Good resources for understanding how the internet works
Hi everyone,
I got quite a lot of spare time at my hands these days, so I thought I might learn about how the internet (and networking in general, after all I'm using the internet daily, and I've even programmed with Java sockets for ages)! Specifically, I'm probably talking about the OSI model and its components.
Historically, reading Wikipedia entries doesn't quite cut it for me, I tend to get the hang of things a lot easier with a book. So, if you know a good book (though a good online guide / explanation is fine, too), please let me know!
Cheers,
- Allan
At my uni, we use "Computer Networking: A Top-Down Approach" by James Kurose and Keith Ross for all our networking classes. I wholeheartedly recommend it; it's clear, approachable, and something you'd want to read if you didn't have to read it.
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Documents/PPT for Understanding how SAP SRM works from SAP website
Hi,
Can some one help me in finding some docs/ppts which helps me to understand how SAP SRM working from SAP website.
Regards,
ManeshHi, thanks for the response.
This is what they get
Fatal error: Call to a member function remove_all() on a non-object in .../.../.../welcome.php
This error is not generated by SAP. It is shopping cart error.
And here is the content of welcome.php
<?php
require("includes/application_top.php");
$cart->remove_all();
$hook = $_REQUEST['HOOK_URL'];
?>
The value of HOOK_URL is empty
<a href="index.php?HOOK_URL=<?php echo $hook; ?>">Start shopping here</a>
Edited by: janjan123 on May 14, 2010 5:06 PM -
Trying to understand how the DDK works
Hi,
1.) If I wanted to be able to use a wide variety of NI DAQ cards
under the QNX RTOS, would the NI Measurement Hardware DDK be able to
faciliate this?
2.) From looking at the web-page describing the DDK, it looks to
me that the driver code written by NI is done in a platform indepedant
way, using only ANSI C/C++ function, and when it needs
to do something platform specific, it calls out to functions that I can
provide. Is this correct? I am envisioning having to
provide code to get PCI resources, attach to interrupt, hw I/O.... am I
on the right track?
3.) I've downloaded the NI HW DDK OTHER code, but it's not clear to me
how the platform-dependant code for QNX will integrate with this. I
have the DAQ PCI_E_series Register Level Programming Manual
and STC manual, but I can't find any docs on how to use the code in
this archive. What am I missing?
ThanksHi,
1.) If I wanted to be able to use a wide variety of NI DAQ cards
under the QNX RTOS, would the NI Measurement Hardware DDK be able to
faciliate this?
Depends. MHDDK provides register information for a number of NI
DAQ devices. There isn't an API that abstracts the measurement
task form the hardware, like DAQmx does.
You would need to write the high level functions for each type of
device you what to use and provide an API to your application that
would select the appropriate device specific function. I guess
something like
startDevice()
// somehow get deviceTypeId
switch (deviceTypeId)
case kMSeries:
mseries_startDevice();
case ESeries
eseries_startDevice();
or using function pointers, or c++ inheritance. There are many possibilities...
2.) .... am I
on the right track?
Yes. MHDDK only abstracts device access using the iBus and
tAddressSpace objects. The iBus contains the address spaces of
the device. You request address spaces from the bus and use it
write/read from the device. For PCI devices the read/write
functions using pointer manipuilation. For a PCMCIA device on a
x86 you would use the port io instructions.
iBus objects are created and destroy using the factory methods
acquireBoard() and releaseBoard(). This is where all the platform
dependent magic should occur. Here are a couple of KBs with more info:
Measurement Hardware Driver Development Kit Register Level Programming Architecture
How to Make an iBus
3.) I've downloaded the NI HW DDK OTHER code, but it's not clear to me
how the platform-dependant code for QNX will integrate with this. I
have the DAQ PCI_E_series Register Level Programming Manual
and STC manual, but I can't find any docs on how to use the code in
this archive. What am I missing?
In osiUserCode.cpp, implement acquireBoard(tChar*) and
releaseBoard(iBus *&). To acquire the board you usually
have to loacte the device, find bar0 and bar1 , and map them to the
current address space.
This article shows exactly how to do that in QNX: Talking to hardware under QNX Neutrino
Also, create a QNX specific structure to
attach to the iBus where you can store any handles you need for
releaseBoard() to clean up.
Hope this helps.
Diego -
Good resources for learning how to use Aperture's adjustments
I'm a long-time visual artist who is just now getting into photography. I own both Lightroom and Aperture, and I must say that, for me, Aperture's interface and philosophy are my favorites. I love the way it handles photo organization. I have one problem, however. Being a relative photographic newbie, I have a terrible time with the adjustments. I seem to have a much easier time making good-looking adjustments in Lightroom. In Aperture, I just aimlessly noodle around, make a mess, and undo all my changes regularly.
I just found the Apple manual on making adjustments. I was wondering what other resources you more experienced photographers used to learn your way around.
Thanks,
MarkThanks I have that one on order from Amazon even as we speak. As an update, I've also found some information on bagelturf.com, and it looks as though Aperture Users Professional Network is going to start a 7-part series on Adjustments in Aperture. That sounds just like what the doctor ordered.
O'Reilly's "Inside Aperture" site also seems worthwhile. I'm sure you all know about these. I'm glad they're there. I've subscribed to a couple of podcasts as well.
Mark -
Trying to understand how the sync works
So this is what i am trying to figure out.
I know that if i create a document in pages on my mac that i need to upload the doc via icould for it to show in iwork. I also know that if i access that file from my iphone or ipad and make changes to that document that it automatically updates it on icloud.
This is my question, Is there a way when i make changes to that document on my mac that it automatically updates it like my iphone and ipad does on icloud. Coz whats happening at the moment is every time i make a change to the doc on my mac its currently NOT updating it on icloud. I am doing something wrong or does it just not update the document?
Thanks for your help!If you change a document on your iOS device, then you need to download it from iCloud.com to make changes to it on your mac. Once you make changes on the mac, if you want to work on it on iOS devices again, you need to upload it again to iCloud.com.
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Need to understand how the dataguard works in a RAC enviornment
We had a dba just left, and I inherited the system now. I want to be sure I monitor right information on the dataguard.
Help please.The DBA would have documented how DG is setup / monitored.
Else, read the DataGuard Administration Guide for the version you are running.
start at http://tahiti.oracle.com
If you are not a DBA, you should be equally and more concerned about the Primary database !
Hemant K Chitale -
How the balance works for http/https in CSS?
I want to understand how the balance works for http/https in the CSS.
As per doc,
- http/1.0=single URL per TCP connection
- http/1.1=persistent connection.
Q1. my understanding is http is stateless connection so needs TCP session for each URL. how the http/1.1 works with persistent. keep the same TCP session for a multiple URL request?
Q2. https is using single URL and continue processing until terminate the https instead of open another URL in the middle of transaction. in this case, I think the client can stick into same service based on the assumption the CSS support persistent. if then, no advanced sticky(ex, srcip) required?
Q3. looks below both are analogy. what's difference between them?
- balance srcip(same src IP to the same service)
- advanced-balance sticky-srcip
Q4. what's balance decision mechanism for "balance roundrobin" to distribute evenly? ex, in case of multiple URL request coming from same client. evenly distribute URLs?
Regards,Hello,
first let me clarify 1 point.
HTTP/HTTPS are standards that are defined in RFC.
For HTTP/1.1 you can check the following RFC
http://www.faqs.org/rfcs/rfc2616.html
Therefore, the behavior of HTTP 1.1 is not defined by the CSS.
Q1- HTTP/1.1 simply keeps 1 TCP connection to send a received mutiplie HTTP request/response.
HTTP/1.0 will open 1 TCP connection for every HTTP request.
Q2- HTTPS is just HTTP over SSL.
So basically the same rule as above applies.
HTTP/1.1 can use 1 SSL connection for many HTTP request/response while HTTP/1.0 will use 1 SSL connection for each HTTP request.
Therefore, if you have customer using HTTP/1.0 you need some form of stickyness to guarantee that every connections will go to the same server.
Even if only using HTTP/1.1 you may need stickyness.
A user could disconnect and reconnect and require to be loadbalanced to the same server as before.
Q3- There is a big different between balance srcip and sticky-srcip.
The balance srcip simply hash the source ip address to find the destination server.
The problem of this method is that the loadbalancing is not guarantee to be evenly distributed between the servers.
With sticky-srcip, you use a normal balance method like round-robin, and then you create a sticky entry in a sticky table.
Next time this user comes back we first check the sticky entry to find the destination server.
The advantage is that it guarantess your users will be evenly distributed among the server.
Q4- roundrobin is applied to connection - not url [by default].
So if you have 2 users and they both open 1 connection, the CSS will send 1 connection to 2 different servers.
So each server has 1 connection.
If one user sens 10 URL and the other 1 sends only 1, one server will have 10 url to process while the other only one.
That's if you are using HTTP/1.1 and use persistent mode on the CSS.
You can break persistency and split the url.
I run out of space and time to explain you everything.
I suggest you go read the RFC or a book on HTTP.
Also read the CSS configuration guide.
There is much more you need to know if you want to take full advantage of the CSS like cookie, ssl offloading, L7 rules vs L3/4 rules, ...
Regards,
Gilles. -
Hello i am needing some assistance as i am not very good at how the cloud works. I need to delete my account and start over. I don't want to loose all of the things that i have on phone. Help!
Slowly
http://www.apple.com/icloud/features/
but surely
http://www.gottabemobile.com/2011/10/18/how-to-sync-email-contacts-and-calendar- with-icloud/
we will come
http://transfer-iphone-contacts.blogspot.com/p/iphone-contacts-sync-via-icloud.h tml
to understanding
http://support.apple.com/kb/PH12519
on how icloud sync and backup work.
http://www.apple.com/support/icloud/backup/
http://support.apple.com/kb/ht1766
And here we will find instructions on how to backup (import) pictures to computer, cause there is no direct transfer to flash drive.
http://support.apple.com/kb/ht4083 -
I don't understand how the drop zone works in Title effects.
I am having trouble understanding how the drop zone in the "Keynote" title effect works. I added the title effect to my storyline. In the inspector, Title tab, I selected the clip in the Event library, in this case a tiff photo. The thumbnail and clip title display in the inspector, but the clip does not display in the Viewer when I play the storyline even after FCPX has rendered.
Am I missing something in my understanding of this title effect or is there a problem in FCPX (10.0.6)? Any ideas or suggestions would be appreciated.
iMac, 3.4GHz Core i7, 16GB ram, OSX 10.8.2,There are two ways in which drop zones are available in the Keynote title template. What Luis has shown you is the normal way in which a title placed over a clip shows you the original clip with the title text. That is called a Final Cut placeholder type of drop zone. Keynote also offers a drop zone to be used as a background choice instead of a gradient or solid as you see in Luis's post. This makes a very nice title effect as you can use any clip for that background. That is what I thought you were refering to when you you said drop zone. Keynote is one of the nicer titles we have available in FCP because of this feature. Glad you got it sorted out.
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When I search for stuff on the internet it says safari could not open the page because the server stopped responding and non of my games work either. What do I do to fix this?
Settings → scroll down to Safari → in Safari settings, I selected both Clear History and Clear Cookies and Data.
IF that does not work -
Restart or reset your iPhone, iPad, or iPod touch - Apple Support
Finally - if problem still present -
Go to Settings>General>Reset
Reset the network settings - you will need to add the password of your home WiFi in your phone once more
The device should turn itself off & back on then go into Settings>Wifi and join your network -
# Question
Can you please help to understand how the firefox decides on the Expires date for a cached javascript file ( my server did not set any Expire header, but firebox set it down). I tried to understand but different javascript file gets different Expires date value when it is being cached. Please help me as I tried lot and could not get proper answer for this. Thanks in Advance.Try posting at the Web Development / Standards Evangelism forum at MozillaZine. The helpers over there are more knowledgeable about web page development issues with Firefox. <br />
http://forums.mozillazine.org/viewforum.php?f=25 <br />
You'll need to register and login to be able to post in that forum. -
How do i get the internet working on my new iphone 4 ? thanks
How do i get the internet working on my new iphone 4 ? thanks
Did you go into settings? There you will see Wifi
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Hello Sir, I am trying to deploy policy "SI-PerDiskAvgServiceTime-AT" on servers in my environment. And after deployment this policy is triggering so many alerts. I read some online forums and learnt that this is an auto-thresholding policy relying on historical data. Can you please help me understand how this policy works. Thank You
I have decided to ditch Visual Communicator as an option.
Apart from the poor support, I have tested the Trial version and it would not make sense to use the application in its cirrent form.
In a ten minute period using 2 cameras as a test, the application froze and crashed four times. Not acceptable as reliability is crucial.
The test was done on a Windows 7 64 bit machine with 4 physical Xeon Quad core 3GHZ processors and 32 GB RAM with a 2GB Graphics card, so performance was not the issue.
the application is just not stable.
I am getting better support and results from both Wirecast 4 and Cutfour. -
I need help understanding how the Apple components connect to create a whole system across all my devices?
Is there a resource that describes current system and associated functionality?
For example:
Buy A, B, C to achieve "X"
You will need:
an internet provider which supports <specs>
add D to achieve "Y"
You will need:
an internet provider which supports <specs>
add "E" to achieve "Z"
You will need:
an internet provider which supports <specs>
For example, I am looking at the Gen 6 Airport extreme. For intended performance do I need broadband? if so what are the specs, or will basic internet service suffice? Do I need the internet provider's modem or does the Airport extreme replace that? And then I think, if I am doing this, I should also look at Apple TV....What do I need and Why? Then I look at the New Desk top coming out in the fall, and I think well, if I wait and get this, what does this component do for the system, and what becomes redundant? What does this awesome desktop do for my ability to sit and use a new macbook air when I travel or sit on the couch in my PJs?
If there was a place that plainly stated "if you buy the new dektop you can configure a system including only these components and achieve <this result> and by adding <additional components> you will achieve this result.
I have been to the genius store a few times, but I come out of there more confused unless I have SPECIFIC questions or already know what to buy.
A "System Configuration App" would be a really great sales tool--Just saying.I have no idea what "fully optimized" means.
No Apple device will let you watch broadcast TV. The Apple TV is a good option for watching streaming TV from iTunes, NetFlix and Hulu. If you want to watch from other sources, you may need to look at other devices.
Any Mac computer or iPad will allow you to surf the web.
What business software?
Time Capsule is a good option for back ups.
Update what across all devices?
For accessing documents from all devices, a service like Dropbox is your best bet.
I have no idea what "step as far away from an internet provider as possible" means. If you want Internet access, you need an Internet provider.
Lighting fast speed for what? Processor? The specs are listed for all devices in the Online Store. Internet? We're back to the service provider.
Technology changes. The only way to keep pace with it beyond a couple of years is to buy new stuff.
The bottom line is you need to look at the specs for devices availble and at your budget and decide what best meets your needs. If you are unable to do that on your own, there are lot of technology consultants out there who will, for a fee, look at your exact situation, make recommendations and even handle the purchase and set up. Perhaps that would be the best route for you.
Best of luck. -
My macbook doesn't connect to the Wi-Fi at home while my iPad connects to the same Wi-Fi. When I try connecting my macbook to my iPhone's personal hotspot, the internet works but the issue is connecting my macbook to the Wi-Fi. Please help!!
I don't understand how to fix this and I don't seem to understand where the problem is coming from.Let's try the simple approach first. Restart your router. Any change?
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