c#: Service Trace

Often time we need to monitor the health and activities of a long running service. In this article I am employing a new technique to query the service in an asynchronous and disconnected fashion.


1. Start a master socket with a port and wait for clients to connect. Once the client is connected, add the client socket to the list of client sockets for sending data

2. Send Trace Data in an asynchronous fashion. Loop through the client sockets and then send the data. If the socket is closed, remove it from the list of client sockets

3. In the client application, start a client socket and connect to the host with the port defined in step 1. Once connected, wait for master socket to send data to this client.


4. Asynchronously receive data from the socket. You define a callback handler and as the data comes from the master socket, this handler will get invoked.

5. Wire up an event handler to the socket's receive event handler

6. Wire up this event handler to a web page or a windows application to show the data. Remember to use Control.Invoke method coupled with UpdateTextCallback to update the Windows Form Control texts

You can use a normal text/log writer to log the activities to a flat file instead of the socket implementation that I showed here. However if you are disconnected or to see the log as it happens, this is one of the ways to achieve that.

download code

-Paul

jsf: hidecontent tag - same as aspnet's placeholder

While working on a java project, I needed to hide certain contents and functionalities from a subset of users. I couldn't find a built-in tag to accomplish this functionality.

Here is a sample page that uses this tag to show Access Denied message when a non-privileged user try to access a page


For example consider a simple application with 2 roles.
Editor role can add/remove items (say products). Admin role approves new/edited items, publish for sale on website and can view all reviews of the products.
Assume that we have 3 sections in our web page, one for Product Details (Editor Role has full privilege), Admin (Admin Role has full privilege), Review ratings(Admin Role has full privilege).
This placeholder component is a perfect fit for such a scenario. This is a very simple component which uses a div tag's visibility attribute to hide contents.

Here is how to make such a component. See jsf documentation on a more detailed explanation of each of these items

1. Create a Render Class. I am using 2 properties to check the privilege (just to show you that you can have as many properties as you like to do business logic checks)


2. Create the Tag Class. Nothing fancy here, couple of getter and setters


3. Create Tag Descriptor. Think tld as an explanation of the properties of our tag.


4. Add to faces-config.xml. Add to faces-config to consume in our web pages


5. Add to Page. Add the taglib prefix and set the variables.


download code and rename to .zip

[Child controls' required attribute need to be changed to false if you are enabling a form post for non-privileged users]

That's it!

-Paul