pdf->Universally accepted format
xps->Only recently printer manufacturers have been adding it.
pdf->Can be opened using acrobat reader on any os.
xps->xps viewer only works on windows xp, server 2003 and vista
Wednesday, October 31, 2007
Monday, October 22, 2007
What is SOA and how does it work?
Previously applications were considered as an isolated entity. They reside on on machine and do not have much ability to communicate with other applications. This lead to the following problems.
1. There was no reuse of the same functionality present in different applications.
2. The applications once deployed have very less chance of changing or updating there functionality.
3. If solid small applications are created with robust testing and they group together to create a composite application, then the chances of them being buggy is minimized.
The idea behind the SOA architecture is that there will be lot of small modular applications which can be called by a composite application on a service basis. This composite applications decides on the services it needs and then groups together all this small applications and gets its job done by delegating tasks to each of these applications. As an example:
A train carrying tourist is traveling between two cities through a scenic terrain and depending on the weather it has the option to decide on multiple pathways. The train can achieve this dynamic calculations of the path by having a software on board the trains computers which determine the weather outside and then do the calculation or it can just call a service running somewhere on the internet and this tells what path it should take.
The problem with the application in the onboard computers is that if there is a change in the pathway, like addition of a new path or closing of a old path, the software needs to be updated on every train that runs in this route, whereas if the train is just using a service then you just update the service once and all the trains will get the correct and up to date information.
Another advantage is that this weather service can also be shared by other people including sports team who are trying to schedule a outdoor event. They could just reuse the weather module of the service instead of writing a new application for that.
SOA solves thses problems.
1. There was no reuse of the same functionality present in different applications.
2. The applications once deployed have very less chance of changing or updating there functionality.
3. If solid small applications are created with robust testing and they group together to create a composite application, then the chances of them being buggy is minimized.
The idea behind the SOA architecture is that there will be lot of small modular applications which can be called by a composite application on a service basis. This composite applications decides on the services it needs and then groups together all this small applications and gets its job done by delegating tasks to each of these applications. As an example:
A train carrying tourist is traveling between two cities through a scenic terrain and depending on the weather it has the option to decide on multiple pathways. The train can achieve this dynamic calculations of the path by having a software on board the trains computers which determine the weather outside and then do the calculation or it can just call a service running somewhere on the internet and this tells what path it should take.
The problem with the application in the onboard computers is that if there is a change in the pathway, like addition of a new path or closing of a old path, the software needs to be updated on every train that runs in this route, whereas if the train is just using a service then you just update the service once and all the trains will get the correct and up to date information.
Another advantage is that this weather service can also be shared by other people including sports team who are trying to schedule a outdoor event. They could just reuse the weather module of the service instead of writing a new application for that.
SOA solves thses problems.
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Friday, October 12, 2007
Why we need libraries in C and how do you create them?
Link to the article:
http://users.actcom.co.il/~choo/lupg/tutorials/libraries/unix-c-libraries.html
1. The c language is a very basic construct with just the language syntax.
2. All the other functionalities are accessed through the libraries.
3. Advantage of the dynamic library is that multiple programs can access the same library at one time and this will save a lot of memory.
4. You do not need to compile each program separately if you change one library.
5. Static library if just the grouping together of the all the object files. Like libstdc++.a is the grouping of math.o string.o stdlib.o ect
6. The static library is created using the "ar" command which just groups the .o files together.
Like ar rc libutil.a util_file.o util_net.o util_math.o
7. Share lib can be Position independent code or can be Library file creation which is platform dependent.
http://users.actcom.co.il/~choo/lupg/tutorials/libraries/unix-c-libraries.html
1. The c language is a very basic construct with just the language syntax.
2. All the other functionalities are accessed through the libraries.
3. Advantage of the dynamic library is that multiple programs can access the same library at one time and this will save a lot of memory.
4. You do not need to compile each program separately if you change one library.
5. Static library if just the grouping together of the all the object files. Like libstdc++.a is the grouping of math.o string.o stdlib.o ect
6. The static library is created using the "ar" command which just groups the .o files together.
Like ar rc libutil.a util_file.o util_net.o util_math.o
7. Share lib can be Position independent code or can be Library file creation which is platform dependent.
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Macromedia Flash?
This is a technology to display audio and video on the websites. The browser needs to download a client program and this reads the .swf files and displays the video. Vector graphics is used in the actionscript language that is used to code a flash program.
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Thursday, October 11, 2007
Component Object Model problems
1. Dll hell is the problem when a old dll is installed over a new on then it overwrites part of the new Dll in the registry and the applications using this DLL stop working correctly.
2. Reference counts and Release reference are particulary difficult to manage in com. Addref and releaseif not implemented correctly can lead to premature release or never release of the COM object
3. COM is mostly windows standard and building bridges from it to other platform is difficult
4. COM interface such IUnknown and IDispatch have a huge learning curve.
2. Reference counts and Release reference are particulary difficult to manage in com. Addref and releaseif not implemented correctly can lead to premature release or never release of the COM object
3. COM is mostly windows standard and building bridges from it to other platform is difficult
4. COM interface such IUnknown and IDispatch have a huge learning curve.
.Net architecture
1. What technology does this replace?
It replaces the Win32 model and attempts to replace the Java technology. Java programs follow the "build once in Java and run on multiple platform" pattern. Net is build in any .net language and run in any platform.
2. Do we need any special software installation to run a .net program?
Just like the Java (JVM) we need to install the CLR to run a .NET program.
3. Is it really true that with .net architecture we can run software on any platform, anytime, anywhere and on small and large devices?
Yes, Developers can create a programin windows and run it in Linux or Mac provided they offer a CLR environment.
4. What are the .net languages?
C++, C#, vb.net, asp.net
5. What does it mean when we say .Net is web enabled?
6. How can a CLR environment be installed in the Mac OS?
It replaces the Win32 model and attempts to replace the Java technology. Java programs follow the "build once in Java and run on multiple platform" pattern. Net is build in any .net language and run in any platform.
2. Do we need any special software installation to run a .net program?
Just like the Java (JVM) we need to install the CLR to run a .NET program.
3. Is it really true that with .net architecture we can run software on any platform, anytime, anywhere and on small and large devices?
Yes, Developers can create a programin windows and run it in Linux or Mac provided they offer a CLR environment.
4. What are the .net languages?
C++, C#, vb.net, asp.net
5. What does it mean when we say .Net is web enabled?
6. How can a CLR environment be installed in the Mac OS?
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