diff --git a/examples/integration/chunk-test.html b/examples/integration/chunk-test.html
new file mode 100644
index 0000000..e6668a0
--- /dev/null
+++ b/examples/integration/chunk-test.html
@@ -0,0 +1,32 @@
+
+
+
+
+
+
+
+
+
\ No newline at end of file
diff --git a/src/main/webapp/resources/js/epics2web.js b/src/main/webapp/resources/js/epics2web.js
index 1f66e10..44bcc25 100644
--- a/src/main/webapp/resources/js/epics2web.js
+++ b/src/main/webapp/resources/js/epics2web.js
@@ -40,7 +40,7 @@ jlab.epics2web.ClientConnection = function (options) {
pingIntervalMillis: 3000, /* Time to wait between pings */
livenessTimoutMillis: 2000, /* Max time allowed for server to respond to a ping (via any message) */
reconnectWaitMillis: 1000, /* Time to wait after socket closed before attempting reconnect */
- chunkedRequestPvsCount: 400, /* Max number of PVs to transmit in a chunked monitor or clear command; 0 to disable chunking */
+ chunkedRequestMaxBytes: 8000, /* Max number of bytes to transmit in a chunked monitor or clear command; 0 to disable chunking. Tomcat default server-side is usually 8KB */
clientName: window.location.href /* Client name is a string used for informational/debugging purposes (appears in console) */
};
@@ -228,12 +228,64 @@ jlab.epics2web.ClientConnection = function (options) {
}
};
+ // JSON Stringify may escape characters with backslash or encode with UNICODE escapes, so we must stringify first.
+ // Stringify adds double quotes that surround String too (2 more bytes)
+ this.getJSONByteSize = function(str) {
+ return new TextEncoder().encode(JSON.stringify(str)).length;
+ }
+
+ this.chunkJSONStringArray = function(strArray, maxBytes) {
+ if (!strArray || strArray.length === 0) {
+ return [];
+ }
+
+ if(maxBytes < 0) {
+ throw new Error('maxBytes must be greater than 0');
+ }
+
+ const result = [];
+ const delimiterBytes = 1; // Comma delimiter prefix before all but first item
+ let currentChunk = [];
+ let currentByteSize = 0;
+
+ for (const str of strArray) {
+ const stringByteSize = this.getJSONByteSize(str);
+
+ const newChunkSize = currentByteSize + stringByteSize + (currentChunk.length > 0 ? delimiterBytes : 0);
+
+ if(currentChunk.length === 0 && newChunkSize > maxBytes) {
+ throw new Error('Single item larger than maxBytes: ' + str + ' has byte size: ' + stringByteSize);
+ }
+
+ if (newChunkSize > maxBytes && currentChunk.length > 0) {
+ // Current chunk would be too big, so save it and start a new one.
+ result.push(currentChunk);
+ currentChunk = [str];
+ currentByteSize = stringByteSize;
+ } else {
+ // Add the string to the current chunk.
+ currentChunk.push(str);
+ currentByteSize += stringByteSize;
+ if (currentChunk.length > 1) {
+ currentByteSize += delimiterBytes;
+ }
+ }
+ }
+
+ // Add the last chunk if it's not empty.
+ if (currentChunk.length > 0) {
+ result.push(currentChunk);
+ }
+
+ return result;
+ };
+
this.monitorPvs = function (pvs) {
- if (self.chunkedRequestPvsCount > 0) {
- var i, j, chunk;
- for (i = 0, j = pvs.length; i < j; i += self.chunkedRequestPvsCount) {
- chunk = pvs.slice(i, i + self.chunkedRequestPvsCount);
- this.monitorPvsChunk(chunk);
+ if (self.chunkedRequestMaxBytes > 0) {
+ var maxBytesPerChunk = self.chunkedRequestMaxBytes - 27; // String JSON message '{"type":"monitor","pvs":[]}' with empty pvs is 27 bytes.
+ var chunks = this.chunkJSONStringArray(pvs, maxBytesPerChunk);
+ for (let i = 0; i < chunks.length; i++) {
+ this.monitorPvsChunk(chunks[i]);
}
} else {
this.monitorPvsChunk(pvs);
@@ -246,11 +298,11 @@ jlab.epics2web.ClientConnection = function (options) {
};
this.clearPvs = function (pvs) {
- if (self.chunkedRequestPvsCount > 0) {
- var i, j, chunk;
- for (i = 0, j = pvs.length; i < j; i += self.chunkedRequestPvsCount) {
- chunk = pvs.slice(i, i + self.chunkedRequestPvsCount);
- this.clearPvsChunk(chunk);
+ if (self.chunkedRequestMaxBytes > 0) {
+ var maxBytesPerChunk = self.chunkedRequestMaxBytes - 25; // String JSON message '{"type":"clear","pvs":[]}' with empty pvs is 25 bytes.
+ var chunks = this.chunkJSONStringArray(pvs, maxBytesPerChunk);
+ for (let i = 0; i < chunks.length; i++) {
+ this.clearPvsChunk(chunks[i]);
}
} else {
this.clearPvsChunk(pvs);