Technical Blog for Programmers
Latest popular technical blogs on LDAP. Java, J2EE, Web Services and Storage Area Networks with source code, examples and implementation strategy.
In a SAN (Storage Area Network), if all the hosts are allowed to access all the drives in the SAN, it may lead to many issues like device contention and mainly data corruption. In addition some Operating Systems (eg. Windows ) writes header information to disks which will lead to data loss (We will discuss it later in this article). To avoid this zoning and LUN masking is used. By doing Zoning and LUN masking storage units are isolated or made invisible to some or all of the hosts in the SAN. Lets look into zoning and LUN masking in detail.
What is LDAP ?
LDAP is a directory access protocol. You can consider LDAP as a hierarchical object oriented database where data is stored in tree structure. LDAP is widely used to store contact informations of users under different categories. LDAP is mainly used in authentication and other lookup services where it may receive large number of look up requests per minute.
Why using LDAP when there are relational databases ?
- LDAP is optimized for large number data look up requests per minute.
- LDAP is standard protocol and many implementations are available for this.
- Since its a standard protocol, you can switch your LDAP server without changing your application code.
- LDAP runs on direct TCP/IP and SSL
- All programming languages have built in support for LDAP. For example in Java you can access LDAP using JNDI ( Java Native Directory Interface ).
Filters can be used to transform the response from a servlet or a JSP page and can perform many functions as follows
- User Authentication- Blocking requests based on user identity.
- Logging and auditing-Tracking users and the actions performed.
- Image conversion- Scaling, squeezing etc
- Data compression-For making the download easier.
- Localization-Targeting the request and response to a particular locale.
A filter is a Java class which implements the javax.servlet.Filter interface . The javax.servlet.Filter interface defines three methods as given below.
If you check the performance of your site using any of the site speed analyser like page insights, you can find the most important suggestion they will be giving would be to set Expires header so that the browser can use the cached copy. You can set the expires header for your site with a few lines of configuration in .htaccess file.
In reality, SQL joins are easy to understand. But people usually seem to get confused between them. In this article, you can find a well known way to remember and understand visual explanation on how SQL joins relate to their corresponding names. Along with the visual representation, we had provide a sample query for each type of Join.
Webservice is an awesome technology when we think of interoperable services. Its very simple, many libraries are available there to expose your existing application as a Webservice with very little effort. But still you can find developers complaining about it when it comes to automatic binding happening at client and server side. Here I'll explain one of the such scenario and how we can override JAXB binding at client side. Most of us will be using IDE to create a webservice or a webservice client, some may be using ant or any other technology. Regardless of the building environment, when you create a client by specifying the WSDL url, the building environment will use wsimport ( or any third party library) command to generate the client side stubs. In the client side stub, all the XmlTypes specified in the WSDL will be converted to corresponding Java Data Types.