Stateless and Conversational VSE Transactions

lvse transactions are classified as stateless or conversational.
dts100
VSE
transactions are classified as
stateless
or
conversational
.
Stateless Transactions
Stateless
transactions include no logical relationships between transactions. For example, HTTP and SOAP are stateless protocols.
A stateless transaction always has a static response, regardless of what calls were made previously. Each stateless transaction is independent of the others. For example:
  • What is the current weather in Dallas? (Operation: weather; Argument: city)
  • What is the current weather in New York? (Operation: weather; Argument: city)
  • What will the weather be in Dallas tomorrow? (Operation: weather; Argument: city; Argument: date)
Conversational Transactions
Conversational transactions are
stateful
. Conversations consist of:
  • The logical transaction that, if matched, starts a unique session
  • The information necessary to create and identify that session
A transaction in a conversation depends on the context that earlier conversations create.
For example, the following conversation involves using an ATM:
  1. Connect to the ATM. (Operation: logon)
  2. Which account do you want? (Argument: checking)
  3. What is my balance? (Operation: balance)
  4. Response.
  5. Withdraw an amount of money. (Operation: withdraw)
  6. How much? (Argument: amount)
  7. What is my balance? (Operation: balance)
  8. Response.
  9. End session. (Operation: logout)
Conversation Starters
The first transaction in a conversation is the
conversation starter
. When a virtual service environment (
VSE
) receives an incoming request, the 
VSE
reviews the conversation starters to determine whether the transaction means a new conversation is starting.
Because all the transactions in a conversation are related to each other, the
VSE
must have a way of determining this relationship. This determination is typically made by using some kind of special token such as "jsessionid" or a cookie in web transactions, or a custom identifier in message traffic.
The following types of conversations are supported:
  • Instance-based conversations
    The protocol layer is responsible for identifying the unique string, which is based on different instances of the client. The string identifies server-side sessions for both recording and playback of the service image.
  • Token-based conversations
    The
    VSE
    generates the token by using a string generation pattern that is stored with the conversation in the service image. After the token is generated, it operates the same as an instance-based conversation. Token-based conversations cannot be automatically inferred during recording. To specify where tokens are found, use the VS Image Recorder.