Use the login() call to log in to the login server and start a client session. A client application must log in and obtain a sessionId and server URL before making any other API calls.
After logging in, a client application needs to perform these tasks:
Set the session ID in the SOAP header so that the API can validate subsequent requests for this session.
Specify the server URL as the target for subsequent service requests. You must change to the server URL, the login server only supports login calls.
Session Expiration
Client applications do not need to explicitly log out to end a session. Sessions expire automatically after a predetermined length of inactivity, which can be configured in Salesforce by clicking Your Name | Setup | Security Controls. The default is 120 minutes (two hours).If you make an API call, the inactivity timer is reset to zero.
Use the login() call to log in to the login server and start a client session. A client application must log in and obtain a sessionId and server URL before making any other API calls.
After logging in, a client application needs to perform these tasks:
Set the session ID in the SOAP header so that the API can validate subsequent requests for this session.
Specify the server URL as the target for subsequent service requests. You must change to the server URL, the login server only supports login calls.
Session Expiration
Client applications do not need to explicitly log out to end a session. Sessions expire automatically after a predetermined length of inactivity, which can be configured in Salesforce by clicking Your Name | Setup | Security Controls. The default is 120 minutes (two hours).If you make an API call, the inactivity timer is reset to zero.
For example, this is the reason when using the SOAP API:
http://www.salesforce.com/us/developer/docs/api/Content/sforce_api_calls_login.htm
Use the login() call to log in to the login server and start a client session. A client application must log in and obtain a sessionId and server URL before making any other API calls.
After logging in, a client application needs to perform these tasks:
Session Expiration
Client applications do not need to explicitly log out to end a session. Sessions expire automatically after a predetermined length of inactivity, which can be configured in Salesforce by clicking Your Name | Setup | Security Controls. The default is 120 minutes (two hours). If you make an API call, the inactivity timer is reset to zero.
All Answers
For example, this is the reason when using the SOAP API:
http://www.salesforce.com/us/developer/docs/api/Content/sforce_api_calls_login.htm
Use the login() call to log in to the login server and start a client session. A client application must log in and obtain a sessionId and server URL before making any other API calls.
After logging in, a client application needs to perform these tasks:
Session Expiration
Client applications do not need to explicitly log out to end a session. Sessions expire automatically after a predetermined length of inactivity, which can be configured in Salesforce by clicking Your Name | Setup | Security Controls. The default is 120 minutes (two hours). If you make an API call, the inactivity timer is reset to zero.
when we are using intigration between two applications like sfdc to java we need sessionid?
but when we are using intigration with middle ware tools like informatica,dataloader,tibco we are not using the sessionid,
with out sessionid we can conect sfdc database and we can access the data? WHY?
why in case of middleware tools we are not using sessionid?
Session id need does not depend on the the factor as direct connection to system or middleware.
Sesion id is needed in case we need to maintain state of the request/response.
In SOAP based request, its stateful and so, session id is maintained to append the response to the valid request based on session id.