This chapter introduces the Ingres Bridge component and describes how it interacts with Ingres. It also describes how Ingres Bridge can be used in an Ingres Net and Ingres Enterprise Access configuration. This chapter concludes with information about configuring and using Ingres Bridge.
|
|
|
Ingres Bridge is a component of Ingres that enables a client application running on one type of local area network to access an Ingres server running on a different type of network. The client and server do not have to communicate over the same network protocol (such as TCP/IP, SNA LU62); Ingres Bridge "bridges" a client using one network protocol to a server using another.
For example, a PC on a TCP/IP network communicates through Ingres Bridge to an EDBC server (such as DB2, IMS, or Datacom/DB) on an SNA network.
Ingres Bridge does not provide any security checking but simply passes the messages through. Security is handled on the server in the usual way.
|
|
|
Ingres Bridge consists of the Bridge Server.
The Bridge Server (iigcb) process connects a client application on one type of network to a server on a different type of network. Modeled on the transport layer of the Ingres Net architecture, the Bridge Server does the following:
|
|
|
You configure the Bridge Server using one of these utilities (based on your environment):
|
|
|
Ingres Bridge is required in any installation configuration where the client and server processes do not reside on the same machine and the client machine is on one type of local area network and the server machine is on another type of network.
Ingres Bridge runs on an intermediate platform between the client and the server; the intermediate platform must support both the client and the server network protocols. Ingres Bridge runs as a stand-alone installation or as a part of an Ingres client or server installation.
Ingres Star provides a similar network bridging capability. Ingres Star is required when the user views different physical databases as a single logical database. Ingres Bridge must be used when this is not the case, and the user wants to connect a client and server that run on different network protocols. Ingres Bridge has a fairly small "footprint" and has little impact on response time.
|
|
|
The following figure shows a sample installation configuration that uses Ingres Net, Ingres Bridge, and EDBC to DB2. Ingres Bridge runs on a separate installation on an intermediate platform.
Node A is an Ingres for VMS installation. Node B is an Ingres Bridge installation in a UNIX environment using TCP/IP. Node C is an EDBC to DB2 installation in a z/OS environment using SNA_LU62. Node A and Node C are not directly connected to each other.
Ingres Net is present on Node A and Node C. Users on Node A can access DB2 data on Node C as if the DB2 tables were Ingres tables stored on Node A.
|
|
|
Ingres Bridge is installed as a component of Ingres. It uses the same installation procedure as Ingres and Ingres tools.
The component appears in the install utility as Ingres Protocol Bridge.
Note: Ingres Bridge is installed as the only component in an installation or with other components such as Ingres Net.
|
|
|
Ingres Bridge is started by reading configuration parameter values from one of the following:
This method gives you have the flexibility of routing the client connections dynamically, and allows multiple routes.
To use values from config.dat, you can start Ingres Bridge using the ingstart command or Visual Manager (if available in your environment).
This method requires you to stop and start Ingres Bridge if you want to route the client connections to a different installation, and allows only a single "from-to" route.
|
|
|
After the installation and setup phases of Ingres Bridge, default configuration entries are defined in the config.dat file in the Ingres Bridge installation. You can change some of the configuration parameters values by using Configuration-By-Forms (cbf) or Configuration Manager (vcbf). These values are then stored in the config.dat file.
Here is an example configuration entry in config.dat:
ii.<hostname>.gcb.*.tcp_ip.port.<vnode>:<listen address>
This entry means that Ingres Bridge accepts the incoming client connections from TCP/IP on the port specified by the listen address and route them to the DBMS Server installation defined by the vnode. The vnode name matches a vnode name defined for the DBMS Server installation.
The vnode name must be set in config.dat before starting the server. Only the connection information can be changed for the vnode name, which enables you to change the routing information without stopping and starting Ingres Bridge.
Login/password (remote authorization) data for the vnode is not required because the login data is obtained from the connecting client; only the connection data for the server is required.
|
|
|
The ingstart command starts the Bridge Server using the values in config.dat.
If Ingres Bridge is installed with other components such as Ingres Net, or has been configured using the Configuration-By-Forms utility, use the following ingstart command to start the Bridge Server:
ingstart -iigcb
Or start the Name Server first and the Bridge Server next, using the following :
ingstart –iigcn
ingstart -iigcb
|
|
|
The Bridge Server process (iigcb) can be executed from the system prompt.
This command has the following format:
iigcb -from prot -to dest_prot hostname listen_addr
Is the local protocol (for example, tcp_ip).
Is the destination protocol (for example, SNA LU62).
Is the network name or address where the target DBMS Server and Communications Server are located (format dependent on protocol).
Is the unique identifier for the Communications Server that is used for Ingres Net connections with the destination protocol.
For example, the following command starts the Bridge Server process:
iigcb -from tcp_ip -to sna_lu62 hostname listen_addr
The following lines are displayed in the errlog.log file:
Network open complete for protocol TCP_IP, port <xx>
Network open complete for protocol SNA_LU62, port <xx>
Protocol Bridge normal startup: rev. level 1.1/02
Ingres Bridge is now ready for clients to make connections to it on the TCP/IP port specified by the listen address in the following line in the config.dat file in the Ingres Bridge installation:
ii.hostname.gcb.*.tcp_ip.port: listen address