I'm a big fan of keeping application logic in the servlet, and keeping the JSP as simple as possible. One of the reasons for this is that any good web designer should be able to expand upon his HTML knowledge to build in a few JSTL tags to do simple iteration, access beans, etc. We also keep the more complex/ajax/js components behind a tag library (similar to displayTag but for our own components).
Most of the time everything works out ok - The servlet does any SQL it needs to, and stores the results in beans for the JSP to access. Where we have a problem is when the records we wish to access are specified by the design.
The clearest example would be the home page - it needs to be eye-catching and effective. It doesn't need to be uniform like rest of the site. There are lots of one-offs or "special cases" here, where we want to query a particular product record, or whatever.
What the designer really wants is a way to get a product bean by the product id so he can access the properties as normal. We obviously don't want to query for all products, and I don't want to query in the presentation.
I'm pretty sure I'm asking the impossible here and that I have to give something up. My question is what?
EDIT
Am I wrong in thinking that all application logic should be complete before calling the JSP? I was under the impression it was considered best practice to do all querying/calculating/processing in the servlet then pass (fairly) dumb beans to a (very) dumb JSP.
There are a couple of methods whereby the actual complexity of the query can be encapsulated in another class (custom tag or bean), and the JSP can call it. This
keeps the JSP simple (goal 1) but the JSP is still "triggering" the query - quite
late in the process.
Have I got this totally wrong and it's fine to do this.
Is it a general rule, but perfectly ok to do this in this instance.
Might I run into problems?
EDIT - Example
I'm hoping this example will help:
The home page isn't a "template" like the category/search pages - it is custom designed to work very well with say a marketing image and a couple of specific product images. It does however have information about those two products which should be obtained dynamically (so the name, and importantly price) stay in sync with the db.
The servlet can't know which products these will be, because if the designer wants to change them/remove them/add more, he should only have to edit the JSP (and possibly XML as one answer suggested).
If I understand correctly, you have logic in the JSP that wants a particular product, but at this point you don't want to query from the DB, and its too late for the servlet to be aware of it.
(A side note, while I respect your will to maintain separation of concerns, the fact that this is an issue clearly shows that your framework has too much logic in the presentation tier...but since we probably can't fix that...moving on).
My recommendation is that your designer creates a configuration XML file that contains whatever special cases it needs for the frontend, and yours servlet can read that, then pass dumb beans back to the JSP.
OR...you break things down into multiple requests using XMLHTTPRequest and call back to the servlet for each individual query, then assemble the page on the client.
It sounds like you need better separation between the display and database code. You should have separate classes that just deal with interacting with the database, and know nothing about display.
Then you just create a method that will look up the product by id and return that bean so the display can pull out the attributes it wants.
You need to create a custom bean which will perform your queries for the front end. Actually, it's probably more like a few beans to get the data for you, according to what you say here.
There's no problem with doing that from a design perspective; it's just that the specific design of the home page has more heterogenous requirements than the rest of your site. Make sure your designer knows that he needs to communicate his needs well to the development team to create the BO for your homepage (or whatever) and thing should go fine.
You are not wrong in thinking that all application logic should be complete before rendering the JSP.
If there is a need to fetch more stuff for displaying in your JSP, it would be another request to the server and another Page cycle. If you are looking for 'interactive' loading experience, you could use AJAX.
In a single page life-cycle, I find it hard to understand why do you have to invoke database calls from a JSP. Hasn't the page been previously posted with all the required form variables to help you find the data in Servlet/Helper classes?
If you could give an example of a case, it would be helpful.
[Edit] Looking at your example, yes your designer (or the admin of the site) should set that information as a configuration, not a part of JSP. Or, you could have a small app/admin page to maintain the information in a database so that it could be changed on the go. When you show your homepage, read the configs and load the appropriate data.
I am not sure what is the question. I f you want to have sql statements out of your jsp pages then you can put them in a property file and just read the property file from the jsp page.
Related
I'm having a problem when trying to A/B test certain nodes in my node-tree in Umbraco.
What I want to do is to copy a node in the node-tree to a specific spot and use that B-structure to see which of the structures works best, using Google analytics.
For example we have two node structures, let's call them "Private" and "Sweden".
Their structure with childnodes and properties are exactly the same. The only difference between them is the propertyvalues (content). The "Private"-URL is www.mysite.com/Private and the "Sweden"-URL is www.mysite.com/Sweden.
What I would like to do is to change every link on the B-structure, so that it points to its match at the A-structure. The problem is that since it's two different structures, it will have two different alternative links.
With other words, it should be a coinsidence that it enters the B-structure, then be moved back to the A-structure in the next click.
We manage what page it should load (either the A-node or the B-node) with scripts, so that it has a 50% chance for each node, and if it lands on the B-node, Google analytics will save data. What we can't manage is that every link on that page will be to the A-node.
I'd appreciate any help I can get.
Regards,
David
There's a couple of ways that seem likely to give you a start at least.
The /config/urlrewriting.config file allows you to set up multiple redirect rules within umbraco so a section like the following might work in sending all requests (whether (/sweden/pagename/ or /private/pagename/) back to the private structure. Not sure how GA will handle it:
rewriteUrlParameter="ExcludeFromClientQueryString" destinationUrl="http://www.mysite.com/private/$1" redirect="Domain" redirectMode="Permanent" ignoreCase="true" />
Secondly a simple httpmodule (http://support.microsoft.com/kb/307996) can process all page requests and redirect as required - you could do a gaq_push here directly or indirectly.
I'd be interested to know how you get on - it seems a good area for extension to Umbraco.
I'm not sure I have understood perfectly what you need to do, so please excuse any assumptions that may prove mistaken. Here's what I think:
Since A & B nodes should share the same html content (besides the links of course), why don't you make the link href attribute dynamic by using a bit of razor in the template or macro:
#{var isANode = CurrentPage.Parent.Name == "Sweden"; }
A similar approach would work if you are using web forms.
We finally came to the final decision to use the alternative template-solution. Since there seem to be no generic solution for my case of this problem we had to create an alternative template with specific macros to render the different information for every documenttype we're using.
Creating dynamic links for every page is a hell of a job in this stage in the project, since there are so many pages and links. Also some links are made in javascript, so there's another problem.
I copied the a-structure to another node, only for the reason to be able to change propertyvalues. There might be a problem logging and track the information with Google Analytics though, so that's the next step for us in this project. In our alternative templates we're getting the propertyvalues from the b-structure.
Still, if anyone have some better solution I'd highly appreciate it!
Regards,
David
So, I'm trying to come up with a better way to do a dynamic help module that displays a distinct help page for each page of a website. Currently there is a help.aspx that has a title and div section that is filled by methods that grab a database record. Each DB record is stored html withy the specific help content. Now, this works but it is an utter pain to maintain when, say an image, changes or the text has to be edited, you have to find and updated 1 or more DB records. I was thinking instead, I could build a single html page that basically shows/hides panels and inside each panel is the appropriate help content. As long as you follow a proper naming convention (name the panels ID to the page/content it represents) using ctrl + f will get you where you need to go and make it easier to find the content you need. What I'm curious of is would this have an impact on performance? The html page would be a fairly large file and would be hosted/ran at the server but it would also remove the need for Database calls. Would the work even be worth the benefit here or am I reinventing the wheel already in place?
Dynamic anything should be stored in the database. A truly usable web application should NEVER need code modified to change content. Hiding content is usually not a good idea, imagine if you expanded your application to 100 different pages that need their own help page. Then when someone clicks help their browser has to load 99 hidden pages to get 1 that it will show. You need to break your help page down into sections and just store the plain text in the database. I would need to know more about what language you're using as well as the architecture you're using to elaborate further but take a look below.
The need your describing is pretty much what MVC (web application architecture type) was built for.
If you're already using ASP.net and you aren't too far into your project I would consider switching to MVC. It's an architecture built specifically with dynamic page content in mind. You build different 'Views' (the V in MVC) that will dynamically build the HTML based on the content it receives from the Controller (The C in MVC) which pulls it's data from the database/Model (The M) and modifies it for the View. Also once you get into MVC you can couple it with Razor and half of your code get's written for you. It's a wonderful thing.
http://www.asp.net/mvc
The client I'm working for has a CMS written in Yii. Currently a part of their business is customizing the CMS to meet the specific needs of each customer. About 90% of the code is reused, essentially by copying and pasting from one directory to another. While I've been working on this project, I've had to merge changes in to the shared codebase several times.
All, or most, of these sites are hosted on the same server, and it would seem that it would make more sense to have a single login, that changed what features we showed based on the login. In some case that means overriding whole or partial views (eg, the _form.php might change from customer to customer) including the controller and model. Most of the time, it means adding a new controller for a bit of functionality written just for that client.
I've read about having both a front and backend site here: http://www.yiiframework.com/wiki/63/organize-directories-for-applications-with-front-end-and-back-end-using-webapplicationend-behavior but that doesn't seem to be the right fit (I don't want everyone coming to a different start php file, for instance)
Ideally, I'd have users log in, and get assigned a site id, which will filter data in the shared MVC objects, and will add in the ones specifically for them, or override the ones where necessary
Intuitively it seems like something like this would make sense:
Shared controllers go here:
/protected/controllers
Overrides and additions for client1 go here:
/protected/controllers/client1
or:
/protected/client1/controllers
But I'm not sure how to get Yii to do this in the most efficient and easy to manage way. Is this something that's going to work with Yii, or am I breaking it in ways unintended? If it will work, what's the best way to accomplish it so that it's clear to me six months from now, or some random developer who replaces me?
Do you know RBAM ?
With Role Based access you can profile your application in more-or-less granular way
I am currently investigating the possibilities of different CMSs for a company-site.
Done quite a few projects in classical ASP, ASP.NET, Joomla etc..
I would like to use Umbraco 5 for the first time.
For that project we have a SQL-Table with Job-Opportunities:
like: JobName, Department, Description, etc..
These should be listed on a page. In ASP.NET I would use something like a Repeater, etc.. with PageSize option and automatic paging.
In the Backend (Backoffice in Umbraco, I assume) there has to be an Insert/Edit/Delete Page with the corresponding input boxes, which are maintained by the company employees, not by web-developers.
Which route should I look at? I am completely stuck, is there an example anywhere?
Can I use my own data-tables, or could/should I use the Umbraco content tables for this?
Thank you,
Reinhard
Welcome to Umbraco.
If you choose to use a pre-existing database, you're going to need the following pieces:
an ORM to access read/write the data
a custom hive provider for that data to allow for Umbrace to read it as an entity
a custom tree to allow for editing and adding data in the backoffice
a macro to display the content on the frontend.
http://web-matters.blogspot.com/2011/11/umbraco-5-hive-provider-tree-editor.html
is a great place to start.
As you're probably picking up on, this is a lot of work.. so, most importantly: Are you trying to maintain two applications?
If so, do you really need to be able to edit the list in both applications? Your task would be much simpler if you only allowed editing from the other application, and displayed the read-only list using web services.
If not, ditch the custom database. Umbraco 5 is a full EAV/CR system, so unlike some CMS products, you'll be able to represent any rdbs structure you can imagine. The simplest way would be to create a custom document type with those properties to represent a job opportunity, and store those job opportunities on a new node in the content tab.
About document types: http://our.umbraco.org/wiki/how-tos/working-with-document-types
I currently have several web parts:
EmailValidation
PrimaryDetails
AdditionalDetails
These are currently all connected together using similar logic to this and share a common RegistrationViewModel.
The issue is I use an Interface that holds all the values for the registration process and need these to be persisted across the web parts. In version 1 of the registration process I used a set of hidden values to hold the bits of information in between posts. We were hoping to get away from this approach and wondered if you knew of a tidier way to maintain state of an interface throughout the page calls. The issue is that each web part only has a portion of the fields on the form.
The only thing I could think of would be to store it in session data but a colleague didn’t sound keen on this due to the additional setup for that on all the servers.
Is there a way of getting the connections to maintain state across all posts?
EDIT:
My issue with using hidden fields is simply that on all the web parts I need the 15+ fields so if you add or remove anything it makes maintenance a bit annoying.
Maybe you can put that information in a cookie.
The hidden field solution doesn't seem bad, what is the exact problem with that?
EDIT: based on the problem with the Hidden fields solution:
You can have a class with the structure and serialize it into one single hidden field. If you need to add anything you just change the class and it will be replicated to the whole system. This is something similar to how the ViewState is implemented.