Open Pluggable Edge Services
Open Pluggable Edge Services WG
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The Internet facilitates the development of networked services at the
application level that both offload origin servers and improve the
user experience. Web proxies, for example, are commonly deployed to
provide services such as Web caching, virus scanning, and request
filtering. Lack of standardized mechanisms to trace and to control
such intermediaries causes problems with respect to failure
detection, data integrity, privacy, and security.
The OPES Working Group has previously developed an architectural
framework to authorize, invoke, and trace such application-level
services for HTTP. The framework follows a one-party consent model,
which requires that each service be authorized explicitly by at least
one of the application-layer endpoints. It further requires that OPES
services are reversible by mutual agreement of the application
In particular, the WG has developed a protocol suite for invocation
and tracking of OPES services inside the net. The protocol suite
includes a generic, application-agnostic protocol core (OCP Core)
that is supplemented by profiles specific to the application-layer
protocol used between the endpoints. So far, the WG has specified an
OCP profile for HTTP, which supports OPES services that operate on
In a next step, the WG will specify one or more OCP profiles that
will support OPES services operating on SMTP. In particular, the
profile to be specified will enable an SMTP server (the OPES
processor) to encapsulate and forward SMTP data and metadata to a
callout server for additional processing. Several kinds of agents
participate in SMTP exchanges, including MSA, MTA, MDA, and MUA. The
first OCP/SMTP profile will address the needs of at least the MTA
and/or MDA. More profiles may be needed to address other
agent-specific needs, such as for LMTP and/or SUBMIT. The security
and privacy concerns of SMTP must be carefully analyzed as part of
the definition of the profile.
In addition, the WG will define a rules language to control selection
and invocation of services by an OPES processor. This includes a
mechanism allowing an OPES processor to perform a runtime check of
service parameters, leveraging existing interface description
standards like WSDL, if possible, or OPES-specific description
otherwise. Defining language(s) for implementing OPES services is out
of the WG scope. The rules language will be based on previous work of
the WG on a rules language named "P". The WG will have a design goal
that the language be compatible with existing policy work within the
IETF (e.g. IETF Policy Framework) and be able to interface with
systems automating distribution of policies to multiple endpoints. It
will be out of scope for this WG to develop the policy framework and
specify multiple-endpoint policy distribution.
The group's new work items can be listed as:
- Develop a document about "Scenarios and Use Cases for
OPES Services operating on SMTP".
- Define profile(s) for OCP core that handle SMTP messages
or parts thereof.
- Define a rules language to control the selection and
invocation of HTTP-based or SMTP-based OPES services.
Each deliverable must follow the previously developed OPES
architecture. As each deliverable is developed, it must address the
IAB considerations specified in RFC 3238.