I have a web-app in Java, Spring, Struts 2 and Hibernate, that servers multiple clients. Each client with multiple users. To create a personal feel for each client, i would like to customize the header for each client.
I'm using sitemesh as decorator, and am looking for tips or examples or someone who can point me in the right direction as to how to acomplish this in the best practice.
What would you think? Should i just code it direct in the header.jsp? Extracting the info about the logged in user and from that create a custom header by code? Or is there a more clever solution out there?
Thanks!
Update:
To further clearify what i want:
Different properties-files for each client is not an option. We are looking at potentionally hundreds of clients. It needs to be database-driven. But thats the easy part. There is no problem storing the information in db and extracting it when needed.
What im trying to figure out is if there is some sort of standard way of doing this. Some sort of filter or Action that is run before the sitemesh decorator that will provide the decorator with the correct info?
Struts2 provides application scope, for variables which are global to the application.
Load all the customer specific strings into #application scope (I would use spring to do this when the application starts up). From there referencing the strings would be pretty obvious: #application.greeting I don't like the idea of using an interceptor because there is nothing to intercept. I would say for what you are doing application scope is the perfect place. If it is a single client system I can see no reason why anything would be stored in application scope.
Aside: Tiles uses a different template paradigm than site mesh, and they have slightly different purposes. As such the two can be complimentary. Tiles relying on XML definitions can have it's definitions stored in a DB and is definitely less computationally intensive, however where there is interplay between different UI components... or disparate elements appearing on the page you need to use sitemesh. So for basic template needs tiles does everything and is quite easy to understand but say you wanted to make add a certain widget in the middle of the page which relies on JS which needs to be added to the header it would be tricky to do this in Tiles (although the obvious solution is to just roll the JS functionality into one JS file for all possible uses in a particular part of the site).
Asside 2: By using a view technology such as velocity or freemarker in conjunction with tiles it is conceivable to move the entire view layer into a database. I just thought I would mention that as for some maintenance issues that could be extremely beneficial.
Sitemesh makes it's decisions about what decoration to use based upon the requested URL string, so unless you have a reference to the client in every url - either as part of the main url string or as a known parameter, then Sitemesh out of the box is not going to help.
This leaves a few possibilities to achieve what you want;
1) Write a filter that runs before Sitemesh that adds, for example, "&clientId="xx" to every incoming request.
2) Dive into the source code for Sitemesh & look for where Sitemesh finally makes it's decision about which decorators to use and override it. I've never tried this so I don't know how practical this might be.
3) Make the style sheet definition in your jsp pages an OGNL expression and provide that information in a base action class that all your actions extend. In this way you end up with (potentially) a different CSS file for each client and you provide your customisation via CSS.
Hope that this helps.
Related
We have a rather large application, with a great deal of dynamic content. Is there anyway to force struts to use a database for the i18n lookups, instead of properties files?
I'd be open for other ways to solve this as well, if anyone has ever done i18n with dynamic content.
I don't know of an easy plug-and-play solution for this, so you will probably have to implement it yourself -- plan on spending quite a bit of time just coming to grips with how the localization features of struts 2 (and XWork) are implemented. The key will probably be to provide your own implementation of com.opensymphony.xwork2.TextProvider (and tell struts to use it by providing a <bean> tag in struts.xml). I can think of at least two ways of fitting this into the overall architecture:
Have your TextProvider implementation access the database directly. In the spirit of YAGNI, this is probably the best way to start (you can always refactor later, if necessary).
Alternatively, you could place the database code into an implementation of Java's ResourceBundle interface, which is what XWork uses internally. To me this sounds like an even more design-heavy approach, but on the plus side there are some articles around describing how to do this.
No, there is no built-in way to have Struts2 load localized content from a database. You would need to write that yourself.
What are your requirements? Do you need for users to be able to dynamically change field prompts, error messages, etc.?
You may be able to do something like that by building a custom interceptor. You could have the interceptor read all the key value pairs from your database and inject them into the value stack. The only thing I am not sure about, not really having messed with i18n with struts before, is if the i18n stuff pulls that information from the value stack. If not, I am not sure if maybe you could do something else in the interceptor to load up the information.
Building a custom interceptor is not too terribly complicated. There are plenty of tutorial sites out there, including (brace for self promotion here) my blog: http://ddubbya.blogspot.com/2011/01/creating-custom-struts2-interceptors.html.
Use properties files just for static content, like labels, messages etc.
For dynamic content start with a database table that includes a language-code-id for every language you want to use. All the dynamic content entries that are already translated go with their respective language-code-id added to their primary key. If a translation is missing, you can program your application to fall back to your default language in order to make things easier until the right translation is present.
Let your users provide their contributions in the language they like and store it with the appropriate language-id. Someone should provide the translation to the other languages in order to make the contribution complete.
...
PRIMARY KEY (`subject_id`,`language_id`),
...
I'm rather unexperienced in GWT, and I have large codebase with working project in this technology. My task refers to assigning id's to html elements witch will be used in automatic testing. We can't use some dynamically assigned id's because in automatic test we have to specify exact values of id's. My way for now was to use method ensureDebug(id), written by hand in code for specific elements.
I think that doing it this way mean that code will be more spaghetti-like, with mixed ensureDebug(id) methods usages there and here. I was thinking if there is any way of doing it that will be more manageable and cleaner than current. Is is maybe possible to use AOP? (I have never used AOP, so I don't know if it is any good idea, or possible in GWT) Or maybe other way than using ensureDebug?
You also can set the IDs for HTML elements like
element.setId("myId");
But this is as much spaghetti like as your approach adding the IDs in the code.
Another possibility would be to use an UiBinder and set the id there. With this approach you have all your ui elements of one view, which should have an id, at one place. With bootstrap for example it would look like this:
<b:TextBox ui:field="searchTextBox" b:id="search-text-box"/>
Like this you can access the field in your view-class via searchTextBox and the id search-text-boxis added to the HTML element (which you could also use for styling etc.)
We have faced same issue for our project while adding test automation. As per my knowledge unfortunately GWT doesn't support anything like AOP yet. So we have to follow any of the spaghetti-like approach only from one mentioned above by #mxlse or the one you are already following.
Based on my experience I can recommend you to create separate constant/property at client or server end. Use this file to save all your id's which you can share latter on with test team as well.
I am making a simple CMS just for learning purposes and I have a question how I would organize it. I have an administration section where you can add new pages, edit content etc, and I also have a public part that the user see for example the pages.
So, I have PageEJB class that has logic for adding a page, edit a page, deleting a page, finding a page etc. in other words logic from the admin section and public section is in the same class. Should I instead make a PageAdminEJB and PageEJB and separte the content?
Since you're doing it for learning purposes only, will you learn anything by having two EJBs instead of one?
I'd say: start with one, see how it grows. When it reaches critical mass (when you see it does too much), refactor it. This way you'll learn how hard/easy is to introduce a new EJB to your system. Perhaps the facade design pattern will help you then.
Based on what you wrote, it's difficult to advise decisively one way or the other.
We have a rather large application, with a great deal of dynamic content. Is there anyway to force struts to use a database for the i18n lookups, instead of properties files?
I'd be open for other ways to solve this as well, if anyone has ever done i18n with dynamic content.
I don't know of an easy plug-and-play solution for this, so you will probably have to implement it yourself -- plan on spending quite a bit of time just coming to grips with how the localization features of struts 2 (and XWork) are implemented. The key will probably be to provide your own implementation of com.opensymphony.xwork2.TextProvider (and tell struts to use it by providing a <bean> tag in struts.xml). I can think of at least two ways of fitting this into the overall architecture:
Have your TextProvider implementation access the database directly. In the spirit of YAGNI, this is probably the best way to start (you can always refactor later, if necessary).
Alternatively, you could place the database code into an implementation of Java's ResourceBundle interface, which is what XWork uses internally. To me this sounds like an even more design-heavy approach, but on the plus side there are some articles around describing how to do this.
No, there is no built-in way to have Struts2 load localized content from a database. You would need to write that yourself.
What are your requirements? Do you need for users to be able to dynamically change field prompts, error messages, etc.?
You may be able to do something like that by building a custom interceptor. You could have the interceptor read all the key value pairs from your database and inject them into the value stack. The only thing I am not sure about, not really having messed with i18n with struts before, is if the i18n stuff pulls that information from the value stack. If not, I am not sure if maybe you could do something else in the interceptor to load up the information.
Building a custom interceptor is not too terribly complicated. There are plenty of tutorial sites out there, including (brace for self promotion here) my blog: http://ddubbya.blogspot.com/2011/01/creating-custom-struts2-interceptors.html.
Use properties files just for static content, like labels, messages etc.
For dynamic content start with a database table that includes a language-code-id for every language you want to use. All the dynamic content entries that are already translated go with their respective language-code-id added to their primary key. If a translation is missing, you can program your application to fall back to your default language in order to make things easier until the right translation is present.
Let your users provide their contributions in the language they like and store it with the appropriate language-id. Someone should provide the translation to the other languages in order to make the contribution complete.
...
PRIMARY KEY (`subject_id`,`language_id`),
...
Over the past year I have heard alot about Velocity and NVelocity. Reading their documentation and doing searches on the net hasn't given me the answers I was looking for.
In what situation would I use this library in my development? What problem does it solve that didn't already have a solution?
Since the dawn of web apps, people started to think about separation of concerns in many applications, including web applications. The challenge is to separate what is view code from what is business code, or logic code. When jsps first arrived, many people where coding lots of logic in jsps directly (stuff like db access and other), breaking the basic principle of separation of concerns (jsps should be responsible for the presentation, not for the logic).
Velocity, Freemarker and others are templating engines that allows the separation of UI logic and business logic, thus facilitating changes in the presentation while minimizing the changes on the business side. These template engines have facilities for doing common UI tasks such as showing a block of html if some condition holds true, or iterating over a list while maintaining logic code outside of the view. This is fundamental for maintaining a complex application in the long run.
I think it's important to point out that compared to JSP/ASP.NET as a templating mechanisim, Velocity/NVelocity really 'ENFORCE' the seperation of concern.
With <% .. %> of JSP/ASP.NET, any Java/.NET code is allowed. Which is why sometimes you do see business logic code in these files.
With Velocity/NVelocity you can't embed long series of code. Instead you are really forced to pass in computed values, which Velocity/NVelocity picks up and displays them according to the way the template is designed.
Another point would be that they can work outside of a Web Container environment (at least Velocity can AFAIK). Imagine that you had designed a report template with JSP/ASP.NET. It works fine from the web. And then suddenly there is a change request to have it be done from a Desktop application. Rather than embed a Web Container in it, you could initialize Velocity/NVelocity, compute the values, then render the template.
It's a template engine. If you have a lot of static text with variable content mixed in, templates are a great way to reduce the amount of work you have to do.
It's a whole lot better than String.Format or loads of concatenation because it's not as repetitive or error prone, and far more maintainable since you can figure out exactly what your template does just by looking at it.
We use templating to generate configuration files for production, UAT, system test, contingency systems etc.
We have a master Spring configuration file into which we inject a property file. We have a master property file that is parsed by Velocity and this allows us to keep all system settings in one file.
As a bonus, for the ones interested, I recommend reading the following:
http://www.artima.com/lejava/articles/stringtemplate.html
http://www.cs.usfca.edu/~parrt/papers/ST.pdf
These are links about StringTemplate, a templating engine by Terence Parr who wrote antlr, a parser that's been used everywhere (ex: hibernate uses antlr).
1 - Velocity engine actually merges the real time data with the xyz.vm file which holds the static information 2 - The vm file uses Velocity Template Language(VTL)
(It can iterate over the java iterable java objects placed on the context , can call the methods accessible by the objects placed on the context) Situations to use Velocity - Brings the power of java to html not only to html 1-When you have to generate report mails often with varying data and constant style.(foreach support)
2-When you want to merge a real time data with dummy place-Holder in deeply nested contents
3-When you want to decide style information based on the value of the data (if else support)and many more
Refer - http://velocity.apache.org/engine/releases/velocity-1.5/user-guide.html