I am doing some grid work just like a stock exchange application which will have good data volume and page should be automatically refresh after some mentioned time say 1 min or 30 sec without being post back.
What is best way to do this ? Should I use grid with ajax or grid with ajax and web service should be used ? If possible please refer me some article or link on implementation of your suggestion.
You can use an UpdatePanel (place the grid inside the panel) and maybe have a JavaScript timer to update the panel periodically.
Alternatively you can have a straight HTML table and periodically call a webservice and update the table from the client side. I think you would get slightly better performance but there is a bit more work involved.
A webservice call from JavaScript will not cause a postback. When calling a webservice you might get better performance because you are only getting data instead of formatted HTML. However, you will probably return the data in XML or Json format, so there will be an overhead (Json will be better in that respect).
If you know that only a small portion of values are going to change between two refreshes, then you will get better performance by only returning the values that have changed.
If you're not very experienced with JavaScript then I would suggest that you use a library such as jQuery. You may read the following resources for implementation details:
Calling an ASP.NET webservice with jQuery
Updating an HTML table from Json data using jQuery
Depending how experienced you are with webservices, Json and jQuery, it may not be an easy task. The UpdatePanel option is definitely easier to implement.
Related
I believe this is a fundamental question regarding asp.net's way of manipulating database items. Basically the server side way of manipulating database items (using ListView or similar) is outdated due to the post back model is outdated compared to AJAX. Let's say you have forward and backward buttons on the gallery to update images from the database. You need to postback in order to update page. Clearly this could use an ajaxfied approach. I have been thinking about this long and hard and have observed most websites that uses ListView or GridView or whatever do not ajaxfy the process, probably due to the difficulty of this problem. For those that ajaxfy the page, they use the UpdatePanel, which is only "pseudo-ajax".
I would like to know do other programmers have a FULLY ajaxfied way of updating a page of a photo gallery, retrieved from database by ListView? As I said I have been thinking about this long and hard and I think there might be two approaches: First, use ListView to first populate photo gallery. On pressing forward or backword button, use jQuery's ajax method to connect to an .ashx page and use .ashx page to retrieve data items and then use jQuery to update the photo gallery at the client side.
The second way I forsee would be abandoning the ListView altogether and use a for loop in .ashx to populate gallery from the beginning. This approach unifies the initial data retrieval method and the "postback" data retrieval method, which could mean less code needed, since you do not need the aspx page at all.
My question is, what is the realistic way to fully ajaxfy the page mentioned above?
I still use code behind in my asp.net website.. but I do use ajax elements on the .aspx page
take a look at ASP.Net Ajax Control Toolkit
All the Ajax elements, with the benefit or still using code behind
So far the best way I have found would be to use jQuery AJAX to update whatever changes, although it can be much more time consuming than posting back to server and update from there
I'm dipping my toes into web development. Based on various bits of advice, I'm going to start by getting a handle on html, css and javascript.
I'm interested in Ajax, I've had a look at the client side code and that looks straight forward enough, I'm slightly confused about what I do on the server side.
I'm using IIS and ASP.NET. I've had a google but I can't find anything that is either simple or current. There's a lot of talk about the Ajax toolkit, which I believe are controls which use Ajax (and may be retired??) Everything else seems to be based on old versions which I don't trust.
So, in really simple terms, what do I have to do in IIS to respond to an AJAX call?
Quick aside, I believe we can use JSON for object serialisation?? I assume I don't need to in the interests of getting a simple sample running?
So I have an Ajax call which will have one parameter, and I want to return "something" based on the parameter. What is the simplest code to achieve that with IIS and ASP.NET?
Thanks
An AJAX call is basically just a regular call to your website. The only difference is how the browser handles it - AJAX calls are done in the background with Javascript (the J in AJAX) and then does something with the data. You could take the URL that you're doing an AJAX call with and put it in your address bar and it'll return the exact same data. So, basically, what you do on the server side is exactly what you would do as if it were a form being submitted, for example.
As far as object serialization, yes, JSON can do that.
First of all, doing ajax has nothing to do with IIS; it has to do with ASP.NET.
There are essentially 2 ways to do AJAX in .net
1) Heavy use of the framework. You can put your asp controls (such as literals, gridviews, listbox...) in a control called an updatepanel. For this to work, you need to add a script manager to the aspx page. Then, when the user raises an event (for example, paging and sorting of a table), the request is handled by the framework and only the part of the page that's in the updatepanel is refreshed. The other way to raise events is by using the __doPostback function that comes with the asp.net framework. The downside of this method is that a lot of data needs to go back and forth between the user and the server so it can be slow. The upside is that you don't have to worry about generating the HTML since the asp controls handle it for you.
2) Heavy use of Json. With this method, you can use jQuery to call a page method or a web service. You send a json object to the server and you get a json object back. With jQuery, this is really easy. The downside of this method is that you're getting just the json data back: no formatted HTML. So, if you're looking to have a table updated, this method would be tedious because you'd have to recreate the entire HTML. However, the upside of the method is that it's very fast because only the raw data is transmitted. If you implement a web service, you don't even need to create an entire page.
What do you need to get from the server?
If you want to return "something" from the server that's "simple" (just data), I'd recommend a web service with jquery to trigger the call. If the return data is "complex" (html code for controls) then I'd recommend using MS ajax with the update panel.
Don't use the AJAX Control Toolkit, ASP.NET AJAX library, updatepanels or the scriptmanager control. Microsoft have pretty much ditched the lot in favour of jQuery and its Plugins (sensibly).
Here are just some of the ways you can use AJAX with jQuery in ASP.NET: Many ways to communicate with your database using jQuery AJAX and ASP.NET
I'm using ASP.NET for a search app web site.
My search retrieves exactly one result per fetch. Once the search is complete and the user selects "Update", a new result is fetched and the old result is written to the ViewState as a generic List. The new result replaces the old one.
I am trying to get the page to update (via partial post-back), so that the old result drops down the screen and the new result sits on top of it. Much like the concept of a stack.
Does anyone know how this can be achieved? I've started looking at the Ajax Control Toolkit.
Would appreciate any hints and tips with regard to my problem.
Thanks!
Using JQuery, this sort of things is fairly straightforward. I would suggest avoiding the partial post-back and using a WebMethod (on a "page method"), then calling that to get the results. In that scenario, JQuery can manage the request to the server and process the response data exactly how you wish.
I'm a just beginning to play around with AJAX animations, but this reference page has been a big help to me.
AJAX Animation Reference
I want to populate a gridview by using jQuery and AJAX. From my calling page jQuery will call a handler (.ashx) that will deliver XML data or HTML markup for the gridview. As I see it I have two choices: 1) deliver XML which is then bound to the design-time gridview on the calling page, or 2) deliver HTML for the gridview. My first question is: which method is easiest?
Now there are two factors which complicate things. First, the gridview must be sortable on all columns. Second, the data will be filtered (some columns will be hidded) by user configuration options which are also to be stored in the database. Knowing this, does your answer to the first question change?
Any comments, insights or gotchas are appreciated.
Dewey
I did something very similar to this on a recent project. I used jqGrid for display purposes - it can easily be bound to JSON-formatted data (and probably XML-formatted data too), and it supports click-column-header-to-sort. I would definitely recommend it for functionality and ease-of-use.
I didn't have to implement user-configurable showing/hiding of columns. However, it could be done with jqGrid pretty easily: the grid columns are configured in javascript, so you could use code-behind logic during the initial page-build to customize the javascript which defines the column configuration.
I definitely wouldn't return HTML from an ASHX class, since you'd have to craft all the HTML by hand using StringBuilder (or something similar). Makes the code tougher to maintain; and if you ever want to change the page layout, you need to re-compile and re-deploy your system. If you desperately want to return fully-formatted HTML, I would probably use jquery/ajax to just call a .ASPX page. That approach is clunky and heavy-handed - but at least .ASPX is geared toward generating full HTML, unlike .ASHX.
You might want to consider returning JSON instead of XML. It makes for smaller, faster responses over the wire, and is amazingly easy to work with, within javascript. In that case, you should consider using ASMX instead of ASHX to generate the JSON, since it can be configured to automatically serialize your returned object as JSON. That's what I did on my project, and it was very fast and easy to develop.
Finally, I VASTLY prefer jquery and ajax to Microsoft's ajax and updatePanels. This stackoverflow thread details the reasons why.
I think delivering HTML is easier.
But I choose delivering XML to dynamically sort and filter data by using a javascript rendering function like:
function render(options) {
}
The options parameter will be an object that stores orderby parameter and hidden column names such as:
options = {orderby:"name", hidecolumns:["surname", "age"]};
I hope that helps.
I want to create something similiar to a facebook wall on my social site. I want to store the posts in an sql database and that should be rather simple. What I am looking for is a good way to display the posts? I guess I don't even really know where to start, as I can only think of using a loop to display asp:textboxes. Which obviously is not correct.
I want there to be multiple posts displayed on the page, which should include:
the user who posted,
the text posted,
the date posted,
and if I want to get crazy...a means of deleting/editing the post.
I really have no idea of how to implement this concept, so any ideas would help greatly.
To get started, view this article from asp.net on the Repeater control, or this great article.
The Repeater control lets you databind to a list of objects, and then define one template for how that object should be displayed. Then, ASP.NET will handle showing it as many times as necessary. You can write the code-behind for dealing with delete and edit as if there were only one instance on the page.
go ahead with jquery, use a lot of ajax. for the mark up, use a repeater control with all clean html mark up (instead of server side controls which would generate a lot of unnecessary mark up quickly creating performance issues)
only populate x number of items on initial load, and then using jquery pull data as required based on user action. you can serve this data via json, decode json on client side using jquery and perform a loop which converts this json into appropriate html and injects it into the correct html element
should be simple ;-)
ASP.NET gives you lots of ways to do this. A Repeater, DataGrid, GridView are the first that come to mind. If you'd rather use ASP.NET MVC, there's always the good old foreach loop.
Additionally, check out ListView too.