7.2 Conclusion

7.2  Conclusion

In this thesis, the TCP/IP was used on top of delay tolerant network fundamentals where store and forward operation perform by data synchronization at each mail server. This approach enables the email flow through the offline mail server to infomediary device and then to the online mail server and internet. The user registration page is implemented at online mail server and accessible from online mail server local area network or from the internet. The email data can remain in the mail server more than one week time delay until it synchronized with infomediary device. Limitation size of the offline email system file attachment is 10MB and total email message is 50MB. This limitation is depending on the size storage of the server computer. All types of data supported for uploading an attachment and system administrator can block various file extension such as bat, cmd, com, cpl, csh, exe, inf, lnk, msi, msp, reg, scf and scr from being uploaded as an email attachment. Multiple sender and receiver can send and receive emails simultaneously and supporting multiple communications between users successfully. Based on calculation, the maximum recommended speed of infomediary device movement through the Wi-Fi range of the server computer is 12.85 km/hr or less and depend on the hardware specifications such as Wi-Fi data transfer rate and storage read and write speed. This offline email system fulfills the objective of this thesis work where the system can be used at the area that has no internet connection such as rural area. This offline email system implementation based on DTN approach can be used for other web application such as blogging.

7.1 Future Work

7.      CONCLUSION

In this final chapter, a brief summary of the research and development work is provided. A recommendation for future work is concluded and conclusions of the research objectives and results are discussed.

In the beginning, an introduction and objective to the thesis work was presented. A comparison between TCP/IP and DTN was discussed. An email architecture and overview of similar work was given. Next, the design of TCP/IP mail system working using a DTN store and forward fundamentals is discussed including the network protocol design followed by offline email system detail design. The idea of using database synchronization as DTN store and forward fundamentals is discussed. Then, the system implementation issues and implementation details of server computer, web server application, mail server, mail client and database synchronization. Lastly, the system test and result of the offline email system was presented.

7.1  Future Work

There is a possibility of this offline email system can support Government’s “Kampung Tanpa Wayar” project where it can benefit in term of cost to expand a portion of internet access such as the email application to rural area. It is also good to improve email security by implementing encrypt and decrypt process in data synchronization between Mail Server and infomediary device. A proper dedicated online mail server with a static IP internet connection is better to replace the current approach to reduce dependency to external services such as DtDNS. This will improve reliability of the system. Additional mail client feature can be added such as email labeling, priority email, send and achieve message etc. Database synchronization speed can be improved with better hardware, especially when dealing with many mail data and bigger attachment files. In the process of database synchronization, there is a need of checking the database path availability continuously between server computer and infomediary device. This process will consume much more power while in rural area there is are constrained that there is a need to conserve power consumption since the power in rural area mostly dependable to electric power generator. Instead of continuously checking the database path availability, the process can be done by checking the database path availability at a set of time or only when the infomediary device is available in the server computer network.

6.10 Summary

6.10  Summary

A brief result of the different testing approach was provided in this chapter 6. A demonstration setup was also explained to show various application scenarios of the offline email system. Next chapter, conclusions and future work are discussed.

6.9 Discussion of Results

6.9  Discussion of Results

The test result shows that user were able to register a new email account locally at online mail server or through internet. Email account created at online mail server is accessible at the offline mail server, online mail server and through internet after mail data synchronization between infomediary device and each mail server. Email system found to be successfully functional to send or receive email through the offline mail server, online mail server and internet. Pending email data is tested for a period of time and found to be able remains in the database and not discarded. Wireless LAN range between server computer access point and infomediary device for it to establish mail data synchronization is 95 Meters or less with a data rate transfer is 54 Mbps which is 54 megabits per second equal to 6.75 MBps which is 6.75 megabytes per second and limited by infomediary device storage write speed which is 2.03 Mbps. The recommended infomediary device move speed through the Wi-Fi range of the server computer is 3.57 m/s equal to 12.85 km/h or less to ensure the mail data synchronization is completed successfully. The maximum size of an email attachment is 10MB with total message size limit is 50MB. It is also recommended to limit the size to lower 10MB to prevent spam attack and viruses. Each email account size quota is set to 250MB. It is dependable on the server computer hard drive storage size. All tested emails are successfully sent and receive within the mail server email size limitation. This offline email system can upload any types of file and have the ability to block attachments with certain extensions on the mail server. Number of email connections is unlimited. It can send or receive emails multiple times without worrying of the mail data overwritten on the mail server database.

6.8 Multiple of Communications Test

6.8  Multiple of Communications Test

6.8.1        Test Design

This test is to check the maximum number of simultaneous SMTP connections to the server. An unlimited number of simultaneous connections will be allowed by configured mail server number of connection values to zero. This value is set to zero by default. This is to ensure no overwrite email occurs and check this offline email system capability of handling the same sender sent an email a few times to multiple receivers.

This test performed with a two way communication. The sender sends an email to receiver and receiver send email to sender at the same time. There are three scenarios tested which are between two users, four users and six users as shown in Figure 6.5. Another test is sender send multiple emails to the receiver to ensure are not overwritten in the mail server database.

Figure 6.5: Multiple communication

6.8.2        Expected Outcome

Expected outcome from all three test samples as shown in Figure 6.5 as per below:

Test 1: User A1 successfully sends email to user B1, while user B1 successfully receives email from user A1 and vice versa.

Test 2: User A1 and A2 successfully sends email to user B1 and user B2, while user B1 and user B2 successfully receive email from user A1 and user A2 and vice versa.

Test 3: User A1, user A2 and user A3 successfully send email to user B1, user B2 and user B3, while user B1, user B2 and user B3 successfully receives email from user A1, user A2 and user A3 and vice versa.

6.8.3        Test Result

Test 1 is to test two way communications between two users. User A1 successfully sends email to user B1, while user B1 successfully receives email from user A1 and vice versa. Test 2 is to test two way communications between four users. User A1 and A2 successfully sends email to user B1 and user B2, while user B1 and user B2 successfully receive email from user A1 and user A2 and vice versa. Test 3 is to test two way communications between six users. User A1, user A2 and user A3 successfully send email to user B1, user B2 and user B3, while user B1, user B2 and user B3 successfully receives email from user A1, user A2 and user A3 and vice versa. The result of multiple communication shown in Table 6.7. Test on multiple emails send from users at offline network environment to users at online network environment shows that the emails is successfully send and received. Test result is produced by actual conduct test.

Test	Sender	Receiver	Email delivery result
			Sending email	Receive email
1	User A1	User B1	User A1 to User B1 - success User B1 to User A1 - success	User B1 from User A1 - success User A1 from User B1 - success
2	User A1	User B1	User A1 to User B1 - success User B1 to User A1 - success	User B1 from User A1 - success User A1 from User B1 - success
		User B2	User A1 to User B2 - success User B2 to User A1 - success	User A1 from User B2 - success User B2 from User A1 - success
	User A2	User B1	User A2 to User B1 - success User B1 to User A2 - success	User B1 from User A2 - success User A2 from User B1 - success
		User B2	User A2 to User B2 - success User B2 to User A2 - success	User B2 from User A2 - success User A2 from User B2 - success
3	User A1	User B1	User A1 to User B1 - success User B1 to User A1 - success	User B1 from User A1 - success User A1 from User B1 - success
		User B2	User A1 to User B2 - success User B2 to User A1 - success	User B2 from User A1 - success User A1 from User B2 - success
		User B3	User A1 to User B3 - success User B3 to User A1 - success	User B3 from User A1 - success User A1 from User B3 - success
	User A2	User B1	User A2 to User B1 - success User B1 to User A2 - success	User B1 from User A2 - success User A2 from User B1 - success
		User B2	User A2 to User B2 - success User B2 to User A2 - success	User B2 from User A2 - success User A2 from User B2 - success
		User B3	User A2 to User B3 - success User B3 to User A2 - success	User B3 from User A2 - success User A2 from User B3 - success
	User A3	User B1	User A3 to User B1 - success User B1 to User A3 - success	User B1 from User A3 - success User A3 from User B1 - success
		User B2	User A3 to User B2 - success User B2 to User A3 - success	User B2 from User A3 - success User A3 from User B2 - success
		User B3	User A3 to User B3 - success User B3 to User A3 - success	User B3 from User A3 - success User A3 from User B3 - success

Table 6.7: Multiple communication test result

6.7 Multiple of Senders and Receivers Test

6.7  Multiple of Senders and Receivers Test

6.7.1        Test Design

SMTP servers may reject messages from mail server if there are too many recipients in a single email. This is because the receiving SMTP server may think that the email message is spam because of sending to a large number of users. The number of recipient uses in the same delivery can be set in the mail server configuration menu. The mail server will disconnect from the recipient server when this number has been reached, connect again and continue with the remaining recipients. This test is to ensure this offline email system can it differentiate different senders sending an email at the same time. This test performed by sending an email between two senders to one receiver which is user offlineA and user offlineB to user onlineC, three senders to one receiver which is user offlineA, user offlineB and user onlineD to user onlineC, one sender to two receivers which is user offlineA to user onlineC and user onlineD and one sender to three receivers which is user offlineA to user offlineB, user onlineC and user onlineD.

6.7.2        Expected Outcome

Expected outcome from this test as per below:

Test 1: User offlineA and user offlineB successfully send email to user onlineC.

Test 2: User offlineA, user offlineB and user onlineD successfully send email to user onlineC.

Test 3: User offlineA successfully send email to user onlineC and user onlineD.

Test 4: User offlineA successfully send email to user offlineB, user onlineC and user onlineD.

6.7.3        Test Result

Test result for multiple sender and receiver sending and receiving email at the same time through infomediary device with DTN based technique shown in the Table 6.6. Test result is produced by actual conduct test.

Test	Number of sender	Number of receivers	Email delivery result
1	2	1	Send email success
2	3	1	Send email success
3	1	2	Send email success
4	1	3	Send email success

Table 6.6: Multiple sender and receiver test result

6.6.2 Expected Outcome

6.6.2 Expected Outcome

         This offline email system is expected to allow user uploading any type of data with various extensions as an email attachment except the block attachment for files with extension bat, cmd, com, cpl, csh, exe, inf, lnk, msi, msp, reg, scf and scr.

6.6.3 Test Result

         Types of data tested by uploading a file with various extensions as an email attachment. File type attachment test result shown in the Table 6.5. Test result is produced by actual conduct test.

Test	File Types	Attachment result
1	pdf, txt	Upload attachment success
2	doc, docx, xls, xlsx, ppt and pptx	Upload attachment success
3	zip, rar and 7z	Upload attachment success
4	jpg, png, gif and bmp	Upload attachment success
5	mp4, avi and mpg	Upload attachment success
6	mp3, wma and ogg	Upload attachment success
7	bat, cmd, com, cpl, csh, exe, inf, lnk, msi, msp, reg, scf and scr	Fail to upload attachment

Table 6.35: Testing types of data attachment

6.6 Types of Data Test

6.6  Types of Data Test

6.6.1   Test Design

Email tested sending with file attachment. Any file format with various extensions is supported for attachment. The administrator can block attachments with certain extensions on the mail server. The default setting for block attachments is for files with extension bat, cmd, com, cpl, csh, exe, inf, lnk, msi, msp, reg, scf and scr. These types of file extensions are recommended to be blocked as to prevent any virus attack.

Types of attachment files tested for pdf, txt, office file format such as doc, docx, xls, xlsx, ppt and pptx, compress file format such as zip, rar and 7z, image file format such as jpg, png, gif and bmp, video file format such as mp4, avi and mpg and audio file format such as mp3, wma and ogg.

6.5.3 Test Result

6.5.3        Test Result

Email size content limitation is depending on the hard disk available storage. This offline email system maximum attachment size is 10MB, maximum message size is 50MB and allocated maximum size storage for each email is 250MB. A test result of sending an email with attachment size 1MB, 5MB, 9MB, 10MB, 20MB and two 10MB files shown in the Table 6.4. Test result is produced by actual conduct test. 

Test	Attachment Size	Total message size	Email delivery result
1	1MB	1.4MB	Upload attachment success Send email success
2	5MB	6.9MB	Upload attachment success Send email success
3	9MB	12MB	Upload attachment success Send email success
4	9.97MB	13MB	Upload attachment success Send email success
5	20MB	-	Fail to upload attachment
6	2 x 9.97MB	27MB	Upload attachment success Send email success
7	6 x 9.97MB	81MB	Upload attachment success Fail to send email

Table 6.4: Testing email data size