sorry but I am really confused here. I read some threads but they could not make it clear for me.
I have an MVC 4 website which is expecting visitors from around the world. The website is in Arabic, and I want all visitor to use the Arabic language, ar-SA culture.
Now comes the problem: dates. Visitors should be able to choose from two supported calendars. Some will choose GregorianCalendar and some will choose HirijiCalendar.
Q1: Where to set the calendar (user-dependent) for better performance?
What I have done is a base controller which all controllers inherit from. In OnActionExecuting, I try to change the: Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat.Calendar
to the visitor preference, which was read from database upon signing in.
Q2: Will this line of code affect: the current request only, the current session only (this visitor), or the whole application (all visitors)? I am afraid it will affect others, I do not know anything about thread scope… I am afraid that changing thread calendar in OnActionExecuting every time is too bad for the performance…
Q3: If I store dates in database according to UTC (like AddedOn, EditedOn), where should I convert it to whatever time zone of a visitor? in controller code? Will the website become slow to do this every time I query the database? What is the best practice here?
Thank you and excuse me, I'm a beginner.
Related
I'm looking for a portlet like-solution that would collect and report usage analytics in Liferay... but google analytics is not an option, unfortunately.
Stats by community, group, session tracking, apart from the usual bounce and exit rates, referrals, origin, etc. I know I'm kind of asking the reinvention of the wheel, but there are plenty of usage data that can be collected by Liferay that google can't. I've already checked PiWik, and it looks very impressive.
Any suggestions? TIA,
As of 2015 there is Audience Targeting plugin, which (at least for Liferay 6.2) comes bundled with analytics-api / analytics-hook modules, which collect some useful analytics data. Mind now:
So far it doesn't look like there is any standalone use for them as they were introduced, I believe, to enable the content visited, page visited and other such rules in the Audience Targeting itself; you can't see the raw events in any of the provided portlets
The events are stored as rows in a SQL database, so I would be concerned about it's performance in the long run (with thousands of clicks every minute etc.), although I say this purely theoretically as I haven't done any tests myself nor checked if there are some performance enhancing measures implemented
What you can do, however, is to put together your own portlet which would create some graphs etc. based on the data stored in CT_Analytics_AnalyticsEvent table.
Right now, I dont think there is any out of the box feature available for this, you might need to create this. There can be 2 things
1) You need to create a javascript library if you need realtime/web analysis (this is same like creating google analytics lib)
2) This option is quite easy. Liferay stores everything in db, you can have a report portlet which will show the report based on the data. We did this for one project where we were tracking the session ids/ip and logged in user details for portlets.
To achieve point 2) you can create new Liferay service, which will be used to store these data and retrieve.
Hope this helps
You already mention Piwik, which is similar to google analytics. You probably have your own theme (almost everybody changes the appearance to look like their own site) and it's quite appropriate to place the relevant piwik-stats-snippet in there.
You can also, as Felix suggests, mine your log files. Liferay stores some data, your webserver access logs also are quite worth to mine. And, of course, you can change your theme to log even more for every page access, just take care that you don't create a performance bottleneck by writing too much during one page request.
So, coming back to your question: Built-in like google analytics: No. Easily integrateable (like Piwik): Yes, of course. Completely customizeable: Yes, of course.
Edit: It just happens that David has created and documented an integration that makes using Piwik even easier
Is there a way to determine if the request coming to a handler (lets assume the handler responds to get and post) is being performed by a real browser versus a programmatic client?
I already know that it is easy to spoof things like the User Agent and the Referrer, but are there other headers that are more difficult to spoof? Maybe headers that are not commonly available in classes like .net's HttpWebRequest?
The other path that I looked at is maybe using the Encrypted View State to send a value to the browser that gets validated on the server side, though couldn't that value simply be scraped from the previous response and added as a post parameter to the next request?
Any help would be much appreciated,
Cheers,
There is no easy way to differentiate because in the end, a post programitically looks the same to the server as a post by a user from the browser.
As mentioned, captcha's can be used to control posting but are not perfect (as it is very hard but not impossible for a computer to solve them). They also can annoy users.
Another route is only allowing authenticated users to post, but this can also still be done programatically.
If you want to get a good feel for how people are going to try to abuse your site, then you may want to look at http://seleniumhq.org/
This is very similar to the famous Halting Problem in computer science. See some more on the proof, and Alan Turing here: http://webcache.googleusercontent.com/search?q=cache:HZ7CMq6XAGwJ:www-inst.eecs.berkeley.edu/~cs70/fa06/lectures/computability/lec30.ps+alan+turing+infinite+loop+compiler&cd=1&hl=en&ct=clnk&gl=us
The most common way is using captcha's. Of course captcha's have their own issues (users don't really care for them) but they do make it much more difficult to programatically post data. Doesn't really help with GETs though you can force them to solve a captcha before delivering content.
Many ways to do this, like dynamically generated XHR requests that can only be made with human tasks.
Here's a great article on NP-Hard problems. I can see a huge possibility here:
http://www.i-programmer.info/news/112-theory/3896-classic-nintendo-games-are-np-hard.html
One way: You could use some tricky JS to handle tokens on click. So your server issues token-id's to elements on the page during the backend render phase. Log these in a database or data file. Then, when users click around and submit, you can compare the id's sent via the onclick() function. There's plenty of ways around this, but you could apply some heuristics to determine if posts are too fast to be a human or not, that is, even if they scripted the hijacking of the token-ids and auto submitted, you could check that the time between click events appears automated. Signed up for a twitter account lately? They use passive human detection that while not 100% foolproof, it is slower and more difficult to break. Many if not all of the spam accounts there had to be human opened.
Another Way: http://areyouahuman.com/
As long as you are using encrypted methods verifying humanity without crappy CAPTCHA is possible.I mean, don't ignore your headers either. These are complimentary ways.
The key is to have enough complexity to make for an NP-Complete problem in terms of number of ways to solve the total number of problems is extraordinary. http://en.wikipedia.org/wiki/NP-complete
When the day comes when AI can solve multiple complex Human problems on their own, we will have other things to worry about than request tampering.
http://louisville.academia.edu/RomanYampolskiy/Papers/1467394/AI-Complete_AI-Hard_or_AI-Easy_Classification_of_Problems_in_Artificial
Another company doing interesting research is http://www.vouchsafe.com/play-games they actually use games designed to trick the RTT into training the RTT how to be more solvable by only humans!
It's C# + .net 2.0, but this can be pretty much any environment
I have a list in my website where you can get coming from several different locations (modules). It is a normal list screen, with add/edit (an other) links in it.
You sometimes get here from one module, sometimes from an other module. The only thing that I would like to fix is the Back link. It should always take you back to the module where you came from.
What is the best way to do this?
Session variable (this is so far my best choice, but I am not really happy to use this)
URL. I could transmit a parameter all over, "carry it with me" (i don't like this a lot because of the number of the pages that are related to this list, I would have to carry that variable with me in add, edit and other screens, too many places to change)
cookies ?(limited number of cookies, and things like that, don't really like this one either.)
4-5-6 ?
How are all you guys handling this issue?
Save the referer in Session and redirect them to this from the back link eventhandler.
This assumes you are doing nothing funky with the querystring.
I have concerns myself about using Session to store information but for this scenario, it is perfectly acceptable.
Cookies are another option, but overkill, unless you factor in the possibility of losing session information on website/app-pool recycle
The Problem
In the stack that we re-use between projects, we are putting a little bit too much data in the session for passing data between pages. This was good in theory because it prevents tampering, replay attacks, and so on, but it creates as many problems as it solves.
Session loss itself is an issue, although it's mostly handled by implementing Session State Server (or by using SQL Server). More importantly, it's tricky to make the back button work correctly, and it's also extra work to create a situation where a user can, say, open the same screen in three tabs to work on different records.
And that's just the tip of the iceberg.
There are workarounds for most of these issues, but as I grind away, all this friction gives me the feeling that passing data between pages using session is the wrong direction.
What I really want to do here is come up with a best practice that my shop can use all the time for passing data between pages, and then, for new apps, replace key parts of our stack that currently rely on Session.
It would also be nice if the final solution did not result in mountains of boilerplate plumbing code.
Proposed Solutions
Session
As mentioned above, leaning heavily on Session seems like a good idea, but it breaks the back button and causes some other problems.
There may be ways to get around all the problems, but it seems like a lot of extra work.
One thing that's very nice about using session is the fact that tampering is just not an issue. Compared to passing everything via the unencrypted QueryString, you end up writing much less guard code.
Cross-Page Posting
In truth I've barely considered this option. I have a problem with how tightly coupled it makes the pages -- if I start doing PreviousPage.FindControl("SomeTextBox"), that seems like a maintenance problem if I ever want to get to this page from another page that maybe does not have a control called SomeTextBox.
It seems limited in other ways as well. Maybe I want to get to the page via a link, for instance.
QueryString
I'm currently leaning towards this strategy, like in the olden days. But I probably want my QueryString to be encrypted to make it harder to tamper with, and I would like to handle the problem of replay attacks as well.
On 4 guys from Rolla, there's an article about this.
However, it should be possible to create an HttpModule that takes care of all this and removes all the encryption sausage-making from the page. Sure enough, Mads Kristensen has an article where he released one. However, the comments make it sound like it has problems with extremely common scenarios.
Other Options
Of course this is not an exaustive look at the options, but rather the main options I'm considering. This link contains a more complete list. The ones I didn't mention such as Cookies and the Cache not appropriate for the purpose of passing data between pages.
In Closing...
So, how are you handling the problem of passing data between pages? What hidden gotchas did you have to work around, and are there any pre-existing tools around this that solve them all flawlessly? Do you feel like you've got a solution that you're completely happy with?
Thanks in advance!
Update: Just in case I'm not being clear enough, by 'passing data between pages' I'm talking about, for instance, passing a CustomerID key from a CustomerSearch.aspx page to Customers.aspx, where the Customer will be opened and editing can occur.
First, the problems with which you are dealing relate to handling state in a state-less environment. The struggles you are having are not new and it is probably one of the things that makes web development harder than windows development or the development of an executable.
With respect to web development, you have five choices, as far as I'm aware, for handling user-specific state which can all be used in combination with each other. You will find that no one solution works for everything. Instead, you need to determine when to use each solution:
Query string - Query strings are good for passing pointers to data (e.g. primary key values) or state values. Query strings by themselves should not be assumed to be secure even if encrypted because of replay. In addition, some browsers have a limit on the length of the url. However, query strings have some advantages such as that they can be bookmarked and emailed to people and are inherently stateless if not used with anything else.
Cookies - Cookies are good for storing very tiny amounts of information for a particular user. The problem is that cookies also have a size limitation after which it will simply truncate the data so you have to be careful with putting custom data in a cookie. In addition, users can kill cookies or stop their use (although that would prevent use of standard Session as well). Similar to query strings, cookies are better, IMO, for pointers to data than for the data itself unless the data is tiny.
Form data - Form data can take quite a bit of information however at the cost of post times and in some cases reload times. ASP.NET's ViewState uses hidden form variables to maintain information. Passing data between pages using something like ViewState has the advantage of working nicer with the back button but can easily create ginormous pages which slow down the experience for the user. In general, ASP.NET model does not work on cross page posting (although it is possible) but instead works on posts back to the same page and from there navigating to the next page.
Session - Session is good for information that relates to a process with which the user is progressing or for general settings. You can store quite a bit of information into session at the cost of server memory or load times from the databases. Conceptually, Session works by loading the entire wad of data for the user all at once either from memory or from a state server. That means that if you have a very large set of data you probably do not want to put it into session. Session can create some back button problems which must be weighed against what the user is actually trying to accomplish. In general you will find that the back button can be the bane of the web developer.
Database - The last solution (which again can be used in combination with others) is that you store the information in the database in its appropriate schema with a column that indicates the state of the item. For example, if you were handling the creation of an order, you could store the order in the Order table with a "state" column that determines whether it was a real order or not. You would store the order identifier in the query string or session. The web site would continue to write data into the table to update the various parts and child items until eventually the user is able to declare that they are done and the order's state is marked as being a real order. This can complicate reports and queries in that they all need to differentiate "real" items from ones that are in process.
One of the items mentioned in your later link was Application Cache. I wouldn't consider this to be user-specific since it is application wide. (It can obviously be shoe-horned into being user-specific but I wouldn't recommend that either). I've never played with storing data in the HttpContext outside of passing it to a handler or module but I'd be skeptical that it was any different than the above mentioned solutions.
In general, there is no one solution to rule them all. The best approach is to assume on each page that the user could have navigated to that page from anywhere (as opposed to assuming they got there by using a link on another page). If you do that, back button issues become easier to handle (although still a pain). In my development, I use the first four extensively and on occasion resort to the last solution when the need calls for it.
Alright, so I want to preface my answer with this; Thomas clearly has the most accurate and comprehensive answer so far for people starting fresh. This answer isn't in the same vein at all. My answer is coming from a "business developer's" standpoint. As we all know too well; sometimes it's just not feasible to spend money re-writing something that already exists and "works"... at least not all in one shot. Sometimes it's best to implement a solution which will let you migrate to a better alternative over time.
The only thing I'd say Thomas is missing is; client-side javascript state. Where I work we've found customers are coming to expect "Web 2.0"-type applications more and more. We've also found these sorts of applications typically result in much higher user satisfaction. With a little practice, and the help of some really great javascript libraries like jQuery (we've even started using GWT and found it to be AWESOME) communicating with JSON-based REST services implemented in WCF can be trivial. This approach also provides a very nice way to start moving towards a SOA-based architecture, and clean separation of UI and business logic.
But I digress.
It sounds to me as though you already have an application, and you've already stretched the limits of ASP.NET's built-in session state management. So... here's my suggestion (assuming you've already tried ASP.NET's out-of-process session management, which scales signifigantly better than the in-process/on-box session management, and it sounds like you have because you mentioned it); NCache.
NCache provides you with a "drop-in" replacement for ASP.NET's session management options. It's super easy to implement, and could "band-aid" your application more than well enough to get you through - without any significant investment in refactoring your existing codebase immediately.
You can use the extra time and money to start reducing your technical debt by focusing new development on things with immediate business-value - using a new approach (such as any of the alternatives offered in the other answers, or mine).
Just my thoughts.
Several months later, I thought I would update this question with the technique I ended up going with, since it has worked out so well.
After playing with more involved session state handling (which resulted in a lot of broken back buttons and so on) I ended up rolling my own code to handle encrypted QueryStrings. It's been a huge win -- all of my problem scenarios (back button, multiple tabs open at the same time, lost session state, etc) are solved and the complexity is minimal since the usage is very familiar.
This is still not a magic bullet for everything but I think it's good for about 90% of the scenarios you run into.
Details
I built a class called CorePage that inherits from Page. It has methods called SecureRequest and SecureRedirect.
So you might call:
SecureRedirect(String.Format("Orders.aspx?ClientID={0}&OrderID={1}, ClientID, OrderID)
CorePage parses out the QueryString and encrypts it into a QueryString variable called CoreSecure. So the actual request looks like this:
Orders.aspx?CoreSecure=1IHXaPzUCYrdmWPkkkuThEes%2fIs4l6grKaznFGAeDDI%3d
If available, the currently logged in UserID is added to the encryption key, so replay attacks are not as much of a problem.
From there, you can call:
X = SecureRequest("ClientID")
Conclusion
Everything works seamlessly, using familiar syntax.
Over the last several months I've also adapted this code to work with edge cases, such as hyperlinks that trigger a download - sometimes you need to generate a hyperlink on the client that has a secure QueryString. That works really well.
Let me know if you would like to see this code and I will put it up somewhere.
One last thought: it's weird to accept my own answer over some of the very thoughtful posts other people put on here, but this really does seem to be the ultimate answer to my problem. Thanks to everyone who helped get me there.
After going through all the above scenarios and answers and this link Data pasing methods My final advice would be :
COOKIES for:
ENCRYPT[userId's]
ENCRYPT[productId]
ENCRYPT[xyzIds..]
ENCRYPT[etc..]
DATABASE for:
datasets BY COOKIE ID
datatables BY COOKIE ID
all other large chunks BY COOKIE ID
My advise also depends on the below statistics and this link details Data pasing methods :
I would never do this. I have never had any issues storing all session data in the database, loading it based on the users cookie. It's a session as far as anything is concerned, but I maintain control over it. Don't give up control of your session data to your web server...
With a little work, you can support sub sessions, and allow multi-tasking in different tabs/windows.
As a starting point, I find using the critical data elements, such as a Customer ID, best put into the query string for processing. You can easily track/filter bad data coming off of these elements, and it also allows for some integration with e-mail or other related sites/applications.
In a previous application, the only way to view an employee or a request record involving them was to log into the application, do a search for the employee or do a search for recent records to find the record in question. This became problematic and a big time sink when somebody from a related department needed to do a simple view on records for auditing purposes.
In the rewrite, I made both the employee Id, and request Ids available through a basic URL of "ViewEmployee.aspx?Id=XXX" and "ViewRequest.aspx?Id=XXX". The application was setup to A) filter out bad Ids and B) authenticate and authorize the user before allowing them to these pages. What this allowed the primarily application users to do was to send simple e-mails to the auditors with a URL in the e-mail. When they were in a big hurry, they were in their bulk processing time, they were able to simply click down a list of URLs and do the appropriate processing.
Other session related data, such as modification dates and maintaining the "state" of the user's interaction with the application gets a little more complex, but hopefully this provides a starting poing for you.
I am looking for guidance regarding the best practice around the use of the Profile feature in ASP.NET.
How do you decide what should be kept in the built-in user Profile, or if you should create your own database table and add a column for the desired fields? For example, a user has a zip code, should I save the zip code in my own table, or should I add it to the web.config xml profile and access it via the user profile ASP.NET mechanism?
The pros/cons I can think of right now are that since I don't know the profile very well (it is a bit of a Matrix right now), I probably can do whatever I want if I go the table route (e.g., SQL to get all the users in the same zip code as the current user). I don't know if I can do the same if I use the ASP.NET profile.
Ive only built 2 applications that used the profile provider. Since then I have stayed away from using it. For both of the apps I used it to store information about the user such as their company name, address and phone number.
This worked fine until our client wanted to be able to find a user by one of these fields.
Searching involved looping through every users profile and comparing the information to the search criteria. As the user base grew the search time became unacceptable to our client. The only solution was to create a table to store the users information. Search speed was increased immensely.
I would recommend storing this type of information in its own table.
user profile is a nice clean framework for individual customization(AKA. Profile Properties). (e.g. iGoogle)
the problem of it is its not designed for query and not ideal for data sharing to public user.(you still would be able to do it, with low performance)
so, if you want to enhance the customized user experience, user profile would be a good way to go. otherwise, use your own class and table would be a much better solution.
In my experience its best to keep an the info in the profile to a bare minimum, only put the essentials in there that are directly needed for authentication. Other information such as addresses should be saved in your own database by your own application logic, this approach is more extensible and maintainable.
I think that depends on how many fields you need. To my knowledge, Profiles are essentially a long string that gets split at the given field sizes, which means that they do not scale very well if you have many fields and users.
On the other hand, they are built in, so it's an easy and standardized way, which means there is not a big learning curve and you can use it in future apps as well without needing to tweak it to a new table structure.
Rolling your own thing allows you to put it in a properly normalized database, which drastically improves performance, but you have to write pretty much all the profile managing code yourself.
Edit: Also, Profiles are not cached, so every access to a profile goes to the database first (it's then cached for that request, but the next request will get it from the database again)
If you're thinking about writing your own thing, maybe a custom Profile Provider gives you the best of both worlds - seamless integration, yet the custom stuff you want to do.
I think it is better off using it for supplementary data that is not critical to the user that is only normally important when that user is logging in anyway. Think data that would not break anything important if it was all wiped.
of course thats personal preference but others have raised some other important issues.
Also very useful considering it can be used for an unauthenticated user whose profile is maintained with an anonymous cookie.