I have to do web service + web page on openwrt device. From web page I can send communications to a program which is running on the device, so I need to build web service and I don't know which to chose for lighttpd web server, I don't know if Soap Lite is compatible with openwrt+lighttpd.
Soap Lite is a "collection of Perl modules" for perl. You can use the cgi extension on lighttpd to use perl. So yes, it would work with lighttpd. The question is if your router has enough processing power to support lighttpd + cgi.
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I would like to know if there is any difference in hosting REST web service APIs in a web server or application server, is there any reason one is preferred over the other?
So i think you are confused about what are application servers and web servers.
Application Server is the name of a machine/server which is running any application used by an organization and it depends of any other servers to run the application functionalities correctly, like Database Servers, Caching Servers and other kind of servers.
Web server is a software which puts an application online for being accessed by clients through the web.
An application server commonly has a web server running inside it, as part of a stack needed to run the application in the server, like libraries and other sofwares need to execute the application objective.
So you can run a REST api inside of an application server with help of the web server application.
Some examples of web servers are Apache, Nginx, LightHttpd, etc.
I am new to the programming world and started with Perl couple of days back. I tried developing a web application using Perl. Initially followed some tutorial and learned how to write simple CGI scripts using Perl and deployed it using Apache2 httpd server. After getting to know about the Perl Dancer it was much easier to develop a web application using the framework.As both serve the same purpose I want to know weather Dancer is a replacement to the Apache httpd server or dancer internally uses apache to start a server. As dancer is just a web application framework how internally it is managing to handle the server request and responses.
Can anybody post a link where I can read and get to know about how the webserver works?
Dancer has a PSGI interface.
PSGI is similar to CGI in that it allows a web server to communicate with the Perl application, but it is more efficient (it keeps the application running all the time so it doesn't need to load everything from scratch for each request) and has more features (e.g. the ability to use Plack middleware).
Dancer comes with a script to run a simple web server (which is not Apache) for development purposes.
It is expected that you'll use a more powerful web server (such as Apache HTTPD) in production.
I am planning to design an application which will require both web server and application server (Java EE based). Modern application servers like Weblogic, Websphere, JBOSS can provide support for both application server and web server. However I have seen many applications where the deployment architecture provides a segregation of web server and application server as a separate entity.
I would like to know:
What is the architectural benefit of segregating the web server and app server as a separate entity?
e.g. Assuming we are going to use weblogic as a web sever and app server do you think if there is any concern for large applications?
There is several resons to use a dedicated web server for static content:
In most case a web server is already present infront of the application server (reverce proxy), it is needed if the app server is clustered. So as it is already present.
If the static content is important (size and trafic), puting it in web server allow to scall the content and the application separeatly.
Historicly pure Java app server was slower that native web server, now NIO allow the same access to system call sending file directly to a socket without going back and forward between system and user mode.
So I think you should start with the contend delivered by the app server and complexify the system if it help you to solve issues you actualy enconter.
Is an application server something like an additional layer of application servicing above a web server?
Does an application server always have a web server as its core?
What is the difference?
No,Application server does not contain web server...
Read following articles...
http://www.answers.com/topic/application-server
http://download.oracle.com/docs/cd/E19159-01/819-3671/ablat/index.html
Basically:
After the Web exploded in the mid-1990s, application servers became Web based.
Also following shows the difference between web server, web container and application server...
Difference between a Web Server, Web Container, and an Application Server
A Web Server is a server capable of receiving HTTP requests, interpreting them, processing the corresponding HTTP Responses and sending them to the appropriate clients (Web Browsers). Example: Apache Web Server. Read more about Web Servers and their working>>
A Web Container is a J2EE compliant implementation which provides an environment for the Servlets and JSPs to run. Putting it differently we can say that a Web Container is combination of a Servlet Engine and a JSP Engine. If an HTTP Request refers to a Web Component (typically a Servlet or a JSP) then the request is forwarded to the Web Container and the result of the request is sent back to Web Server, which uses that result to prepare the HTTP Response for the particular HTTP Request. Example: Tomcat is a typical Web Container. A typical setup would be to have Apache HTTP Server as the Web Server and Tomcat as the Web Container.
An Application Server is a complete server which provides an environment for running the business components (EJBs, ADF BCs, etc.) in addition to providing the capabilities of a Web Container as well as of a Web Server. Example: Bea WebLogic, IBM WebSphere, Oracle
Application Server, etc.
Actually, with the explosion of the web, and in particular "web services", all modern App Servers can also function as Web Servers. For example, the current version of Tomcat includes built-in Web Server functionality so you no longer must run a separate Apache HTTP server. In the past, running separate dedicated Web Servers such as Apache was preferable since the App Server was optimized for App Server rather than for Web Server, processing; but the performance of App Servers as Web Servers has improved such that any remaining performance difference is irrelevant - and certainly does not justify the expense of running separate servers.
Today, the major difference is that an App Server is designed to support programming languages such as Java or, on the .net platform, C# - as well as to provide an underlying infrastructure that includes automatic fault-tolerance, session mgmt, transaction mgmt, multi-threading - and everything else required to build scalable enterprise applications. Current Web Servers are designed to support languages such as Ruby, PHP, Python and Perl - and lack the built-in infrastructure of an App Server.
However, the distinction between App Servers and Web Servers is blurring and will continue to do so as "Web Services" becomes ever-more popular and languages such as Ruby mature and therefore require Web Servers to provide much of the same underlying infrastructure as today's App Servers. In the end, the primary difference will be (not yet): if you want to develop the back-end (cloud) layer of your application employing Java or C#, employ an App Server; if you want to develop your application employing Ruby, PHP or Perl, employ a Web Server.
While a Web server mainly deals with
sending HTML for display in a Web
browser, an application server
provides access to business logic for
use by client application programs.
Read App server, Web server: What's the difference?
Hosting an application on a web application server e.g. JBoss automatically brings in lots of app server specific functionalities with it e.g. security, clustering & load balancing etc. I have a situation where I have to develop a server app with which, legacy apps can talk to over TCP/IP socket as well as be highly available. Initially, I had though of using JBoss app server to leverage its clustering support for HA. However, I am not sure whether it would be possible to connect to a JBoss web app using pure TCP/IP sockets from both java and non-java apps.
What is the best way to achieve this without using web service or Http approach?
UPDATE: I am specially interested to know how legacy apps will connect to the hosted web app through TCP/IP socket.
A really simple solution to bridge the two worlds would be to add a simple Java server which maps the old TCP/IP requests to HTTP requests. This is probably a pretty braindead task, so this "server" will be simple to write and maintain. Also, this server won't need as much power since it just accepts and forwards connections (no business logic or DB code).
On the JBoss server, you develop like you normally would. The legacy apps connect to the little bridge server which passes the requests on to JBoss and translate the result back.
This ensures that you're building for the future: When new apps are developed, they can connect directly to JBoss and use all the great HTTP features.
There's no reason why you can't open up a normal socket in (say) a servlet application hosted in JBoss.
You can then get a byte stream from this. The headache is then to decide on a platform-independent representation of your messages, such that your client end can format and send such that the JBoss-hosted end can read. But it's all perfectly feasible.
I would implement a very simple http (1.0) client.