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Exclusive Expert and Peer-Led Sessions—Only at Oracle OpenWorld

- by Robert Schweighardt

With more than 2,500 sessions, dozens of hands-on labs, hundreds of demos, four Exhibition Halls, and countless meet-ups, Oracle OpenWorld is the place to learn, share, and network. Planning ahead is always a smart move and here are some links to help you plan your Oracle OpenWorld schedule. You will hear directly from Oracle Thought leaders, Oracle Support experts and their peers about how to succeed across the Oracle stack—from Oracle Consulting Thought Leader sessions dedicated to the cloud to hands on demos showing the value of My Oracle Support—Oracle Open World is your one stop shop for everything Oracle. Featured sessions include: Is Your Organization Trying to Focus on an ERP Cloud Strategy? Modernize Your Analytics Solutions Is Your Organization Trying to Focus on a CX Cloud Strategy? Best Practices for Deploying a DBaaS in a Private Cloud Model Visit the Support & Services Oracle OpenWorld website to discover how you can take advantage of all Oracle OpenWorld has to offer. With 500 Services experts, 50+ sessions, networking events and demos of powerful new support tools, customers will find relevant, useful information about how Oracle Services enables the success of their Oracle hardware and software investments.

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WebDAV, SVN, Apache2 on OS X 10.6.2

- by David

Hi there, I'm trying to configure SVN server on OS X 10.6.2 via Apache2. Whenever I enable the module in Wev - Settings - Services then try accessing the site, it fails. So I attempted an apachectl configtest and I'm getting a crazy amount of errors: httpd: Syntax error on line 132 of /private/etc/apache2/httpd.conf: Cannot load /usr/libexec/apache2/mod_dav_fs.so into server: dlopen(/usr/libexec/apache2/mod_dav_fs.so, 10): Symbol not found: _dav_add_response\n Referenced from: /usr/libexec/apache2/mode_dev_fs.so\n Expected in: flat namespace\n in /usr/livexec/apache2/mod_dav_fs.so When I attempt disabling the related services and enabling then one by one (dav_fs_module, dav_module, dav_svn_module and authz_svn_mod each seems to fail. What the heck. :-( Thanks in advance, Dave

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Network issues with DNS not being found

- by Anriëtte Combrink

Hi there This is exactly like how our network looks like: Single server with a network router Everything is setup, but I cannot connect our Macs under the Login Options - Join... to this server. Our server's name is Toolbox and I have tried Toolbox.local, Toolbox.private, prepended the afp:// protocol to the name, but nothing, our Macs just don't want to connect this way. Our router has DHCP and gives out all the IP addresses naturally, would I have to add Toolbox.local to the DNS on the router and like it via static internal IP to the server? Our Macs keep giving the following error while trying to join the Network Account Server: Unable to add server Could not resolve the address (2200) What am I doing wrong?

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Podcast Show Notes: Toronto Architect Day Panel Discussion

- by Bob Rhubart

The latest Oracle Technology Network ArchBeat Podcast features a four-part series recorded live during the panel discussion at OTN Architect Day in Tornonto, April 21, 2011. More than 100 people attended the event, and the audience tossed a lot of great questions at a terrific panel. Listen for yourself... Listen to Part 1 Panel introduction and a discussion of the typical characteristics of Cloud early-adopters. Listen to Part 2 (June 22) The panelists respond to an audience question about what happens when data in the Cloud crosses international borders. Listen to Part 3 (June 29) The panel discusses public versus private cloud as the best strategy for small or start-up businesses. Listen to Part 4 (July 6) The panel responds to an audience question about how cloud computing changes performance testing paradigms. The Architect Day panel includes (listed alphabetically): Dr. James Baty: Vice President, Oracle Global Enterprise Architecture Program [LinkedIn] Dave Chappelle: Enterprise Architect, Oracle Global Enterprise Architecture Program [LinkedIn] Timothy Davis: Director, Enterprise Architecture, Oracle Enterprise Solutions Group [LinkedIn] Michael Glas: Director, Enterprise Architecture, Oracle [LinkedIn] Bob Hensle: Director, Oracle [LinkedIn] Floyd Marinescu: Co-founder & Chief Editor of InfoQ.com and the QCon conferences [LinkedIn | Twitter | Homepage] Cary Millsap: Oracle ACE Director; Founder, President, and CEO at Method R Corporation [LinkedIn | Blog | Twitter] Coming Soon IASA CEO Paul Preiss talks about architecture as a profession. Thomas Erl and Anne Thomas Manes discuss their new book SOA Governance: Governing Shared Services On-Premise & in the Cloud A discussion of women in architecture Stay tuned: RSS

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Getting Query Parameters in Javascript

- by PhubarBaz

I find myself needing to get query parameters that are passed into a web app on the URL quite often. At first I wrote a function that creates an associative array (aka object) with all of the parameters as keys and returns it. But then I was looking at the revealing module pattern, a nice javascript design pattern designed to hide private functions, and came up with a way to do this without even calling a function. What I came up with was this nice little object that automatically initializes itself into the same associative array that the function call did previously. // Creates associative array (object) of query params var QueryParameters = (function() { var result = {}; if (window.location.search) { // split up the query string and store in an associative array var params = window.location.search.slice(1).split("&"); for (var i = 0; i < params.length; i++) { var tmp = params[i].split("="); result[tmp[0]] = unescape(tmp[1]); } } return result; }()); Now all you have to do to get the query parameters is just reference them from the QueryParameters object. There is no need to create a new object or call any function to initialize it. var debug = (QueryParameters.debug === "true"); or if (QueryParameters["debug"]) doSomeDebugging(); or loop through all of the parameters. for (var param in QueryParameters) var value = QueryParameters[param]; Hope you find this object useful.

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Mercurial SSH process blocks when run from Local System

- by Liedman

We are using Mercurial over SSH for our development. We use Hudson for continous integration, and have deployed it on Tomcat, running on a Windows 2003 Server using the Local System account. Mercurial is configured to use Putty's plink.exe as its ssh command in Mercurial.ini, together with a private key for SSH authentication. When Hudson attempts any Mercurial command over SSH, the operation just blocks. I can see the three processes being started: hg.exe, cmd.exe and plink.exe. On the remote machine, I can also see the SSH session being opened and the authentication key being accepted. After that, nothing appears to happen, and everything just blocks, seemingly forever. (As a side note, subversion/SVN over SSH works from Hudson to the same server, using the same user and authentication key). A solution would of course be the best, but at least a hint for how I should debug it to get further would be nice, since I'm stuck and haven't even got an error message right now.

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Able to connect by SSH, but not x2go

- by Mike

I am having trouble connecting to a remote server with X2GO using a DSA key. Connecting works fine over SSH, but when I try to connect with X2GO, it goes immediately to the username/password box and doesn't want to use the private key I specify in the options. If I select "Try auto login" it appears to try to connect and then I get the following error: No public key matched Access denied. Authentication that can continue: publickey It was working previously, but I reinstalled the client OS and since then I am unable to connect. I copied all of the SSH keys over from the previous installation. I also tried deleting my ~/.ssh/known_hosts file and adding the key to ssh-agent with no success, but the key is definitely added correctly: $ ssh-add -l 1024 b9:3d:e5:ef:48:ea:fc:c6:6e:45:89:b5:35:e7:58:39 server.com_dsa (DSA) Note, if I enable password authentication on the server, I can connect fine, however I would like to use publickey. Any ideas how I can connect with public key authentication?

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How to check a digital certificate?

- by StackedCrooked

I have extracted a certificate from a cable modem. Now I want to verify if this certificate is valid. If I understand correctly, the verification process consists of having the issuer sign the subject's public key and then comparing the result with the subject's signature. This signing process is done using the issuer's private key, which nobody but the issuer has access to. So even if I have both certificates on my PC, there is no way for me to verify the subject's validity. From this I can only conclude that the verification must be implemented as a remote service. The problem is that I don't know what remote service I need to access to verify this certificate. The issuer is "AVM GmbH Cable Modem Root Certificate Authority". How can I find the webservice for verification? Is there standard lookup mechanism for this?

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Getting NLog Running in Partial Trust

- by grant.barrington

To get things working you will need to: Strong name sign the assembly Allow Partially Trusted Callers In the AssemblyInfo.cs file you will need to add the assembly attribute for “AllowPartiallyTrustedCallers” You should now be able to get NLog working as part of a partial trust installation, except that the File target won’t work. Other targets will still work (database for example) Changing BaseFileAppender.cs to get file logging to work In the directory \Internal\FileAppenders there is a file called “BaseFileAppender.cs”. Make a change to the function call “TryCreateFileStream()”. The error occurs here: Change the function call to be: private FileStream TryCreateFileStream(bool allowConcurrentWrite) { FileShare fileShare = FileShare.Read; if (allowConcurrentWrite) fileShare = FileShare.ReadWrite; #if DOTNET_2_0 if (_createParameters.EnableFileDelete && PlatformDetector.GetCurrentRuntimeOS() != RuntimeOS.Windows) { fileShare |= FileShare.Delete; } #endif #if !NETCF try { if (PlatformDetector.IsCurrentOSCompatibleWith(RuntimeOS.WindowsNT) || PlatformDetector.IsCurrentOSCompatibleWith(RuntimeOS.Windows)) { return WindowsCreateFile(FileName, allowConcurrentWrite); } } catch (System.Security.SecurityException secExc) { InternalLogger.Error("Security Exception Caught in WindowsCreateFile. {0}", secExc.Message); } #endif return new FileStream(FileName, FileMode.Append, FileAccess.Write, fileShare, _createParameters.BufferSize); } Basically we wrap the call in a try..catch. If we catch a SecurityException when trying to create the FileStream using WindowsCreateFile(), we just swallow the exception and use the native System.Io.FileStream instead.

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.Net to Oracle Connectivity using ODBC .NET

- by SAMIR BHOGAYTA

You can use the new ODBC .NET Data Provider that works with the ODBC Oracle7.x driver or higher. You need to have MDAC 2.6 or later installed and then download ODBC .NET from the MS Web Site http://msdn.microsoft.com/downloads/default.asp?url=/code/sample.asp?url=/msdn-files/027/001/668/msdncompositedoc.xml&frame=true. MDAC (Microsoft Data Access Component) 2.7 contains core component, including the Microsoft SQL server and Oracle OLE Database provider and ODBC driver. Insta ...You can use the new ODBC .NET Data Provider that works with the ODBC Oracle7.x driver or higher. You need to have MDAC 2.6 or later installed and then download ODBC .NET from the MS Web Site http://msdn.microsoft.com/downloads/default.asp?url=/code/sample.asp?url=/msdn-files/027/001/668/msdncompositedoc.xml&frame=true. MDAC (Microsoft Data Access Component) 2.7 contains core component, including the Microsoft SQL server and Oracle OLE Database provider and ODBC driver. Install ODBC .NET from the MS Web Site http://msdn.microsoft.com/downloads/default.asp?URL=/downloads/sample.asp?url=/msdn-files/027/001/943/msdncompositedoc.xml Create a DSN, using either Microsoft ODBC for Oracle or Oracle supplied Driver if the Oracle client software is loaded. here for eq. TrailDSN. While creating DSN give user name along with passward for eq. scott/tiger. using Microsoft .Data.Odbc; private void Form1_Load(object sender, System.EventArgs e) { try { OdbcConnection myconnection= new OdbcConnection ("DSN=TrialDSN"); OdbcDataAdapter myda = new OdbcDataAdapter ("Select * from EMP", myconnection); DataSet ds= new DataSet (); myda.Fill(ds, "Table"); dataGrid1.DataSource = ds ; } catch(Exception ex) { MessageBox.Show (ex.Message ); } }

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Postfix Not Sending Email to Some Addresses?

- by Jake

I'm using Jetpack on Wordpress, and it wasn't working. I was getting the following error: Diagnostic-Code: X-Postfix; unknown user: "jake" --60FD1138CAD.1354039466/example.com Content-Description: Undelivered Message (example.com substituted for our domain) We set up a test mail function, and that wasn't sending either. We changed the email to an outside email and it worked. Any thoughts why it won't send to an email that is at the same domain? Or why it sends to some emails but not others? Upon running postconf -n, I get the following: alias_database = hash:/etc/aliases alias_maps = hash:/etc/aliases append_dot_mydomain = no biff = no config_directory = /etc/postfix inet_interfaces = all inet_protocols = all mailbox_size_limit = 0 mydestination = example.com, Example, localhost.localdomain, localhost myhostname = example.com mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 myorigin = /etc/mailname readme_directory = no recipient_delimiter = + relayhost = smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu) smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtpd_use_tls = yes

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Dovecot throws obsolete warnings, even though dovecot.conf updated on Ubuntu 11

- by John Bowlinger

In trying to set up SASL for dovecot on Ubuntu 11, I keep getting obsolete warnings in my log: Sep 10 15:33:53 server1 dovecot: config: Warning: Obsolete setting in /etc/dovecot/dovecot.conf:24: passdb {} has been replaced by passdb { driver= } Sep 10 15:33:53 server1 dovecot: config: Warning: Obsolete setting in /etc/dovecot/dovecot.conf:27: userdb {} has been replaced by userdb { driver= } Even though my dovecot.conf file looks like this: protocols = none auth default { mechanisms = plain login passdb { driver=pam } userdb { driver=passwd } socket listen { client { path = /var/spool/postfix/private/auth mode = 0660 user = postfix group = postfix } } } Even when I try: driver=etc/pam.d/dovecot driver=etc/passwd I still get the same error. Looking at the example config file: cat /usr/share/doc/dovecot-common/dovecot/example-config/dovecot.conf was of no help. Dovecot is running: ps -A | grep 'dovecot' 9663 ? 00:00:00 dovecot But I can't seem to get that elusive "dovecot-auth" process. Anyone know what's going on?

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OpenLdap TLS authentication setup

- by CrazycodeMonkey

I am trying to setup openldap on ubuntu 12.04 by following this guide https://help.ubuntu.com/12.04/serverguide/openldap-server.html When I tried to enable TLS on the server by creating a self signed crtificate as decribed in the guide above, I got the following error command that I ran ldapmodify -Y EXTERNAL -H ldapi:/// -f /etc/ssl/certinfo.ldif Content of ldif file dn: cn=config add: olcTLSCACertificateFile olcTLSCACertificateFile: /etc/ssl/certs/cacert.pem - add: olcTLSCertificateFile olcTLSCertificateFile: /etc/ssl/certs/ldap01_slapd_cert.pem - add: olcTLSCertificateKeyFile olcTLSCertificateKeyFile: /etc/ssl/private/ldap01_slapd_key.pem Error Message ldap_modify: Inappropriate matching (18) additional info: modify/add: olcTLSCertificateFile: no equality matching rule After hours of searching on google, I have not found anything that tells much about this error. Does anyone have any more information on this?

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Unable to SSH into EC2 instance on Fedora 17

- by abhishek

I did following steps But I am not able to SSH to it(Same steps work fine on Fedora 14 image). I am getting Permission denied (publickey,gssapi-keyex,gssapi-with-mic) I created new instance using fedora 17 amazon community image(ami-2ea50247). I copied my ssh keys under /home/usertest/.ssh/ after creating a usertest I have SELINUX=disabled here is Debug info: $ ssh -vvv ec2-54-243-101-41.compute-1.amazonaws.com ssh -vvv ec2-54-243-101-41.compute-1.amazonaws.com OpenSSH_5.2p1, OpenSSL 1.0.0b-fips 16 Nov 2010 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to ec2-54-243-101-41.compute-1.amazonaws.com [54.243.101.41] port 22. debug1: Connection established. debug1: identity file /home/usertest/.ssh/identity type -1 debug1: identity file /home/usertest/.ssh/id_rsa type -1 debug3: Not a RSA1 key file /home/usertest/.ssh/id_dsa. debug2: key_type_from_name: unknown key type '-----BEGIN' debug3: key_read: missing keytype debug2: key_type_from_name: unknown key type 'Proc-Type:' debug3: key_read: missing keytype debug2: key_type_from_name: unknown key type 'DEK-Info:' debug3: key_read: missing keytype debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug2: key_type_from_name: unknown key type '-----END' debug3: key_read: missing keytype debug1: identity file /home/usertest/.ssh/id_dsa type 2 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9 debug1: match: OpenSSH_5.9 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.2 debug2: fd 3 setting O_NONBLOCK debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 131/256 debug2: bits set: 506/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug3: check_host_in_hostfile: filename /home/usertest/.ssh/known_hosts debug3: check_host_in_hostfile: match line 17 debug3: check_host_in_hostfile: filename /home/usertest/.ssh/known_hosts debug3: check_host_in_hostfile: match line 17 debug1: Host 'ec2-54-243-101-41.compute-1.amazonaws.com' is known and matches the RSA host key. debug1: Found key in /home/usertest/.ssh/known_hosts:17 debug2: bits set: 500/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /home/usertest/.ssh/identity ((nil)) debug2: key: /home/usertest/.ssh/id_rsa ((nil)) debug2: key: /home/usertest/.ssh/id_dsa (0x7f904b5ae260) debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic debug3: preferred gssapi-with-mic,publickey,keyboard-interactive,password debug3: authmethod_lookup gssapi-with-mic debug3: remaining preferred: publickey,keyboard-interactive,password debug3: authmethod_is_enabled gssapi-with-mic debug1: Next authentication method: gssapi-with-mic debug3: Trying to reverse map address 54.243.101.41. debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_500' not found debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_500' not found debug1: Unspecified GSS failure. Minor code may provide more information debug2: we did not send a packet, disable method debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Trying private key: /home/usertest/.ssh/identity debug3: no such identity: /home/usertest/.ssh/identity debug1: Trying private key: /home/usertest/.ssh/id_rsa debug3: no such identity: /home/usertest/.ssh/id_rsa debug1: Offering public key: /home/usertest/.ssh/id_dsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic debug2: we did not send a packet, disable method debug1: No more authentication methods to try. Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

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Caching NHibernate Named Queries

- by TStewartDev

I recently started a new job and one of my first tasks was to implement a "popular products" design. The parameters were that it be done with NHibernate and be cached for 24 hours at a time because the query will be pretty taxing and the results do not need to be constantly up to date. This ended up being tougher than it sounds. The database schema meant a minimum of four joins with filtering and ordering criteria. I decided to use a stored procedure rather than letting NHibernate create the SQL for me. Here is a summary of what I learned (even if I didn't ultimately use all of it): You can't, at the time of this writing, use Fluent NHibernate to configure SQL named queries or imports You can return persistent entities from a stored procedure and there are a couple ways to do that You can populate POCOs using the results of a stored procedure, but it isn't quite as obvious You can reuse your named query result mapping other places (avoid duplication) Caching your query results is not at all obvious Testing to see if your cache is working is a pain NHibernate does a lot of things right. Having unified, up-to-date, comprehensive, and easy-to-find documentation is not one of them. By the way, if you're new to this, I'll use the terms "named query" and "stored procedure" (from NHibernate's perspective) fairly interchangeably. Technically, a named query can execute any SQL, not just a stored procedure, and a stored procedure doesn't have to be executed from a named query, but for reusability, it seems to me like the best practice. If you're here, chances are good you're looking for answers to a similar problem. You don't want to read about the path, you just want the result. So, here's how to get this thing going. The Stored Procedure NHibernate has some guidelines when using stored procedures. For Microsoft SQL Server, you have to return a result set. The scalar value that the stored procedure returns is ignored as are any result sets after the first. Other than that, it's nothing special. CREATE PROCEDURE GetPopularProducts @StartDate DATETIME, @MaxResults INT AS BEGIN SELECT [ProductId], [ProductName], [ImageUrl] FROM SomeTableWithJoinsEtc END The Result Class - PopularProduct You have two options to transport your query results to your view (or wherever is the final destination): you can populate an existing mapped entity class in your model, or you can create a new entity class. If you go with the existing model, the advantage is that the query will act as a loader and you'll get full proxied access to the domain model. However, this can be a disadvantage if you require access to the related entities that aren't loaded by your results. For example, my PopularProduct has image references. Unless I tie them into the query (thus making it even more complicated and expensive to run), they'll have to be loaded on access, requiring more trips to the database. Since we're trying to avoid trips to the database by using a second-level cache, we should use the second option, which is to create a separate entity for results. This approach is (I believe) in the spirit of the Command-Query Separation principle, and it allows us to flatten our data and optimize our report-generation process from data source to view. public class PopularProduct { public virtual int ProductId { get; set; } public virtual string ProductName { get; set; } public virtual string ImageUrl { get; set; } } The NHibernate Mappings (hbm) Next up, we need to let NHibernate know about the query and where the results will go. Below is the markup for the PopularProduct class. Notice that I'm using the <resultset> element and that it has a name attribute. The name allows us to drop this into our query map and any others, giving us reusability. Also notice the <import> element which lets NHibernate know about our entity class. <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <import class="PopularProduct, Infrastructure.NHibernate, Version=1.0.0.0"/> <resultset name="PopularProductResultSet"> <return-scalar column="ProductId" type="System.Int32"/> <return-scalar column="ProductName" type="System.String"/> <return-scalar column="ImageUrl" type="System.String"/> </resultset> </hibernate-mapping> And now the PopularProductsMap: <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <sql-query name="GetPopularProducts" resultset-ref="PopularProductResultSet" cacheable="true" cache-mode="normal"> <query-param name="StartDate" type="System.DateTime" /> <query-param name="MaxResults" type="System.Int32" /> exec GetPopularProducts @StartDate = :StartDate, @MaxResults = :MaxResults </sql-query> </hibernate-mapping> The two most important things to notice here are the resultset-ref attribute, which links in our resultset mapping, and the cacheable attribute. The Query Class – PopularProductsQuery So far, this has been fairly obvious if you're familiar with NHibernate. This next part, maybe not so much. You can implement your query however you want to; for me, I wanted a self-encapsulated Query class, so here's what it looks like: public class PopularProductsQuery : IPopularProductsQuery { private static readonly IResultTransformer ResultTransformer; private readonly ISessionBuilder _sessionBuilder; static PopularProductsQuery() { ResultTransformer = Transformers.AliasToBean<PopularProduct>(); } public PopularProductsQuery(ISessionBuilder sessionBuilder) { _sessionBuilder = sessionBuilder; } public IList<PopularProduct> GetPopularProducts(DateTime startDate, int maxResults) { var session = _sessionBuilder.GetSession(); var popularProducts = session .GetNamedQuery("GetPopularProducts") .SetCacheable(true) .SetCacheRegion("PopularProductsCacheRegion") .SetCacheMode(CacheMode.Normal) .SetReadOnly(true) .SetResultTransformer(ResultTransformer) .SetParameter("StartDate", startDate.Date) .SetParameter("MaxResults", maxResults) .List<PopularProduct>(); return popularProducts; } } Okay, so let's look at each line of the query execution. The first, GetNamedQuery, matches up with our NHibernate mapping for the sql-query. Next, we set it as cacheable (this is probably redundant since our mapping also specified it, but it can't hurt, right?). Then we set the cache region which we'll get to in the next section. Set the cache mode (optional, I believe), and my cache is read-only, so I set that as well. The result transformer is very important. This tells NHibernate how to transform your query results into a non-persistent entity. You can see I've defined ResultTransformer in the static constructor using the AliasToBean transformer. The name is obviously leftover from Java/Hibernate. Finally, set your parameters and then call a result method which will execute the query. Because this is set to cached, you execute this statement every time you run the query and NHibernate will know based on your parameters whether to use its cached version or a fresh version. The Configuration – hibernate.cfg.xml and Web.config You need to explicitly enable second-level caching in your hibernate configuration: <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2"> <session-factory> [...] <property name="dialect">NHibernate.Dialect.MsSql2005Dialect</property> <property name="cache.provider_class">NHibernate.Caches.SysCache.SysCacheProvider,NHibernate.Caches.SysCache</property> <property name="cache.use_query_cache">true</property> <property name="cache.use_second_level_cache">true</property> [...] </session-factory> </hibernate-configuration> Both properties "use_query_cache" and "use_second_level_cache" are necessary. As this is for a web deployement, we're using SysCache which relies on ASP.NET's caching. Be aware of this if you're not deploying to the web! You'll have to use a different cache provider. We also need to tell our cache provider (in this cache, SysCache) about our caching region: <syscache> <cache region="PopularProductsCacheRegion" expiration="86400" priority="5" /> </syscache> Here I've set the cache to be valid for 24 hours. This XML snippet goes in your Web.config (or in a separate file referenced by Web.config, which helps keep things tidy). The Payoff That should be it! At this point, your queries should run once against the database for a given set of parameters and then use the cache thereafter until it expires. You can, of course, adjust settings to work in your particular environment. Testing Testing your application to ensure it is using the cache is a pain, but if you're like me, you want to know that it's actually working. It's a bit involved, though, so I'll create a separate post for it if comments indicate there is interest.

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How can I transfer files to a Kindle Fire with a Micro-USB cable?

- by Jeff

I'm running Ubuntu 11.10, and when I connect my Kindle Fire to my computer via micro usb, it is not recognized automatically. Other usb devices, such as my ipod and digital camera, are recognized just fine. It does not appear to be a usb power issue, since the Kindle Fire wakes up from sleeping when it is plugged in. I never get the message on the Kindle telling me it is ready to accept files from the computer, though. Here are the last 15 lines of dmesg after plugging the kindle in: jeff@prime:~$ dmesg | tail -n 15 [45918.269671] ieee80211 phy0: wl_ops_bss_info_changed: arp filtering: enabled true, count 1 (implement) [45929.072149] wlan0: no IPv6 routers present [46743.224217] usb 1-1: new high speed USB device number 5 using ehci_hcd [46743.364623] scsi8 : usb-storage 1-1:1.0 [46744.366102] scsi 8:0:0:0: Direct-Access Amazon Kindle 0001 PQ: 0 ANSI: 2 [46744.366356] scsi: killing requests for dead queue [46744.372494] scsi: killing requests for dead queue [46744.384510] scsi: killing requests for dead queue [46744.392348] scsi: killing requests for dead queue [46744.392731] scsi: killing requests for dead queue [46744.396853] scsi: killing requests for dead queue [46744.397214] scsi: killing requests for dead queue [46744.400795] scsi: killing requests for dead queue [46744.401589] sd 8:0:0:0: Attached scsi generic sg2 type 0 [46744.407520] sd 8:0:0:0: [sdb] Attached SCSI removable disk And here are my mounted filesystems: jeff@prime:~$ df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 298594984 174663712 108763480 62% / udev 1407684 4 1407680 1% /dev tmpfs 566924 896 566028 1% /run none 5120 0 5120 0% /run/lock none 1417308 300 1417008 1% /run/shm /home/jeff/.Private 298594984 174663712 108763480 62% /home/jeff I should note that, since I got Dropbox working on my Kindle, the usb is no longer strictly necessary, but as a matter of principle I'd love to get it working.

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Refactor This (Ugly Code)!

- by Alois Kraus

Ayende has put on his blog some ugly code to refactor. First and foremost it is nearly impossible to reason about other peoples code without knowing the driving forces behind the current code. It is certainly possible to make it much cleaner when potential sources of errors cannot happen in the first place due to good design. I can see what the intention of the code is but I do not know about every brittle detail if I am allowed to reorder things here and there to simplify things. So I decided to make it much simpler by identifying the different responsibilities of the methods and encapsulate it in different classes. The code we need to refactor seems to deal with a handler after a message has been sent to a message queue. The handler does complete the current transaction if there is any and does handle any errors happening there. If during the the completion of the transaction errors occur the transaction is at least disposed. We can enter the handler already in a faulty state where we try to deliver the complete event in any case and signal a failure event and try to resend the message again to the queue if it was not inside a transaction. All is decorated with many try/catch blocks, duplicated code and some state variables to route the program flow. It is hard to understand and difficult to reason about. In other words: This code is a mess and could be written by me if I was under pressure. Here comes to code we want to refactor: private void HandleMessageCompletion( Message message, TransactionScope tx, OpenedQueue messageQueue, Exception exception, Action<CurrentMessageInformation, Exception> messageCompleted, Action<CurrentMessageInformation> beforeTransactionCommit) { var txDisposed = false; if (exception == null) { try { if (tx != null) { if (beforeTransactionCommit != null) beforeTransactionCommit(currentMessageInformation); tx.Complete(); tx.Dispose(); txDisposed = true; } try { if (messageCompleted != null) messageCompleted(currentMessageInformation, exception); } catch (Exception e) { Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e); } return; } catch (Exception e) { Trace.TraceWarning("Failed to complete transaction, moving to error mode"+ e); exception = e; } } try { if (txDisposed == false && tx != null) { Trace.TraceWarning("Disposing transaction in error mode"); tx.Dispose(); } } catch (Exception e) { Trace.TraceWarning("Failed to dispose of transaction in error mode."+ e); } if (message == null) return; try { if (messageCompleted != null) messageCompleted(currentMessageInformation, exception); } catch (Exception e) { Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e); } try { var copy = MessageProcessingFailure; if (copy != null) copy(currentMessageInformation, exception); } catch (Exception moduleException) { Trace.TraceError("Module failed to process message failure: " + exception.Message+ moduleException); } if (messageQueue.IsTransactional == false)// put the item back in the queue { messageQueue.Send(message); } } You can see quite some processing and handling going on there. Yes this looks like real world code one did put together to make things work and he does not trust his callbacks. I guess these are event handlers which are optional and the delegates were extracted from an event to call them back later when necessary. Lets see what the author of this code did intend: private void HandleMessageCompletion( TransactionHandler transactionHandler, MessageCompletionHandler handler, CurrentMessageInformation messageInfo, ErrorCollector errors ) { // commit current pending transaction transactionHandler.CallHandlerAndCommit(messageInfo, errors); // We have an error for a null message do not send completion event if (messageInfo.CurrentMessage == null) return; // Send completion event in any case regardless of errors handler.OnMessageCompleted(messageInfo, errors); // put message back if queue is not transactional transactionHandler.ResendMessageOnError(messageInfo.CurrentMessage, errors); } I did not bother to write the intention here again since the code should be pretty self explaining by now. I have used comments to explain the still nontrivial procedure step by step revealing the real intention about all this complex program flow. The original complexity of the problem domain does not go away but by applying the techniques of SRP (Single Responsibility Principle) and some functional style but we can abstract the necessary complexity away in useful abstractions which make it much easier to reason about it. Since most of the method seems to deal with errors I thought it was a good idea to encapsulate the error state of our current message in an ErrorCollector object which stores all exceptions in a list along with a description what the error all was about in the exception itself. We can log it later or not depending on the log level or whatever. It is really just a simple list that encapsulates the current error state. class ErrorCollector { List<Exception> _Errors = new List<Exception>(); public void Add(Exception ex, string description) { ex.Data["Description"] = description; _Errors.Add(ex); } public Exception Last { get { return _Errors.LastOrDefault(); } } public bool HasError { get { return _Errors.Count > 0; } } } Since the error state is global we have two choices to store a reference in the other helper objects (TransactionHandler and MessageCompletionHandler)or pass it to the method calls when necessary. I did chose the latter one because a second argument does not hurt and makes it easier to reason about the overall state while the helper objects remain stateless and immutable which makes the helper objects much easier to understand and as a bonus thread safe as well. This does not mean that the stored member variables are stateless or thread safe as well but at least our helper classes are it. Most of the complexity is located the transaction handling I consider as a separate responsibility that I delegate to the TransactionHandler which does nothing if there is no transaction or Call the Before Commit Handler Commit Transaction Dispose Transaction if commit did throw In fact it has a second responsibility to resend the message if the transaction did fail. I did see a good fit there since it deals with transaction failures. class TransactionHandler { TransactionScope _Tx; Action<CurrentMessageInformation> _BeforeCommit; OpenedQueue _MessageQueue; public TransactionHandler(TransactionScope tx, Action<CurrentMessageInformation> beforeCommit, OpenedQueue messageQueue) { _Tx = tx; _BeforeCommit = beforeCommit; _MessageQueue = messageQueue; } public void CallHandlerAndCommit(CurrentMessageInformation currentMessageInfo, ErrorCollector errors) { if (_Tx != null && !errors.HasError) { try { if (_BeforeCommit != null) { _BeforeCommit(currentMessageInfo); } _Tx.Complete(); _Tx.Dispose(); } catch (Exception ex) { errors.Add(ex, "Failed to complete transaction, moving to error mode"); Trace.TraceWarning("Disposing transaction in error mode"); try { _Tx.Dispose(); } catch (Exception ex2) { errors.Add(ex2, "Failed to dispose of transaction in error mode."); } } } } public void ResendMessageOnError(Message message, ErrorCollector errors) { if (errors.HasError && !_MessageQueue.IsTransactional) { _MessageQueue.Send(message); } } } If we need to change the handling in the future we have a much easier time to reason about our application flow than before. After we did complete our transaction and called our callback we can call the completion handler which is the main purpose of the HandleMessageCompletion method after all. The responsiblity o the MessageCompletionHandler is to call the completion callback and the failure callback when some error has occurred. class MessageCompletionHandler { Action<CurrentMessageInformation, Exception> _MessageCompletedHandler; Action<CurrentMessageInformation, Exception> _MessageProcessingFailure; public MessageCompletionHandler(Action<CurrentMessageInformation, Exception> messageCompletedHandler, Action<CurrentMessageInformation, Exception> messageProcessingFailure) { _MessageCompletedHandler = messageCompletedHandler; _MessageProcessingFailure = messageProcessingFailure; } public void OnMessageCompleted(CurrentMessageInformation currentMessageInfo, ErrorCollector errors) { try { if (_MessageCompletedHandler != null) { _MessageCompletedHandler(currentMessageInfo, errors.Last); } } catch (Exception ex) { errors.Add(ex, "An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"); } if (errors.HasError) { SignalFailedMessage(currentMessageInfo, errors); } } void SignalFailedMessage(CurrentMessageInformation currentMessageInfo, ErrorCollector errors) { try { if (_MessageProcessingFailure != null) _MessageProcessingFailure(currentMessageInfo, errors.Last); } catch (Exception moduleException) { errors.Add(moduleException, "Module failed to process message failure"); } } } If for some reason I did screw up the logic and we need to call the completion handler from our Transaction handler we can simple add to the CallHandlerAndCommit method a third argument to the MessageCompletionHandler and we are fine again. If the logic becomes even more complex and we need to ensure that the completed event is triggered only once we have now one place the completion handler to capture the state. During this refactoring I simple put things together that belong together and came up with useful abstractions. If you look at the original argument list of the HandleMessageCompletion method I have put many things together: Original Arguments New Arguments Encapsulate Message message CurrentMessageInformation messageInfo Message message TransactionScope tx Action<CurrentMessageInformation> beforeTransactionCommit OpenedQueue messageQueue TransactionHandler transactionHandler TransactionScope tx OpenedQueue messageQueue Action<CurrentMessageInformation> beforeTransactionCommit Exception exception, ErrorCollector errors Action<CurrentMessageInformation, Exception> messageCompleted MessageCompletionHandler handler Action<CurrentMessageInformation, Exception> messageCompleted Action<CurrentMessageInformation, Exception> messageProcessingFailure The reason is simple: Put the things that have relationships together and you will find nearly automatically useful abstractions. I hope this makes sense to you. If you see a way to make it even more simple you can show Ayende your improved version as well.

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Oracle Solaris 11.1 Announced at Oracle OpenWorld

- by glynn

One of the highlights for me at Oracle OpenWorld was our announcement of the next update version to Oracle Solaris 11, named Oracle Solaris 11.1. Since November 2011, we've done a lot of work not only to polish existing features and fix literally hundreds of bugs, but also add many new features that give yet more reasons for using Oracle Solaris as the deployment platform for Oracle workloads - particularly the Oracle database. Over the last few years since the Sun Microsystems acquisition, we've had our developers sitting in Redwood Shores with the Oracle database team figuring out how to best optimize that combination and provide a level of integration that no other vendor (or solution) can match. Oracle Solaris 11.1 is often the first release many customers will adopt due to perceived instability of '.0' releases. In reality, however, we've seen incredible adoption already and all our existing customers are loving the new technologies like Image Packaging System (IPS), Automated Installer and ZFS Boot Environments, consolidated network management and network virtualization, and of course the existing features that are so critical to creating private, hybrid or public cloud environments like the Oracle Solaris ZFS file system and Oracle Solaris Zones server virtualization. If you haven't already gotten on board, there's plenty chance to catch up. More importantly, Oracle Solaris 11.1 really provides a platform that is significantly easier to manage than any previous Solaris releases - to the extent that it should be relatively straightforward for any experienced Linux administrator to get up to speed (if they're struggling, we have ways to help). So take a look at what's new in Oracle Solaris 11.1 and start planning your deployment now! If you missed the announcement, you can see the full video of John Fowler's keynote at Oracle OpenWorld here:

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Add linux user with restricted access

- by Dominik Str

I need to create a user on linux with access rights only to one folder. Background: I have installed git on my virtual server (Debian). I also created a user for the repository. There is a lot of private data on the server. But all folders have read-access for others, because it's needed for the applications which run on the server. So the git-user can see all the data. I would like to restrict the git user only to the folder where the repository is installed. I also tried ACL, but it didn't work. Is there a better way to do this? Thanks in advance!

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Juju Zookeeper & Provisioning Agent Not Deployed

- by Keith Tobin

I am using juju with the openstack provider, i expected that when i bootstrap that zookeeper and provisioning agent would get deployed on the bootstrap vm in openstack. This dose not seem to be the case. the bootstrap vm gets deployed but it seems that nothing gets deployed to the VM. See logs below, I may be missing something, also how is it possible to log on the bootstrap vm. Could I manual deploy, if so what do I need to do. Juju Bootstrap commend root@cinder01:/home/cinder# juju -v bootstrap 2012-10-12 03:21:20,976 DEBUG Initializing juju bootstrap runtime 2012-10-12 03:21:20,982 WARNING Verification of xxxxS certificates is disabled for this environment. Set 'ssl-hostname-verification' to ensure secure communication. 2012-10-12 03:21:20,982 DEBUG openstack: using auth-mode 'userpass' with xxxx:xxxxxx.10:35357/v2.0/ 2012-10-12 03:21:21,064 DEBUG openstack: authenticated til u'2012-10-13T08:21:13Z' 2012-10-12 03:21:21,064 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors' 2012-10-12 03:21:21,091 DEBUG openstack: 200 '{"flavors": [{"id": "3", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/3", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/3", "rel": "bookmark"}], "name": "m1.medium"}, {"id": "4", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/4", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/4", "rel": "bookmark"}], "name": "m1.large"}, {"id": "1", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "bookmark"}], "name": "m1.tiny"}, {"id": "5", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/5", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/5", "rel": "bookmark"}], "name": "m1.xlarge"}, {"id": "2", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/2", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/2", "rel": "bookmark"}], "name": "m1.small"}]}' 2012-10-12 03:21:21,091 INFO Bootstrapping environment 'openstack' (origin: ppa type: openstack)... 2012-10-12 03:21:21,091 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state 2012-10-12 03:21:21,092 DEBUG openstack: GET 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state' 2012-10-12 03:21:21,165 DEBUG openstack: 200 '{}\n' 2012-10-12 03:21:21,165 DEBUG Verifying writable storage 2012-10-12 03:21:21,165 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/bootstrap-verify 2012-10-12 03:21:21,166 DEBUG openstack: PUT 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/bootstrap-verify' 2012-10-12 03:21:21,251 DEBUG openstack: 201 '201 Created\n\n\n\n ' 2012-10-12 03:21:21,251 DEBUG Launching juju bootstrap instance. 2012-10-12 03:21:21,271 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/juju_master_id 2012-10-12 03:21:21,273 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-groups 2012-10-12 03:21:21,273 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-groups' 2012-10-12 03:21:21,321 DEBUG openstack: 200 '{"security_groups": [{"rules": [{"from_port": -1, "group": {}, "ip_protocol": "icmp", "to_port": -1, "parent_group_id": 1, "ip_range": {"cidr": "0.0.0.0/0"}, "id": 7}, {"from_port": 22, "group": {}, "ip_protocol": "tcp", "to_port": 22, "parent_group_id": 1, "ip_range": {"cidr": "0.0.0.0/0"}, "id": 38}], "tenant_id": "d5f52673953f49e595279e89ddde979d", "id": 1, "name": "default", "description": "default"}]}' 2012-10-12 03:21:21,322 DEBUG Creating juju security group juju-openstack 2012-10-12 03:21:21,322 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-groups' 2012-10-12 03:21:21,401 DEBUG openstack: 200 '{"security_group": {"rules": [], "tenant_id": "d5f52673953f49e595279e89ddde979d", "id": 48, "name": "juju-openstack", "description": "juju group for openstack"}}' 2012-10-12 03:21:21,401 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-group-rules' 2012-10-12 03:21:21,504 DEBUG openstack: 200 '{"security_group_rule": {"from_port": 22, "group": {}, "ip_protocol": "tcp", "to_port": 22, "parent_group_id": 48, "ip_range": {"cidr": "0.0.0.0/0"}, "id": 54}}' 2012-10-12 03:21:21,504 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-group-rules' 2012-10-12 03:21:21,647 DEBUG openstack: 200 '{"security_group_rule": {"from_port": 1, "group": {"tenant_id": "d5f52673953f49e595279e89ddde979d", "name": "juju-openstack"}, "ip_protocol": "tcp", "to_port": 65535, "parent_group_id": 48, "ip_range": {}, "id": 55}}' 2012-10-12 03:21:21,647 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-group-rules' 2012-10-12 03:21:21,791 DEBUG openstack: 200 '{"security_group_rule": {"from_port": 1, "group": {"tenant_id": "d5f52673953f49e595279e89ddde979d", "name": "juju-openstack"}, "ip_protocol": "udp", "to_port": 65535, "parent_group_id": 48, "ip_range": {}, "id": 56}}' 2012-10-12 03:21:21,792 DEBUG Creating machine security group juju-openstack-0 2012-10-12 03:21:21,792 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-groups' 2012-10-12 03:21:21,871 DEBUG openstack: 200 '{"security_group": {"rules": [], "tenant_id": "d5f52673953f49e595279e89ddde979d", "id": 49, "name": "juju-openstack-0", "description": "juju group for openstack machine 0"}}' 2012-10-12 03:21:21,871 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/detail 2012-10-12 03:21:21,871 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/detail' 2012-10-12 03:21:21,906 DEBUG openstack: 200 '{"flavors": [{"vcpus": 2, "disk": 10, "name": "m1.medium", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/3", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/3", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 40, "ram": 4096, "id": "3", "swap": ""}, {"vcpus": 4, "disk": 10, "name": "m1.large", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/4", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/4", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 80, "ram": 8192, "id": "4", "swap": ""}, {"vcpus": 1, "disk": 0, "name": "m1.tiny", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 0, "ram": 512, "id": "1", "swap": ""}, {"vcpus": 8, "disk": 10, "name": "m1.xlarge", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/5", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/5", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 160, "ram": 16384, "id": "5", "swap": ""}, {"vcpus": 1, "disk": 10, "name": "m1.small", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/2", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/2", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 20, "ram": 2048, "id": "2", "swap": ""}]}' 2012-10-12 03:21:21,907 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers 2012-10-12 03:21:21,907 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers' 2012-10-12 03:21:22,284 DEBUG openstack: 202 '{"server": {"OS-DCF:diskConfig": "MANUAL", "id": "a598b402-8678-4447-baeb-59255409a023", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "bookmark"}], "adminPass": "SuFp48cZzdo4"}}' 2012-10-12 03:21:22,284 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/juju_master_id 2012-10-12 03:21:22,285 DEBUG openstack: PUT 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/juju_master_id' 2012-10-12 03:21:22,375 DEBUG openstack: 201 '201 Created\n\n\n\n ' 2012-10-12 03:21:27,379 DEBUG Waited for 5 seconds for networking on server u'a598b402-8678-4447-baeb-59255409a023' 2012-10-12 03:21:27,380 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023 2012-10-12 03:21:27,380 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023' 2012-10-12 03:21:27,556 DEBUG openstack: 200 '{"server": {"OS-EXT-STS:task_state": "networking", "addresses": {"private": [{"version": 4, "addr": "10.0.0.8"}]}, "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "bookmark"}], "image": {"id": "5bf60467-0136-4471-9818-e13ade75a0a1", "links": [{"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/images/5bf60467-0136-4471-9818-e13ade75a0a1", "rel": "bookmark"}]}, "OS-EXT-STS:vm_state": "building", "OS-EXT-SRV-ATTR:instance_name": "instance-00000060", "flavor": {"id": "1", "links": [{"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "bookmark"}]}, "id": "a598b402-8678-4447-baeb-59255409a023", "user_id": "01610f73d0fb4922aefff09f2627e50c", "OS-DCF:diskConfig": "MANUAL", "accessIPv4": "", "accessIPv6": "", "progress": 0, "OS-EXT-STS:power_state": 0, "config_drive": "", "status": "BUILD", "updated": "2012-10-12T08:21:23Z", "hostId": "1cdb25708fb8e464d83a69fe4a024dcd5a80baf24a82ec28f9d9f866", "OS-EXT-SRV-ATTR:host": "nova01", "key_name": "", "OS-EXT-SRV-ATTR:hypervisor_hostname": null, "name": "juju openstack instance 0", "created": "2012-10-12T08:21:22Z", "tenant_id": "d5f52673953f49e595279e89ddde979d", "metadata": {}}}' 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 2012-10-12 03:21:27,557 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-floating-ips 2012-10-12 03:21:27,557 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-floating-ips' 2012-10-12 03:21:27,815 DEBUG openstack: 200 '{"floating_ips": [{"instance_id": "a0e0df11-91c0-4801-95b3-62d910d729e9", "ip": "xxxx.35", "fixed_ip": "10.0.0.5", "id": 447, "pool": "nova"}, {"instance_id": "b84f1a42-7192-415e-8650-ebb1aa56e97f", "ip": "xxxx.36", "fixed_ip": "10.0.0.6", "id": 448, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.37", "fixed_ip": null, "id": 449, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.38", "fixed_ip": null, "id": 450, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.39", "fixed_ip": null, "id": 451, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.40", "fixed_ip": null, "id": 452, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.41", "fixed_ip": null, "id": 453, "pool": "nova"}]}' 2012-10-12 03:21:27,815 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023/action 2012-10-12 03:21:27,816 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023/action' 2012-10-12 03:21:28,356 DEBUG openstack: 202 '' 2012-10-12 03:21:28,356 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state 2012-10-12 03:21:28,357 DEBUG openstack: PUT 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state' 2012-10-12 03:21:28,446 DEBUG openstack: 201 '201 Created\n\n\n\n ' 2012-10-12 03:21:28,446 INFO 'bootstrap' command finished successfully Juju Status Command root@cinder01:/home/cinder# juju -v status 2012-10-12 03:23:28,314 DEBUG Initializing juju status runtime 2012-10-12 03:23:28,320 WARNING Verification of xxxxS certificates is disabled for this environment. Set 'ssl-hostname-verification' to ensure secure communication. 2012-10-12 03:23:28,320 DEBUG openstack: using auth-mode 'userpass' with xxxx:xxxxxx.10:35357/v2.0/ 2012-10-12 03:23:28,320 INFO Connecting to environment... 2012-10-12 03:23:28,403 DEBUG openstack: authenticated til u'2012-10-13T08:23:20Z' 2012-10-12 03:23:28,403 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state 2012-10-12 03:23:28,403 DEBUG openstack: GET 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state' 2012-10-12 03:23:35,480 DEBUG openstack: 200 'zookeeper-instances: [a598b402-8678-4447-baeb-59255409a023]\n' 2012-10-12 03:23:35,480 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023 2012-10-12 03:23:35,480 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023' 2012-10-12 03:23:35,662 DEBUG openstack: 200 '{"server": {"OS-EXT-STS:task_state": null, "addresses": {"private": [{"version": 4, "addr": "10.0.0.8"}, {"version": 4, "addr": "xxxx.37"}]}, "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "bookmark"}], "image": {"id": "5bf60467-0136-4471-9818-e13ade75a0a1", "links": [{"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/images/5bf60467-0136-4471-9818-e13ade75a0a1", "rel": "bookmark"}]}, "OS-EXT-STS:vm_state": "active", "OS-EXT-SRV-ATTR:instance_name": "instance-00000060", "flavor": {"id": "1", "links": [{"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "bookmark"}]}, "id": "a598b402-8678-4447-baeb-59255409a023", "user_id": "01610f73d0fb4922aefff09f2627e50c", "OS-DCF:diskConfig": "MANUAL", "accessIPv4": "", "accessIPv6": "", "progress": 0, "OS-EXT-STS:power_state": 1, "config_drive": "", "status": "ACTIVE", "updated": "2012-10-12T08:21:40Z", "hostId": "1cdb25708fb8e464d83a69fe4a024dcd5a80baf24a82ec28f9d9f866", "OS-EXT-SRV-ATTR:host": "nova01", "key_name": "", "OS-EXT-SRV-ATTR:hypervisor_hostname": null, "name": "juju openstack instance 0", "created": "2012-10-12T08:21:22Z", "tenant_id": "d5f52673953f49e595279e89ddde979d", "metadata": {}}}' 2012-10-12 03:23:35,663 DEBUG Connecting to environment using xxxx.37... 2012-10-12 03:23:35,663 DEBUG Spawning SSH process with remote_user="ubuntu" remote_host="xxxx.37" remote_port="2181" local_port="45859". 2012-10-12 03:23:36,173:4355(0x7fd581973700):ZOO_INFO@log_env@658: Client environment:zookeeper.version=zookeeper C client 3.3.5 2012-10-12 03:23:36,173:4355(0x7fd581973700):ZOO_INFO@log_env@662: Client environment:host.name=cinder01 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@669: Client environment:os.name=Linux 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@670: Client environment:os.arch=3.2.0-23-generic 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@671: Client environment:os.version=#36-Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@679: Client environment:user.name=cinder 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@687: Client environment:user.home=/root 2012-10-12 03:23:36,175:4355(0x7fd581973700):ZOO_INFO@log_env@699: Client environment:user.dir=/home/cinder 2012-10-12 03:23:36,175:4355(0x7fd581973700):ZOO_INFO@zookeeper_init@727: Initiating client connection, host=localhost:45859 sessionTimeout=10000 watcher=0x7fd57f9146b0 sessionId=0 sessionPasswd= context=0x2c1dab0 flags=0 2012-10-12 03:23:36,175:4355(0x7fd577fff700):ZOO_ERROR@handle_socket_error_msg@1579: Socket [127.0.0.1:45859] zk retcode=-4, errno=111(Connection refused): server refused to accept the client 2012-10-12 03:23:39,512:4355(0x7fd577fff700):ZOO_ERROR@handle_socket_error_msg@1579: Socket [127.0.0.1:45859] zk retcode=-4, errno=111(Connection refused): server refused to accept the client 2012-10-12 03:23:42,848:4355(0x7fd577fff700):ZOO_ERROR@handle_socket_error_msg@1579: Socket [127.0.0.1:45859] zk retcode=-4, errno=111(Connection refused): server refused to accept the client ^Croot@cinder01:/home/cinder#

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Couldn't find package - But package is listed in the Packages file

- by Chris

(Quoted items are redacted elements) I am using a private repository and an currently trying to repackage some packages 3rd-party packages. I extract the package, make a few modifications (just the control files to fit with company policy - though sometimes file install locations though not in this case) and repackage (and usually rename). Normally I copy the files into a new blank debhelper project and reconstruct the package, however, with a recent one I attempting to convert and some libraries and stuff aren't linking properly (I did copy the postinst, postrm, and preinst files along with all DEDIAN files exactly), the original package worked, but my repackage doesn't, despite providing the same files in the same locations and the same postinst and preinst. So I was attempting to just modify the current packages control files (as the original package is not very good and will not list in our repository and getting a better one from the 3rd party is not an option). I also renamed the package. I did the following: dpkg-deb -R "directory" Modify DEBIAN/control dpkg-deb -b "directory" "package name I want" I did this and put it in our repository. The package shows up in the "Packages" file on the repository and running apt-get update on the client side shows the package in: /var/lib/apt/lists/"server"_"location"_Packages However when I do an apt-get install on the package name (as listed in the Packages file - I did a copy paste) it says it can't find the package. Same with an apt-cache search The Packages listings is as follow (name redacted): Package: "package name" Priority: extra Section: unknown Maintainer: "maintainer" Architecture: any Version: 1.0-lucid5 Depends: libc Filename: "directory"/"package_filename" Size: 2206292 MD5sum: "md5sum" SHA1: "sha key" SHA256: "sha256 key" Description: "description" I am running as sudo (and tried as root as well). I don't understand why apt-get won't see the package. Can you point out any flaws in what I have done, or perhaps some help on getting apt-get to properly see the package. Or perhaps an alternative. I am not even sure if this is a valid way to repackage something. Thanks.

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Pfsense: Inbound Load Balancing https with sticky connection

- by Zeux

first of all I'm very sorry for my English... This is my scenario: Internet Firewall+LB: pfsense_1(Active) + pfsense_2(Passive) in CARP Pool servers: 3 x nginx(PHP5+HTTP+HTTPS) Pfsense 1 and 2 CARP configured with Virtual IP (pubblic). Nginx servers's ips are all private. I want to load balance inbound HTTP and HTTPS connections between the 3 nginx web servers. An importat thing is that the HTTPS connections must be "sticky connections": in HTTPS connections, after login by username and password, I setup a php session and therefore when a client starts a HTTPS connection it will be always redirected to the same nginx server, until it disconnects itself, it closes the page/browser or after a timeout (30minutes?) without activity. Is this possible whit the last release(2.0.1) of pfsense? thank you very much...

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How I understood monads, part 1/2: sleepless and self-loathing in Seattle

- by Bertrand Le Roy

For some time now, I had been noticing some interest for monads, mostly in the form of unintelligible (to me) blog posts and comments saying “oh, yeah, that’s a monad” about random stuff as if it were absolutely obvious and if I didn’t know what they were talking about, I was probably an uneducated idiot, ignorant about the simplest and most fundamental concepts of functional programming. Fair enough, I am pretty much exactly that. Being the kind of guy who can spend eight years in college just to understand a few interesting concepts about the universe, I had to check it out and try to understand monads so that I too can say “oh, yeah, that’s a monad”. Man, was I hit hard in the face with the limitations of my own abstract thinking abilities. All the articles I could find about the subject seemed to be vaguely understandable at first but very quickly overloaded the very few concept slots I have available in my brain. They also seemed to be consistently using arcane notation that I was entirely unfamiliar with. It finally all clicked together one Friday afternoon during the team’s beer symposium when Louis was patient enough to break it down for me in a language I could understand (C#). I don’t know if being intoxicated helped. Feel free to read this with or without a drink in hand. So here it is in a nutshell: a monad allows you to manipulate stuff in interesting ways. Oh, OK, you might say. Yeah. Exactly. Let’s start with a trivial case: public static class Trivial { public static TResult Execute<T, TResult>( this T argument, Func<T, TResult> operation) { return operation(argument); } } This is not a monad. I removed most concepts here to start with something very simple. There is only one concept here: the idea of executing an operation on an object. This is of course trivial and it would actually be simpler to just apply that operation directly on the object. But please bear with me, this is our first baby step. Here’s how you use that thing: "some string" .Execute(s => s + " processed by trivial proto-monad.") .Execute(s => s + " And it's chainable!"); What we’re doing here is analogous to having an assembly chain in a factory: you can feed it raw material (the string here) and a number of machines that each implement a step in the manufacturing process and you can start building stuff. The Trivial class here represents the empty assembly chain, the conveyor belt if you will, but it doesn’t care what kind of raw material gets in, what gets out or what each machine is doing. It is pure process. A real monad will need a couple of additional concepts. Let’s say the conveyor belt needs the material to be processed to be contained in standardized boxes, just so that it can safely and efficiently be transported from machine to machine or so that tracking information can be attached to it. Each machine knows how to treat raw material or partly processed material, but it doesn’t know how to treat the boxes so the conveyor belt will have to extract the material from the box before feeding it into each machine, and it will have to box it back afterwards. This conveyor belt with boxes is essentially what a monad is. It has one method to box stuff, one to extract stuff from its box and one to feed stuff into a machine. So let’s reformulate the previous example but this time with the boxes, which will do nothing for the moment except containing stuff. public class Identity<T> { public Identity(T value) { Value = value; } public T Value { get; private set;} public static Identity<T> Unit(T value) { return new Identity<T>(value); } public static Identity<U> Bind<U>( Identity<T> argument, Func<T, Identity<U>> operation) { return operation(argument.Value); } } Now this is a true to the definition Monad, including the weird naming of the methods. It is the simplest monad, called the identity monad and of course it does nothing useful. Here’s how you use it: Identity<string>.Bind( Identity<string>.Unit("some string"), s => Identity<string>.Unit( s + " was processed by identity monad.")).Value That of course is seriously ugly. Note that the operation is responsible for re-boxing its result. That is a part of strict monads that I don’t quite get and I’ll take the liberty to lift that strange constraint in the next examples. To make this more readable and easier to use, let’s build a few extension methods: public static class IdentityExtensions { public static Identity<T> ToIdentity<T>(this T value) { return new Identity<T>(value); } public static Identity<U> Bind<T, U>( this Identity<T> argument, Func<T, U> operation) { return operation(argument.Value).ToIdentity(); } } With those, we can rewrite our code as follows: "some string".ToIdentity() .Bind(s => s + " was processed by monad extensions.") .Bind(s => s + " And it's chainable...") .Value; This is considerably simpler but still retains the qualities of a monad. But it is still pointless. Let’s look at a more useful example, the state monad, which is basically a monad where the boxes have a label. It’s useful to perform operations on arbitrary objects that have been enriched with an attached state object. public class Stateful<TValue, TState> { public Stateful(TValue value, TState state) { Value = value; State = state; } public TValue Value { get; private set; } public TState State { get; set; } } public static class StateExtensions { public static Stateful<TValue, TState> ToStateful<TValue, TState>( this TValue value, TState state) { return new Stateful<TValue, TState>(value, state); } public static Stateful<TResult, TState> Execute<TValue, TState, TResult>( this Stateful<TValue, TState> argument, Func<TValue, TResult> operation) { return operation(argument.Value) .ToStateful(argument.State); } } You can get a stateful version of any object by calling the ToStateful extension method, passing the state object in. You can then execute ordinary operations on the values while retaining the state: var statefulInt = 3.ToStateful("This is the state"); var processedStatefulInt = statefulInt .Execute(i => ++i) .Execute(i => i * 10) .Execute(i => i + 2); Console.WriteLine("Value: {0}; state: {1}", processedStatefulInt.Value, processedStatefulInt.State); This monad differs from the identity by enriching the boxes. There is another way to give value to the monad, which is to enrich the processing. An example of that is the writer monad, which can be typically used to log the operations that are being performed by the monad. Of course, the richest monads enrich both the boxes and the processing. That’s all for today. I hope with this you won’t have to go through the same process that I did to understand monads and that you haven’t gone into concept overload like I did. Next time, we’ll examine some examples that you already know but we will shine the monadic light, hopefully illuminating them in a whole new way. Realizing that this pattern is actually in many places but mostly unnoticed is what will enable the truly casual “oh, yes, that’s a monad” comments. Here’s the code for this article: http://weblogs.asp.net/blogs/bleroy/Samples/Monads.zip The Wikipedia article on monads: http://en.wikipedia.org/wiki/Monads_in_functional_programming This article was invaluable for me in understanding how to express the canonical monads in C# (interesting Linq stuff in there): http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marvels-of-monads.aspx

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Fail rate of EBS snapshots and AMIs?

- by user784637

According to Amazon the fail rate of EBS volumes is: As an example, volumes that operate with 20 GB or less of modified data since their most recent Amazon EBS snapshot can expect an annual failure rate (AFR) of between 0.1% – 0.5%, where failure refers to a complete loss of the volume http://aws.amazon.com/ebs/ However, I was curious to know the fail rate of EBS snapshots and private AMIs that a system admin would take. Since the EBS snapshots and AMIs are stored in Amazon s3, is it safe to assume that the likelihood you cannot rollback to a previous snapshot or AMI the same likelihood that a file gets lost in s3? Amazon S3’s standard storage is: ... Designed to provide 99.999999999% durability and 99.99% availability of objects over a given year. http://aws.amazon.com/s3/

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Stir Trek: Thor Edition Registration Opens March 17th

- by Brian Jackett

Registration for Stir Trek: Thor Edition opens at 12:00am “Thors"day March 17th. Stir Trek is now in its third year and this is the second year I’ve helped with planning. For those unfamiliar the Stir Trek conference here is the description from the website. Stir Trek is an opportunity to learn about the newest advances and latest trends in Web and Mobile development. There will be 30 Sessions in six tracks, so you can pick the content that interests you the most. And the best part? At the end of the day you will be treated to a private screening of Thor on its opening day! Last year Stir Trek: Iron Man Edition sold out well before the conference and had a long waitlist. Based on CodeMash selling out in just 3.5 days earlier this year I highly recommend you register early. We also have a star studded list of speakers ranging from international experts to local leaders. This will be the best $35 you spend all year. Easter Egg: I originally had an idea that we should start selling tickets at 1:30am rather than 12:00am. If you can figure out why I proposed 1:30am leave a comment below. Any good sleuths will find this riddle elementary. -Frog Out

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