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• Classical task-scheduling assignment

  - by Bruno

  I am working on a flight scheduling app (disclaimer: it's for a college project, so no code answers, please). Please read this question w/ a quantum of attention before answering as it has a lot of peculiarities :( First, some terminology issues: You have planes and flights, and you have to pair them up. For simplicity's sake, we'll assume that a plane is free as soon as the flight using it prior lands. Flights are seen as tasks: They have a duration They have dependencies They have an expected date/time for beginning Planes can be seen as resources to be used by tasks (or flights, in our terminology). Flights have a specific type of plane needed. e.g. flight 200 needs a plane of type B. Planes obviously are of one and only one specific type, e.g., Plane Airforce One is of type C. A "project" is the set of all the flights by an airline in a given time period. The functionality required is: Finding the shortest possible duration for a said project The earliest and latest possible start for a task (flight) The critical tasks, with basis on provided data, complete with identifiers of preceding tasks. Automatically pair up flights and planes, so as to get all flights paired up with a plane. (Note: the duration of flights is fixed) Get a Gantt diagram with the projects scheduling, in which all flights begin as early as possible, showing all previously referred data graphically (dependencies, time info, etc.) So the questions is: How in the world do I achieve this? Particularly: We are required to use a graph. What do the graph's edges and nodes respectively symbolise? Are we required to discard tasks to achieve the critical tasks set? If you could also recommend some algorithms for us to look up, that'd be great.

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• Coordinate system problem with the grid control

  - by Jason94

  In my WPF application im trying to visualize some temperature data. I have a list of temperatures for the 7 past days and want to make a point to point line diagram. My problem is with the different koordinatesystems and adjusting data to the grid. XAML: <Grid Height="167" HorizontalAlignment="Left" Margin="6,6,0,0" Name="grid1" VerticalAlignment="Bottom" Width="455" /> C# (draft): http://pastebin.com/6UWkMFj1 scale is a global variable that changes with a slider (1-10). How to i correct my application so the line always is centered? As it is now it starts out centeded but if i crank up the slider to 3-4 the line goes up and above the applicationwindow. I also would like to use the full height of the grid window not just a small piece like images below: http://img32.imageshack.us/i/002wtvu.jpg/ http://img691.imageshack.us/i/001tqco.jpg/ As you can see i have worked out my data so day 1 with temperature 62 F is lower then day 2 with temperature of 76 F but i have scaling issues and placementissues... could somebody straighten out my math? :-)

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• Zend, slow load, "waiting for response" for 20-80 seconds on local site

  - by Tony C.

  So I have several sites running under the same zend setup. All of the sites run pretty normally except one. Upon loading or reloading this one site, reguardless of which page your on (excluding the 404 page explanation later...) you get a serious pause before any content begins to download. Using firebugs net panel you can see that the first request which is www.(siteaddress).com.local you see a "waiting for response" bar (purple) that is going for anywhere from 20 to sometimes 80+ seconds and this isn't on a dev site, this is on a local site under localhost. What I've managed to figure out so far is that all the pages do this except my 404 page. The reason the 404 page doesn't succumb to this is because it uses a seperate controller (the error controller) and therefore bypasses much of the controller and functions the other parts of the site use. Using exit statements I've manged to figure out that the problem happens somewhere between my post dispatch and my main (top most) controllers Init function. If i exit in the main controllers init the page loads (then exits instantly, no wait). If i do the same in the pre or post dispatch the page waits the 20-80 seconds then exits. Is there a diagram or explanation somewhere or a way for me to find out what events fire inbetween the post dispatch and the main controllers init function? Or does anyone have any clue what might cause this? Any help would be greatly appreciated...

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• What does the Kernel Virtual Memory of each process contain?

  - by claws

  When say 3 programs (executables) are loaded into memory the layout might look something like this: I've following questions: Is the concept of Virtual Memory limited to user processes? Because, I am wondering where does the Operating System Kernel, Drivers live? How is its memory layout? I know its operating system specific make your choice (windows/linux). They say, on a 32 bit machine in a 4GB address space. Half of it (or more recently 1GB) is occupied by kernel. I can see in this diagram that "Kernel Virtual memory" is occupying 0xc0000000 - 0xffffffff (= 1 GB). Are they talking about this? or is it something else? Just want to confirm. What exactly does the Kernel Virtual Memory of each of these processes contain? What is its layout? When we do IPC we talk about shared memory. I don't see any memory shared between these processes. Where does it live? Resources (files, registries in windows) are global to all processes. So, the resource/file handle table must be in some global space. Which area would that be in? Where can I know more about this kernel side stuff.

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• Running Sitecore Production Site under a Virtual Directory

  - by danswain

  We are using Sitecore 6 on a Windows Server 2003 (32bit) dev machine. I know it's not recommended for the CMS editing site, but we've been told it is possible to get the front-end Sitecore websites to run from within a virtual directory. Here's the issue: we'd like to achieve what the below poor mans diagram shows. We have a website (.net 1.1) /WebSiteRoot (.net 1.1) | | |---- Custom .net 1.1 Web Application | |---- SiteCore frontend WebApplication (.net 2.0) | |---- Custom .net 2.0 WebApplication The Sitecore webApplication would contain the Sitecore pipeline in its web.config and we'd make use of the section to configure the virtual folder to allow for where our Sitecore app sits and point it to the appropriate place in the Content Tree. Is it possible to pull this off? This is just the customer facing website, there will be no CMS editing functionality on these servers, that will be done from a more standard Sitecore install inside the firewall on a different server. The errors we're encountering are centered around loading the the various config files in the App_Config folder. It seems to do a Server.MapPath on "/" initially (which is wrong for us) so we've tried putting absolute paths in the web.config and still no joy (I think there must be some hardcoded piece that looks for the Include directory). Any help would be greatly appreciated. Thanks

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• What is the "right" way to make a modular ASP.NET page?

  - by Wayne Werner

  Hi, I'm writing an internal program using ASP.NET (Visual Studio 2008). The basic premise is that folks will connect to the page through their web browser, put in some data (which will be validated and sanitized of course), click "submit" and then a query will be run on a database. I told you that story so I can tell you this story - I want to make my program modular for the likelihood that this program will be updated later on, and probably extended. My initial thought is to compile the database handler as a dll and then use its functionality on my page (see my little diagram). But I can't figure out how to hook the dll into my page - My Google-fu has failed which leads me to my questions: 1) Is creating a dll the "right" solution? If so, continue to question 2, if not, what should I be doing? Any resources/tutorial links would be appreciated. 2) How do I attach a dll? Visual Studio tells me I can't Imports from an .aspx page, and I've tried <%@ Import namespace="MyDllName" % and a few other variations, none of which worked. Thanks!

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• how are association, aggregation and composition written?

  - by ajsie

  i have read some posts about the differences between these 3 relationships and i think i get the point. i just wonder, are all these written the same when coding? question 1: all 3 are just a value of the object type in a instance variable? class A { public $b = '' public function __construct($object) { $this->b = $object // <-- could be a association, aggregation or a composition relation? } } question 2: does it have to be an instance variable or can it be a static one? class A { public static $b = '' // <-- nothing changed? public function __construct($object) { $this->b = $object } } question 3: is there a difference in where the object is created? i tend to think that composition object is created inside the object: class A { public $b = '' public function __construct() { $this->b = new Object // is created inside the object } } and aggregation/association is passed through a constructor or another method: class A { public $b = '' public function __construct($object) { // passed through a method $this->b = $object } } question 4: why/when is this important to know. do i have to comment an object inside another what relation its about or do you do it in an UML diagram? could someone shed a light on these questions. thanks!

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• Howto display or view encrypted data in encrypted form?

  - by Brian Gianforcaro

  In the Wikipedia Article on Block Cipher Modes they have a neat little diagram of an unencrypted image, the same image encrypted using ECB mode and another version of the same image encrypted using another method. At university I have developed my own implementation of DES (you can find it here) and we must demo our implementation in a presentation. I would like to display a similar example as shown above using our implementation. However most image files have header blocks associated with them, which when encrypting the file with our implementation, also get encrypted. So when you go to open them in an image viewer, they are assumed to be corrupted and can't be viewed. I was wondering if anybody new of a simple header-less image format which we could use to display these? Or if anyone had any idea's as to how the original creator of the images above achieved the above result? Any help would be appreciated, Thanks Note: I realise rolling your own cryptography library is stupid, and DES is considered broken, and ECB mode is very flawed for any useful cryptography, this was purely an academic exercise for school. So please, no lectures, I know the drill.

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• Looking for home networking hardware and software advice

  - by phobos7

  Note: I originally wrote this up in a blog post. I've removed any affiliate links that I put in my original post to ensure I don't annoy anybody. I've recently moved home and I now need to go to the trouble of sorting out my home network yet again. We had Virgin broadband in Hertford but you can't get Virgin in the street we've moved to so I've had to go with O2 Broadband. Normally I prefer to use my own hardward, and previously used the DLink DIR-655 router which was great, but in this situation I am using the O2 Wirelss Box III since I only have an old Netgear DG834PN Wireless G modem router and I'd rather be using Wireless N. Anyway, the place we have moved into has only one phone point in the hallway, has the best TV point in one room and the best place to put the TV and other entertainment stuff in yet another room. So, networking the house up for Internet and TV is required. The diagram below shows the things that I'll have in my home network but there are three points where I'm not quite sure what hardware to us. Wireless Access Point/Bridge, that acts only as a wireless to wire bridge and not an AP, that links up a Media Centre/PC and a couple of consoles to the network. I'm pretty much settled on us an Acer Aspire Revo R3600 as my media PC, probably with Ubuntu or Windows and XBMC installed. Wireless Access Point/Bridge, that acts only as a wireless to wire bridge and not an AP, that links up a device that can decode and stream TV from a TV aerial across the network. The device that is connected to 2). At the moment I'm considering a HDHomeRun by SiliconDust. At the moment I'm considering either the TP LINK TL-WA701ND 150Mbps Wireless Lite N Access Point (very cheap at Amazon) or the Netgear 5 GHz Wireless-N HD Access Point/Bridge. I'd love to get some insight into what you would do in my situation. What Wireless Access Point/Bridge should I put at points 1) and 2)? What device should I choose for point 3) that can decode and stream a TV signal? Is the Acer Aspire Revo R3600 a good choice? ![alt text][6] Note 2: I've also posted this question on AVForums.

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• VPN iptables Forwarding: Net-to-net

  - by Mike Holler

  I've tried to look elsewhere on this site but I couldn't find anything matching this problem. Right now I have an ipsec tunnel open between our local network and a remote network. Currently, the local box running Openswan ipsec with the tunnel open can ping the remote ipsec box and any of the other computers in the remote network. When logged into on of the remote computers, I can ping any box in our local network. That's what works, this is what doesn't: I can't ping any of the remote computers via a local machine that is not the ipsec box. Here's a diagram of our network: [local ipsec box] ----------\ \ [arbitrary local computer] --[local gateway/router] -- [internet] -- [remote ipsec box] -- [arbitrary remote computer] The local ipsec box and the arbitrary local computer have no direct contact, instead they communicate through the gateway/router. The router has been set up to forward requests from local computers for the remote subnet to the ipsec box. This works. The problem is the ipsec box doesn't forward anything. Whenever an arbitrary local computer pings something on the remote subnet, this is the response: [user@localhost ~]# ping 172.16.53.12 PING 172.16.53.12 (172.16.53.12) 56(84) bytes of data. From 10.31.14.16 icmp_seq=1 Destination Host Prohibited From 10.31.14.16 icmp_seq=2 Destination Host Prohibited From 10.31.14.16 icmp_seq=3 Destination Host Prohibited Here's the traceroute: [root@localhost ~]# traceroute 172.16.53.12 traceroute to 172.16.53.12 (172.16.53.12), 30 hops max, 60 byte packets 1 router.address.net (10.31.14.1) 0.374 ms 0.566 ms 0.651 ms 2 10.31.14.16 (10.31.14.16) 2.068 ms 2.081 ms 2.100 ms 3 10.31.14.16 (10.31.14.16) 2.132 ms !X 2.272 ms !X 2.312 ms !X That's the IP for our ipsec box it's reaching, but it's not being forwarded. On the IPSec box I have enabled IP Forwarding in /etc/sysctl.conf net.ipv4.ip_forward = 1 And I have tried to set up IPTables to forward: *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [759:71213] -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -A INPUT -p icmp -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT -A INPUT -p tcp -m state --state NEW -m tcp --dport 25 -j ACCEPT -A INPUT -p udp -m state --state NEW -m udp --dport 500 -j ACCEPT -A INPUT -p udp -m state --state NEW -m udp --dport 4500 -j ACCEPT -A INPUT -m policy --dir in --pol ipsec -j ACCEPT -A INPUT -p esp -j ACCEPT -A INPUT -j REJECT --reject-with icmp-host-prohibited -A FORWARD -s 10.31.14.0/24 -d 172.16.53.0/24 -j ACCEPT -A FORWARD -m policy --dir in --pol ipsec -j ACCEPT -A FORWARD -j REJECT --reject-with icmp-host-prohibited COMMIT Am I missing a rule in IPTables? Is there something I forgot? NOTE: All the machines are running CentOS 6.x Edit: Note 2: eth1 is the only network interface on the local ipsec box.

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• Configuring VLAN's on two HP procurve switches

  - by pan

  Trying to route a new ISP (Microwave link) from one of my out buildings to my computer room and hence my firewall. Old ISP came direct into firewall. In the outbuilding the Microwave modem connects with cat5 to HP Procurve 2524 switch. Because this ISP is coming through my internal network, I plan on using a new vlan called "airspeed" only for this ISP traffic. Up until now I've just been using the Default_vlan on both HP switches (4108 + 2524). So far I've been unable to ping from my laptop to the ISP modem both of which are on the new vlan 2 ("Airspeed"). No traffic needs to cross from vlan 2 to vlan 1 so I've left the ports as untagged. I've used the subnet provide from my ISP as the new vlan 2 subnet. Can anybody see what I'm doing wrong here? I've added the configuration of both switch below. Rough diagram: Microwave modem (Gateway IP 77.75.00.49) | HP 2524 switch (port 24) | HP 2524 switch fibre link | HP 4108GL switch fibre link | HP 4108GL switch (port D1) | Laptop configured with IP 77.75.00.50 (for testing but will be connected to firewall) And my 4108GL config: ; J4865A Configuration Editor; Created on release #G.07.21 hostname "HP ProCurve Switch 4108GL" cdp run module 1 type J4864A module 2 type J4862B module 3 type J4862B module 4 type J4862B ip default-gateway 128.1.146.50 snmp-server community "public" Unrestricted snmp-server host 128.1.146.51 "public" Not-INFO snmp-server host 128.1.146.38 "public" vlan 1 name "DEFAULT_VLAN" untagged A1-A3,B1-B24,C1-C24,D2-D24 ip address 128.1.146.203 255.255.0.0 no untagged D1 exit vlan 2 name "Airspeed" untagged D1 ip address 77.75.00.51 255.255.255.248 exit Finally my 2524 config: ; J4813A Configuration Editor; Created on release #F.04.08 hostname "HP ProCurve Switch 2524" cdp run ip default-gateway 0.0.0.0 snmp-server community "public" Unrestricted snmp-server host 128.1.146.51 "public" Not-INFO snmp-server host 128.1.146.51 "public" snmp-server host 128.1.146.38 "public" vlan 1 name "DEFAULT_VLAN" untagged 1-23,25-26 no untagged 24 ip address 128.1.146.204 255.255.0.0 exit vlan 2 name "Airspeed" untagged 24 ip address 77.75.00.51 255.255.255.248 exit no aaa port-access authenticator active

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• Does a router have a receiving range?

  - by Aadit M Shah

  So my dad bought a TP-Link router (Model No. TL-WA7510N) which apparently has a transmitting range of 1km; and he believes that it also has a receiving range of 1km. So he's arguing with me that the router (which is a trans-receiver) can communicate with any device in the range of 1km whether or not that device has a transmitting range of 1km. To put it graphically: +----+ 1km +----+ | |------------------------------------------------->| | | TR | | TR | | | <----| | +----+ 100m+----+ So here's the problem: The two devices are 1km apart. The first device has a transmitting range of 1km. The second device only has a transmitting range of 100m. According to my dad the two devices can talk to each other. He says that the first device has a transmitting and a receiving range of 1km which means that it can both send data to devices 1km away and receive data from devices 1km away. To me this makes no sense. If the second device can only send data to devices 100m away then how can the first device catch the transmission? He further argues that for bidirectional communication both the sender and the reciver should have overlapping areas of transmission: According to him if two devices have an overlapping area of transmission then they can communicate. Here neither device has enough transmission power to reach the other. However they have enough receiving power to capture the transmission. Obviously this makes absolutely no sense to me. How can a device sense a transmission which hasn't even reached it yet and go out, capture it and bring it back it. To me a trans-receiver only has a transmission power. It has zero receiving power. Hence for two devices to be able to communicate bidirectionally, the diagram should look like: Hence, from my point of view, both the devices should have a transmission range far enough to reach the other for bidirectional communication to be possible; but no matter how much I try to explain to my dad he adamantly disagrees. So, to put an end to this debate once and for all, who is correct? Is there even such a thing as a receiving range? Can a device fetch a transmission that would otherwise never reach it? I would like a canonical answer on this.

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• Forwarding RDP via a Linux machine using iptables: Not working

  - by Nimmy Lebby

  I have a Linux machine and a Windows machine behind a router that implements NAT (the diagram might be overkill, but was fun to make): I am forwarding RDP port (3389) on the router to the Linux machine because I want to audit RDP connections. For the Linux machine to forward RDP traffic, I wrote these iptables rules: iptables -t nat -A PREROUTING -p tcp --dport 3389 -j DNAT --to-destination win-box iptables -A FORWARD -p tcp --dport 3389 -j ACCEPT The port is listening on the Windows machine: C:\Users\nimmy>netstat -a Active Connections Proto Local Address Foreign Address State (..snip..) TCP 0.0.0.0:3389 WIN-BOX:0 LISTENING (..snip..) And the port is forwarding on the Linux machine: # tcpdump port 3389 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 01:33:11.451663 IP shieldsup.grc.com.56387 > linux-box.myapt.lan.ms-wbt-server: Flags [S], seq 94663035, win 8192, options [mss 1460], length 0 01:33:11.451846 IP shieldsup.grc.com.56387 > win-box.myapt.lan.ms-wbt-server: Flags [S], seq 94663035, win 8192, options [mss 1460], length 0 However, I am not getting any successful RDP connections from the outside. The port is not even responding: C:\Users\outside-nimmy>telnet example.com 3389 Connecting To example.com...Could not open connection to the host, on port 3389: Connect failed Any ideas? Update Per @Zhiqiang Ma, I looked at nf_conntrack proc file during a connection attempt and this is what I see (192.168.3.1 = linux-box, 192.168.3.5 = win-box): # cat /proc/net/nf_conntrack | grep 3389 ipv4 2 tcp 6 118 SYN_SENT src=4.79.142.206 dst=192.168.3.1 sport=43142 dport=3389 packets=6 bytes=264 [UNREPLIED] src=192.168.3.5 dst=4.79.142.206 sport=3389 dport=43142 packets=0 bytes=0 mark=0 secmark=0 zone=0 use=2 2nd update Got tcpdump on the router and it seems that win-box is sending an RST packet: 21:20:24.767792 IP shieldsup.grc.com.45349 > linux-box.myapt.lan.3389: S 19088743:19088743(0) win 8192 <mss 1460> 21:20:24.768038 IP shieldsup.grc.com.45349 > win-box.myapt.lan.3389: S 19088743:19088743(0) win 8192 <mss 1460> 21:20:24.770674 IP win-box.myapt.lan.3389 > shieldsup.grc.com.45349: R 721745706:721745706(0) ack 755785049 win 0 Why would Windows be doing this?

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• High I/O latency with software RAID, LUKS encrypted and LVM partitioned KVM setup

  - by aef

  I found out a performance problems with a Mumble server, which I described in a previous question are caused by an I/O latency problem of unknown origin. As I have no idea what is causing this and how to further debug it, I'm asking for your ideas on the topic. I'm running a Hetzner EX4S root server as KVM hypervisor. The server is running Debian Wheezy Beta 4 and KVM virtualisation is utilized through LibVirt. The server has two different 3TB hard drives as one of the hard drives was replaced after S.M.A.R.T. errors were reported. The first hard disk is a Seagate Barracuda XT ST33000651AS (512 bytes logical, 4096 bytes physical sector size), the other one a Seagate Barracuda 7200.14 (AF) ST3000DM001-9YN166 (512 bytes logical and physical sector size). There are two Linux software RAID1 devices. One for the unencrypted boot partition and one as container for the encrypted rest, using both hard drives. Inside the latter RAID device lies an AES encrypted LUKS container. Inside the LUKS container there is a LVM physical volume. The hypervisor's VFS is split on three logical volumes on the described LVM physical volume: one for /, one for /home and one for swap. Here is a diagram of the block device configuration stack: sda (Physical HDD) - md0 (RAID1) - md1 (RAID1) sdb (Physical HDD) - md0 (RAID1) - md1 (RAID1) md0 (Boot RAID) - ext4 (/boot) md1 (Data RAID) - LUKS container - LVM Physical volume - LVM volume hypervisor-root - LVM volume hypervisor-home - LVM volume hypervisor-swap - … (Virtual machine volumes) The guest systems (virtual machines) are mostly running Debian Wheezy Beta 4 too. We have one additional Ubuntu Precise instance. They get their block devices from the LVM physical volume, too. The volumes are accessed through Virtio drivers in native writethrough mode. The IO scheduler (elevator) on both the hypervisor and the guest system is set to deadline instead of the default cfs as that happened to be the most performant setup according to our bonnie++ test series. The I/O latency problem is experienced not only inside the guest systems but is also affecting services running on the hypervisor system itself. The setup seems complex, but I'm sure that not the basic structure causes the latency problems, as my previous server ran four years with almost the same basic setup, without any of the performance problems. On the old setup the following things were different: Debian Lenny was the OS for both hypervisor and almost all guests Xen software virtualisation (therefore no Virtio, also) no LibVirt management Different hard drives, each 1.5TB in size (one of them was a Seagate Barracuda 7200.11 ST31500341AS, the other one I can't tell anymore) We had no IPv6 connectivity Neither in the hypervisor nor in guests we had noticable I/O latency problems According the the datasheets, the current hard drives and the one of the old machine have an average latency of 4.12ms.

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• Automatic layout of manual network mapping

  - by Paul

  So I have a small business network mainly consisting of two routed layer-2 domains with a total of ca. 100 devices spread over ca. 2000m² production and office spaces. Typical problems to solve using the graph would be: Over what (cable) path is a PC connected to the server? Where to expect devices connected to a switch port? I want to generate a graph of the physical network topology: Nodes are endpoint devices, switch ports, wall outlets, patch panel ports etc. Edges are cable connections. Ideally, grouping edges (or segments) that pass through the same bundle could be grouped. Also I would like to augment the graph data with automatically gathered data (monitoring state, MAC address, Switch port <- MAC entries to build up parts of the map). At the moment I use graphviz for this inside a Confluence wiki like that: layout = "neato" overlap = scale subgraph { rankdir = "TB" subgraph cluster_r1pf1 { r1pf1 [label="{ Rack 1 PF 1 | { <p1>P1 | <p2>P2 | <p3>P3} }", shape=record] } subgraph cluster_switch1 { switch1 [label="{ Rack 1 Switch 1 | { <p1> P1 | <p1> P1 | <p3> P3} }", shape=record] } r1pf1:p1 -> switch1:p1 (obviously there are dozens of entries omitted here) Problem is: I have a hard time to influence graphviz to generate a bearable layout. Edges overlap so bad that you can't read the diagram anymore. The question is: What other tools (be it interactive like Visio, Omnigraffle or I/O-oriented like graphviz) exist that would allow an easily versionable (as in: Operates on a text file) documentation that is both machine and human readable and editable? Why not OmniGraffle or Visio? Well we don't have Macs and Visio is not available at the moment. To buy it I would need good arguments. Automation would be one of that. But last time I looked, versioning Visio files or even thinking about automatic handling was a nightmare. Related: Network Mapping Tools basically asks the same with a focus on generating the complete graph automatically (but without the need to document cabling connections) Recommendations for automatic computer inventory brings up links of "all-in-one" solutions

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• Building an SSL server farm

  - by dan

  I'm interested in building the the architecture in the article referenced below. I currently have a modestly-priced layer-4 load balancer and my application servers are the SSL endpoints. I want to put an SSL server farm in between my load balancer and my app servers. Then I will put another inexpensive load balancer between the SSL farm and my app servers, to do layer-7 routing. My web application has a fairly high amount of consumer traffic, that 6 servers can handle at about 50% capacity. Additionally, I have infrastructure traffic that is several orders of magnitude heavier than my consumer traffic. This is data coming in from all over the world that must integrate with my web application in real time. In total I have 18 app servers to handle all the traffic, plus 6 database servers. I will be adding 6 more app servers over the next 2 weeks and another 6 the 2 weeks after that. Conservatively, I estimate I will need to scale to 120 servers by the end of the year. My motivation right now is to separate the consumer traffic from the infrastructure traffic. The consumer traffic is higher priority than the infrastructure traffic and I cannot allow a stampede on the infrastructure side to take down my consumer-facing servers. Having a website that is always up is the top priority. However if there is a failure in one of the consumer app servers, I want to route that traffic to the servers designated for infrastructure traffic. The complication is that all the traffic is addressed using the same hostname and is nearly 100% https. The only way in my case to distinguish infrastructure from consumer traffic is by URL (poor architecture I inherited), so I need a layer 7 load balancer to be able to route. However for that to work I need either a fancy hardware-based SSL terminator or an SSL server farm as described above. Because my user base is rapidly scaling, I worry that if I go down the hardware path it will become very expensive very fast, especially since I will need 4 of everything for high availability (2 identical setups in 2 facilities). Meanwhile, the above diagram seems very flexible and more horizontally scalable. Has anyone built this before? Are there pre-built configurations? What considerations should I make and what software should I use (I've heard of people using apache with mod-ssl, nginx, and stunnel)? Also, when does it make sense to buy an expensive load balancer vs building an SSL server farm? http://1wt.eu/articles/2006_lb/index_05.html

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• What are the most likely bottlenecks determining the performance of CamStudio screen recording?

  - by Steve314

  When doing screen recording, I can get a frame rate of maybe 15 frames per second for the full screen on my 1080p monitor using the XVID codec. I can increase the speed a bit by recording a region, changing screen modes, and tweaking other settings, but I'm curious what hardware upgrades might give me the biggest bang for my buck. My PC is budget, but modern... Athlon 2 X4 645 (3.1GHz, quad core, limited cache) processor. 4GB single channel DDR3 1066 RAM. ASRock motherboard with NVidia GeForce 7025/nForce 630a Chipset. ATI Radeon HD 5450 graphics card - 512MB on board, not configured to steal system RAM. I dual-boot Windows XP and Windows 7. For the moment, XP is my bigger performance concern as it's still my getting-things-done O/S as opposed to my browser-host O/S. My goal is to make a few programming-related tutorials. For a lot of that I don't need screen recording - I can make up some slides, record audio with the PC switched off, yada yada. When I do need screen recording, I'll mostly be recording Notepad++, Visual Studio or a command prompt. Occasionally, I may be recording some kind of graphics or diagram program and using my pre-Bamboo cheap Wacom tablet - I have the CS2 versions of Photoshop and Illustrator, but I'd much more likely be using Microsoft Paint. Basically, what I'll be recording won't be making huge demands on the machine - but recording a fair number of pixels (720p preferred) will be useful. What's particularly wierd - not so long ago I still had a five-year-old Pentium 4 based PC. And (with the same 1080p monitor) it could record at not far from the same frame rate. So clearly the performance issues are more subtle than just throw-money-at-it. My first guess would be that the main bottleneck is the bandwidth for transferring data to/from the graphics card. Is that likely to be correct? In support of that, see this [Radeon HD 5450 review][1] - the memory bandwidth is only 12.8 GB/s. If you can't get data out of graphics memory quickly, you can't transfer it back to the system memory quickly. Apparently, that's slower than some top-end cards in 2002.

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• Enterprise IPv6 Migration - End of proxypac ? Start of Point-to-Point ? +10K users

  - by Yohann

  Let's start with a diagram : We can see a "typical" IPv4 company network with : An Internet acces through a proxy An "Others companys" access through an dedicated proxy A direct access to local resources All computers have a proxy.pac file that indicates which proxy to use or whether to connect directly. Computers have access to just a local DNS (no name resolution for google.com for example.) By the way ... The company does not respect the RFC1918 internally and uses public addresses! (historical reason). The use of internet proxy explicitly makes it possible to not to have problem. What if we would migrate to IPv6? Step 1 : IPv6 internet access Internet access in IPv6 is easy. Indeed, just connect the proxy in Internet IPv4 and IPv6. There is nothing to do in internal network : Step 2 : IPv6 AND IPv4 in internal network And why not full IPv6 network directly? Because there is always the old servers that are not compatible IPv6 .. Option 1 : Same architecture as in IPv4 with a proxy pac This is probably the easiest solution. But is this the best? I think the transition to IPv6 is an opportunity not to bother with this proxy pac! Option 2 : New architecture with transparent proxy, whithout proxypac, recursive DNS Oh yes! In this new architecture, we have: Explicit Internet Proxy becomes a Transparent Internet Proxy Local DNS becomes a Normal Recursive DNS + authorative for local domains No proxypac Explicit Company Proxy becomes a Transparent Company Proxy Routing Internal Routers reditect IP of appx.ext.example.com to Company Proxy. The default gateway is the Transparent Internet proxy. Questions What do you think of this architecture IPv6? This architecture will reveal the IP addresses of our internal network but it is protected by firewalls. Is this a real big problem? Should we keep the explicit use of a proxy? -How would you make for this migration scenario? -And you, how do you do in your company? Thanks! Feel free to edit my post to make it better.

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• Bridging and iptables SNAT conflict

  - by sad_admin

  Hello I am working on a setup here and have it working with one minor exception. Devices on one side of my bridge aren't getting SNAT'd to the Internet. The Diagram / Overview: Primary_Network (Site_A) | | Internet ------- Linux_Bridge_GW (GW) | | Secondary/CoLo Site (Site_B) Here is the setup: 1.) Site_A has all the production servers and workstations. 2.) Site_B has a set of servers that we would like to fail-over to and also serve our internet facing services from. 3.) GW has two interfaces that are trunked and carrying the appropriate VLAN traffic (allow layer-2 propagation of traffic between sites) //this all works perfectly fine. 4.) The problem that is being encountered is, hosts from Site_B have their default GW at Site_A (same subnet) GW does not have IPs on the VLANs that are being passed. 5.) All hosts at Site_A can reach the Internet without problem. 6.) GW has an addresses on a subnet that is ONLY for Internet destined traffic. (This was done so that Websense would not have to parse unnecessary traffic. We use this VLAN as the monitor port's source on the switch where Websense is sitting). What I think is happening: 1.) Packet/Frame comes in on physdev at Site_B destined for Internet. 2.) Kernel sees packet, and forwards it out the other side of the bridge to that host's default GW. 3.) Site_A (containing core-network's Default-GW) sees that packet is destined for a host it doesn't know about, so it sends it to it's default GW (the linux bridge, since it's Internet bound). 4.) The kernel says "Hey, I've seen you before" and therefore doesn't do SNAT'ing on the packet and sends it out to the Internet where it's black-holed. Why I think it's happening: 1.) A tcpdump on the internet facing NIC shows the packet leaving the interface with the private address as it's source. What I would like: 1.) Have the packet SNAT'd. 2.) Something like the below would be awesome a.) packet comes in from Site_B b.) kernel sees that the packet is NOT destined for itself or any private address c.) kernel says "OK, well since you're destined for the Internet I'm going to send you out this interface rather than forward you to your normal default GW that's WAAAY over there." d.) packet comes in from internet and is sent out the appropriate bridge physdev depending on which site the host it's destined for is at. Thanks for any assistance or guidance that you are willing to offer. Best Regards, Sad Admin

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• is it a good idea to change a recovery partition from primary to logical? [HP laptop]

  - by DiegoDD

  I have a new HP laptop, model dv6-6c85la, with 1TB hard drive, and it has 4 primary partitions, like this: |<- system [199 MB] -|<- c: [899.8 GB] -|<- d:(recovery) [27.5 GB] -|<- e:(hp_tools) [4 GB] -| I wanted to make another partition, splitting "C" which is the main partition, into TWO partitions, and leave the rest as it is. but it doesn't let me because they are already 4 primary partitions (the ones in the diagram). I read somewhere, that i could in fact split C into 2 partitions, but only if the adjacent partition (in this case d:(recovery) is converted into a "logical" partition. That way, the new unallocated part taken from C, and the recovery partition, would each be logical, "inside" an extended partition (right???) As i understand, the resulting partitions would be: primary (system, no letter), primary (c:), extended [ logical (x:) | logical(d:recovery) ], primary (e: hp_tools) "x" being the new one. am i correct? My question is, if i do convert the recovery partition to logical (and thus, it is inside an extended partition adjacent to the new "x:" one), would i have any problems when in case of a disaster i would like to restore the system using the now logical instead of primary RECOVERY partition? Or it is completely safe to change it to logical? My main concern is because i think i may need to be primary so the recovery can proceed in boot time? Or i am completely wrong? how does the recovery process happens? I also understand that i can simply create recovery media, in DVDs, and then even i would be able to delete that recovery partition completely, but as of now, i don't want to do that. I may create the disks, but i don't want to delete the partition, simply because it would be a lot faster and easier to recover from a hard drive than disks. Wrapping up: if i change a recovery partition from primary to logical, will the system still be capable of using it to recover? or it NEEDS to be primary to work? The whole point is that i want to split C:, but as things are, i cant directly, i'd need to change the recovery partition to logical. Or is there another way? thanks.

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• Eine komplette Virtualisierungslandschaft auf dem eigenen Laptop – So geht’s

  - by Manuel Hossfeld

  Eine komplette Virtualisierungslandschaftauf dem eigenen Laptop – So geht’s Wenn man sich mit dem Virtualisierungsprodukt Oracle VM in der aktuellen Version 3.x näher befassen möchte, bietet es sich natürlich an, eine eigene Umgebung zu Lern- und Testzwecken zu installieren. Doch leichter gesagt als getan: Bei näherer Betrachtung der Architektur wird man schnell feststellen, dass mehrere Rechner benötigt werden, um überhaupt alle Komponenten abbilden zu können: Zum einen gilt es, den oder die OVM Server selbst zu installieren. Das ist recht leicht und schnell erledigt, aber da Oracle VM ein „Typ 1 Hypervisor ist“ - also direkt auf dem Rechner („bare metal“) installiert wird – ist der eigenen Arbeits-PC oder Laptop dafür recht ungeeignet. (Eine Dual-Boot Umgebung wäre zwar denkbar, aber recht unpraktisch.) Zum anderen wird auch ein Rechner benötigt, auf dem der OVM Manager installiert wird. Im Gegensatz zum OVM Server erfolgt dessen Installation nicht „bare metal“, sondern auf einem bestehenden Oracle Linux. Aber was tun, wenn man gerade keinen Linux-Server griffbereit hat und auch keine extra Hardware dafür opfern will? Möchte man alle Funktionen von Oracle VM austesten, so sollte man zusätzlich über einen Shared Storag everüfugen. Dieser kann wahlweise über NFS oder über ein SAN (per iSCSI oder FibreChannel) angebunden werden. Zwar braucht man zum Testen nicht zwingend entsprechende „echte“ Storage-Hardware, aber auch die „Simulation“ entsprechender Komponenten erfordert zusätzliche Hardware mit entsprechendem freien Plattenplatz.(Alternativ können auch fertige „Software Storage Appliances“ wie z.B. OpenFiler oder FreeNAS verwendet werden). Angenommen, es stehen tatsächlich keine „echte“ Server- und Storage Hardware zur Verfügung, so benötigt man für die oben genannten drei Punkte  drei bzw. vier Rechner (PCs, Laptops...) - je nachdem ob man einen oder zwei OVM Server starten möchte. Erfreulicherweise geht es aber auch mit deutlich weniger Aufwand: Wie bereits kurz im Blogpost anlässlich des letzten OVM-Releases 3.1.1 beschrieben, ist die aktuelle Version in der Lage, selbst vollständig innerhalb von VirtualBox als Gast zu laufen. Wer bei dieser „doppelten Virtualisierung“ nun an das Prinzip der russischen Matroschka-Puppen denkt, liegt genau richtig. Oracle VM VirtualBox stellt dabei gewissermaßen die äußere Hülle dar – und da es sich bei VirtualBox im Gegensatz zu Oracle VM Server um einen „Typ 2 Hypervisor“ handelt, funktioniert dieser Ansatz auch auf einem „normalen“ Arbeits-PC bzw. Laptop, ohne dessen eigentliche Betriebsystem komplett zu überschreiben. Doch das beste dabei ist: Die Installation der jeweiligen VirtualBox VMs muss man nicht selber durchführen. Der OVM Manager als auch der OVM Server stehen bereits als vorgefertigte „VirtualBox Appliances“ im Oracle Technology Network zum Download zur Verfügung und müssen im Grunde nur noch importiert und konfiguriert werden. Das folgende Schaubild verdeutlicht das Prinzip: Die dunkelgrünen Bereiche stellen jeweils Instanzen der eben erwähnten VirtualBox Appliances für OVM Server und OVM Manager dar. (Hier im Bild sind zwei OVM Server zu sehen, als Minimum würde natürlich auch einer genügen. Dann können aber viele Features wie z.B. OVM HA nicht ausprobieren werden.) Als cleveren Trick zur Einsparung einer weiteren VM für Storage-Zwecke hat Wim Coekaerts (Senior Vice President of Linux and Virtualization Engineering bei Oracle), der „Erbauer“ der VirtualBox Appliances, die OVM Manager Appliance bereits so vorbereitet, dass diese gleichzeitig als NFS-Share (oder ggf. sogar als iSCSI Target) dienen kann. Dies beschreibt er auch kurz auf seinem Blog. Die hellgrünen Ovale stellen die VMs dar, welche dann innerhalb einer der virtualisierten OVM Server laufen können. Aufgrund der Tatsache, dass durch diese „doppelte Virtualisierung“ die Fähigkeit zur Hardware-Virtualisierung verloren geht, können diese „Nutz-VMs“ demzufolge nur paravirtualisiert sein (PVM). Die hier in blau eingezeichneten Netzwerk-Schnittstellen sind virtuelle Interfaces, welche beliebig innerhalb von VirtualBox eingerichtet werden können. Wer die verschiedenen Netzwerk-Rollen innerhalb von Oracle VM im Detail ausprobieren will, kann hier natürlich auch mehr als zwei dieser Interfaces konfigurieren. Die Vorteile dieser Lösung für Test- und Demozwecke liegen auf der Hand: Mit lediglich einem PC bzw. Laptop auf dem VirtualBox installiert ist, können alle oben genannten Komponenten installiert und genutzt werden – genügend RAM vorausgesetzt. Als Minimum darf hier 8GB gelten. Soll auf der „Host-Umgebung“ (also dem PC auf dem VirtualBox läuft) nebenbei noch gearbeiten werden und/oder mehrere „Nutz-VMs“ in dieser simulierten OVM-Server-Umgebung laufen, empfehlen sich natürlich eher 16GB oder mehr. Da die nötigen Schritte zum Installieren und initialen Konfigurieren der Umgebung ausführlich in einem entsprechenden Paper beschrieben sind, möchte ich im Rest dieses Artikels noch einige zusätzliche Tipps und Details erwähnen, welche einem das Leben etwas leichter machen können: Um möglichst entstpannt und mit zusätzlichen „Sicherheitsnetz“ an die Konfiguration der Umgebung herangehen zu können, empfiehlt es sich, ausgiebigen Gebrauch von der in VirtualBox eingebauten Funktionalität der VM Snapshots zu machen. Dies ermöglicht nicht nur ein Zurücksetzen falls einmal etwas schiefgehen sollte, sondern auch ein beliebiges Wiederholen von bereits absolvierten Teilschritten (z.B. um eine andere Idee oder Variante der Umgebung auszuprobieren). Sowohl bei den gerade erwähnten Snapshots als auch bei den VMs selbst sollte man aussagekräftige Namen verwenden. So ist sichergestellt, dass man nicht durcheinander kommt und auch nach ein paar Wochen noch weiß, welche Umgebung man da eigentlich vor sich hat. Dies beinhaltet auch die genaue Versions- und Buildnr. des jeweiligen OVM-Releases. (Siehe dazu auch folgenden Screenshot.) Weitere Informationen und Details zum aktuellen Zustand sowie Zweck der jeweiligen VMs kann in dem oft übersehenen Beschreibungsfeld hinterlegt werden. Es empfiehlt sich, bereits VOR der Installation einen Notizzettel (oder eine Textdatei) mit den geplanten IP-Adressen und Namen für die VMs zu erstellen. (Nicht vergessen: Auch der Server Pool benötigt eine eigene IP.) Dabei sollte man auch nochmal die tatsächlichen Netzwerke der zu verwendenden Virtualbox-Interfaces prüfen und notieren. Achtung: Es gibt im Rahmen der Installation einige Passworte, die vom Nutzer gesetzt werden können – und solche, die zunächst fest eingestellt sind. Zu letzterem gehört das Passwort für den ovs-agent sowie den root-User auf den OVM Servern, welche beide per Default „ovsroot“ lauten. (Alle weiteren Passwort-Informationen sind in dem „Read me first“ Dokument zu finden, welches auf dem Desktop der OVM Manager VM liegt.) Aufpassen muss man ggf. auch in der initialen „Interview-Phase“ welche die VirtualBox VMs durchlaufen, nachdem sie das erste mal gebootet werden. Zu diesem Zeitpunkt ist nämlich auf jeden Fall noch die amerikanische Tastaturbelegung aktiv, so dass man z.B. besser kein „y“ und „z“ in seinem selbst gewählten Passwort verwendet. Aufgrund der Tatsache, dass wie oben erwähnt der OVM Manager auch gleichzeitig den Shared Storage bereitstellt, sollte darauf geachtet werden, dass dessen VM vor den OVM Server VMs gestartet wird. (Andernfalls „findet“ der dem OVM Server Pool zugrundeliegende Cluster sein sog. „Server Pool File System“ nicht.)

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• May 20th Links: ASP.NET MVC, ASP.NET, .NET 4, VS 2010, Silverlight

  - by ScottGu

  Here is the latest in my link-listing series.  Also check out my VS 2010 and .NET 4 series and ASP.NET MVC 2 series for other on-going blog series I’m working on. [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] ASP.NET MVC How to Localize an ASP.NET MVC Application: Michael Ceranski has a good blog post that describes how to localize ASP.NET MVC 2 applications. ASP.NET MVC with jTemplates Part 1 and Part 2: Steve Gentile has a nice two-part set of blog posts that demonstrate how to use the jTemplate and DataTable jQuery libraries to implement client-side data binding with ASP.NET MVC. CascadingDropDown jQuery Plugin for ASP.NET MVC: Raj Kaimal has a nice blog post that demonstrates how to implement a dynamically constructed cascading dropdownlist on the client using jQuery and ASP.NET MVC. How to Configure VS 2010 Code Coverage for ASP.NET MVC Unit Tests: Visual Studio enables you to calculate the “code coverage” of your unit tests.  This measures the percentage of code within your application that is exercised by your tests – and can give you a sense of how much test coverage you have.  Gunnar Peipman demonstrates how to configure this for ASP.NET MVC projects. Shrinkr URL Shortening Service Sample: A nice open source application and code sample built by Kazi Manzur that demonstrates how to implement a URL Shortening Services (like bit.ly) using ASP.NET MVC 2 and EF4.  More details here. Creating RSS Feeds in ASP.NET MVC: Damien Guard has a nice post that describes a cool new “FeedResult” class he created that makes it easy to publish and expose RSS feeds from within ASP.NET MVC sites. NoSQL with MongoDB, NoRM and ASP.NET MVC Part 1 and Part 2: Nice two-part blog series by Shiju Varghese on how to use MongoDB (a document database) with ASP.NET MVC.  If you are interested in document databases also make sure to check out the Raven DB project from Ayende. Using the FCKEditor with ASP.NET MVC: Quick blog post that describes how to use FCKEditor – an open source HTML Text Editor – with ASP.NET MVC. ASP.NET Replace Html.Encode Calls with the New HTML Encoding Syntax: Phil Haack has a good blog post that describes a useful way to quickly update your ASP.NET pages and ASP.NET MVC views to use the new <%: %> encoding syntax in ASP.NET 4.  I blogged about the new <%: %> syntax – it provides an easy and concise way to HTML encode content. Integrating Twitter into an ASP.NET Website using OAuth: Scott Mitchell has a nice article that describes how to take advantage of Twiter within an ASP.NET Website using the OAuth protocol – which is a simple, secure protocol for granting API access. Creating an ASP.NET report using VS 2010 Part 1, Part 2, and Part 3: Raj Kaimal has a nice three part set of blog posts that detail how to use SQL Server Reporting Services, ASP.NET 4 and VS 2010 to create a dynamic reporting solution. Three Hidden Extensibility Gems in ASP.NET 4: Phil Haack blogs about three obscure but useful extensibility points enabled with ASP.NET 4. .NET 4 Entity Framework 4 Video Series: Julie Lerman has a nice, free, 7-part video series on MSDN that walks through how to use the new EF4 capabilities with VS 2010 and .NET 4.  I’ll be covering EF4 in a blog series that I’m going to start shortly as well. Getting Lazy with System.Lazy: System.Lazy and System.Lazy<T> are new features in .NET 4 that provide a way to create objects that may need to perform time consuming operations and defer the execution of the operation until it is needed.  Derik Whittaker has a nice write-up that describes how to use it. LINQ to Twitter: Nifty open source library on Codeplex that enables you to use LINQ syntax to query Twitter. Visual Studio 2010 Using Intellitrace in VS 2010: Chris Koenig has a nice 10 minute video that demonstrates how to use the new Intellitrace features of VS 2010 to enable DVR playback of your debug sessions. Make the VS 2010 IDE Colors look like VS 2008: Scott Hanselman has a nice blog post that covers the Visual Studio Color Theme Editor extension – which allows you to customize the VS 2010 IDE however you want. How to understand your code using Dependency Graphs, Sequence Diagrams, and the Architecture Explorer: Jennifer Marsman has a nice blog post describes how to take advantage of some of the new architecture features within VS 2010 to quickly analyze applications and legacy code-bases. How to maintain control of your code using Layer Diagrams: Another great blog post by Jennifer Marsman that demonstrates how to setup a “layer diagram” within VS 2010 to enforce clean layering within your applications.  This enables you to enforce a compiler error if someone inadvertently violates a layer design rule. Collapse Selection in Solution Explorer Extension: Useful VS 2010 extension that enables you to quickly collapse “child nodes” within the Visual Studio Solution Explorer.  If you have deeply nested project structures this extension is useful. Silverlight and Windows Phone 7 Building a Simple Windows Phone 7 Application: A nice tutorial blog post that demonstrates how to take advantage of Expression Blend to create an animated Windows Phone 7 application. If you haven’t checked out my Windows Phone 7 Twitter Tutorial I also recommend reading that. Hope this helps, Scott P.S. If you haven’t already, check out this month’s "Find a Hoster” page on the www.asp.net website to learn about great (and very inexpensive) ASP.NET hosting offers.

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• Searching for tasks with code – Executables and Event Handlers

  Searching packages or just enumerating through all tasks is not quite as straightforward as it may first appear, mainly because of the way you can nest tasks within other containers. You can see this illustrated in the sample package below where I have used several sequence containers and loops. To complicate this further all containers types, including packages and tasks, can have event handlers which can then support the full range of nested containers again. Towards the lower right, the task called SQL In FEL also has an event handler not shown, within which is another Execute SQL Task, so that makes a total of 6 Execute SQL Tasks 6 tasks spread across the package. In my previous post about such as adding a property expressionI kept it simple and just looked at tasks at the package level, but what if you wanted to find any or all tasks in a package? For this post I've written a console program that will search a package looking at all tasks no matter how deeply nested, and check to see if the name starts with "SQL". When it finds a matching task it writes out the hierarchy by name for that task, starting with the package and working down to the task itself. The output for our sample package is shown below, note it has found all 6 tasks, including the one on the OnPreExecute event of the SQL In FEL task TaskSearch v1.0.0.0 (1.0.0.0) Copyright (C) 2009 Konesans Ltd Processing File - C:\Projects\Alpha\Packages\MyPackage.dtsx MyPackage\FOR Counter Loop\SQL In Counter Loop MyPackage\SEQ For Each Loop Wrapper\FEL Simple Loop\SQL In FEL MyPackage\SEQ For Each Loop Wrapper\FEL Simple Loop\SQL In FEL\OnPreExecute\SQL On Pre Execute for FEL SQL Task MyPackage\SEQ Top Level\SEQ Nested Lvl 1\SEQ Nested Lvl 2\SQL In Nested Lvl 2 MyPackage\SEQ Top Level\SEQ Nested Lvl 1\SQL In Nested Lvl 1 #1 MyPackage\SEQ Top Level\SEQ Nested Lvl 1\SQL In Nested Lvl 1 #2 6 matching tasks found in package. The full project and code is available for download below, but first we can walk through the project to highlight the most important sections of code. This code has been abbreviated for this description, but is complete in the download. First of all we load the package, and then start by looking at the Executables for the package. // Load the package file Application application = new Application(); using (Package package = application.LoadPackage(filename, null)) { int matchCount = 0; // Look in the package's executables ProcessExecutables(package.Executables, ref matchCount); ... // // ... // Write out final count Console.WriteLine("{0} matching tasks found in package.", matchCount); } The ProcessExecutables method is a key method, as an executable could be described as the the highest level of a working functionality or container. There are several of types of executables, such as tasks, or sequence containers and loops. To know what to do next we need to work out what type of executable we are dealing with as the abbreviated version of method shows below. private static void ProcessExecutables(Executables executables, ref int matchCount) { foreach (Executable executable in executables) { TaskHost taskHost = executable as TaskHost; if (taskHost != null) { ProcessTaskHost(taskHost, ref matchCount); ProcessEventHandlers(taskHost.EventHandlers, ref matchCount); continue; } ... // // ... ForEachLoop forEachLoop = executable as ForEachLoop; if (forEachLoop != null) { ProcessExecutables(forEachLoop.Executables, ref matchCount); ProcessEventHandlers(forEachLoop.EventHandlers, ref matchCount); continue; } } } As you can see if the executable we find is a task we then call out to our ProcessTaskHost method. As with all of our executables a task can have event handlers which themselves contain more executables such as task and loops, so we also make a call out our ProcessEventHandlers method. The other types of executables such as loops can also have event handlers as well as executables. As shown with the example for the ForEachLoop we call the same ProcessExecutables and ProcessEventHandlers methods again to drill down into the hierarchy of objects that the package may contain. This code needs to explicitly check for each type of executable (TaskHost, Sequence, ForLoop and ForEachLoop) because whilst they all have an Executables property this is not from a common base class or interface. This example was just a simple find a task by its name, so ProcessTaskHost really just does that. We also get the hierarchy of objects so we can write out for information, obviously you can adapt this method to do something more interesting such as adding a property expression. private static void ProcessTaskHost(TaskHost taskHost, ref int matchCount) { if (taskHost == null) { return; } // Check if the task matches our match name if (taskHost.Name.StartsWith(TaskNameFilter, StringComparison.OrdinalIgnoreCase)) { // Build up the full object hierarchy of the task // so we can write it out for information StringBuilder path = new StringBuilder(); DtsContainer container = taskHost; while (container != null) { path.Insert(0, container.Name); container = container.Parent; if (container != null) { path.Insert(0, "\\"); } } // Write the task path // e.g. Package\Container\Event\Task Console.WriteLine(path); Console.WriteLine(); // Increment match counter for info matchCount++; } } Just for completeness, the other processing method we covered above is for event handlers, but really that just calls back to the executables. This same method is called in our main package method, but it was omitted for brevity here. private static void ProcessEventHandlers(DtsEventHandlers eventHandlers, ref int matchCount) { foreach (DtsEventHandler eventHandler in eventHandlers) { ProcessExecutables(eventHandler.Executables, ref matchCount); } } As hopefully the code demonstrates, executables (Microsoft.SqlServer.Dts.Runtime.Executable) are the workers, but within them you can nest more executables (except for task tasks).Executables themselves can have event handlers which can in turn hold more executables. I have tried to illustrate this highlight the relationships in the following diagram. Download Sample code project TaskSearch.zip (11KB)

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• BizTalk Server 2009 - Architecture Options

  - by StuartBrierley

  I recently needed to put forward a proposal for a BizTalk 2009 implementation and as a part of this needed to describe some of the basic architecture options available for consideration.  While I already had an idea of the type of environment that I would be looking to recommend, I felt that presenting a range of options while trying to explain some of the strengths and weaknesses of those options was a good place to start.  These outline architecture options should be equally valid for any version of BizTalk Server from 2004, through 2006 and R2, up to 2009.   The following diagram shows a crude representation of the common implementation options to consider when designing a BizTalk environment.         Each of these options provides differing levels of resilience in the case of failure or disaster, with the later options also providing more scope for performance tuning and scalability.   Some of the options presented above make use of clustering. Clustering may best be described as a technology that automatically allows one physical server to take over the tasks and responsibilities of another physical server that has failed. Given that all computer hardware and software will eventually fail, the goal of clustering is to ensure that mission-critical applications will have little or no downtime when such a failure occurs. Clustering can also be configured to provide load balancing, which should generally lead to performance gains and increased capacity and throughput.   (A) Single Servers   This option is the most basic BizTalk implementation that should be considered. It involves the deployment of a single BizTalk server in conjunction with a single SQL server. This configuration does not provide for any resilience in the case of the failure of either server. It is however the cheapest and easiest to implement option of those available.   Using a single BizTalk server does not provide for the level of performance tuning that is otherwise available when using more than one BizTalk server in a cluster.   The common edition of BizTalk used in single server implementations is the standard edition. It should be noted however that if future demand requires increased capacity for a solution, this BizTalk edition is limited to scaling up the implementation and not scaling out the number of servers in use. Any need to scale out the solution would require an upgrade to the enterprise edition of BizTalk.   (B) Single BizTalk Server with Clustered SQL Servers   This option uses a single BizTalk server with a cluster of SQL servers. By utilising clustered SQL servers we can ensure that there is some resilience to the implementation in respect of the databases that BizTalk relies on to operate. The clustering of two SQL servers is possible with the standard edition but to go beyond this would require the enterprise level edition. While this option offers improved resilience over option (A) it does still present a potential single point of failure at the BizTalk server.   Using a single BizTalk server does not provide for the level of performance tuning that is otherwise available when using more than one BizTalk server in a cluster.   The common edition of BizTalk used in single server implementations is the standard edition. It should be noted however that if future demand requires increased capacity for a solution, this BizTalk edition is limited to scaling up the implementation and not scaling out the number of servers in use. You are also unable to take advantage of multiple message boxes, which would allow us to balance the SQL load in the event of any bottlenecks in this area of the implementation. Any need to scale out the solution would require an upgrade to the enterprise edition of BizTalk.   (C) Clustered BizTalk Servers with Clustered SQL Servers   This option makes use of a cluster of BizTalk servers with a cluster of SQL servers to offer high availability and resilience in the case of failure of either of the server types involved. Clustering of BizTalk is only available with the enterprise edition of the product. Clustering of two SQL servers is possible with the standard edition but to go beyond this would require the enterprise level edition.    The use of a BizTalk cluster also provides for the ability to balance load across the servers and gives more scope for performance tuning any implemented solutions. It is also possible to add more BizTalk servers to an existing cluster, giving scope for scaling out the solution as future demand requires.   This might be seen as the middle cost option, providing a good level of protection in the case of failure, a decent level of future proofing, but at a higher cost than the single BizTalk server implementations.   (D) Clustered BizTalk Servers with Clustered SQL Servers – with disaster recovery/service continuity   This option is similar to that offered by (C) and makes use of a cluster of BizTalk servers with a cluster of SQL servers to offer high availability and resilience in case of failure of either of the server types involved. Clustering of BizTalk is only available with the enterprise edition of the product. Clustering of two SQL servers is possible with the standard edition but to go beyond this would require the enterprise level edition.    As with (C) the use of a BizTalk cluster also provides for the ability to balance load across the servers and gives more scope for performance tuning the implemented solution. It is also possible to add more BizTalk servers to an existing cluster, giving scope for scaling the solution out as future demand requires.   In this scenario however, we would be including some form of disaster recovery or service continuity. An example of this would be making use of multiple sites, with the BizTalk server cluster operating across sites to offer resilience in case of the loss of one or more sites. In this scenario there are options available for the SQL implementation depending on the network implementation; making use of either one cluster per site or a single SQL cluster across the network. A multi-site SQL implementation would require some form of data replication across the sites involved.   This is obviously an expensive and complex option, but does provide an extraordinary amount of protection in the case of failure.

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• SQL SERVER – Beginning of SQL Server Architecture – Terminology – Guest Post

  - by pinaldave

  SQL Server Architecture is a very deep subject. Covering it in a single post is an almost impossible task. However, this subject is very popular topic among beginners and advanced users.  I have requested my friend Anil Kumar who is expert in SQL Domain to help me write  a simple post about Beginning SQL Server Architecture. As stated earlier this subject is very deep subject and in this first article series he has covered basic terminologies. In future article he will explore the subject further down. Anil Kumar Yadav is Trainer, SQL Domain, Koenig Solutions. Koenig is a premier IT training firm that provides several IT certifications, such as Oracle 11g, Server+, RHCA, SQL Server Training, Prince2 Foundation etc. In this Article we will discuss about MS SQL Server architecture. The major components of SQL Server are: Relational Engine Storage Engine SQL OS Now we will discuss and understand each one of them. 1) Relational Engine: Also called as the query processor, Relational Engine includes the components of SQL Server that determine what your query exactly needs to do and the best way to do it. It manages the execution of queries as it requests data from the storage engine and processes the results returned. Different Tasks of Relational Engine: Query Processing Memory Management Thread and Task Management Buffer Management Distributed Query Processing 2) Storage Engine: Storage Engine is responsible for storage and retrieval of the data on to the storage system (Disk, SAN etc.). to understand more, let’s focus on the following diagram. When we talk about any database in SQL server, there are 2 types of files that are created at the disk level – Data file and Log file. Data file physically stores the data in data pages. Log files that are also known as write ahead logs, are used for storing transactions performed on the database. Let’s understand data file and log file in more details: Data File: Data File stores data in the form of Data Page (8KB) and these data pages are logically organized in extents. Extents: Extents are logical units in the database. They are a combination of 8 data pages i.e. 64 KB forms an extent. Extents can be of two types, Mixed and Uniform. Mixed extents hold different types of pages like index, System, Object data etc. On the other hand, Uniform extents are dedicated to only one type. Pages: As we should know what type of data pages can be stored in SQL Server, below mentioned are some of them: Data Page: It holds the data entered by the user but not the data which is of type text, ntext, nvarchar(max), varchar(max), varbinary(max), image and xml data. Index: It stores the index entries. Text/Image: It stores LOB ( Large Object data) like text, ntext, varchar(max), nvarchar(max),  varbinary(max), image and xml data. GAM & SGAM (Global Allocation Map & Shared Global Allocation Map): They are used for saving information related to the allocation of extents. PFS (Page Free Space): Information related to page allocation and unused space available on pages. IAM (Index Allocation Map): Information pertaining to extents that are used by a table or index per allocation unit. BCM (Bulk Changed Map): Keeps information about the extents changed in a Bulk Operation. DCM (Differential Change Map): This is the information of extents that have modified since the last BACKUP DATABASE statement as per allocation unit. Log File: It also known as write ahead log. It stores modification to the database (DML and DDL). Sufficient information is logged to be able to: Roll back transactions if requested Recover the database in case of failure Write Ahead Logging is used to create log entries Transaction logs are written in chronological order in a circular way Truncation policy for logs is based on the recovery model SQL OS: This lies between the host machine (Windows OS) and SQL Server. All the activities performed on database engine are taken care of by SQL OS. It is a highly configurable operating system with powerful API (application programming interface), enabling automatic locality and advanced parallelism. SQL OS provides various operating system services, such as memory management deals with buffer pool, log buffer and deadlock detection using the blocking and locking structure. Other services include exception handling, hosting for external components like Common Language Runtime, CLR etc. I guess this brief article gives you an idea about the various terminologies used related to SQL Server Architecture. In future articles we will explore them further. Guest Author  The author of the article is Anil Kumar Yadav is Trainer, SQL Domain, Koenig Solutions. Koenig is a premier IT training firm that provides several IT certifications, such as Oracle 11g, Server+, RHCA, SQL Server Training, Prince2 Foundation etc. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, SQL Training, T SQL, Technology

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