Presentation given at the EUROMICRO SEAA conference at Polytech' Lille, France.

1. Automated Deployment of a Heterogeneous
Service-Oriented System
Sander van der Burg Eelco Dolstra
Delft University of Technology, EEMCS,
Department of Software Technology
September 3, 2010
Sander van der Burg, Eelco Dolstra Automated Deployment of a Heterogeneous Service-Oriented Sys

2. Service Oriented Computing
The Service Oriented Computing (SOC) paradigm is very popular
to build distributed applications.
Sander van der Burg, Eelco Dolstra Automated Deployment

3. Service Development Support System (SDS2)
Philips has developed a service oriented architecture for Asset
Tracking & Utilisation services in a hospital environment.
Service Development Support System (SDS2)
Motivating example throughout the paper
Sander van der Burg, Eelco Dolstra Automated Deployment

4. Service Development Support System (SDS2)
Sander van der Burg, Eelco Dolstra Automated Deployment

5. Service Development Support System (SDS2)
Sander van der Burg, Eelco Dolstra Automated Deployment
Purpose
A hospital contains a wide range of medical devices
Each produce status and event logs in their own format
Difficult to perform analysis on data
How can we transform these implicit datasets into
something useful?

6. SDS2: Architecture
Sander van der Burg, Eelco Dolstra Automated Deployment

7. SDS2: Utilisation Service
Sander van der Burg, Eelco Dolstra Automated Deployment

8. SDS2: Technologies
MySQL: data storage
Ejabberd: messaging system for transmitting status and
location events
Java: implementation language
Apache Axis: for implementing web services
Google Web Toolkit: for implementing web application
front-ends
Sander van der Burg, Eelco Dolstra Automated Deployment

9. SDS2: Deployment
SDS2 must be eventually deployed, i.e. made available for use
Sander van der Burg, Eelco Dolstra Automated Deployment

10. SDS2: Deployment
Create a global configuration file with service locations, and:
Databases:
Transfer schema to target machine
Install database on MySQL server
Web services:
Compile Java web service code
Package web application archive
Activate web service on target machine
Web applications:
Compile Java code to JavaScript code
Compile Java web application code
Package web application archive
Activate web application on target machine
Sander van der Burg, Eelco Dolstra Automated Deployment

11. SDS2: Distribution
Sander van der Burg, Eelco Dolstra Automated Deployment

12. SDS2: Deployment
Deploying a service oriented system such as SDS2 is very difficult!
Sander van der Burg, Eelco Dolstra Automated Deployment

13. Challenges
Deploying is labourious:
Time consuming. Deploying SDS2 takes several hours for a
single machine
Subject to errors. Because it is performed manually
Complexity is proportional to number of machines in the
network
Sander van der Burg, Eelco Dolstra Automated Deployment

14. Challenges
Deployment steps must be performed in the right order:
For a web service providing data from a database, the
database must be activated first
If activated in the wrong order, data may be inaccessible
Sander van der Burg, Eelco Dolstra Automated Deployment

15. Challenges
We do not exactly know what the dependencies of a service are:
Difficult to upgrade reliably
Difficult to upgrade efficiently
Sander van der Burg, Eelco Dolstra Automated Deployment

16. Challenges
Upgrading is not atomic:
A user can observe that the system is changing
While upgrading certain features may become inaccessible
Sander van der Burg, Eelco Dolstra Automated Deployment

17. Challenges
Deploying in heterogeneous networks is even more complex.
Sander van der Burg, Eelco Dolstra Automated Deployment

18. Challenges
Existing deployment tools have various limitations:
Designed for specific component technologies (requires to
exclusively use one type of language/implementation):
Enterprise Java Beans
OSGi
Embedded systems
Designed for specific environments:
GoDIET: Designed for the DIET grid computing platform
CODEWAN: Ad-hoc networks
Generic approaches (lack desirable non-functional properties):
Software Dock: no dependency-completeness, atomic
upgrading
TACOMA: no dependency-completeness, atomic upgrading
Sander van der Burg, Eelco Dolstra Automated Deployment

19. Disnix
Distributed deployment extension for the Nix package
manager
Captures deployment specification in models
Performs complete deployment process from models
Guarantees complete dependencies
Component agnostic
Supports atomic upgrades and rollbacks
Sander van der Burg, Eelco Dolstra Automated Deployment

20. Disnix
$ disnix-env -s services.nix -i infrastructure.nix -d distribution.nix
Sander van der Burg, Eelco Dolstra Automated Deployment

21. Service model
{distribution, system}:
let pkgs = import ../top-level/all-packages.nix {
inherit distribution system;
}; in
{ mobileeventlogs = {
name = "mobileeventlogs";
pkg = pkgs.mobileeventlogs;
type = "mysql-database";
};
MELogService = {
name = "MELogService";
pkg = pkgs.MELogService;
dependsOn = { inherit mobileeventlogs; };
type = "tomcat-webapplication";
};
SDS2AssetTracker = {
name = "SDS2AssetTracker";
pkg = pkgs.SDS2AssetTracker;
dependsOn = { inherit MELogService ...; };
type = "tomcat-webapplication";
};
...
}
Sander van der Burg, Eelco Dolstra Automated Deployment

22. Infrastructure model
{
test1 = {
hostname = "test1.net";
tomcatPort = 8080;
mysqlUser = "user";
mysqlPassword = "secret";
mysqlPort = 3306;
targetEPR = http://test1.net/.../DisnixService;
system = "i686-linux";
};
test2 = {
hostname = "test2.net";
tomcatPort = 8080;
...
targetEPR = http://test2.net/.../DisnixService;
system = "x86_64-linux";
};
}
Captures machines in the network and their relevant properties and
capabilities.
Sander van der Burg, Eelco Dolstra Automated Deployment

23. Distribution model
{infrastructure}:
{
mobileeventlogs = [ infrastructure.test1 ];
MELogService = [ infrastructure.test2 ];
SDS2AssetTracker = [ infrastructure.test1 infrastructure.test2 ];
...
}
Maps services to machines
Sander van der Burg, Eelco Dolstra Automated Deployment

24. Deployment process
Specifications are used to derive deployment process:
Building services from source code
Transferring services to target machines
Deactivating obsolete services and activating new services
Sander van der Burg, Eelco Dolstra Automated Deployment

25. Building services
Every component built from source code is stored in the Nix store:
/nix/store/y2ssvzcd86...-SDS2EventGenerator
Former part: y2ssvzcd86..., SHA256 hash code derived
from all build-time dependencies of the component:
compilers, libraries, build scripts
Latter part: SDS2EventGenerator: name of the component
Sander van der Burg, Eelco Dolstra Automated Deployment

26. Building services
/nix/store
nqapqr5cyk...-glibc-2.9
lib
libc.so.6
ccayqylscm...-jre-1.6.0 16
bin
java
n7s283c5yg...-SDS2Util
share
java
SDS2Util.jar
y2ssvzcd86...-SDS2EventGenerator
bin
SDS2EventGenerator
share
java
SDS2EventGenerator.jar
Sander van der Burg, Eelco Dolstra Automated Deployment

27. Building services
/nix/store
nqapqr5cyk...-glibc-2.9
lib
libc.so.6
ccayqylscm...-jre-1.6.0 16
bin
java
n7s283c5yg...-SDS2Util
share
java
SDS2Util.jar
y2ssvzcd86...-SDS2EventGenerator
bin
SDS2EventGenerator
share
java
SDS2EventGenerator.jar
Sander van der Burg, Eelco Dolstra Automated Deployment

28. Transferring closures
Copy services and intra-dependencies to target machines in
the network
Only components missing on target machines are transferred
Always safe. Files are never overwritten/removed
Sander van der Burg, Eelco Dolstra Automated Deployment

29. Transition phase
Inter-dependency graph is derived from specifications
Deactivate obsolete services (none, if activating new
configuration)
Activate new services
Derive order and dependencies from dependency-graph
Sander van der Burg, Eelco Dolstra Automated Deployment

30. Service activation
Every service has a type: mysql-database,
tomcat-webapplication, process, ...
Types are attached to external processes, which take 2
arguments
activate or deactivate
Nix store component
Infrastructure model properties are passed as environment
variables
Sander van der Burg, Eelco Dolstra Automated Deployment

31. Atomic upgrading
Two-phase commit protocol mapped onto Nix primitives
Commit-request-phase (distribution phase):
Build sources
Transfer service closures
Commit-phase (transition phase):
Deactivating/activating services
Optionally block/queue connections from end-users
Sander van der Burg, Eelco Dolstra Automated Deployment

32. Atomic upgrading
In case of failure during commit-request: system is not
affected
No files overwritten
Will be removed by garbage collector
In case of failure during commit:
Rollback (transition to previous configuration)
Sander van der Burg, Eelco Dolstra Automated Deployment

33. Results
We have created deployment models for SDS2
Used to atomatically deploy SDS2 in a network of 4 32-bit
Linux and 4 64-bit Linux machines
Deployment takes minutes for a single machine. For each
additional machine a couple of minutes.
Upgrading only took seconds in most cases (only changed
parts were replaced)
Sander van der Burg, Eelco Dolstra Automated Deployment

34. Results
Because all components and dependencies are known:
Deployment steps were always performed in the right order
No failures due to breaking inter-dependencies
Upgrading is efficient; we only have to upgrade what is
necessary
Upgrading is reliable; we always know and include the
prerequisites
Sander van der Burg, Eelco Dolstra Automated Deployment

35. Results
Upgrades are (almost) atomic
Minor issue: web application in browser must be refreshed,
which is not under Disnix’ control
Components can be built for a particular platform
On the coordinator machine (if capable)
On the target machines
Sander van der Burg, Eelco Dolstra Automated Deployment

36. Conclusion and future work
Conclusion:
With Disnix we can automatically, efficiently and reliably
deploy service oriented systems similar to SDS2 in
heterogeneous environments
Future work:
Support dynamic migration of database (and other mutable
state)
Experimenting in larger networks
More investigation in upgrading web applications
Sander van der Burg, Eelco Dolstra Automated Deployment

37. Questions
Disnix and other related Nix software can be found at:
http://nixos.org
Any questions?
Sander van der Burg, Eelco Dolstra Automated Deployment