2018.1

Request/Process/Response cycle
Once a process using the HTTP Server Input task is created, it is important to understand the
cycle that is triggered when such a process runs. Note that this is the process when the default
HTTP Server Input task options are used (more on how that behavior changes later):
1. A request is received by the HTTP service.
2. This request is converted into an XML request file along with one or more attachments
when present.
3. The XML request file and attachments are saved in a local folder, if the HTTP Action is a
valid one (otherwise, the files are deleted).
4. The HTTP service keeps the request from the client open (it does not yet respond ot it),
and waits.
5. The HTTP process corresponding to the HTTP Action captures the XML file and
attachments and the process begins.
6. The process runs its course just like any other process would (including subprocesses,
send to process, etc).
7. The very last file that is active when the process finishes is then returned to the HTTP
service.
8. The HTTP service returns the file to the client and then closes the connection.
9. If, during this time, the timeout has expired (if the process takes more than 120 seconds),
the HTTP service returns a "timeout" to the client, but the process stills finishes on its
own. When the process finishes, the return file is ignored by the HTTP service.
Point 7 is critical to understand, as it has an impact on what the client receives. If a process
receives a file that is split into multiple parts and each of these parts generates and output, the
last split's output will be sent to the client. If the last output task generates a PostScript file for
printing, this PostScript is returned to the client.
In most cases, what is returned is what remains after the last task, but only if this task's
processing is done in PReS Workflow. For example, if the data file is a text file and this file is
sent to PReS Image using the Image connector, it is a text file that is returned, not the output of
the Imaging. Similarly, ending a process with the Delete task does not return an empty file, it
returns the actual data file.
This is actually the most used way of returning a response: Generate an HTML file using either
Create File or Load External File, then delete the file as a last output. The HTML is thus
returned to the client.
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