Mobile Blogger. Project Guide : Dr. M. B. Srinivas. Submitted By : Anurag Singh Rana ( ) Md. Shakeeb ( ) Parag Agrawal ( )

Transcription

1 Mobile Blogger Project Guide : Dr. M. B. Srinivas Submitted By : Anurag Singh Rana ( ) Md. Shakeeb ( ) Parag Agrawal ( )

2 Introduction With around 40 million of people around the globe blogging every day, we feel that soon people will crave for mobile blogging i.e. instead of waiting for the day to end or to find a terminal. They would like something handy and convenient to put up their experiences of the day, in the form of writings or images, as soon as it eventuates. Also call costs falling to the floor will eventually make people turn to this alternative. Java is everywhere. It is because of its platform independence. Many hand held devices, PDAs and smart phones are being manufactured with capability to run Java programs. As a result, Java is a defacto choice to build applications for mobile phones. There are other alternatives like C++ on Windows CE and Symbian OS, but they tend to limit the portability of the application. Requirements Analysis The requirements of the project are divided into three parts. The blogging server web interface. The Java based mobile device client. The blogging server mobile device interface. The Web Interface The aim of the project is to build a demonstration of Mobile Blogging. Hence, we need to build a complete solution for the same, so that any company can use the design too. We need to build a webbased Blog server, its Mobile interfaces and the Java based Mobile client. The blog server needs to have capability to authenticate users, enable blogging as well as uploading images into their photo albums. There should be an interface to sign up for the blog server website, edit the profile and change passwords. In order to communicate our thoughts and images to other people, there needs to be a mechanism to view other people s blogs and images. Hence, we need an interface to view other profiles. Some people might want to keep personal information on their blogs. Hence, we need a mechanism for users to specify a list of friends too. A blog editor page, along with mechanisms to edit new and old posts, specify their access rights needs to be developed. There should be an interface to view a persons archives month wise as well as view the recent posts by a person. The user can create albums to upload images of various occasions on the blog. An album can contain

3 any number of images as the user likes. Each image will have a caption describing the context in which the image was taken, to help them recall or to help other people understand the context. Java based client The major novel idea of this project is blogging through hand held devices. Hence, one of the core components required in this project is the Java enabled client for mobile devices. This client will be the interface for the user on the mobile phone. It will connect to the blog server and fetch or send required information in order to accomplish its goal. Similar to the web based interface, we need to provide an authentication interface for the mobile phone user in order to restrict unauthorized access, and also because the blog server is secure in itself. The user will have less but sufficient set of tasks that can be performed through the mobile device. The first requirement of blogging through the mobile phone is to be able to write text based posts from the mobile phone. Hence, a write a new post interface needs to be provided, with the capability of settings its title as well as access permissions. After posting the blog, the user might want to view it, or might want to recall the post he had written earlier. Hence, another core functionality in the mobile interface is listing, viewing and editing posts that have been written earlier. In order to help the user share images that he takes from his mobile phone, we need to provide an interface to upload images from the mobile device. Also, if the user wants to view some old pictures already on the server to refresh his old memories, we need to provide an interface to browse through the albums. The Mobile Device Interface Along with a fully functional standalone web interface, the blog server needs to implement a mobile device interface too. This interface will be used by various hand held devices to contact the server, authenticate, send and receive text and images. The capabilities supported by the mobile phone needs to be backed by the server interface. Design and implementation Server side The blog server needs to implement a secure and fast method to provide services to its clients. Hence,

4 we choose the famous LAMP architecture (i.e. Linux Apache MySQL and PHP). This solution is being used by many small upcoming business solutions as it is cheap, fast to build and deploy, stable and fast. The blog will be storing its data inside a database. After doing a requirements gathering and analysis, this are the various database tables that we came up with. Table person name char (40) Name of the person login char(30) Login name password char(40) Password of the user dob date Date of birth (Not used) description text About of the user (Not used) address char(255) Address (Not used) occupation char(50) Occupation (Not used) plevel int Access level for profile Table friendrequest requester char(30) Person requesting friendship requestee char(30) Person being requested Table friend user char(30) The user pal char(30) The friend of the user Table post postid int Post identifier login char(30) Login name of user decr char(100) Title of the post data text The content of the post

5 dop int Timestamp access int The permissions for the post Table album login char(30) The username albumid int Album Identifier name char(30) Name of the album doc int Timestamp of creation access int Access rights for album Table photo login char(30) The username albumid int Album Identifier photoid int Photo Identifier filename char(30) Filename of the image decr char(50) Caption for the image The blog server has various screens in the web interface in order to implement its requirements. It uses PHP sessions in order to maintain the authenticated sessions. The navigation occurs by propagating a session id across links. The user can logout to destroy his session to avoid other people from making unauthorized changes later. The mobile interface of the server implemented XML based communication, and authentication was done in every action, without maintaining any sessions. The Mobile Interface As discussed in the introduction, Java is the language of choice for development of an application for mobile devices. The Java language provides an extension for mobile devices called Java 2 Micro Edition or J2ME. The J2ME programming paradigm provides clean API for displaying GUI on the mobile phone (using Midlets), Media API for playing videos and animation, Connector API for communication and an optional FileConnection and PIM API for accessing the mobile device s storage devices and address books.

6 The Netbeans 5.0 editor is a standard choice for programming in J2ME. With its rich code checking features, code help features as well as some GUI tools to develop the screens of the mobile application, it is the first choice of J2ME programmers world wide. Netbeans can be added with a mobility pack in order to run the mobile device emulators through the IDE, making it easy and intuitive for the developer. The mobile device has many constraints on the memory. Even with advanced tools available (code obfuscation), one needs to check the memory usage of the program. Hence, we also need a memory profiler in order to generate good code. The programmer needs to explicitly call the Garbage Collector time to time in order to keep the memory usage at a low level. The mobile devices do not implement the fully functional API for connecting to HTTP servers and sending POST messages. As a result, the first step in the project was to understand and develop a library to package and send POST messages to the blog server. Hence, we developed a PostPackager and InfoExchanger classes to perform these tasks. The mobile devices also don t have any API to parse Xml by default. As a result, we looked for various available parsers in the market. These included Kxml, Kxml2, Xparse and so on. Finally, we chose the Xparse parser, which is a set of 3 Java files in order to be compact and fast. Hence, this parser helps us meet our requirements with the minimum possible size constraints. When the project development began, the Netbeans editor didn t have any capability to create screens for the application. As a result, the programmer was fixed to writing his own code to display and switch screens, display images and so on. With the introduction of Visual Midlets in Netbeans, it became easier to design and deploy the look and feel of the application. Hence, after implementing the GUI with the old technology, we upgraded to the new tool in order to develop the application faster and to keep it most manageable and expandable in the future. Although the look and feel of the application are mostly handled by the IDE, the functionality with each click needs to be programmed manually. Hence, we developed various classes in order to authenticate the user submit new posts fetch old posts, display, edit and resubmit them fetch a list of available albums and view images in them read the storage devices on the phone, view and upload new images from it All these functionalities were programmed into SimpleCancellableTasks with beautiful WaitScreens till those tasks finish/fail. The look and feel of the interface is intuitive, simple and easy to use. The interface provides the right buttons at the right place to keep it simple and still functionally rich.

7 The communication with the server is primarily XML. The client sends its requests as a POST message as discussed before and gets an XML reply. This reply is then parsed using Xparse and the required actions are taken. A sample XML code for authentication response is <login>ok</login> An XML response for the list of albums is <post> <status>ok</status> <noofalbums>5</noofalbums> <albums> <album><name>independence Day</name><id>1</id></album> <album><name>srisailum Trip</name><id>2</id></album> <album><name>accv 2006</name><id>3</id></album> <album><name>ganpati 2005</name><id>4</id></album> <album><name>mobile</name><id>5</id></album> </albums> </post> Similarly other type of data is sent and received through the mobile. Images are stored on the webserver as PNG images by default. As a result, all images sent and received are converted into PNG format first. The J2ME API explicitly mentions support for PNG formats and hence is used to transfer and display images on the mobile device. Conclusion It was a great learning experience for us in learning J2ME and PHP. The project successfully implemented a server and client mechanism for blogging and sharing images from the web as well as from mobile devices.