Distributed Transactions on Windows 2008 Systems - I
When using distributed transactions between distinct databases, using Microsoft Windows technology, one relies on the MSDTC - Microsoft Distributed Transaction Coordinator.
The main catch to this distributed architecture is that it works based on the hosts NetBIOS names, which is specific to the Windows operating systems and is used for network resource sharing and the like.
There are at least four relevant deployment scenarios concerning this technology:
The first scenario, full stack, isn't challenging because it assumes you have the Application Server and Databases all in the same machine. It can be imagined as the common scenario for developer machines which often have the IDE, DB Server and App Server all-in-one.
The second scenario where all hosts reside on the same network segment, usually a net mask of 255.255.255.0, requires only additional configuration if there are no WINS server available and network broadcast of packages has been disabled. Otherwise the default configuration will work fine.
Next post will discuss a configuration scenario with a firewall in between the Application Server and the Database Server.
The main catch to this distributed architecture is that it works based on the hosts NetBIOS names, which is specific to the Windows operating systems and is used for network resource sharing and the like.
There are at least four relevant deployment scenarios concerning this technology:
- Full stack on the same physical host
- DHCP reliant network, all hosts on the same segment
- DHCP reliant networks, with firewalls between segments
- Static Address network with firewalls
The first scenario, full stack, isn't challenging because it assumes you have the Application Server and Databases all in the same machine. It can be imagined as the common scenario for developer machines which often have the IDE, DB Server and App Server all-in-one.
The second scenario where all hosts reside on the same network segment, usually a net mask of 255.255.255.0, requires only additional configuration if there are no WINS server available and network broadcast of packages has been disabled. Otherwise the default configuration will work fine.
Next post will discuss a configuration scenario with a firewall in between the Application Server and the Database Server.
Free alternative to XML Spy
Professionally I'm sometimes faced with the challenge of being assigned a task, without having the adequate tools to perform it. An example of that is working with XML files.
Not having acquired a commercial software like XML Spy, I had to find a free alternative. To open XML files, pretty-print them and check for issues, I adopted XML Copy Editor:
XML Copy Editor is a free editor that enables you to:
Not having acquired a commercial software like XML Spy, I had to find a free alternative. To open XML files, pretty-print them and check for issues, I adopted XML Copy Editor:
XML Copy Editor is a free editor that enables you to:
- open XML files
- edit your own XML
- check if the XML is well formed
- check the XML for compliance with a given schema
Additionally it also performs advanced user operations like syntax highlighting and XPath evaluations. Overall, XML Copy Editor performs all the tasks necessary for XML analysis.
Delete Blogger pictures from Picasa
Before this one, I had a couple of blogs hosted on Blogger. The pictures I used on the blogs posts were uploaded into Picasa Web Albums.
Having deleted thos blogs I no longer need the pictures, but the delete option was disabled.
The solution to delete an album associated with a blog is to first delete all the pictures on it, and then delete the album.
You don't need to delete a picture at once. If you select the option "Edit > Reorganize & Reorder", you can select all pictures and delete them.
HTH y'all!
Netbeans and Glassfish Error: CLI130 Could not create domain
Having Netbeans 6.8 installed, with Glassfish V3 on a laptop running Windows 7, I had the following error upon starting the IDE:
CLI130 Could not create domain
Apparently, the J2EE development server domain could not be created. I opened a command prompt, navigated to the Glassfish installation folder and executed the "asaadmin create-domain" to create a new domain. Still no luck! A lack of privileges prevented the new domain folder creation.
Next, I repeated the same step, but opened the prompt with the "Run as administrator" option. The domain creation went smoothly and after starting the IDE, the same error appeared because it would always try to start the default domain.
I carried on, manually starting my domain with the "asadmin start-domain" command and connecting to the server as if it was a remote server. But I was not pleased with the solution.
So, I tried to start the IDE with "Run as Administrator" option. And it worked. After all, it had a really simple work around.
CLI130 Could not create domain
Apparently, the J2EE development server domain could not be created. I opened a command prompt, navigated to the Glassfish installation folder and executed the "asaadmin create-domain" to create a new domain. Still no luck! A lack of privileges prevented the new domain folder creation.
Next, I repeated the same step, but opened the prompt with the "Run as administrator" option. The domain creation went smoothly and after starting the IDE, the same error appeared because it would always try to start the default domain.
I carried on, manually starting my domain with the "asadmin start-domain" command and connecting to the server as if it was a remote server. But I was not pleased with the solution.
So, I tried to start the IDE with "Run as Administrator" option. And it worked. After all, it had a really simple work around.
Migrating from Wordpress to Blogger
As you might know, if you were following my blog on the previous address, I've migrated it from Wordpress to Blogger. The reason for doing so is just that Blogger let's you control the page's content with a finer grain, even write raw HTML it you want to.
I managed to get all my posts from Wordpress and import them to blogger. The problem at hand with that is Blogger only supports file exported from another Blogger hosted blog.
The solution I found was as follows:
- Export all the posts from the previous site, hosted on Wordpress, to a file in the WordPress eXtended RSS (WXR) format. You can do this going to "Tools > Export" on your Wordpress dashboard.
- Next I found this tool, called Wordpress2Blogger, uploaded my WXR file and downloaded a new file, this one on the Blogger RSS format.
- Finally, I imported the given file into Blogger, using the available import option,
With three simple steps, not counting the new blog account registration, the migration is successful.
Security on ASP.NET applications
The evolution of information systems places more and more applications on web-based architectures. The concern with security on this type of systems has to evolve also. Any programmer familiar with Web development is a potential script kiddie. The task of corrupting, destroying or getting illicit access to data cannot be facilitated.
There is a series of guides on Microsoft Developer's Network, on how to protect an ASP.NET application against injection attacks. The guides are pretty straightforward, giving a brief notion of the attacks and also the counter measures one can adopt to prevent them:
Even if you have already deployed applications, it's very well worth it to spend some time analyzing them and integrating the security enhancements explained. Better safe than sorry.
There is a series of guides on Microsoft Developer's Network, on how to protect an ASP.NET application against injection attacks. The guides are pretty straightforward, giving a brief notion of the attacks and also the counter measures one can adopt to prevent them:
- How To: Protect From Injection Attacks in ASP.NET
- How To: Protect From SQL Injection in ASP.NET
- How To: Prevent Cross-Site Scripting in ASP.NET
- How To: Use Regular Expressions to Constrain Input in ASP.NET
Even if you have already deployed applications, it's very well worth it to spend some time analyzing them and integrating the security enhancements explained. Better safe than sorry.
Connecting VPN on Ubuntu
Sometimes, to insure a service's quality stated on a Service Level Agreement, one has to do interventions on the systems at any given hour of the day. Even late at night, or on holidays.
Given the possibility of connecting to my Workplace´s network through VPN, I faced the challenge of configuring a VPN network client on Ubuntu Linux (9.10). Our communications staff had a ready to use setup for Windows, but that didn't help much. So I took the exported Cisco PCF file and got engaged on this task.
Overall, it wasn't as tricky as I would expect. I performed the following steps:
Having finished the installation:
I tried to import the pcf file directly, without using the wizard and it didn't work. Anyway, when your VPN connection is active, open a terminal window and run the command "ifconfig". Your VPN tunnel should be listed on the active connections.
Given the possibility of connecting to my Workplace´s network through VPN, I faced the challenge of configuring a VPN network client on Ubuntu Linux (9.10). Our communications staff had a ready to use setup for Windows, but that didn't help much. So I took the exported Cisco PCF file and got engaged on this task.
Overall, it wasn't as tricky as I would expect. I performed the following steps:
- Open the Synaptic Package Manager
- Selected the following packages: vpnc, network-manager-vpnc, KVpnc
- Apply the changes
Having finished the installation:
- Go to the Application menu, select Internet/KVpnc
- Start the new connection wizard and import the pcf file
- Save your new profile
- Connect and ... that's it!
I tried to import the pcf file directly, without using the wizard and it didn't work. Anyway, when your VPN connection is active, open a terminal window and run the command "ifconfig". Your VPN tunnel should be listed on the active connections.
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