Controls Middleware renovation – technical overview 26th June 201 3

CONTROLS MIDDLEWARE RENOVATION –TECHNICAL OVERVIEW

26TH JUNE 2013

Wojciech Sliwinski BE-CO-INfor the BE-CO Middleware team:

Felix Ehm, Kris Kostro, Joel Lauener, Radoslaw Orecki, Ilia Yastrebov, [Andrzej Dworak]

Special thanks to: Vito Baggiolini and Pierre Charrue

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Agenda

Context & Motivation for Renovation

Middleware Review process

Technical evaluation of the transport layer

Changes in the MW Architecture in LS1

MW Upgrade milestones in 2013

Conclusions

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Agenda

Context & Motivation for Renovation

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Motivations for MW Renovation Current CORBA-based CMW-RDA

Integrated in the Control system Used to operate all CERN accelerators Provides widely accepted Device/Property model > 10 years old

Why to review & upgrade MW ? CORBA was choosen 15 years ago Technical limitations of CORBA-based transport Functional limitations of the current CMW-RDA Codebase with long history difficult to maintain, needs architecture review Major issue of long-term support & future evolution Evolution of technology over last 10 years: HW, OS, middleware, 3rd party libraries Human factor less & less CORBA expertise on the market

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Technical limitations of CORBA transport Became legacy, not actively supported maintenance issue

Shrinking community, slow response time omniORB (C++) – 1 developer/maintainer, last release mid-2011 JacORB (Java) – few developers, small community

Major technical limitations Lack of fully asynchronous processing channel Blocking communication infamous JacORB blocking issue Lack of low-level control of IO resources (sockets, request queues)

Development issues Difficult to extend the wire protocol Backward compatibility issue Complex, error prone API Heavy in memory usage

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Summary: Why change CORBA?

CORBA was choosen 15 years ago Not actively maintained big risk for the MW project Better solutions exist on the market Invest in future solution rather than maintaining old one

With current CORBA-based middleware we can’t solve the pending operational issues

We can’t provide better scalability & reliability CMW-RDA is difficult to evolve & extend

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Agenda

Middleware Review process

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Middleware Renovation process MW Renovation = MW Review + MW Upgrade

MW Review aims to provide the most appropriate technical solution satisfying the user requirements

MW Upgrade establishes the plan & strategy for introduction of the new MW Objective: LS1 the unique opportunity for the major MW upgrade

Middleware Review Process Gathering of users feedback and requirements (2010-11) Review of communication and serialization libraries (2011-12) Prototyping using selected communication products (2012) Design & impl. of new RDA3: Data, Client & Server (2012-13) Testing & validation of core MW infrastructure (summer’13) Upgrade of all dependent MW libraries & services (2013-14)

○ JAPC, Directory Service, Proxy, DIP Gateway

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Review of users requirements 2010-11 – series of interviews with major users

Lars Jensen, Stephen Jackson (BI) Andy Butterworth, Frode Weierud, Roman Sorokoletov (RF) Brice Copy, Clara Gaspar (DIP, DIM) Frederic Bernard, Herve Milcent, Alexander Egorov (PVSS) Alexey Dubrovskiy (CTF), Kris Kostro (DIP gateways) Marine Gourber-Pace, Nicolas Hoibian (Logging) Nicolas De Metz-Noblat (Front-Ends), Alastair Bland (Infrastructure) Michel Arruat (FESA), Stephen Page (FGC) Niall Stapley, Mark Buttner, Marek Misiowiec (LASER & DIAMON) Nicolas Magnin, Christophe Chanavat (ABT) Stephane Deghaye, Jakub Wozniak (InCA, SIS) Vito Baggiolini, Roman Gorbonosov (JAPC & DA systems) + regular feedback from OP + internal team input

http://wikis/display/MW/Interviews+with+Experts

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New RDA3: Accepted requirements General

Java & C++ API, Win (64-bit) & Linux (SLC5 32-bit & SLC6 64-bit) Accelerator Device Model (i.e. Device/Property) Get, Set, Async-Get, Async-Set, Subscribe Early detection of communication failures Improve error reporting in all the layers: client, server, gateways Admin interface & runtime diagnostics & statistics

Data support Data object: primitives, n-dim arrays, data structures

Subscription mechanism Subscription behaviour the same regardless condition of the server (active, down) Several client subscription policies (default: continuous) Provide subscription notification ordering First-Update enforced via CMW on server-side

○ Provide callback to front-end framework for the server-side Get Drop support for on-change flag Standardise use of subscription filters and update flags (e.g. immediate update) Add header for acquired Data common metadata (e.g. acq. stamp, cycle name) All loss of data (dropped updates) must be notified to clients

New requirement

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New RDA3: Accepted requirements Client side

RDA3 client API connects with both: RDA2 (old) & RDA3 (new) servers Efficient mechanism for: connection, disconnection & reconnection Must be able to recover from any interruption of communication with the server

○ Server restarts, IP address change, rename/move of a device to another server Improved semantics of Array Calls, i.e. handling of individual parameters Enhanced diagnostics & collection of statistics

Server side Policies for discarding notifications, i.e. deal with overflows and ’bad clients’

○ Instrument with counters & timings allowing to diagnose the notifications delivery Prioritisation of Get/Set requests for high-priority clients Server-side subscription tree fully managed by CMW

○ Server does not need to manage client subscriptions any more Manage the client connections, e.g. forced disconnect of a client Client lifetime callbacks (i.e. connected, disconnected)

New requirement

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New RDA3: Accepted requirements Server side (cont.)

Client discovery for the diagnostics purposes (i.e. connected clients with payload) Enhanced diagnostics & collection of statistics

Ongoing discussions (not accepted yet) Prioritisation of subscription notifications for high-priority clients

Technical notes Invest in asynchronous & non-blocking communication Prefer 0-copy & lock-free data structures, message queues

http://wikis/display/MW/Design+of+New+RDA

New requirement

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New RDA3: Summary of requirements

UnchangedDevice/Property modelSet of basic operations (Get, Set, Subscribe)

Fixes & improvementsSubscription mechanismConnection managementDiagnostics & statistics

New functionality Policies for subscription management (client & server)Client prioritiesServer-side subscription treeExtended Data supportStandardise First-Update concept

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Agenda

Technical evaluation of thetransport layer

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Middleware transport requirements

Desirable

Mandatory

Fundamental

Lightweight

Friendly API, documentation

Request/reply & pub/sub patterns

Open source license

Asynchronous

Active community

Stability, Maturity & Longevity

Performance & Scalability

C++/Java

Linux/Windows

Over TCP/IP LAN

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Evaluated middleware products

Ice

Thrift

omniORB

YAMI

OpenSpliceDDS

OpenAMQCoreDXRTI DDS

ZeroMQ

QPid

MQtt RSMBJacORB

Mosquito

All opinions are based only on our knowledge and evaluation. Each of the products, depending on the requirements, may constitute a good solution.

RabbitMQ

Andrzej Dworak, ICALEPCS 2011

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Products comparison (according to the criteria)

Sync, async & msg patterns

QoS

Dependencies & memory f-p

Performance

Look & feel, API, docs

Community & maturity

Score

ZeroMQ 6Ice 5

YAMI4 4RTI 3

Qpid 3CORBA 2

Thrift 2

Andrzej Dworak, ICALEPCS 2011

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Conclusions Several good middleware solutions available The choice is dictated by the most critical requirements Not easy performance matters but also ease of use, community, … Prototyping was done with the most promising candidates:

ZeroMQ, Ice & YAMI

Finally we decided to choose ZeroMQ (http://www.zeromq.org/) Asynchronous & non-blocking communication 0-copy & lock-free data structures, message queues Nice API, good documentation & active community

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New RDA3 Java – Sync Get round-trip time

Test setup: 1kB message payload, cs-ccr-* machines, 1 server host & 10 client hosts

0

2

4

6

8

10

12

14

16

18

0 100 200 300 400 500 600 700 800 900 1000

Roun

d-tr

ip(m

s)

Number of clients

Syn Get round-trip (1kB message payload)

max

average

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New RDA3 Java – subscription notification latency

Test setup: 1kB message payload, cs-ccr-* machines, 1 server host & 10 client hosts

0

50

100

150

200

250

0 100 200 300 400 500 600 700 800 900 1000

Late

ncy

(ms)

Number of clients

Subscription notification latency (1kB message payload)

min

max

average

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New RDA3 Java – subscription notification latency

Test setup: 1kB message payload, cs-ccr-* machines, 1 server host & 10 client hosts

0

1

2

3

4

5

6

0 20 40 60 80 100 120 140 160 180 200

Late

ncy

(ms)

Number of clients

Subscription notification latency (a closer look)

min

max

average

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Agenda

Changes in the MW Architecture in LS1

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Current MW ArchitectureUser written

Middleware

Central services

Physical Devices (BI, BT, CRYO, COLL, QPS, PC, RF, VAC, …)

Java Control Programs

RDA Client API (C++/Java)Device/Property Model

DirectoryService

ConfigurationDatabase

CCDB

VB, Excel, LabView

ServersClients

Virtual Devices(Java)

PS-GMServer

FESAServer

FGCServer

PVSSGateway

C++ Programs

MoreServers

Administrationconsole

Passerelle C++

CMW InfrastructureCORBA-IIOP

RDA Server API (C++/Java)Device/Property Model

RBAC A1Service

DirectoryService

RBAC Service

JAPC API

CMW integr. CMW int. CMW int.CMW int.CMW int. CMW int.

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Changes in MW Architecture in LS1User written

Middleware

Central services

Physical Devices (BI, BT, CRYO, COLL, QPS, PC, RF, VAC, …)

Java Control Programs

RDA Client API (C++/Java)Device/Property Model

DirectoryService

ConfigurationDatabase

CCDB

VB, Excel, LabView

ServersClients

Virtual Devices(Java)

PS-GMServer

FESAServer

FGCServer

PVSSGateway

C++ Programs

MoreServers

Administrationconsole

Passerelle C++

CMW InfrastructureZeroMQ

RDA Server API (C++/Java)Device/Property Model

RBAC A1Service

DirectoryService

RBAC Service

JAPC API

CMW integr. CMW int. CMW int.CMW int.CMW int. CMW int.

Upgrade in LS1

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Agenda

MW Upgrade milestones in 2013

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MW Upgrade Milestones in 2013Milestone Completed by ?

RDA3 Java (client/server) (alpha) June’13

RDA3 C++ server (alpha) July’13

RDA3 integration with: FESA, FGC, PVSS July-Oct’13

RDA3 C++/Java (client/server) validated September’13

New JAPC release with RDA3 Java September’13

New FESA3.2 release with RDA3 December’13

RDA3 C++ Integration with FESA, FGC, PVSS

RDA3 validatedNew JAPC New FESA3.2 Tests with eqp. End LS1

July’13 July-Oct’13 September’13 Winter’13/14 August’14December’13

End-of-Life for RDA2: LS2

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MW Upgrade strategy in LS1 and towards LS2

No BIG-BANG migration but gradual Backward compatible (connection-wise) new RDA3 client library

New RDA3 clients can communicate with RDA2 & RDA3 servers FESA3 will exist with both: old RDA2 (FESA3.1) and new RDA3 (FESA3.2)

Old JAPC

Old RDA2server

FESA2.10 FESA3.1

Old RDA2server

New RDA3server

FESA3.2

Old RDA2client

New JAPC

New RDA3client

RDA2 RDA3 Gateway

Client apps will migrate during LS1

Only for justified, exceptional cases

FEC developers should migrate to

FESA3.2 ASAP

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Conclusions

We have to replace CORBA with a new solution

We collected updated users requirements

MW upgrade will be performed during LS1 (2013-2014)

Interoperability between RDA2 RDA3

Gradual control system migration until LS2 (end-2017)

End-of-Life for RDA2: LS2