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JavaCamPush

V5.0.5

From V5.0.5 of Webcam32 onwards, access to Server Push streams changed.  In previous releases, two TCP/IP ports were required.  One for obtaining the applet and one for obtaining the Server Push stream.  In the new releases, only one TCP/IP port is required.  This page describes the new, single port, mechanism in detail.  For migration instructions from the old, two port, JavaCamPush to the new version, see here.

What is JavaCamPush?


JavaCamPush is a Java applet supplied integrated as part of Webcam32.  Using JavaCamPush, an Internet Explorer or Netscape user can view real time live streaming video from Webcam32.   Prior to JavaCamPush, this capability was only available to Netscape browser users.   JavaCamPush has been tested with Internet Explorer V4 and Netscape V4 but should work with other browsers.

A tutorial is available for JavaCamPush here.


How does JavaCamPush work?

JavaCamPush is a Java language applet.  An applet is a program that is dynamically downloaded into the browser over the Internet.  The purpose of the applet is to accept Server Push streams of images from Webcam32 and display these images as fast as possible in a flicker free environment.

The following diagram provides a conceptual view of the relationship between JavaCamPush, Webcam32 and the browser.


When a user invokes a browser and downloads a web page, the web page will contain an HTML <APPLET> tag.  This tag will cause the JavaCamPush applet to be quickly dynamically loaded over the network.  Webcam32 is the source of the applet so there is no need to separately upload and install this applet on the webserver.  Once the browser has downloaded the applet from Webcam32, the applet will execute and start receiving a stream of images from Webcam32.


How is JavaCamPush configured?

To correctly configure JavaCamPush, the Webcam32 TCP/IP settings must have both the Server Push and Applet functions enabled.

Note: by default, the Server Push port of Webcam32 is disabled.

The following screen capture illustrates Webcam32's TCP/IP settings configured to:

TCP/IP Settings for JavaCamPush

How is the Web page configured?


The Web page which an end user will see must have a correct HTML Applet tag inserted to download the JavaCamPush applet from Webcam32.  The following is the correct HTML for this content and is valid for both Internet Explorer and Netscape browsers:

1   <applet code="JavaCamPush.class"
2   codebase="http://3   archive="JavaCamPush.jar"
4   width="160"
5   height="120">
6      <param name="URL" value="http://param name="cabbase" value="JavaCamPush.cab">
8   applet>

The following is a description of the meaning of each line of HTML above:

1 Start of the applet tag and the name of Java class to load.
2 Location of Java classes.  These will normally be loaded directly from Webcam32.   The value should be a URL pointing to the computer running Webcam32 and the port number specified in the Webcam32 TCP/IP settings for the remote access port (e.g.. 8888).
3 Name of archive for Netscape browsers.
4 Width of the applet.  The images received from Webcam32 will be horizontally scaled to this width before display.
5 Height of the applet.  The images received from Webcam32 will be vertically scaled to this height before display.
6 The URL specifying the location of Webcam32's server push data.  The value should point to the computer running Webcam32 and the remote access port (e.g. 8888).
7 This is an Internet Explorer required parameter.  The JavaCamPush class is downloaded as a compressed cab file.  This parameter names the cab file expected.
8 End of the applet tag block.


New JavaCamPush versions

With Webcam32 V5.0.5 and V5.0.6, the LATEST JavaCamPush classes are built into Webcam32.  They need NOT be downloaded from the web and copied to the local file system.  They will be obtained directly from the internals of Webcam32.

New versions of JavaCamPush will become available over time as new features are added and old defects removed.  New JavaCamPush versions are downloaded separately from Webcam32.  The following instructions describe getting new JavaCamPush versions:

  1. Download the ZIP file from here.
  2. Extract the contents (JavaCamPush.cab and JavaCamPush.jar) into the Webcam32 install directory.  This is usually C:\Program Files\Surveyor Corporation\Webcam32
  3. Run Webcam32

When Webcam32 serves the applets to browsers on the web, it first looks for a version on disk before sending the internal versions.

To determine the current version of JavaCamPush, view a page which contain the JavaCamPush applet and right-click on the applet.  A popup menu will appear.   From the popup menu, the About option may be selected which will display information about the current version including the release level installed.

V1.4    Bug fixes for Netscape; better images
V1.5    Bug fixes for Netscape; transfer speed in status bar option
V2.0    Version for single port access


JavaCamPush sample

To see a demonstration of JavaCamPush in action:

  1. View this page with Internet Explorer V4 or later or Netscape V4 or later
  2. Start Webcam32 on the same machine as the browser
  3. Ensure that Remote Access port is set to 8888
  4. Ensure that both Applet and JavaCamPush are enabled
  5. Click here to view a JavaCamPush sample page


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