BaaS is a tool that helps you implement a web service composition framework. One important step in dynamic web service composition is the binding of concrete web services to the activities involved in the composition. BaaS provides this functionality as a service.
Service binding is a complex task, which poses some significant challenges. For each task in the abstract composition model associated with a composite service, there are usually several web services offering the required functionality. However, they may differ in non-functional properties such as reliability, cost, or response time. Therefore, the quality of service (QoS) is the deciding factor in choosing which concrete web service to bind to each task.
In order to make a qualitative comparison of service compositions, it is necessary to estimate the QoS of a composite service based on the QoS of its component services. For this purpose, BaaS uses the QoS extension for BPStruct, which can compute the aggregated QoS values for composite services with complex structures.
Comparing composite services characterized by multiple QoS attributes is not a trivial task, because there is usually no solution that simultaneously optimizes all attributes. BaaS allows its clients to express trade-offs between different QoS parameters, by using the QoSPref approach.
A presentation of BaaS can be found in this paper.
Download and unzip the binaries. This will create a directory called baas-1.0
, which we will refer to as <BAAS_HOME>
.
Open the file <BAAS_HOME>\bin\_settings.bat
in a text editor and:
JAVA_HOME
to point to your 32-bit java installation directory.BAAS_PORT
, if you are not happy with the default value (9090) of the port used by the BaaS server.Open a command line window, go to the directory <BAAS_HOME>\bin
and type:
startBaas
Open another command line window, go to the directory <BAAS_HOME>\bin
and type:
client ..\config\test1.properties
Congratulations! You have successfully sent a binding request to the BaaS server.
Now it's time to take a closer look at the scripts in the <BAAS_HOME>\bin
directory.
Starts the Baas server on the port configured in _settings.bat
.
Assuming that the default port 9090 is used, the service will be available at http://localhost:9090/baas
.
Sends a binding request to the BaaS server. It takes as argument the path to a configuration file containing the following information about the request to be sent:
Usage example:
client ..\config\test1.properties
In the configuration file, the abstract composition model is specified by means of two properties:
Two formats are currently supported: xml
and bpmn
.
The xml
format is a BaaS-specific representation of the abstract composition model.
The bpmn
format is a business process representation conforming to the OMG specifications.
The file ..\config\test1.properties
in the usage example above specifies an xml
representation of the abstract composition model.
You can experiment with a bpmn
format by opening the file <BAAS_HOME>\config\test1.properties
in a text editor and replacing the lines:
workflow.path = ../example/example1.xmlwith the lines:
workflow.type = xml
workflow.path = ../example/example1.bpmn
workflow.type = bpmn
Generates and sends a batch of binding requests to the BaaS server. It takes two arguments:
xml
format)Usage example:
performanceClient ..\workflows ..\config\perftest1\config.properties
Generates a batch of binding requests for which the best solution is computed. Instead of sending the requests to the BaaS server, it directly calls the solver. The script takes two arguments:
xml
format)The configuration directory must contain three files:
config.properties
, having the same structure as the configuration file needed by the performanceClient
scriptrun.properties
, used to configure the number of runs for each workflow and the parameters of the solverlogback.xml
, used to configure the logging settingsUsage example:
performanceTest ..\workflows ..\config\perftest1
Converts files from the bpmn
format to the BaaS-specific xml
format. Several bpmn
models created with the Oryx Editor are provided in the directory <BAAS_HOME>\models\oryx
. The script takes two arguments:
bpmn
formatUsage example:
oryxModelToWorkflow ..\models\oryx ..\tmp-workflows
Converts files in the XML format used by IBM WebSphere Business Modeler to the BaaS-specific xml
format. Several files in this format taken from the IBM Bit process library are provided in the directory <BAAS_HOME>\models\bit
. The script takes two arguments:
Usage example:
bitModelToWorkflow ..\models\bit ..\tmp-workflows
From the workflows available in a given directory, selects those being sound and (optionally) satisfying some constraints related to the number of tasks in the abstract composition model.The script takes the following arguments:
-inputDir <path>
: the path to a directory containing workflows in the BaaS-specific xml
format-outputDir <path>
: the directory in which the selected workflows should be stored-minTaskCount <number>
(optional argument): the minimum number of tasks of the selected workflows-maxTaskCount <number>
(optional argument): the maximum number of tasks of the selected workflowsUsage example:
workflowPicker -inputDir ..\tmp-workflows -outputDir ..\picked-workflows -minTaskCount 5
The BaaS source code is managed with Git. If not already available, install git from here.
Open a command line window, go to a directory of your choice and type:
git clone git://git.code.sf.net/p/baas/code baas
This command will create a directory called baas
, in which it will place a clone of the git repository.
In the baas
directory you will find a subdirectory called projects
.
From here on, the projects
subdirectory will be referred as <BAAS_PROJ>
.
If not already available, install a 32 bit JDK. You need a 32-bit JDK even on a 64-bit machine. BaaS uses the QoS4BPStruct library, which loads a native library compiled only for 32-bit Windows platforms.
Open <BAAS_PROJ>\gradlew.env
in a text editor and set JAVA_HOME
to point to your 32-bit JDK.
Edit the value of baasPort
in <BAAS_PROJ>\gradle.properties
.
Open a command line window, go to the <BAAS_PROJ>
directory and type:
gradlew assemble
Open a command line window, go to the <BAAS_PROJ>
directory and type:
gradlew tasks
This will display a list of available gradle tasks. Some of these tasks are BaaS-specific and are shortly presented in the paragraphs below.
Starts the Baas server on http://localhost:9090/baas
(port value can be configured in <BAAS_PROJ>\gradle.properties
).
Usage example:
open a command line window, go to the <BAAS_PROJ>
directory and type:
gradlew runBaaS
Starts the client program that sends a binding request to the BaaS server.
Usage example:
open a command line window, go to the <BAAS_PROJ>
directory and type:
gradlew runClient -PconfigFile=src/dist/config/test1.properties
Starts the performance client program that sends a batch of binding requests to the BaaS server.
Usage example:
open a command line window, go to the <BAAS_PROJ>
directory and type (on a single line):
gradlew runPerformanceClient -PworkflowsDir=../experiment/src/dist/workflows -PconfigFile=../experiment/src/dist/config/perftest1/config.properties
Creates the binary distribution zip: <BAAS_PROJ>\build\distributions\baas-1.0.zip
Usage example:
open a command line window, go to the <BAAS_PROJ>
directory and type:
gradlew distZip
Install a recent version of Eclipse (Kepler or Juno recommended).
Configure your 32-bit JDK as standard JRE for Eclipse:
Install the Dynamic Languages Toolkit Core
plugin from http://download.eclipse.org/releases/indigo
:
Install the ANTLRv3 eclipse plugin from http://antlrv3ide.sourceforge.net/updates
:
If not already available, download and install ANTLRv3.
In Eclipse, configure the ANTLR package as shown in the image below:
In order to generate the Eclipse project files for BaaS, open a command line window, go to the <BAAS_PROJ>
directory and type:
gradlew eclipse
In Eclipse, import all projects found in the directory <BAAS_PROJ>
Several launch configurations are already available for the BaaS projects, as seen in the image below:
Have fun experimenting with BaaS!