[BlackBerry Development Path] [00] [BlackBerry Platform Architecture Overview] [07] [Network connection and transmission mode]

network connection and transmission mode

The BlackBerry Solution acts as a bridge between the wired and mobile networks, the public network (the Internet) and the Internal network (intranet), leading to a wide variety of internet connections and data transmission patterns involved in BlackBerry.

From an application perspective, the following factors need to be considered in selecting the data transfer mode:

1. BlackBerry user type;

2. Safety and reliability of the importance of the degree;

3. The network used by the program and the support for roaming users;

4. The transmission configuration of the program;

5. Program upgrades and alarm needs of the active push;

6. Location of the target server

Wireless transmission Mode

Push (push, push)

The client listens for ports that receive data, and the server sends the content to the phone when the data changes, close to real-time updates, and the client does not have to send additional packets to get the data or maintain an open connection.

The difficulty of its implementation is:

L KNOW the location of the mobile phone and the current network address;

L to ensure that the mobile phone can still reliably obtain data outside the signal coverage area;

l Cancel or replace expired, outdated push data;

L Guarantee Push Data security

Poll (pull, query)

The server queues the new data available, and the client periodically queries the server for updates. Poll mode is easy to develop but not real time, increasing the frequency of updates will increase the data flow, thereby increasing the consumption of electricity and service costs.

Persistent Connection (permanent connection)

The client initializes a permanent socket connection to the server and keeps it open, and the client will get the new data through the open socket when the server has data updates. However, the socket connection will be closed in idle time, in order to keep its open to continue to send keep-alive packets, resulting in a lot of useless data transmission, a large number of socket connections to the server gateway caused by resource constraints and performance degradation.

Wireless Gateway

Mds

The target server is located inside the enterprise LAN, and after the firewall, the program uses the MDS as a gateway to connect to the company's internal programs, and can connect to the internet-based server. MDS is an enterprise environment that is independent of the existence of mobile networks.

IP gateways for mobile operators

BlackBerry software V4.0 later support the real TCP and HTTP protocol stack and socket connection, the program through the operator's IP gateway can directly connect to the Internet. The data transfer is separate from the BlackBerry service and may have to be signed with additional protocols. Its viability depends on whether the operator supports and opens the service. In some networks, the push initiated by the server is supported.

WAP Gateway for mobile operators

Like IP gateways, programs can establish an HTTP connection with an internet-based server through a WAP gateway. However, using a WAP gateway only supports client-initiated connections and does not support WAP push.

Comparison of HTTP/TCP connections using different gateways:

	Connecting through the MDS	Connect via carrier Gateway
Protocol stack	HTTP	TCP sockets	HTTP (IP)	TCP Sockets (IP)	HTTP (WAP)
Gateway	Mds	Mds	IP Gateways	IP Gateways	WAP Gateway
Agreement	Http/https	TCP Socket,ssl/tls	Http/https	TCP Socket,ssl/tls	HTTP (WAP), HTTPS (WAP/WTLS)
User type	Bes	Bes	Bes,bis	Bes,bis	Bes,bis
Poll (Client initiated)	✔ (HTTP get/post)	✔	✔ (HTTP get/post)	✔	✔ (HTTP Get)
Push (Server initiated)	✔	✘	✘ (Iden support)	✘ (Iden support)	✘
Permanent connection	✘	✔	✘	✔	✘
Data encryption	3des/aes	3des/aes	HTTPS	Ssl/tls	HTTPS (WTLS/SSL)
Authorized Support	✔ (Http,ntlm,kerberos)	✘ (provided by the program)	✔ (HTTP)	✘