authentication succeeded CHAP authentication succeeded sent [CCP ConfReq id=0x1 ] sent [IPCP ConfReq id=0x1 ] rcvd [IPCP ConfReq id=0x1 ] sent [IPCP ConfAck id=0x1 ] rcvd [CCP ConfReq id=0x1] sent [CCP ConfAck id=0x1] rcvd [CCP ConfRej id=0x1 ] sent [CCP ConfReq id=0x2] rcvd [IPCP ConfRej id=0x1 ] sent [IPCP ConfReq id=0x2 ] rcvd [CCP ConfAck id=0x2] rcvd [IPCP ConfNak id=0x2 ] sent [IPCP ConfReq id=0x3 ] rcvd [IPCP ConfAck id=0x3 ] not replacing existing default route via 192.168.3.1 local IP address 10.191.248.154 remote IP address 10.17.95.25 primary DNS address 10.17.3.244 secondary DNS address 10.17.3.245 as you can see there is a problem with "not replacing existing default route via 192.168.3.1" This it the out put of route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default 192.168.3.1 0.0.0.0 UG 0 0 0 wlan0 link-local * 255.255.0.0 U 1000 0 0 wlan0 192.168.3.0 * 255.255.255.0 U 2 0 0 wlan0 I had tried these commands, which had previously worked in the earlier kernel: route del default route add default ppp0 but that broke my wireless internet connection. I then added the default routing as shown above with sudo route add default gw 192.168.3.1 wlan0 So it seems I need to add or change the routing to show a ppp0 connection, but I don't know how to do that.

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• System broken after installing Gtk+-3.4.1 with broadway backend enabled

  - by Roman D. Boiko

  I am running Ubuntu 11.10 from VirtualBox. I installed Gtk+ 3.4.1 (latest stable release) from sources with X11 and broadway backends enabled. In order to do that, I also installed latest versions of glib, libffi, libtiff, libjped, gdk-pixbuf, and pango. Each of them was configured with default options. I.e., they were installed to /usr/local (at least, I see respective folders in /usr/local/include). After reboot and login (regardless which user), desktop is grey for about 30 sec, nothing is displayed. Then Nautilus starts, but nothing else (my locale is Ukrainian, but there is nothing important in text): . During boot, I can access command prompt as root, use dpkg, etc. But I don't know what to do. One idea is to reinstall Gtk+ and other libraries with prefix /usr or /usr/shared. I will try that, but it is quite time-consuming, so any ideas would be welcome. Reverting to earlier snapshot is still possible, but it is 6 days old and I would like to try to solve the problem.

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• MLGPO for Windows Server 2003 R2?

  - by 5graeham5

  Is there something like MLGPO (Multiple Local Group Policy Objects) for Windows Server 2003 R2? I have a 2003 Terminal Server that isn't part of a domain/AD and I'm trying to set local group policies which applies only to certain users and/or groups and the policies differ between those entities. I wanted to avoid using the file permissions trick for on C:\WINDOWS\system32\GroupPolicy as that's an all-or-nothing approach. I can't upgrade this box to Windows Server 2008 as the software used is only supported and only works on 2003. Are there any third-party tools to achieve this?

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• Emails not being delivered

  - by Tomtiger11

  Comment pointed out that this may fix my problem, and it did: Why don't mails show up in the recipient's mailspool? I use Postfix with Dovecot, and when I send an email from my gmail to my server, it is received at the server, but not at my email client using POP3. I can verify it being received at the server using the mail command. This is my main.cf: queue_directory = /var/spool/postfix command_directory = /usr/sbin daemon_directory = /usr/libexec/postfix data_directory = /var/lib/postfix mail_owner = postfix myhostname = tom4u.eu myorigin = $myhostname inet_interfaces = all inet_protocols = all unknown_local_recipient_reject_code = 550 relay_domains = $mydomain alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases debug_peer_level = 2 debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5 sendmail_path = /usr/sbin/sendmail.postfix newaliases_path = /usr/bin/newaliases.postfix mailq_path = /usr/bin/mailq.postfix setgid_group = postdrop html_directory = no manpage_directory = /usr/share/man sample_directory = /usr/share/doc/postfix-2.6.6/samples readme_directory = /usr/share/doc/postfix-2.6.6/README_FILES smtpd_tls_cert_file = /etc/postfix/certs/cert.pem milter_protocol = 2 milter_default_action = accept smtpd_milters = inet:localhost:8891 non_smtpd_milters = inet:localhost:8891 smtpd_sasl_auth_enable = yes smtpd_sasl_security_options = noanonymous smtpd_sasl_local_domain = $myhostname smtpd_recipient_restrictions = reject_non_fqdn_recipient,permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination,permit broken_sasl_auth_clients = yes smtpd_sasl_type = dovecot smtpd_sasl_path = private/auth If you could help me with this, I'd be most grateful, if you need any more information, please ask. var/log/maillog: May 30 22:44:25 tom4u postfix/smtpd[18626]: connect from mail-we0-f181.google.com[74.125.82.181] May 30 22:44:25 tom4u postfix/smtpd[18626]: 318F679B7F: client=mail-we0-f181.google.com[74.125.82.181] May 30 22:44:25 tom4u postfix/cleanup[18631]: 318F679B7F: message-id=<CAA_0zdxY-WUFGOC57K_yVn0G+5hN=8KSXuohJqMDB5Rm7bqu8w@mail.gmail.com> May 30 22:44:25 tom4u opendkim[15006]: 318F679B7F: mail-we0-f181.google.com [74.125.82.181] not internal May 30 22:44:25 tom4u opendkim[15006]: 318F679B7F: not authenticated May 30 22:44:25 tom4u opendkim[15006]: 318F679B7F: DKIM verification successful May 30 22:44:25 tom4u opendkim[15006]: 318F679B7F: s=20120113 d=gmail.com SSL May 30 22:44:25 tom4u postfix/qmgr[16282]: 318F679B7F: from=<[email protected]>, size=1720, nrcpt=1 (queue active) May 30 22:44:25 tom4u postfix/smtpd[18626]: disconnect from mail-we0-f181.google.com[74.125.82.181] May 30 22:44:25 tom4u postfix/local[18632]: 318F679B7F: to=<[email protected]>, relay=local, delay=0.17, delays=0.12/0.01/0/0.03, dsn=2.0.0, status=sent (delivered to mailbox) May 30 22:44:25 tom4u postfix/qmgr[16282]: 318F679B7F: removed May 30 22:45:32 tom4u dovecot: pop3-login: Login: user=<tom>, method=PLAIN, rip=SNIP, lip=176.31.127.165, mpid=18679 May 30 22:45:32 tom4u dovecot: pop3(tom): Disconnected: Logged out top=0/0, retr=0/0, del=0/0, size=0 May 30 22:46:32 tom4u dovecot: pop3-login: Login: user=<tom>, method=PLAIN, rip=SNIP, lip=176.31.127.165, mpid=18725 May 30 22:46:32 tom4u dovecot: pop3(tom): Disconnected: Logged out top=0/0, retr=0/0, del=0/0, size=0

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• How to remove settings from a Microsoft Account Windows 8?

  - by Stevie G

  When installing windows 8 for the first time, I did not create a microsoft account and just installed as the local user. However I recently updated to Windows 8.1 and it forces you to use a microsoft account. I did not want to create an account so one of my friends used his and I logged in. After logging in all the friend's details like apps, wallpaper, lock screen, search mechanism, when I use search i see the friends facebook friends popping up. it is really annoying. How can I remove all of this excess, as I have logged out of the microsoft account and am just using local user but these problems have persisted. Thanks

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• Is a big name computer science degree worth the cost?

  - by Serplat

  I'm currently in High School and trying to look into what I want to do after I graduate. I know that I will be going to college, and that I want a degree in Computer Science, however, I'm not entirely sure where I want to go (I haven't started the application process yet). I already have built up a decent amount of experience in programming (over the summers I have been hired to program at a local university), and I'm pretty capable of teaching myself most of the material I've come across through either books or web documentation. I'm interested in whether it is worth it to get a degree from a major, big-name computer science university for $50,000 each year, as opposed to going to a local state school for only $20,000. For my Bachelor's degree alone, this would be $120,000 more than the state school. I've also heard that where you get your Bachelor's doesn't matter much if you plan to get a Master's degree. Many people recommend going somewhere like a state school for your Bachelor's, and then try to get into a more major school for your Master's. Has anybody found any truth in this? Basically, is going to a big name computer science school for a Bachelor's degree really worth the added expense?

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• Sharing folder in a Virtual Private Windows Server 2008 R2 ?

  - by Triztian

  See Edit 2: Hello all, seems my involvement with computers has grown and I've found my self in the need to access a shared folder on a server. I've read some documentation and managed to set up the folder as a share, for this I created a local group and for now just one local user that has access to the share, the folder is in the public user folder and it's permissions should be (and I believe they are) read/write. The problem is that I can't connect from a remote machine I mean I don't know how the way it should be accessed, the server has a public IP and we use it also as a host to our website I don't know if that affects it though, the folder will be used as the "keeper" for the QuickBooks company files and has the database server manager installed. I've tried setting up a VPN Connection to the but no success. The server has a domain name a "http://www.example.com" that redirects to our website, I am unsure if it could be accessed that way, also the share has a location displayed when I right-click properties Heres what I've tried Setting up a VPN Connection (Windows Vista and 7) Got to the point where I got asked for credential and entered the user I created (which is not an admin) but I got a "Connection fail error 800" I suppose this is because in the domain field I entered the servers workgroup. right-click add network connection (Windows 7) Went through the wizard until I reached the point of entering the location, tried many things, the name in the share's properties(\\SOMETHING\Share), the http://www.example.com , the IP address I'm quite unfamiliar with this, so I have my guesses: Since the group and user are local they do not have access to the folder. The firewall in the server is blocking my connection. Anyways, any help and guidence is truly appreciated. EDIT 1: As @tony roth pointed out it may be a security fail, an I commented it out to management and said that that is not an issue, so please bare with me. EDIT 2: I've found out that the real question could be streamlined to "Sharing folder in a Virtual Private Server?", as thats what we have, a virtual private windows server 2008 R2, and I would like to know how to make it show like a normal folder in the client computer. Thanks again for all of your support.

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• Can't access LAN computers with SSH

  - by endolith

  I got a new Windows 7 machine, and was using VNC,SSH etc to connect to my Ubuntu machine, and it worked fine previously. Now it doesn't work if I use the machine's hostname or local IP, but if I use the DynDNS name, it works. I can also access it from my Android phone using the local hostname over SSH. If I try to connect with SSH to the hostname, it says "Host does not exist". VNC says "Failed to get server address". NX says "no address associated with name", and I don't see it in Windows' "Network" folder. I've rebooted everything. I've turned off Windows firewall. It was working fine a few days ago, but now it's not. How do I figure out what's blocking it?

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• Permissions needed to read event log messages remotely?

  - by Neolisk

  When running under a limited account, local event log messages are displaying fine, for remote computer I am getting this error: The description for Event ID ( xxxxx ) in Source ( yyyyy ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: zzzzz. Same remote computer works fine under domain administrator. I am currently experimenting with just the Event Viewer, by using Run As. Original issue is a PowerShell script which does Get-EventLog. Are there any special permissions that need to be in place to able to read event log messages remotely? Supposedly there is a simple solution in Windows 2008 and higher, i.e. just add user to Event Log Readers group. Is there anything like that for Windows 2003?

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• ESXi v5.5 is having random crashes

  - by Darkmage

  HW: Type: HP Proliant ML350 G5 RAM 22GB CPU 1 x Intel Xenon E5405 2.00GHz OP: ESXi 5.5 just updated from 5.1 to try and fix the crashes occurring on ESXi 5.1 on same hardware. I'm trying to find the error on why one of our servers is crashing, it has had two lock ups in 24 hours now. The internal error light on the front is blinking red, on the inside only "#5 and #6 page 76 manual" the "Processor 2" light "amber" and the "Power" light "green" is shining. in the logs the only errors i can see in the relevant time frame is in log under. Is this the reason? or is there anything else i can do to try and log/locate the error. from zcat syslog.6.gz | less 2014-05-26T11:55:47Z sfcbd[35064]: Error opening socket pair for getProviderContext: Too many open files 2014-05-26T11:55:47Z sfcbd[35064]: Failed to set recv timeout (30) for socket -1. Errno = 9 2014-05-26T11:55:47Z sfcbd[35064]: Failed to set timeout for local socket (e.g. provider) 2014-05-26T11:55:47Z sfcbd[35064]: spGetMsg receiving from -1 35064-9 Bad file descriptor 2014-05-26T11:55:47Z sfcbd[35064]: rcvMsg receiving from -1 35064-9 Bad file descriptor 2014-05-26T11:55:47Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:55:47Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:55:47Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:55:47Z sfcbd[35064]: Error opening socket pair for getProviderContext: Too many open files 2014-05-26T11:55:47Z sfcbd[35064]: Failed to set recv timeout (30) for socket -1. Errno = 9 2014-05-26T11:55:47Z sfcbd[35064]: Failed to set timeout for local socket (e.g. provider) 2014-05-26T11:55:47Z sfcbd[35064]: spGetMsg receiving from -1 35064-9 Bad file descriptor 2014-05-26T11:55:47Z sfcbd[35064]: rcvMsg receiving from -1 35064-9 Bad file descriptor 2014-05-26T11:55:47Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:55:47Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:55:47Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:55:53Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:55:57Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:01Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:04Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:15Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:17Z sfcbd[35064]: Error opening socket pair for getProviderContext: Too many open files 2014-05-26T11:56:17Z sfcbd[35064]: Failed to set recv timeout (30) for socket -1. Errno = 9 2014-05-26T11:56:17Z sfcbd[35064]: Failed to set timeout for local socket (e.g. provider) 2014-05-26T11:56:17Z sfcbd[35064]: spGetMsg receiving from -1 35064-9 Bad file descriptor 2014-05-26T11:56:17Z sfcbd[35064]: rcvMsg receiving from -1 35064-9 Bad file descriptor 2014-05-26T11:56:17Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:17Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:17Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:17Z sfcbd[35064]: Error opening socket pair for getProviderContext: Too many open files 2014-05-26T11:56:17Z sfcbd[35064]: Failed to set recv timeout (30) for socket -1. Errno = 9 2014-05-26T11:56:17Z sfcbd[35064]: Failed to set timeout for local socket (e.g. provider) 2014-05-26T11:56:17Z sfcbd[35064]: spGetMsg receiving from -1 35064-9 Bad file descriptor 2014-05-26T11:56:17Z sfcbd[35064]: rcvMsg receiving from -1 35064-9 Bad file descriptor 2014-05-26T11:56:17Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:17Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:17Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:23Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:27Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:31Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:34Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:34Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:34Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:34Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:34Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:44Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:44Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:44Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:44Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:46Z sfcb-ProviderManager[34828]: SendMsg sending to 1 34828-9 Bad file descriptor 2014-05-26T11:56:48Z sfcbd[35064]: Error opening socket pair for getProviderContext: Too many open files -- manual

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• Is code like this a "train wreck" (in violation of Law of Demeter)?

  - by Michael Kjörling

  Browsing through some code I've written, I came across the following construct which got me thinking. At a first glance, it seems clean enough. Yes, in the actual code the getLocation() method has a slightly more specific name which better describes exactly which location it gets. service.setLocation(this.configuration.getLocation().toString()); In this case, service is an instance variable of a known type, declared within the method. this.configuration comes from being passed in to the class constructor, and is an instance of a class implementing a specific interface (which mandates a public getLocation() method). Hence, the return type of the expression this.configuration.getLocation() is known; specifically in this case, it is a java.net.URL, whereas service.setLocation() wants a String. Since the two types String and URL are not directly compatible, some sort of conversion is required to fit the square peg in the round hole. However, according to the Law of Demeter as cited in Clean Code, a method f in class C should only call methods on C, objects created by or passed as arguments to f, and objects held in instance variables of C. Anything beyond that (the final toString() in my particular case above, unless you consider a temporary object created as a result of the method invocation itself, in which case the whole Law seems to be moot) is disallowed. Is there a valid reasoning why a call like the above, given the constraints listed, should be discouraged or even disallowed? Or am I just being overly nitpicky? If I were to implement a method URLToString() which simply calls toString() on a URL object (such as that returned by getLocation()) passed to it as a parameter, and returns the result, I could wrap the getLocation() call in it to achieve exactly the same result; effectively, I would just move the conversion one step outward. Would that somehow make it acceptable? (It seems to me, intuitively, that it should not make any difference either way, since all that does is move things around a little. However, going by the letter of the Law of Demeter as cited, it would be acceptable, since I would then be operating directly on a parameter to a function.) Would it make any difference if this was about something slightly more exotic than calling toString() on a standard type? When answering, do keep in mind that altering the behavior or API of the type that the service variable is of is not practical. Also, for the sake of argument, let's say that altering the return type of getLocation() is also impractical.

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• Why do some languages recommend using spaces rather than tabs?

  - by TK Kocheran

  Maybe I'm alone in this, but few things annoy me like people indenting using spaces rather than tabs. How is typing SpaceSpaceSpaceSpace easier and more intuitive than typing Tab? Sure, tab width is variable, but it's much more indicative of indentation space than spaces. The same thing goes for backspacing; backspace once or four times? Why do languages like Python recommend using spaces over tabs?

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• StreamInsight 2.1, meet LINQ

  - by Roman Schindlauer

  Someone recently called LINQ “magic” in my hearing. I leapt to LINQ’s defense immediately. Turns out some people don’t realize “magic” is can be a pejorative term. I thought LINQ needed demystification. Here’s your best demystification resource: http://blogs.msdn.com/b/mattwar/archive/2008/11/18/linq-links.aspx. I won’t repeat much of what Matt Warren says in his excellent series, but will talk about some core ideas and how they affect the 2.1 release of StreamInsight. Let’s tell the story of a LINQ query. Compile time It begins with some code: IQueryable<Product> products = ...; var query = from p in products             where p.Name == "Widget"             select p.ProductID; foreach (int id in query) {     ... When the code is compiled, the C# compiler (among other things) de-sugars the query expression (see C# spec section 7.16): ... var query = products.Where(p => p.Name == "Widget").Select(p => p.ProductID); ... Overload resolution subsequently binds the Queryable.Where<Product> and Queryable.Select<Product, int> extension methods (see C# spec sections 7.5 and 7.6.5). After overload resolution, the compiler knows something interesting about the anonymous functions (lambda syntax) in the de-sugared code: they must be converted to expression trees, i.e.,“an object structure that represents the structure of the anonymous function itself” (see C# spec section 6.5). The conversion is equivalent to the following rewrite: ... var prm1 = Expression.Parameter(typeof(Product), "p"); var prm2 = Expression.Parameter(typeof(Product), "p"); var query = Queryable.Select<Product, int>(     Queryable.Where<Product>(         products,         Expression.Lambda<Func<Product, bool>>(Expression.Property(prm1, "Name"), prm1)),         Expression.Lambda<Func<Product, int>>(Expression.Property(prm2, "ProductID"), prm2)); ... If the “products” expression had type IEnumerable<Product>, the compiler would have chosen the Enumerable.Where and Enumerable.Select extension methods instead, in which case the anonymous functions would have been converted to delegates. At this point, we’ve reduced the LINQ query to familiar code that will compile in C# 2.0. (Note that I’m using C# snippets to illustrate transformations that occur in the compiler, not to suggest a viable compiler design!) Runtime When the above program is executed, the Queryable.Where method is invoked. It takes two arguments. The first is an IQueryable<> instance that exposes an Expression property and a Provider property. The second is an expression tree. The Queryable.Where method implementation looks something like this: public static IQueryable<T> Where<T>(this IQueryable<T> source, Expression<Func<T, bool>> predicate) {     return source.Provider.CreateQuery<T>(     Expression.Call(this method, source.Expression, Expression.Quote(predicate))); } Notice that the method is really just composing a new expression tree that calls itself with arguments derived from the source and predicate arguments. Also notice that the query object returned from the method is associated with the same provider as the source query. By invoking operator methods, we’re constructing an expression tree that describes a query. Interestingly, the compiler and operator methods are colluding to construct a query expression tree. The important takeaway is that expression trees are built in one of two ways: (1) by the compiler when it sees an anonymous function that needs to be converted to an expression tree, and; (2) by a query operator method that constructs a new queryable object with an expression tree rooted in a call to the operator method (self-referential). Next we hit the foreach block. At this point, the power of LINQ queries becomes apparent. The provider is able to determine how the query expression tree is evaluated! The code that began our story was intentionally vague about the definition of the “products” collection. Maybe it is a queryable in-memory collection of products: var products = new[]     { new Product { Name = "Widget", ProductID = 1 } }.AsQueryable(); The in-memory LINQ provider works by rewriting Queryable method calls to Enumerable method calls in the query expression tree. It then compiles the expression tree and evaluates it. It should be mentioned that the provider does not blindly rewrite all Queryable calls. It only rewrites a call when its arguments have been rewritten in a way that introduces a type mismatch, e.g. the first argument to Queryable.Where<Product> being rewritten as an expression of type IEnumerable<Product> from IQueryable<Product>. The type mismatch is triggered initially by a “leaf” expression like the one associated with the AsQueryable query: when the provider recognizes one of its own leaf expressions, it replaces the expression with the original IEnumerable<> constant expression. I like to think of this rewrite process as “type irritation” because the rewritten leaf expression is like a foreign body that triggers an immune response (further rewrites) in the tree. The technique ensures that only those portions of the expression tree constructed by a particular provider are rewritten by that provider: no type irritation, no rewrite. Let’s consider the behavior of an alternative LINQ provider. If “products” is a collection created by a LINQ to SQL provider: var products = new NorthwindDataContext().Products; the provider rewrites the expression tree as a SQL query that is then evaluated by your favorite RDBMS. The predicate may ultimately be evaluated using an index! In this example, the expression associated with the Products property is the “leaf” expression. StreamInsight 2.1 For the in-memory LINQ to Objects provider, a leaf is an in-memory collection. For LINQ to SQL, a leaf is a table or view. When defining a “process” in StreamInsight 2.1, what is a leaf? To StreamInsight a leaf is logic: an adapter, a sequence, or even a query targeting an entirely different LINQ provider! How do we represent the logic? Remember that a standing query may outlive the client that provisioned it. A reference to a sequence object in the client application is therefore not terribly useful. But if we instead represent the code constructing the sequence as an expression, we can host the sequence in the server: using (var server = Server.Connect(...)) {     var app = server.Applications["my application"];     var source = app.DefineObservable(() => Observable.Range(0, 10, Scheduler.NewThread));     var query = from i in source where i % 2 == 0 select i; } Example 1: defining a source and composing a query Let’s look in more detail at what’s happening in example 1. We first connect to the remote server and retrieve an existing app. Next, we define a simple Reactive sequence using the Observable.Range method. Notice that the call to the Range method is in the body of an anonymous function. This is important because it means the source sequence definition is in the form of an expression, rather than simply an opaque reference to an IObservable<int> object. The variation in Example 2 fails. Although it looks similar, the sequence is now a reference to an in-memory observable collection: var local = Observable.Range(0, 10, Scheduler.NewThread); var source = app.DefineObservable(() => local); // can’t serialize ‘local’! Example 2: error referencing unserializable local object The Define* methods support definitions of operator tree leaves that target the StreamInsight server. These methods all have the same basic structure. The definition argument is a lambda expression taking between 0 and 16 arguments and returning a source or sink. The method returns a proxy for the source or sink that can then be used for the usual style of LINQ query composition. The “define” methods exploit the compile-time C# feature that converts anonymous functions into translatable expression trees! Query composition exploits the runtime pattern that allows expression trees to be constructed by operators taking queryable and expression (Expression<>) arguments. The practical upshot: once you’ve Defined a source, you can compose LINQ queries in the familiar way using query expressions and operator combinators. Notably, queries can be composed using pull-sequences (LINQ to Objects IQueryable<> inputs), push sequences (Reactive IQbservable<> inputs), and temporal sequences (StreamInsight IQStreamable<> inputs). You can even construct processes that span these three domains using “bridge” method overloads (ToEnumerable, ToObservable and To*Streamable). Finally, the targeted rewrite via type irritation pattern is used to ensure that StreamInsight computations can leverage other LINQ providers as well. Consider the following example (this example depends on Interactive Extensions): var source = app.DefineEnumerable((int id) =>     EnumerableEx.Using(() =>         new NorthwindDataContext(), context =>             from p in context.Products             where p.ProductID == id             select p.ProductName)); Within the definition, StreamInsight has no reason to suspect that it ‘owns’ the Queryable.Where and Queryable.Select calls, and it can therefore defer to LINQ to SQL! Let’s use this source in the context of a StreamInsight process: var sink = app.DefineObserver(() => Observer.Create<string>(Console.WriteLine)); var query = from name in source(1).ToObservable()             where name == "Widget"             select name; using (query.Bind(sink).Run("process")) {     ... } When we run the binding, the source portion which filters on product ID and projects the product name is evaluated by SQL Server. Outside of the definition, responsibility for evaluation shifts to the StreamInsight server where we create a bridge to the Reactive Framework (using ToObservable) and evaluate an additional predicate. It’s incredibly easy to define computations that span multiple domains using these new features in StreamInsight 2.1! Regards, The StreamInsight Team

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