soap-response: is Content-Length required in http-header?

I didn't found a answer to this in w3.org.

Almost all examples include the content length in the soap-response http-header.

first Q:
But is it technically necessary?

i am struggling with an soap-service where the php-soap-library is setting the right content length of the response xml, but lighttpd afterwards is compressing the content, and so i am getting a smaller response than the content length.

And some applications like soapUI is waiting for alle the content (set by the http-header) to arrive.

second Q:

• Who is behaving/configured wrong in this chain? php -> lighttpd -> soapUI


• is it the php-code


• which sets the unzipped content-length?


• is it lighttpd which compresses the response, but doesn't override or delete the
  content-length header?


• Or is it soapUI, which shouldn't wait 15sec for further content?

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